Come up with sillier names for the binaries

I'm not entirely sure, but it looks like some people might not like
jokes about the Holocaust.

On a more serious note, the project has become more serious over
the 7 or so years of its existence.

1 files changed, 4079 insertions, 0 deletions

diff --git a/xD.c b/xD.c
new file mode 100644
index 0000000..5e8d6a9
--- /dev/null
+++ b/xD.c
@@ -0,0 +1,4079 @@
+/*
+ * xD.c: an IRC daemon
+ *
+ * Copyright (c) 2014 - 2020, Přemysl Eric Janouch <p@janouch.name>
+ *
+ * Permission to use, copy, modify, and/or distribute this software for any
+ * purpose with or without fee is hereby granted.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
+ * SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
+ * OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
+ * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ *
+ */
+
+#include "config.h"
+#define PROGRAM_NAME "xD"
+
+#define WANT_SYSLOG_LOGGING
+#include "common.c"
+#include "xD-replies.c"
+#include <nl_types.h>
+
+enum { PIPE_READ, PIPE_WRITE };
+
+// FIXME: don't use time_t to compute time deltas
+
+// --- Configuration (application-specific) ------------------------------------
+
+// Just get rid of the crappiest ciphers available by default
+#define DEFAULT_CIPHERS "DEFAULT:!MEDIUM:!LOW"
+
+static struct simple_config_item g_config_table[] =
+{
+	{ "pid_file",        NULL,              "Path or name of the PID file"   },
+	{ "server_name",     NULL,              "Server name"                    },
+	{ "server_info",     "My server",       "Brief server description"       },
+	{ "motd",            NULL,              "MOTD filename"                  },
+	{ "catalog",         NULL,              "catgets localization catalog"   },
+
+	{ "bind_host",       NULL,              "Address of the IRC server"      },
+	{ "bind_port",       "6667",            "Port of the IRC server"         },
+	{ "tls_cert",        NULL,              "Server TLS certificate (PEM)"   },
+	{ "tls_key",         NULL,              "Server TLS private key (PEM)"   },
+	{ "tls_ciphers",     DEFAULT_CIPHERS,   "OpenSSL cipher list"            },
+
+	{ "operators",       NULL, "IRCop TLS client cert. SHA-1 fingerprints"   },
+
+	{ "max_connections", "0",               "Global connection limit"        },
+	{ "ping_interval",   "180",             "Interval between PINGs (sec)"   },
+	{ NULL,              NULL,              NULL                             }
+};
+
+// --- Signals -----------------------------------------------------------------
+
+static int g_signal_pipe[2];            ///< A pipe used to signal... signals
+
+/// Program termination has been requested by a signal
+static volatile sig_atomic_t g_termination_requested;
+
+static void
+sigterm_handler (int signum)
+{
+	(void) signum;
+
+	g_termination_requested = true;
+
+	int original_errno = errno;
+	if (write (g_signal_pipe[1], "t", 1) == -1)
+		soft_assert (errno == EAGAIN);
+	errno = original_errno;
+}
+
+static void
+setup_signal_handlers (void)
+{
+	if (pipe (g_signal_pipe) == -1)
+		exit_fatal ("%s: %s", "pipe", strerror (errno));
+
+	set_cloexec (g_signal_pipe[0]);
+	set_cloexec (g_signal_pipe[1]);
+
+	// So that the pipe cannot overflow; it would make write() block within
+	// the signal handler, which is something we really don't want to happen.
+	// The same holds true for read().
+	set_blocking (g_signal_pipe[0], false);
+	set_blocking (g_signal_pipe[1], false);
+
+	signal (SIGPIPE, SIG_IGN);
+
+	struct sigaction sa;
+	sa.sa_flags = SA_RESTART;
+	sigemptyset (&sa.sa_mask);
+	sa.sa_handler = sigterm_handler;
+	if (sigaction (SIGINT, &sa, NULL) == -1
+	 || sigaction (SIGTERM, &sa, NULL) == -1)
+		exit_fatal ("%s: %s", "sigaction", strerror (errno));
+}
+
+// --- Rate limiter ------------------------------------------------------------
+
+struct flood_detector
+{
+	unsigned interval;                  ///< Interval for the limit
+	unsigned limit;                     ///< Maximum number of events allowed
+
+	time_t *timestamps;                 ///< Timestamps of last events
+	unsigned pos;                       ///< Index of the oldest event
+};
+
+static void
+flood_detector_init (struct flood_detector *self,
+	unsigned interval, unsigned limit)
+{
+	self->interval = interval;
+	self->limit = limit;
+	self->timestamps = xcalloc (limit + 1, sizeof *self->timestamps);
+	self->pos = 0;
+}
+
+static void
+flood_detector_free (struct flood_detector *self)
+{
+	free (self->timestamps);
+}
+
+static bool
+flood_detector_check (struct flood_detector *self)
+{
+	time_t now = time (NULL);
+	self->timestamps[self->pos++] = now;
+	if (self->pos > self->limit)
+		self->pos = 0;
+
+	time_t begin = now - self->interval;
+	size_t count = 0;
+	for (size_t i = 0; i <= self->limit; i++)
+		if (self->timestamps[i] >= begin)
+			count++;
+	return count <= self->limit;
+}
+
+// --- IRC token validation ----------------------------------------------------
+
+// Use the enum only if applicable and a simple boolean isn't sufficient.
+
+enum validation_result
+{
+	VALIDATION_OK,
+	VALIDATION_ERROR_EMPTY,
+	VALIDATION_ERROR_TOO_LONG,
+	VALIDATION_ERROR_INVALID
+};
+
+// Everything as per RFC 2812
+#define IRC_MAX_NICKNAME          9
+#define IRC_MAX_HOSTNAME         63
+#define IRC_MAX_CHANNEL_NAME     50
+#define IRC_MAX_MESSAGE_LENGTH  510
+
+static bool
+irc_regex_match (const char *regex, const char *s)
+{
+	static struct str_map cache;
+	static bool initialized;
+
+	if (!initialized)
+	{
+		cache = regex_cache_make ();
+		initialized = true;
+	}
+
+	struct error *e = NULL;
+	bool result = regex_cache_match (&cache, regex,
+		REG_EXTENDED | REG_NOSUB, s, &e);
+	hard_assert (!e);
+	return result;
+}
+
+static const char *
+irc_validate_to_str (enum validation_result result)
+{
+	switch (result)
+	{
+	case VALIDATION_OK:              return "success";
+	case VALIDATION_ERROR_EMPTY:     return "the value is empty";
+	case VALIDATION_ERROR_INVALID:   return "invalid format";
+	case VALIDATION_ERROR_TOO_LONG:  return "the value is too long";
+	default:                         abort ();
+	}
+}
+
+// Anything to keep it as short as possible
+// "shortname" from RFC 2812 doesn't work how its author thought it would.
+#define SN "[0-9A-Za-z](-*[0-9A-Za-z])*"
+#define N4 "[0-9]{1,3}"
+#define N6 "[0-9ABCDEFabcdef]{1,}"
+
+#define LE "A-Za-z"
+#define SP "][\\\\`_^{|}"
+
+static enum validation_result
+irc_validate_hostname (const char *hostname)
+{
+	if (!*hostname)
+		return VALIDATION_ERROR_EMPTY;
+	if (!irc_regex_match ("^" SN "(\\." SN ")*$", hostname))
+		return VALIDATION_ERROR_INVALID;
+	if (strlen (hostname) > IRC_MAX_HOSTNAME)
+		return VALIDATION_ERROR_TOO_LONG;
+	return VALIDATION_OK;
+}
+
+static bool
+irc_is_valid_hostaddr (const char *hostaddr)
+{
+	if (irc_regex_match ("^" N4 "\\." N4 "\\." N4 "\\." N4 "$", hostaddr)
+	 || irc_regex_match ("^" N6 ":" N6 ":" N6 ":" N6 ":"
+		N6 ":" N6 ":" N6 ":" N6 "$", hostaddr)
+	 || irc_regex_match ("^0:0:0:0:0:(0|[Ff]{4}):"
+		N4 "\\." N4 "\\." N4 "\\." N4 "$", hostaddr))
+		return true;
+	return false;
+}
+
+// TODO: we should actually use this, though what should we do on failure?
+static bool
+irc_is_valid_host (const char *host)
+{
+	return irc_validate_hostname (host) == VALIDATION_OK
+		|| irc_is_valid_hostaddr (host);
+}
+
+// TODO: currently, we are almost encoding-agnostic (strings just need to be
+// ASCII-compatible).  We should at least have an option to enforce a specific
+// encoding, such as UTF-8.  Note that with Unicode we should not allow all
+// character clasess and exclude the likes of \pM with the goal of enforcing
+// NFC-normalized identifiers--utf8proc is a good candidate library to handle
+// the categorization and validation.
+
+static bool
+irc_is_valid_user (const char *user)
+{
+	return irc_regex_match ("^[^\r\n @]+$", user);
+}
+
+static bool
+irc_validate_nickname (const char *nickname)
+{
+	if (!*nickname)
+		return VALIDATION_ERROR_EMPTY;
+	if (!irc_regex_match ("^[" SP LE "][" SP LE "0-9-]*$", nickname))
+		return VALIDATION_ERROR_INVALID;
+	if (strlen (nickname) > IRC_MAX_NICKNAME)
+		return VALIDATION_ERROR_TOO_LONG;
+	return VALIDATION_OK;
+}
+
+static enum validation_result
+irc_validate_channel_name (const char *channel_name)
+{
+	if (!*channel_name)
+		return VALIDATION_ERROR_EMPTY;
+	if (*channel_name != '#' || strpbrk (channel_name, "\7\r\n ,:"))
+		return VALIDATION_ERROR_INVALID;
+	if (strlen (channel_name) > IRC_MAX_CHANNEL_NAME)
+		return VALIDATION_ERROR_TOO_LONG;
+	return VALIDATION_OK;
+}
+
+static bool
+irc_is_valid_key (const char *key)
+{
+	// XXX: should be 7-bit as well but whatever
+	return irc_regex_match ("^[^\r\n\f\t\v ]{1,23}$", key);
+}
+
+#undef SN
+#undef N4
+#undef N6
+
+#undef LE
+#undef SP
+
+static bool
+irc_is_valid_user_mask (const char *mask)
+{
+	return irc_regex_match ("^[^!@]+![^!@]+@[^@!]+$", mask);
+}
+
+static bool
+irc_is_valid_fingerprint (const char *fp)
+{
+	return irc_regex_match ("^[a-fA-F0-9]{40}$", fp);
+}
+
+// --- Clients (equals users) --------------------------------------------------
+
+#define IRC_SUPPORTED_USER_MODES "aiwros"
+
+enum
+{
+	IRC_USER_MODE_INVISIBLE          = (1 << 0),
+	IRC_USER_MODE_RX_WALLOPS         = (1 << 1),
+	IRC_USER_MODE_RESTRICTED         = (1 << 2),
+	IRC_USER_MODE_OPERATOR           = (1 << 3),
+	IRC_USER_MODE_RX_SERVER_NOTICES  = (1 << 4)
+};
+
+enum
+{
+	IRC_CAP_MULTI_PREFIX             = (1 << 0),
+	IRC_CAP_INVITE_NOTIFY            = (1 << 1),
+	IRC_CAP_ECHO_MESSAGE             = (1 << 2),
+	IRC_CAP_USERHOST_IN_NAMES        = (1 << 3),
+	IRC_CAP_SERVER_TIME              = (1 << 4)
+};
+
+struct client
+{
+	LIST_HEADER (struct client)
+	struct server_context *ctx;         ///< Server context
+
+	time_t opened;                      ///< When the connection was opened
+	size_t n_sent_messages;             ///< Number of sent messages total
+	size_t sent_bytes;                  ///< Number of sent bytes total
+	size_t n_received_messages;         ///< Number of received messages total
+	size_t received_bytes;              ///< Number of received bytes total
+
+	int socket_fd;                      ///< The TCP socket
+	struct str read_buffer;             ///< Unprocessed input
+	struct str write_buffer;            ///< Output yet to be sent out
+
+	struct poller_fd socket_event;      ///< The socket can be read/written to
+	struct poller_timer ping_timer;     ///< We should send a ping
+	struct poller_timer timeout_timer;  ///< Connection seems to be dead
+	struct poller_timer kill_timer;     ///< Hard kill timeout
+
+	unsigned long cap_version;          ///< CAP protocol version
+	unsigned caps_enabled;              ///< Enabled capabilities
+
+	unsigned initialized     : 1;       ///< Has any data been received yet?
+	unsigned cap_negotiating : 1;       ///< Negotiating capabilities
+	unsigned registered      : 1;       ///< The user has registered
+	unsigned closing_link    : 1;       ///< Closing link
+	unsigned half_closed     : 1;       ///< Closing link: conn. is half-closed
+
+	unsigned ssl_rx_want_tx  : 1;       ///< SSL_read() wants to write
+	unsigned ssl_tx_want_rx  : 1;       ///< SSL_write() wants to read
+	SSL *ssl;                           ///< SSL connection
+	char *ssl_cert_fingerprint;         ///< Client certificate fingerprint
+
+	char *nickname;                     ///< IRC nickname (main identifier)
+	char *username;                     ///< IRC username
+	char *realname;                     ///< IRC realname (e-mail)
+
+	char *hostname;                     ///< Hostname shown to the network
+	char *port;                         ///< Port of the peer as a string
+	char *address;                      ///< Full address
+
+	unsigned mode;                      ///< User's mode
+	char *away_message;                 ///< Away message
+	time_t last_active;                 ///< Last PRIVMSG, to get idle time
+	struct str_map invites;             ///< Channel invitations by operators
+	struct flood_detector antiflood;    ///< Flood detector
+
+	struct async_getnameinfo *gni;      ///< Backwards DNS resolution
+	struct poller_timer gni_timer;      ///< Backwards DNS resolution timeout
+};
+
+static struct client *
+client_new (void)
+{
+	struct client *self = xcalloc (1, sizeof *self);
+	self->socket_fd = -1;
+	self->read_buffer = str_make ();
+	self->write_buffer = str_make ();
+	self->cap_version = 301;
+	// TODO: make this configurable and more fine-grained
+	flood_detector_init (&self->antiflood, 10, 20);
+	self->invites = str_map_make (NULL);
+	self->invites.key_xfrm = irc_strxfrm;
+	return self;
+}
+
+static void
+client_destroy (struct client *self)
+{
+	if (!soft_assert (self->socket_fd == -1))
+		xclose (self->socket_fd);
+	if (self->ssl)
+		SSL_free (self->ssl);
+
+	str_free (&self->read_buffer);
+	str_free (&self->write_buffer);
+	free (self->ssl_cert_fingerprint);
+
+	free (self->nickname);
+	free (self->username);
+	free (self->realname);
+
+	free (self->hostname);
+	free (self->port);
+	free (self->address);
+
+	free (self->away_message);
+	flood_detector_free (&self->antiflood);
+	str_map_free (&self->invites);
+
+	if (self->gni)
+		async_cancel (&self->gni->async);
+	free (self);
+}
+
+static void client_close_link (struct client *c, const char *reason);
+static void client_kill (struct client *c, const char *reason);
+static void client_send (struct client *, const char *, ...)
+	ATTRIBUTE_PRINTF (2, 3);
+static void client_cancel_timers (struct client *);
+static void client_set_kill_timer (struct client *);
+static void client_update_poller (struct client *, const struct pollfd *);
+
+// --- Channels ----------------------------------------------------------------
+
+#define IRC_SUPPORTED_CHAN_MODES "ov" "beI" "imnqpst" "kl"
+
+enum
+{
+	IRC_CHAN_MODE_INVITE_ONLY      = (1 << 0),
+	IRC_CHAN_MODE_MODERATED        = (1 << 1),
+	IRC_CHAN_MODE_NO_OUTSIDE_MSGS  = (1 << 2),
+	IRC_CHAN_MODE_QUIET            = (1 << 3),
+	IRC_CHAN_MODE_PRIVATE          = (1 << 4),
+	IRC_CHAN_MODE_SECRET           = (1 << 5),
+	IRC_CHAN_MODE_PROTECTED_TOPIC  = (1 << 6),
+
+	IRC_CHAN_MODE_OPERATOR         = (1 << 7),
+	IRC_CHAN_MODE_VOICE            = (1 << 8)
+};
+
+struct channel_user
+{
+	LIST_HEADER (struct channel_user)
+
+	unsigned modes;
+	struct client *c;
+};
+
+struct channel
+{
+	struct server_context *ctx;         ///< Server context
+
+	char *name;                         ///< Channel name
+	unsigned modes;                     ///< Channel modes
+	char *key;                          ///< Channel key
+	long user_limit;                    ///< User limit or -1
+	time_t created;                     ///< Creation time
+
+	char *topic;                        ///< Channel topic
+	char *topic_who;                    ///< Who set the topic
+	time_t topic_time;                  ///< When the topic was set
+
+	struct channel_user *users;         ///< Channel users
+
+	struct strv ban_list;               ///< Ban list
+	struct strv exception_list;         ///< Exceptions from bans
+	struct strv invite_list;            ///< Exceptions from +I
+};
+
+static struct channel *
+channel_new (void)
+{
+	struct channel *self = xcalloc (1, sizeof *self);
+
+	self->user_limit = -1;
+	self->topic = xstrdup ("");
+
+	self->ban_list = strv_make ();
+	self->exception_list = strv_make ();
+	self->invite_list = strv_make ();
+	return self;
+}
+
+static void
+channel_delete (struct channel *self)
+{
+	free (self->name);
+	free (self->key);
+	free (self->topic);
+	free (self->topic_who);
+
+	struct channel_user *link, *tmp;
+	for (link = self->users; link; link = tmp)
+	{
+		tmp = link->next;
+		free (link);
+	}
+
+	strv_free (&self->ban_list);
+	strv_free (&self->exception_list);
+	strv_free (&self->invite_list);
+
+	free (self);
+}
+
+static char *
+channel_get_mode (struct channel *self, bool disclose_secrets)
+{
+	struct str mode = str_make ();
+	unsigned m = self->modes;
+	if (m & IRC_CHAN_MODE_INVITE_ONLY)      str_append_c (&mode, 'i');
+	if (m & IRC_CHAN_MODE_MODERATED)        str_append_c (&mode, 'm');
+	if (m & IRC_CHAN_MODE_NO_OUTSIDE_MSGS)  str_append_c (&mode, 'n');
+	if (m & IRC_CHAN_MODE_QUIET)            str_append_c (&mode, 'q');
+	if (m & IRC_CHAN_MODE_PRIVATE)          str_append_c (&mode, 'p');
+	if (m & IRC_CHAN_MODE_SECRET)           str_append_c (&mode, 's');
+	if (m & IRC_CHAN_MODE_PROTECTED_TOPIC)  str_append_c (&mode, 't');
+
+	if (self->user_limit != -1)             str_append_c (&mode, 'l');
+	if (self->key)                          str_append_c (&mode, 'k');
+
+	// XXX: is it correct to split it?  Try it on an existing implementation.
+	if (disclose_secrets)
+	{
+		if (self->user_limit != -1)
+			str_append_printf (&mode, " %ld", self->user_limit);
+		if (self->key)
+			str_append_printf (&mode, " %s", self->key);
+	}
+	return str_steal (&mode);
+}
+
+static struct channel_user *
+channel_get_user (const struct channel *chan, const struct client *c)
+{
+	for (struct channel_user *iter = chan->users; iter; iter = iter->next)
+		if (iter->c == c)
+			return iter;
+	return NULL;
+}
+
+static struct channel_user *
+channel_add_user (struct channel *chan, struct client *c)
+{
+	struct channel_user *link = xcalloc (1, sizeof *link);
+	link->c = c;
+	LIST_PREPEND (chan->users, link);
+	return link;
+}
+
+static void
+channel_remove_user (struct channel *chan, struct channel_user *user)
+{
+	LIST_UNLINK (chan->users, user);
+	free (user);
+}
+
+static size_t
+channel_user_count (const struct channel *chan)
+{
+	size_t result = 0;
+	for (struct channel_user *iter = chan->users; iter; iter = iter->next)
+		result++;
+	return result;
+}
+
+// --- IRC server context ------------------------------------------------------
+
+struct whowas_info
+{
+	char *nickname;                     ///< IRC nickname
+	char *username;                     ///< IRC username
+	char *realname;                     ///< IRC realname
+	char *hostname;                     ///< Hostname shown to the network
+};
+
+struct whowas_info *
+whowas_info_new (struct client *c)
+{
+	struct whowas_info *self = xmalloc (sizeof *self);
+	self->nickname = xstrdup (c->nickname);
+	self->username = xstrdup (c->username);
+	self->realname = xstrdup (c->realname);
+	self->hostname = xstrdup (c->hostname);
+	return self;
+}
+
+static void
+whowas_info_destroy (struct whowas_info *self)
+{
+	free (self->nickname);
+	free (self->username);
+	free (self->realname);
+	free (self->hostname);
+	free (self);
+}
+
+// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+
+struct irc_command
+{
+	const char *name;
+	bool requires_registration;
+	void (*handler) (const struct irc_message *, struct client *);
+
+	size_t n_received;                  ///< Number of commands received
+	size_t bytes_received;              ///< Number of bytes received total
+};
+
+struct server_context
+{
+	int *listen_fds;                    ///< Listening socket FD's
+	struct poller_fd *listen_events;    ///< New connections available
+	size_t listen_len;                  ///< Number of listening sockets
+	size_t listen_alloc;                ///< How many we've allocated
+
+	time_t started;                     ///< When has the server been started
+
+	SSL_CTX *ssl_ctx;                   ///< SSL context
+	struct client *clients;             ///< Clients
+	unsigned n_clients;                 ///< Current number of connections
+
+	struct str_map users;               ///< Maps nicknames to clients
+	struct str_map channels;            ///< Maps channel names to data
+	struct str_map handlers;            ///< Message handlers
+	struct str_map cap_handlers;        ///< CAP message handlers
+
+	struct str_map whowas;              ///< WHOWAS registry
+
+	struct poller poller;               ///< Manages polled description
+	struct poller_timer quit_timer;     ///< Quit timeout timer
+	bool quitting;                      ///< User requested quitting
+	bool polling;                       ///< The event loop is running
+
+	struct poller_fd signal_event;      ///< Got a signal
+
+	struct str_map config;              ///< Server configuration
+	char *server_name;                  ///< Our server name
+	unsigned ping_interval;             ///< Ping interval in seconds
+	unsigned max_connections;           ///< Max. connections allowed or 0
+	struct strv motd;                   ///< MOTD (none if empty)
+	nl_catd catalog;                    ///< Message catalog for server msgs
+	struct str_map operators;           ///< TLS cert. fingerprints for IRCops
+};
+
+static void
+on_irc_quit_timeout (void *user_data)
+{
+	struct server_context *ctx = user_data;
+	struct client *iter, *next;
+	for (iter = ctx->clients; iter; iter = next)
+	{
+		next = iter->next;
+		// irc_initiate_quit() has already unregistered the client
+		client_kill (iter, "Shutting down");
+	}
+}
+
+static void
+server_context_init (struct server_context *self)
+{
+	memset (self, 0, sizeof *self);
+
+	self->users = str_map_make (NULL);
+	self->users.key_xfrm = irc_strxfrm;
+	self->channels = str_map_make ((str_map_free_fn) channel_delete);
+	self->channels.key_xfrm = irc_strxfrm;
+	self->handlers = str_map_make (NULL);
+	self->handlers.key_xfrm = irc_strxfrm;
+	self->cap_handlers = str_map_make (NULL);
+	self->cap_handlers.key_xfrm = irc_strxfrm;
+
+	self->whowas = str_map_make ((str_map_free_fn) whowas_info_destroy);
+	self->whowas.key_xfrm = irc_strxfrm;
+
+	poller_init (&self->poller);
+	self->quit_timer = poller_timer_make (&self->poller);
+	self->quit_timer.dispatcher = on_irc_quit_timeout;
+	self->quit_timer.user_data = self;
+
+	self->config = str_map_make (free);
+	simple_config_load_defaults (&self->config, g_config_table);
+
+	self->motd = strv_make ();
+	self->catalog = (nl_catd) -1;
+	self->operators = str_map_make (NULL);
+	// The regular irc_strxfrm() is sufficient for fingerprints
+	self->operators.key_xfrm = irc_strxfrm;
+}
+
+static void
+server_context_free (struct server_context *self)
+{
+	str_map_free (&self->config);
+
+	for (size_t i = 0; i < self->listen_len; i++)
+	{
+		poller_fd_reset (&self->listen_events[i]);
+		xclose (self->listen_fds[i]);
+	}
+	free (self->listen_fds);
+	free (self->listen_events);
+
+	hard_assert (!self->clients);
+	if (self->ssl_ctx)
+		SSL_CTX_free (self->ssl_ctx);
+
+	free (self->server_name);
+	str_map_free (&self->users);
+	str_map_free (&self->channels);
+	str_map_free (&self->handlers);
+	str_map_free (&self->cap_handlers);
+	str_map_free (&self->whowas);
+	poller_free (&self->poller);
+
+	strv_free (&self->motd);
+	if (self->catalog != (nl_catd) -1)
+		catclose (self->catalog);
+	str_map_free (&self->operators);
+}
+
+static const char *
+irc_get_text (struct server_context *ctx, int id, const char *def)
+{
+	if (!soft_assert (def != NULL))
+		def = "";
+	if (ctx->catalog == (nl_catd) -1)
+		return def;
+	return catgets (ctx->catalog, 1, id, def);
+}
+
+static void
+irc_try_finish_quit (struct server_context *ctx)
+{
+	if (!ctx->n_clients && ctx->quitting)
+	{
+		poller_timer_reset (&ctx->quit_timer);
+		ctx->polling = false;
+	}
+}
+
+static void
+irc_initiate_quit (struct server_context *ctx)
+{
+	print_status ("shutting down");
+
+	for (size_t i = 0; i < ctx->listen_len; i++)
+	{
+		poller_fd_reset (&ctx->listen_events[i]);
+		xclose (ctx->listen_fds[i]);
+	}
+	ctx->listen_len = 0;
+
+	for (struct client *iter = ctx->clients; iter; iter = iter->next)
+		if (!iter->closing_link)
+			client_close_link (iter, "Shutting down");
+
+	ctx->quitting = true;
+	poller_timer_set (&ctx->quit_timer, 5000);
+	irc_try_finish_quit (ctx);
+}
+
+static struct channel *
+irc_channel_create (struct server_context *ctx, const char *name)
+{
+	struct channel *chan = channel_new ();
+	chan->ctx = ctx;
+	chan->name = xstrdup (name);
+	chan->created = time (NULL);
+	str_map_set (&ctx->channels, name, chan);
+	return chan;
+}
+
+static void
+irc_channel_destroy_if_empty (struct server_context *ctx, struct channel *chan)
+{
+	if (!chan->users)
+		str_map_set (&ctx->channels, chan->name, NULL);
+}
+
+static void
+irc_send_to_roommates (struct client *c, const char *message)
+{
+	struct str_map targets = str_map_make (NULL);
+	targets.key_xfrm = irc_strxfrm;
+
+	struct str_map_iter iter = str_map_iter_make (&c->ctx->channels);
+	struct channel *chan;
+	while ((chan = str_map_iter_next (&iter)))
+	{
+		if (chan->modes & IRC_CHAN_MODE_QUIET
+		 || !channel_get_user (chan, c))
+			continue;
+		for (struct channel_user *iter = chan->users; iter; iter = iter->next)
+			str_map_set (&targets, iter->c->nickname, iter->c);
+	}
+
+	iter = str_map_iter_make (&targets);
+	struct client *target;
+	while ((target = str_map_iter_next (&iter)))
+		if (target != c)
+			client_send (target, "%s", message);
+	str_map_free (&targets);
+}
+
+// --- Clients (continued) -----------------------------------------------------
+
+static void
+client_mode_to_str (unsigned m, struct str *out)
+{
+	if (m & IRC_USER_MODE_INVISIBLE)           str_append_c (out, 'i');
+	if (m & IRC_USER_MODE_RX_WALLOPS)          str_append_c (out, 'w');
+	if (m & IRC_USER_MODE_RESTRICTED)          str_append_c (out, 'r');
+	if (m & IRC_USER_MODE_OPERATOR)            str_append_c (out, 'o');
+	if (m & IRC_USER_MODE_RX_SERVER_NOTICES)   str_append_c (out, 's');
+}
+
+static char *
+client_get_mode (struct client *self)
+{
+	struct str mode = str_make ();
+	if (self->away_message)
+		str_append_c (&mode, 'a');
+	client_mode_to_str (self->mode, &mode);
+	return str_steal (&mode);
+}
+
+static void
+client_send_str (struct client *c, const struct str *s)
+{
+	hard_assert (!c->closing_link);
+
+	size_t old_sendq = c->write_buffer.len;
+
+	// So far there's only one message tag we use, so we can do it simple;
+	// note that a 1024-character limit applies to messages with tags on
+	if (c->caps_enabled & IRC_CAP_SERVER_TIME)
+	{
+		long milliseconds; char buf[32]; struct tm tm;
+		time_t now = unixtime_msec (&milliseconds);
+		if (soft_assert (strftime (buf, sizeof buf,
+			"%Y-%m-%dT%T", gmtime_r (&now, &tm))))
+			str_append_printf (&c->write_buffer,
+				"@time=%s.%03ldZ ", buf, milliseconds);
+	}
+
+	// TODO: kill the connection above some "SendQ" threshold (careful!)
+	str_append_data (&c->write_buffer, s->str,
+		MIN (s->len, IRC_MAX_MESSAGE_LENGTH));
+	str_append (&c->write_buffer, "\r\n");
+	// XXX: we might want to move this elsewhere, so that it doesn't get called
+	//   as often; it's going to cause a lot of syscalls with epoll.
+	client_update_poller (c, NULL);
+
+	// Technically we haven't sent it yet but that's a minor detail
+	c->n_sent_messages++;
+	c->sent_bytes += c->write_buffer.len - old_sendq;
+}
+
+static void
+client_send (struct client *c, const char *format, ...)
+{
+	struct str tmp = str_make ();
+
+	va_list ap;
+	va_start (ap, format);
+	str_append_vprintf (&tmp, format, ap);
+	va_end (ap);
+
+	client_send_str (c, &tmp);
+	str_free (&tmp);
+}
+
+static void
+client_add_to_whowas (struct client *c)
+{
+	// Only keeping one entry for each nickname
+	// TODO: make sure this list doesn't get too long, for example by
+	//   putting them in a linked list ordered by time
+	str_map_set (&c->ctx->whowas, c->nickname, whowas_info_new (c));
+}
+
+static void
+client_unregister (struct client *c, const char *reason)
+{
+	if (!c->registered)
+		return;
+
+	char *message = xstrdup_printf (":%s!%s@%s QUIT :%s",
+		c->nickname, c->username, c->hostname, reason);
+	irc_send_to_roommates (c, message);
+	free (message);
+
+	struct str_map_unset_iter iter =
+		str_map_unset_iter_make (&c->ctx->channels);
+	struct channel *chan;
+	while ((chan = str_map_unset_iter_next (&iter)))
+	{
+		struct channel_user *user;
+		if (!(user = channel_get_user (chan, c)))
+			continue;
+		channel_remove_user (chan, user);
+		irc_channel_destroy_if_empty (c->ctx, chan);
+	}
+	str_map_unset_iter_free (&iter);
+
+	client_add_to_whowas (c);
+
+	str_map_set (&c->ctx->users, c->nickname, NULL);
+	cstr_set (&c->nickname, NULL);
+	c->registered = false;
+}
+
+static void
+client_kill (struct client *c, const char *reason)
+{
+	struct server_context *ctx = c->ctx;
+	client_unregister (c, reason ? reason : "Client exited");
+
+	if (c->address)
+		// Only log the event if address resolution has finished
+		print_debug ("closed connection to %s (%s)", c->address,
+			reason ? reason : "");
+
+	if (c->ssl)
+		// Note that we might have already called this once, but that is fine
+		(void) SSL_shutdown (c->ssl);
+
+	xclose (c->socket_fd);
+	c->socket_fd = -1;
+
+	// We don't fork any children, this is okay
+	c->socket_event.closed = true;
+	poller_fd_reset (&c->socket_event);
+	client_cancel_timers (c);
+
+	LIST_UNLINK (ctx->clients, c);
+	ctx->n_clients--;
+	client_destroy (c);
+
+	irc_try_finish_quit (ctx);
+}
+
+static void
+client_close_link (struct client *c, const char *reason)
+{
+	// Let's just cut the connection, the client can try again later.
+	// We also want to avoid accidentally setting poller events before
+	// address resolution has finished.
+	if (!c->initialized)
+	{
+		client_kill (c, reason);
+		return;
+	}
+	if (!soft_assert (!c->closing_link))
+		return;
+
+	// We push an `ERROR' message to the write buffer and let the poller send
+	// it, with some arbitrary timeout.  The `closing_link' state makes sure
+	// that a/ we ignore any successive messages, and b/ that the connection
+	// is killed after the write buffer is transferred and emptied.
+	client_send (c, "ERROR :Closing Link: %s[%s] (%s)",
+		c->nickname ? c->nickname : "*",
+		c->hostname /* TODO host IP? */, reason);
+	c->closing_link = true;
+
+	client_unregister (c, reason);
+	client_set_kill_timer (c);
+}
+
+static bool
+client_in_mask_list (const struct client *c, const struct strv *mask)
+{
+	char *client = xstrdup_printf ("%s!%s@%s",
+		c->nickname, c->username, c->hostname);
+	bool result = false;
+	for (size_t i = 0; i < mask->len; i++)
+		if (!irc_fnmatch (mask->vector[i], client))
+		{
+			result = true;
+			break;
+		}
+	free (client);
+	return result;
+}
+
+static char *
+client_get_ssl_cert_fingerprint (struct client *c)
+{
+	if (!c->ssl)
+		return NULL;
+
+	X509 *peer_cert = SSL_get_peer_certificate (c->ssl);
+	if (!peer_cert)
+		return NULL;
+
+	int cert_len = i2d_X509 (peer_cert, NULL);
+	if (cert_len < 0)
+		return NULL;
+
+	unsigned char cert[cert_len], *p = cert;
+	if (i2d_X509 (peer_cert, &p) < 0)
+		return NULL;
+
+	unsigned char hash[SHA_DIGEST_LENGTH];
+	SHA1 (cert, cert_len, hash);
+
+	struct str fingerprint = str_make ();
+	for (size_t i = 0; i < sizeof hash; i++)
+		str_append_printf (&fingerprint, "%02x", hash[i]);
+	return str_steal (&fingerprint);
+}
+
+// --- Timers ------------------------------------------------------------------
+
+static void
+client_cancel_timers (struct client *c)
+{
+	poller_timer_reset (&c->kill_timer);
+	poller_timer_reset (&c->timeout_timer);
+	poller_timer_reset (&c->ping_timer);
+	poller_timer_reset (&c->gni_timer);
+}
+
+static void
+client_set_timer (struct client *c,
+	struct poller_timer *timer, unsigned interval)
+{
+	client_cancel_timers (c);
+	poller_timer_set (timer, interval * 1000);
+}
+
+static void
+on_client_kill_timer (struct client *c)
+{
+	hard_assert (!c->initialized || c->closing_link);
+	client_kill (c, NULL);
+}
+
+static void
+client_set_kill_timer (struct client *c)
+{
+	client_set_timer (c, &c->kill_timer, c->ctx->ping_interval);
+}
+
+static void
+on_client_timeout_timer (struct client *c)
+{
+	char *reason = xstrdup_printf
+		("Ping timeout: >%u seconds", c->ctx->ping_interval);
+	client_close_link (c, reason);
+	free (reason);
+}
+
+static void
+on_client_ping_timer (struct client *c)
+{
+	hard_assert (!c->closing_link);
+	client_send (c, "PING :%s", c->ctx->server_name);
+	client_set_timer (c, &c->timeout_timer, c->ctx->ping_interval);
+}
+
+static void
+client_set_ping_timer (struct client *c)
+{
+	client_set_timer (c, &c->ping_timer, c->ctx->ping_interval);
+}
+
+// --- IRC command handling ----------------------------------------------------
+
+static void
+irc_make_reply (struct client *c, int id, va_list ap, struct str *output)
+{
+	str_append_printf (output, ":%s %03d %s ",
+		c->ctx->server_name, id, c->nickname ? c->nickname : "*");
+	str_append_vprintf (output,
+		irc_get_text (c->ctx, id, g_default_replies[id]), ap);
+}
+
+// XXX: this way we cannot typecheck the arguments, so we must be careful
+static void
+irc_send_reply (struct client *c, int id, ...)
+{
+	struct str reply = str_make ();
+
+	va_list ap;
+	va_start (ap, id);
+	irc_make_reply (c, id, ap, &reply);
+	va_end (ap);
+
+	client_send_str (c, &reply);
+	str_free (&reply);
+}
+
+/// Send a space-separated list of words across as many replies as needed
+static void
+irc_send_reply_vector (struct client *c, int id, char **items, ...)
+{
+	struct str common = str_make ();
+
+	va_list ap;
+	va_start (ap, items);
+	irc_make_reply (c, id, ap, &common);
+	va_end (ap);
+
+	// We always send at least one message (there might be a client that
+	// expects us to send this message at least once)
+	do
+	{
+		struct str reply = str_make ();
+		str_append_str (&reply, &common);
+
+		// If not even a single item fits in the limit (which may happen,
+		// in theory) it just gets cropped.  We could also skip it.
+		if (*items)
+			str_append (&reply, *items++);
+
+		// Append as many items as fits in a single message
+		while (*items
+			&& reply.len + 1 + strlen (*items) <= IRC_MAX_MESSAGE_LENGTH)
+			str_append_printf (&reply, " %s", *items++);
+
+		client_send_str (c, &reply);
+		str_free (&reply);
+	}
+	while (*items);
+	str_free (&common);
+}
+
+#define RETURN_WITH_REPLY(c, ...)                                              \
+	BLOCK_START                                                                \
+		irc_send_reply ((c), __VA_ARGS__);                                     \
+		return;                                                                \
+	BLOCK_END
+
+static void
+irc_send_motd (struct client *c)
+{
+	struct server_context *ctx = c->ctx;
+	if (!ctx->motd.len)
+		RETURN_WITH_REPLY (c, IRC_ERR_NOMOTD);
+
+	irc_send_reply (c, IRC_RPL_MOTDSTART, ctx->server_name);
+	for (size_t i = 0; i < ctx->motd.len; i++)
+		irc_send_reply (c, IRC_RPL_MOTD, ctx->motd.vector[i]);
+	irc_send_reply (c, IRC_RPL_ENDOFMOTD);
+}
+
+static void
+irc_send_lusers (struct client *c)
+{
+	int n_users = 0, n_services = 0, n_opers = 0, n_unknown = 0;
+	for (struct client *link = c->ctx->clients; link; link = link->next)
+	{
+		if (link->registered)
+			n_users++;
+		else
+			n_unknown++;
+		if (link->mode & IRC_USER_MODE_OPERATOR)
+			n_opers++;
+	}
+
+	int n_channels = 0;
+	struct str_map_iter iter = str_map_iter_make (&c->ctx->channels);
+	struct channel *chan;
+	while ((chan = str_map_iter_next (&iter)))
+		if (!(chan->modes & IRC_CHAN_MODE_SECRET)
+		 || channel_get_user (chan, c))
+			n_channels++;
+
+	irc_send_reply (c, IRC_RPL_LUSERCLIENT,
+		n_users, n_services, 1 /* servers total */);
+	if (n_opers)
+		irc_send_reply (c, IRC_RPL_LUSEROP, n_opers);
+	if (n_unknown)
+		irc_send_reply (c, IRC_RPL_LUSERUNKNOWN, n_unknown);
+	if (n_channels)
+		irc_send_reply (c, IRC_RPL_LUSERCHANNELS, n_channels);
+	irc_send_reply (c, IRC_RPL_LUSERME,
+		n_users + n_services + n_unknown, 0 /* peer servers */);
+}
+
+static bool
+irc_is_this_me (struct server_context *ctx, const char *target)
+{
+	// Target servers can also be matched by their users
+	return !irc_fnmatch (target, ctx->server_name)
+		|| str_map_find (&ctx->users, target);
+}
+
+static void
+irc_send_isupport (struct client *c)
+{
+	// Only # channels, +e supported, +I supported, unlimited arguments to MODE
+	irc_send_reply (c, IRC_RPL_ISUPPORT, "CHANTYPES=# EXCEPTS INVEX MODES"
+		" TARGMAX=WHOIS:,LIST:,NAMES:,PRIVMSG:1,NOTICE:1,KICK:"
+		" NICKLEN=" XSTRINGIFY (IRC_MAX_NICKNAME)
+		" CHANNELLEN=" XSTRINGIFY (IRC_MAX_CHANNEL_NAME));
+}
+
+static void
+irc_try_finish_registration (struct client *c)
+{
+	struct server_context *ctx = c->ctx;
+	if (!c->nickname || !c->username || !c->realname)
+		return;
+	if (c->registered || c->cap_negotiating)
+		return;
+
+	c->registered = true;
+	irc_send_reply (c, IRC_RPL_WELCOME, c->nickname, c->username, c->hostname);
+
+	irc_send_reply (c, IRC_RPL_YOURHOST, ctx->server_name, PROGRAM_VERSION);
+	// The purpose of this message eludes me
+	irc_send_reply (c, IRC_RPL_CREATED, __DATE__);
+	irc_send_reply (c, IRC_RPL_MYINFO, ctx->server_name, PROGRAM_VERSION,
+		IRC_SUPPORTED_USER_MODES, IRC_SUPPORTED_CHAN_MODES);
+
+	irc_send_isupport (c);
+	irc_send_lusers (c);
+	irc_send_motd (c);
+
+	char *mode = client_get_mode (c);
+	if (*mode)
+		client_send (c, ":%s MODE %s :+%s", c->nickname, c->nickname, mode);
+	free (mode);
+
+	hard_assert (c->ssl_cert_fingerprint == NULL);
+	if ((c->ssl_cert_fingerprint = client_get_ssl_cert_fingerprint (c)))
+		client_send (c, ":%s NOTICE %s :"
+			"Your TLS client certificate fingerprint is %s",
+			ctx->server_name, c->nickname, c->ssl_cert_fingerprint);
+
+	str_map_set (&ctx->whowas, c->nickname, NULL);
+}
+
+// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+
+// IRCv3 capability negotiation.  See http://ircv3.org for details.
+
+struct irc_cap_args
+{
+	const char *subcommand;             ///< The subcommand being processed
+	const char *full_params;            ///< Whole parameter string
+	struct strv params;                 ///< Split parameters
+	const char *target;                 ///< Target parameter for replies
+};
+
+static struct
+{
+	unsigned flag;                      ///< Flag
+	const char *name;                   ///< Name of the capability
+}
+irc_cap_table[] =
+{
+	{ IRC_CAP_MULTI_PREFIX,             "multi-prefix"      },
+	{ IRC_CAP_INVITE_NOTIFY,            "invite-notify"     },
+	{ IRC_CAP_ECHO_MESSAGE,             "echo-message"      },
+	{ IRC_CAP_USERHOST_IN_NAMES,        "userhost-in-names" },
+	{ IRC_CAP_SERVER_TIME,              "server-time"       },
+};
+
+static void
+irc_handle_cap_ls (struct client *c, struct irc_cap_args *a)
+{
+	if (a->params.len == 1
+	 && !xstrtoul (&c->cap_version, a->params.vector[0], 10))
+		irc_send_reply (c, IRC_ERR_INVALIDCAPCMD,
+			a->subcommand, "Ignoring invalid protocol version number");
+
+	c->cap_negotiating = true;
+	client_send (c, ":%s CAP %s LS :multi-prefix invite-notify echo-message"
+		" userhost-in-names server-time", c->ctx->server_name, a->target);
+}
+
+static void
+irc_handle_cap_list (struct client *c, struct irc_cap_args *a)
+{
+	struct strv caps = strv_make ();
+	for (size_t i = 0; i < N_ELEMENTS (irc_cap_table); i++)
+		if (c->caps_enabled & irc_cap_table[i].flag)
+			strv_append (&caps, irc_cap_table[i].name);
+
+	char *caps_str = strv_join (&caps, " ");
+	strv_free (&caps);
+	client_send (c, ":%s CAP %s LIST :%s",
+		c->ctx->server_name, a->target, caps_str);
+	free (caps_str);
+}
+
+static unsigned
+irc_decode_capability (const char *name)
+{
+	for (size_t i = 0; i < N_ELEMENTS (irc_cap_table); i++)
+		if (!strcmp (irc_cap_table[i].name, name))
+			return irc_cap_table[i].flag;
+	return 0;
+}
+
+static void
+irc_handle_cap_req (struct client *c, struct irc_cap_args *a)
+{
+	c->cap_negotiating = true;
+
+	unsigned new_caps = c->caps_enabled;
+	bool success = true;
+	for (size_t i = 0; i < a->params.len; i++)
+	{
+		bool removing = false;
+		const char *name = a->params.vector[i];
+		if (*name == '-')
+		{
+			removing = true;
+			name++;
+		}
+
+		unsigned cap;
+		if (!(cap = irc_decode_capability (name)))
+			success = false;
+		else if (removing)
+			new_caps &= ~cap;
+		else
+			new_caps |=  cap;
+	}
+
+	if (success)
+	{
+		c->caps_enabled = new_caps;
+		client_send (c, ":%s CAP %s ACK :%s",
+			c->ctx->server_name, a->target, a->full_params);
+	}
+	else
+		client_send (c, ":%s CAP %s NAK :%s",
+			c->ctx->server_name, a->target, a->full_params);
+}
+
+static void
+irc_handle_cap_ack (struct client *c, struct irc_cap_args *a)
+{
+	if (a->params.len)
+		irc_send_reply (c, IRC_ERR_INVALIDCAPCMD,
+			a->subcommand, "No acknowledgable capabilities supported");
+}
+
+static void
+irc_handle_cap_end (struct client *c, struct irc_cap_args *a)
+{
+	(void) a;
+
+	c->cap_negotiating = false;
+	irc_try_finish_registration (c);
+}
+
+// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+
+struct irc_cap_command
+{
+	const char *name;
+	void (*handler) (struct client *, struct irc_cap_args *);
+};
+
+static void
+irc_register_cap_handlers (struct server_context *ctx)
+{
+	static const struct irc_cap_command cap_handlers[] =
+	{
+		{ "LS",   irc_handle_cap_ls   },
+		{ "LIST", irc_handle_cap_list },
+		{ "REQ",  irc_handle_cap_req  },
+		{ "ACK",  irc_handle_cap_ack  },
+		{ "END",  irc_handle_cap_end  },
+	};
+
+	for (size_t i = 0; i < N_ELEMENTS (cap_handlers); i++)
+	{
+		const struct irc_cap_command *cmd = &cap_handlers[i];
+		str_map_set (&ctx->cap_handlers, cmd->name, (void *) cmd);
+	}
+}
+
+static void
+irc_handle_cap (const struct irc_message *msg, struct client *c)
+{
+	if (msg->params.len < 1)
+		RETURN_WITH_REPLY (c, IRC_ERR_NEEDMOREPARAMS, msg->command);
+
+	struct irc_cap_args args;
+	args.target = c->nickname ? c->nickname : "*";
+	args.subcommand = msg->params.vector[0];
+	args.full_params = "";
+	args.params = strv_make ();
+
+	if (msg->params.len > 1)
+	{
+		args.full_params = msg->params.vector[1];
+		cstr_split (args.full_params, " ", true, &args.params);
+	}
+
+	struct irc_cap_command *cmd =
+		str_map_find (&c->ctx->cap_handlers, args.subcommand);
+	if (!cmd)
+		irc_send_reply (c, IRC_ERR_INVALIDCAPCMD,
+			args.subcommand, "Invalid CAP subcommand");
+	else
+		cmd->handler (c, &args);
+
+	strv_free (&args.params);
+}
+
+static void
+irc_handle_pass (const struct irc_message *msg, struct client *c)
+{
+	if (c->registered)
+		irc_send_reply (c, IRC_ERR_ALREADYREGISTERED);
+	else if (msg->params.len < 1)
+		irc_send_reply (c, IRC_ERR_NEEDMOREPARAMS, msg->command);
+
+	// We have TLS client certificates for this purpose; ignoring
+}
+
+static void
+irc_handle_nick (const struct irc_message *msg, struct client *c)
+{
+	struct server_context *ctx = c->ctx;
+
+	if (msg->params.len < 1)
+		RETURN_WITH_REPLY (c, IRC_ERR_NONICKNAMEGIVEN);
+
+	const char *nickname = msg->params.vector[0];
+	if (irc_validate_nickname (nickname) != VALIDATION_OK)
+		RETURN_WITH_REPLY (c, IRC_ERR_ERRONEOUSNICKNAME, nickname);
+
+	struct client *client = str_map_find (&ctx->users, nickname);
+	if (client && client != c)
+		RETURN_WITH_REPLY (c, IRC_ERR_NICKNAMEINUSE, nickname);
+
+	// Nothing to do here, let's not annoy roommates
+	if (c->nickname && !strcmp (c->nickname, nickname))
+		return;
+
+	if (c->registered)
+	{
+		client_add_to_whowas (c);
+
+		char *message = xstrdup_printf (":%s!%s@%s NICK :%s",
+			c->nickname, c->username, c->hostname, nickname);
+		irc_send_to_roommates (c, message);
+		client_send (c, "%s", message);
+		free (message);
+	}
+
+	// Release the old nickname and allocate a new one
+	if (c->nickname)
+		str_map_set (&ctx->users, c->nickname, NULL);
+
+	cstr_set (&c->nickname, xstrdup (nickname));
+	str_map_set (&ctx->users, nickname, c);
+
+	irc_try_finish_registration (c);
+}
+
+static void
+irc_handle_user (const struct irc_message *msg, struct client *c)
+{
+	if (c->registered)
+		RETURN_WITH_REPLY (c, IRC_ERR_ALREADYREGISTERED);
+	if (msg->params.len < 4)
+		RETURN_WITH_REPLY (c, IRC_ERR_NEEDMOREPARAMS, msg->command);
+
+	const char *username = msg->params.vector[0];
+	const char *mode     = msg->params.vector[1];
+	const char *realname = msg->params.vector[3];
+
+	// Unfortunately the protocol doesn't give us any means of rejecting it
+	if (!irc_is_valid_user (username))
+		username = "xxx";
+
+	cstr_set (&c->username, xstrdup (username));
+	cstr_set (&c->realname, xstrdup (realname));
+	c->mode = 0;
+
+	unsigned long m;
+	if (xstrtoul (&m, mode, 10))
+	{
+		if (m & 4)  c->mode |= IRC_USER_MODE_RX_WALLOPS;
+		if (m & 8)  c->mode |= IRC_USER_MODE_INVISIBLE;
+	}
+
+	irc_try_finish_registration (c);
+}
+
+static void
+irc_handle_userhost (const struct irc_message *msg, struct client *c)
+{
+	if (msg->params.len < 1)
+		RETURN_WITH_REPLY (c, IRC_ERR_NEEDMOREPARAMS, msg->command);
+
+	struct str reply = str_make ();
+	for (size_t i = 0; i < 5 && i < msg->params.len; i++)
+	{
+		const char *nick = msg->params.vector[i];
+		struct client *target = str_map_find (&c->ctx->users, nick);
+		if (!target)
+			continue;
+
+		if (i)
+			str_append_c (&reply, ' ');
+		str_append (&reply, nick);
+		if (target->mode & IRC_USER_MODE_OPERATOR)
+			str_append_c (&reply, '*');
+		str_append_printf (&reply, "=%c%s@%s",
+			target->away_message ? '-' : '+',
+			target->username, target->hostname);
+	}
+	irc_send_reply (c, IRC_RPL_USERHOST, reply.str);
+	str_free (&reply);
+}
+
+static void
+irc_handle_lusers (const struct irc_message *msg, struct client *c)
+{
+	if (msg->params.len > 1 && !irc_is_this_me (c->ctx, msg->params.vector[1]))
+		irc_send_reply (c, IRC_ERR_NOSUCHSERVER, msg->params.vector[1]);
+	else
+		irc_send_lusers (c);
+}
+
+static void
+irc_handle_motd (const struct irc_message *msg, struct client *c)
+{
+	if (msg->params.len > 0 && !irc_is_this_me (c->ctx, msg->params.vector[0]))
+		irc_send_reply (c, IRC_ERR_NOSUCHSERVER, msg->params.vector[0]);
+	else
+		irc_send_motd (c);
+}
+
+static void
+irc_handle_ping (const struct irc_message *msg, struct client *c)
+{
+	// XXX: the RFC is pretty incomprehensible about the exact usage
+	if (msg->params.len > 1 && !irc_is_this_me (c->ctx, msg->params.vector[1]))
+		irc_send_reply (c, IRC_ERR_NOSUCHSERVER, msg->params.vector[1]);
+	else if (msg->params.len < 1)
+		irc_send_reply (c, IRC_ERR_NOORIGIN);
+	else
+		client_send (c, ":%s PONG :%s",
+			c->ctx->server_name, msg->params.vector[0]);
+}
+
+static void
+irc_handle_pong (const struct irc_message *msg, struct client *c)
+{
+	// We are the only server, so we don't have to care too much
+	if (msg->params.len < 1)
+		irc_send_reply (c, IRC_ERR_NOORIGIN);
+	else
+		// Set a new timer to send another PING
+		client_set_ping_timer (c);
+}
+
+static void
+irc_handle_quit (const struct irc_message *msg, struct client *c)
+{
+	char *reason = xstrdup_printf ("Quit: %s",
+		msg->params.len > 0 ? msg->params.vector[0] : c->nickname);
+	client_close_link (c, reason);
+	free (reason);
+}
+
+static void
+irc_handle_time (const struct irc_message *msg, struct client *c)
+{
+	if (msg->params.len > 0 && !irc_is_this_me (c->ctx, msg->params.vector[0]))
+		RETURN_WITH_REPLY (c, IRC_ERR_NOSUCHSERVER, msg->params.vector[0]);
+
+	char buf[32] = "";
+	time_t now = time (NULL);
+	struct tm tm;
+	strftime (buf, sizeof buf, "%a %b %d %Y %T", localtime_r (&now, &tm));
+	irc_send_reply (c, IRC_RPL_TIME, c->ctx->server_name, buf);
+}
+
+static void
+irc_handle_version (const struct irc_message *msg, struct client *c)
+{
+	if (msg->params.len > 0 && !irc_is_this_me (c->ctx, msg->params.vector[0]))
+		RETURN_WITH_REPLY (c, IRC_ERR_NOSUCHSERVER, msg->params.vector[0]);
+
+	irc_send_reply (c, IRC_RPL_VERSION, PROGRAM_VERSION, g_debug_mode,
+		c->ctx->server_name, PROGRAM_NAME " " PROGRAM_VERSION);
+	irc_send_isupport (c);
+}
+
+static void
+irc_channel_multicast (struct channel *chan, const char *message,
+	struct client *except)
+{
+	for (struct channel_user *iter = chan->users; iter; iter = iter->next)
+		if (iter->c != except)
+			client_send (iter->c, "%s", message);
+}
+
+static bool
+irc_modify_mode (unsigned *mask, unsigned mode, bool add)
+{
+	unsigned orig = *mask;
+	if (add)
+		*mask |= mode;
+	else
+		*mask &= ~mode;
+	return *mask != orig;
+}
+
+static void
+irc_update_user_mode (struct client *c, unsigned new_mode)
+{
+	unsigned old_mode = c->mode;
+	c->mode = new_mode;
+
+	unsigned added   = new_mode & ~old_mode;
+	unsigned removed = old_mode & ~new_mode;
+
+	struct str diff = str_make ();
+	if (added)
+	{
+		str_append_c (&diff, '+');
+		client_mode_to_str (added, &diff);
+	}
+	if (removed)
+	{
+		str_append_c (&diff, '-');
+		client_mode_to_str (removed, &diff);
+	}
+
+	if (diff.len)
+		client_send (c, ":%s MODE %s :%s",
+			c->nickname, c->nickname, diff.str);
+	str_free (&diff);
+}
+
+static void
+irc_handle_user_mode_change (struct client *c, const char *mode_string)
+{
+	unsigned new_mode = c->mode;
+	bool adding = true;
+
+	while (*mode_string)
+	switch (*mode_string++)
+	{
+	case '+':  adding = true;   break;
+	case '-':  adding = false;  break;
+
+	case 'a':
+		// Ignore, the client should use AWAY
+		break;
+	case 'i':
+		irc_modify_mode (&new_mode, IRC_USER_MODE_INVISIBLE, adding);
+		break;
+	case 'w':
+		irc_modify_mode (&new_mode, IRC_USER_MODE_RX_WALLOPS, adding);
+		break;
+	case 'r':
+		// It's not possible to un-restrict yourself
+		if (adding)
+			new_mode |= IRC_USER_MODE_RESTRICTED;
+		break;
+	case 'o':
+		if (!adding)
+			new_mode &= ~IRC_USER_MODE_OPERATOR;
+		else if (c->ssl_cert_fingerprint
+			&& str_map_find (&c->ctx->operators, c->ssl_cert_fingerprint))
+			new_mode |= IRC_USER_MODE_OPERATOR;
+		else
+			client_send (c, ":%s NOTICE %s :Either you're not using an TLS"
+				" client certificate, or the fingerprint doesn't match",
+				c->ctx->server_name, c->nickname);
+		break;
+	case 's':
+		irc_modify_mode (&new_mode, IRC_USER_MODE_RX_SERVER_NOTICES, adding);
+		break;
+	default:
+		RETURN_WITH_REPLY (c, IRC_ERR_UMODEUNKNOWNFLAG);
+	}
+	irc_update_user_mode (c, new_mode);
+}
+
+static void
+irc_send_channel_list (struct client *c, const char *channel_name,
+	const struct strv *list, int reply, int end_reply)
+{
+	for (size_t i = 0; i < list->len; i++)
+		irc_send_reply (c, reply, channel_name, list->vector[i]);
+	irc_send_reply (c, end_reply, channel_name);
+}
+
+static char *
+irc_check_expand_user_mask (const char *mask)
+{
+	struct str result = str_make ();
+	str_append (&result, mask);
+
+	// Make sure it is a complete mask
+	if (!strchr (result.str, '!'))
+		str_append (&result, "!*");
+	if (!strchr (result.str, '@'))
+		str_append (&result, "@*");
+
+	// And validate whatever the result is
+	if (!irc_is_valid_user_mask (result.str))
+	{
+		str_free (&result);
+		return NULL;
+	}
+	return str_steal (&result);
+}
+
+// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+
+// Channel MODE command handling.  This is by far the worst command to implement
+// from the whole RFC; don't blame me if it doesn't work exactly as expected.
+
+struct mode_processor
+{
+	// Inputs to set after initialization:
+
+	char **params;                      ///< Mode string parameters
+
+	struct client *c;                   ///< Who does the changes
+	struct channel *channel;            ///< The channel we're modifying
+	struct channel_user *user;          ///< Presence of the client in the chan
+
+	// Internals:
+
+	bool adding;                        ///< Currently adding modes
+	char mode_char;                     ///< Currently processed mode char
+
+	struct str added;                   ///< Added modes
+	struct str removed;                 ///< Removed modes
+
+	struct strv added_params;           ///< Params for added modes
+	struct strv removed_params;         ///< Params for removed modes
+
+	struct str *output;                 ///< "added" or "removed"
+	struct strv *output_params;         ///< Similarly for "*_params"
+};
+
+static struct mode_processor
+mode_processor_make (void)
+{
+	return (struct mode_processor)
+	{
+		.added   = str_make (), .added_params   = strv_make (),
+		.removed = str_make (), .removed_params = strv_make (),
+	};
+}
+
+static void
+mode_processor_free (struct mode_processor *self)
+{
+	str_free (&self->added);
+	str_free (&self->removed);
+
+	strv_free (&self->added_params);
+	strv_free (&self->removed_params);
+}
+
+static const char *
+mode_processor_next_param (struct mode_processor *self)
+{
+	if (!*self->params)
+		return NULL;
+	return *self->params++;
+}
+
+static bool
+mode_processor_check_operator (struct mode_processor *self)
+{
+	if ((self->user && (self->user->modes & IRC_CHAN_MODE_OPERATOR))
+		|| (self->c->mode & IRC_USER_MODE_OPERATOR))
+		return true;
+
+	irc_send_reply (self->c, IRC_ERR_CHANOPRIVSNEEDED, self->channel->name);
+	return false;
+}
+
+static void
+mode_processor_do_user (struct mode_processor *self, int mode)
+{
+	const char *target = mode_processor_next_param (self);
+	if (!mode_processor_check_operator (self) || !target)
+		return;
+
+	struct client *client;
+	struct channel_user *target_user;
+	if (!(client = str_map_find (&self->c->ctx->users, target)))
+		irc_send_reply (self->c, IRC_ERR_NOSUCHNICK, target);
+	else if (!(target_user = channel_get_user (self->channel, client)))
+		irc_send_reply (self->c, IRC_ERR_USERNOTINCHANNEL,
+			target, self->channel->name);
+	else if (irc_modify_mode (&target_user->modes, mode, self->adding))
+	{
+		str_append_c (self->output, self->mode_char);
+		strv_append (self->output_params, client->nickname);
+	}
+}
+
+static bool
+mode_processor_do_chan (struct mode_processor *self, int mode)
+{
+	if (!mode_processor_check_operator (self)
+	 || !irc_modify_mode (&self->channel->modes, mode, self->adding))
+		return false;
+
+	str_append_c (self->output, self->mode_char);
+	return true;
+}
+
+static void
+mode_processor_do_chan_remove
+	(struct mode_processor *self, char mode_char, int mode)
+{
+	if (self->adding
+	 && irc_modify_mode (&self->channel->modes, mode, false))
+		str_append_c (&self->removed, mode_char);
+}
+
+static void
+mode_processor_do_list (struct mode_processor *self,
+	struct strv *list, int list_msg, int end_msg)
+{
+	const char *target = mode_processor_next_param (self);
+	if (!target)
+	{
+		if (self->adding)
+			irc_send_channel_list (self->c, self->channel->name,
+				list, list_msg, end_msg);
+		return;
+	}
+
+	if (!mode_processor_check_operator (self))
+		return;
+
+	char *mask = irc_check_expand_user_mask (target);
+	if (!mask)
+		return;
+
+	size_t i;
+	for (i = 0; i < list->len; i++)
+		if (!irc_strcmp (list->vector[i], mask))
+			break;
+
+	bool found = i != list->len;
+	if (found != self->adding)
+	{
+		if (self->adding)
+			strv_append (list, mask);
+		else
+			strv_remove (list, i);
+
+		str_append_c (self->output, self->mode_char);
+		strv_append (self->output_params, mask);
+	}
+	free (mask);
+}
+
+static void
+mode_processor_do_key (struct mode_processor *self)
+{
+	const char *target = mode_processor_next_param (self);
+	if (!mode_processor_check_operator (self) || !target)
+		return;
+
+	if (!self->adding)
+	{
+		if (!self->channel->key || irc_strcmp (target, self->channel->key))
+			return;
+
+		str_append_c (&self->removed, self->mode_char);
+		strv_append (&self->removed_params, self->channel->key);
+		cstr_set (&self->channel->key, NULL);
+	}
+	else if (!irc_is_valid_key (target))
+		// TODO: we should notify the user somehow
+		return;
+	else if (self->channel->key)
+		irc_send_reply (self->c, IRC_ERR_KEYSET, self->channel->name);
+	else
+	{
+		self->channel->key = xstrdup (target);
+		str_append_c (&self->added, self->mode_char);
+		strv_append (&self->added_params, self->channel->key);
+	}
+}
+
+static void
+mode_processor_do_limit (struct mode_processor *self)
+{
+	if (!mode_processor_check_operator (self))
+		return;
+
+	const char *target;
+	if (!self->adding)
+	{
+		if (self->channel->user_limit == -1)
+			return;
+
+		self->channel->user_limit = -1;
+		str_append_c (&self->removed, self->mode_char);
+	}
+	else if ((target = mode_processor_next_param (self)))
+	{
+		unsigned long x;
+		if (xstrtoul (&x, target, 10) && x > 0 && x <= LONG_MAX)
+		{
+			self->channel->user_limit = x;
+			str_append_c (&self->added, self->mode_char);
+			strv_append (&self->added_params, target);
+		}
+	}
+}
+
+static bool
+mode_processor_step (struct mode_processor *self, char mode_char)
+{
+	switch ((self->mode_char = mode_char))
+	{
+	case '+':
+		self->adding = true;
+		self->output = &self->added;
+		self->output_params = &self->added_params;
+		break;
+	case '-':
+		self->adding = false;
+		self->output = &self->removed;
+		self->output_params = &self->removed_params;
+		break;
+
+#define USER(mode) mode_processor_do_user (self, (mode))
+#define CHAN(mode) mode_processor_do_chan (self, (mode))
+
+	case 'o': USER (IRC_CHAN_MODE_OPERATOR);         break;
+	case 'v': USER (IRC_CHAN_MODE_VOICE);            break;
+
+	case 'i': CHAN (IRC_CHAN_MODE_INVITE_ONLY);      break;
+	case 'm': CHAN (IRC_CHAN_MODE_MODERATED);        break;
+	case 'n': CHAN (IRC_CHAN_MODE_NO_OUTSIDE_MSGS);  break;
+	case 'q': CHAN (IRC_CHAN_MODE_QUIET);            break;
+	case 't': CHAN (IRC_CHAN_MODE_PROTECTED_TOPIC);  break;
+
+	case 'p':
+		if (CHAN (IRC_CHAN_MODE_PRIVATE))
+			mode_processor_do_chan_remove (self, 's', IRC_CHAN_MODE_SECRET);
+		break;
+	case 's':
+		if (CHAN (IRC_CHAN_MODE_SECRET))
+			mode_processor_do_chan_remove (self, 'p', IRC_CHAN_MODE_PRIVATE);
+		break;
+
+#undef USER
+#undef CHAN
+
+	case 'b':
+		mode_processor_do_list (self, &self->channel->ban_list,
+			IRC_RPL_BANLIST, IRC_RPL_ENDOFBANLIST);
+		break;
+	case 'e':
+		mode_processor_do_list (self, &self->channel->exception_list,
+			IRC_RPL_EXCEPTLIST, IRC_RPL_ENDOFEXCEPTLIST);
+		break;
+	case 'I':
+		mode_processor_do_list (self, &self->channel->invite_list,
+			IRC_RPL_INVITELIST, IRC_RPL_ENDOFINVITELIST);
+		break;
+
+	case 'k':
+		mode_processor_do_key (self);
+		break;
+	case 'l':
+		mode_processor_do_limit (self);
+		break;
+
+	default:
+		// It's not safe to continue, results could be undesired
+		irc_send_reply (self->c, IRC_ERR_UNKNOWNMODE,
+			mode_char, self->channel->name);
+		return false;
+	}
+	return true;
+}
+
+static void
+irc_handle_chan_mode_change
+	(struct client *c, struct channel *chan, char *params[])
+{
+	struct mode_processor p = mode_processor_make ();
+	p.params = params;
+	p.channel = chan;
+	p.c = c;
+	p.user = channel_get_user (chan, c);
+
+	const char *mode_string;
+	while ((mode_string = mode_processor_next_param (&p)))
+	{
+		mode_processor_step (&p, '+');
+		while (*mode_string)
+			if (!mode_processor_step (&p, *mode_string++))
+				goto done_processing;
+	}
+
+	// TODO: limit to three changes with parameter per command
+done_processing:
+	if (p.added.len || p.removed.len)
+	{
+		struct str message = str_make ();
+		str_append_printf (&message, ":%s!%s@%s MODE %s ",
+			p.c->nickname, p.c->username, p.c->hostname,
+			p.channel->name);
+		if (p.added.len)
+			str_append_printf (&message, "+%s", p.added.str);
+		if (p.removed.len)
+			str_append_printf (&message, "-%s", p.removed.str);
+		for (size_t i = 0; i < p.added_params.len; i++)
+			str_append_printf (&message, " %s", p.added_params.vector[i]);
+		for (size_t i = 0; i < p.removed_params.len; i++)
+			str_append_printf (&message, " %s", p.removed_params.vector[i]);
+		irc_channel_multicast (p.channel, message.str, NULL);
+		str_free (&message);
+	}
+	mode_processor_free (&p);
+}
+
+// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+
+static void
+irc_handle_mode (const struct irc_message *msg, struct client *c)
+{
+	if (msg->params.len < 1)
+		RETURN_WITH_REPLY (c, IRC_ERR_NEEDMOREPARAMS, msg->command);
+
+	const char *target = msg->params.vector[0];
+	struct client *client = str_map_find (&c->ctx->users, target);
+	struct channel *chan = str_map_find (&c->ctx->channels, target);
+
+	if (client)
+	{
+		if (irc_strcmp (target, c->nickname))
+			RETURN_WITH_REPLY (c, IRC_ERR_USERSDONTMATCH);
+
+		if (msg->params.len < 2)
+		{
+			char *mode = client_get_mode (client);
+			irc_send_reply (c, IRC_RPL_UMODEIS, mode);
+			free (mode);
+		}
+		else
+			irc_handle_user_mode_change (c, msg->params.vector[1]);
+	}
+	else if (chan)
+	{
+		if (msg->params.len < 2)
+		{
+			char *mode = channel_get_mode (chan, channel_get_user (chan, c));
+			irc_send_reply (c, IRC_RPL_CHANNELMODEIS, target, mode);
+			irc_send_reply (c, IRC_RPL_CREATIONTIME,
+				target, (long long) chan->created);
+			free (mode);
+		}
+		else
+			irc_handle_chan_mode_change (c, chan, &msg->params.vector[1]);
+	}
+	else
+		irc_send_reply (c, IRC_ERR_NOSUCHNICK, target);
+}
+
+static void
+irc_handle_user_message (const struct irc_message *msg, struct client *c,
+	const char *command, bool allow_away_reply)
+{
+	if (msg->params.len < 1)
+		RETURN_WITH_REPLY (c, IRC_ERR_NORECIPIENT, msg->command);
+	if (msg->params.len < 2 || !*msg->params.vector[1])
+		RETURN_WITH_REPLY (c, IRC_ERR_NOTEXTTOSEND);
+
+	const char *target = msg->params.vector[0];
+	const char *text   = msg->params.vector[1];
+	struct client *client = str_map_find (&c->ctx->users, target);
+	if (client)
+	{
+		client_send (client, ":%s!%s@%s %s %s :%s",
+			c->nickname, c->username, c->hostname, command, target, text);
+		if (allow_away_reply && client->away_message)
+			irc_send_reply (c, IRC_RPL_AWAY, target, client->away_message);
+
+		// Acknowledging a message from the client to itself would be silly
+		if (client != c && (c->caps_enabled & IRC_CAP_ECHO_MESSAGE))
+			client_send (c, ":%s!%s@%s %s %s :%s",
+				c->nickname, c->username, c->hostname, command, target, text);
+		return;
+	}
+
+	struct channel *chan = str_map_find (&c->ctx->channels, target);
+	if (chan)
+	{
+		struct channel_user *user = channel_get_user (chan, c);
+		if ((chan->modes & IRC_CHAN_MODE_NO_OUTSIDE_MSGS) && !user)
+			RETURN_WITH_REPLY (c, IRC_ERR_CANNOTSENDTOCHAN, target);
+		if ((chan->modes & IRC_CHAN_MODE_MODERATED) && (!user ||
+			!(user->modes & (IRC_CHAN_MODE_VOICE | IRC_CHAN_MODE_OPERATOR))))
+			RETURN_WITH_REPLY (c, IRC_ERR_CANNOTSENDTOCHAN, target);
+		if (client_in_mask_list (c, &chan->ban_list)
+		 && !client_in_mask_list (c, &chan->exception_list))
+			RETURN_WITH_REPLY (c, IRC_ERR_CANNOTSENDTOCHAN, target);
+
+		char *message = xstrdup_printf (":%s!%s@%s %s %s :%s",
+			c->nickname, c->username, c->hostname, command, target, text);
+		irc_channel_multicast (chan, message,
+			(c->caps_enabled & IRC_CAP_ECHO_MESSAGE) ? NULL : c);
+		free (message);
+		return;
+	}
+
+	irc_send_reply (c, IRC_ERR_NOSUCHNICK, target);
+}
+
+static void
+irc_handle_privmsg (const struct irc_message *msg, struct client *c)
+{
+	irc_handle_user_message (msg, c, "PRIVMSG", true);
+	// Let's not care too much about success or failure
+	c->last_active = time (NULL);
+}
+
+static void
+irc_handle_notice (const struct irc_message *msg, struct client *c)
+{
+	irc_handle_user_message (msg, c, "NOTICE", false);
+}
+
+static void
+irc_send_rpl_list (struct client *c, const struct channel *chan)
+{
+	int visible = 0;
+	for (struct channel_user *user = chan->users;
+		 user; user = user->next)
+		// XXX: maybe we should skip IRC_USER_MODE_INVISIBLE
+		visible++;
+
+	irc_send_reply (c, IRC_RPL_LIST, chan->name, visible, chan->topic);
+}
+
+static void
+irc_handle_list (const struct irc_message *msg, struct client *c)
+{
+	if (msg->params.len > 1 && !irc_is_this_me (c->ctx, msg->params.vector[1]))
+		RETURN_WITH_REPLY (c, IRC_ERR_NOSUCHSERVER, msg->params.vector[1]);
+
+	struct channel *chan;
+	if (msg->params.len == 0)
+	{
+		struct str_map_iter iter = str_map_iter_make (&c->ctx->channels);
+		while ((chan = str_map_iter_next (&iter)))
+			if (!(chan->modes & (IRC_CHAN_MODE_PRIVATE | IRC_CHAN_MODE_SECRET))
+			 || channel_get_user (chan, c))
+				irc_send_rpl_list (c, chan);
+	}
+	else
+	{
+		struct strv channels = strv_make ();
+		cstr_split (msg->params.vector[0], ",", true, &channels);
+		for (size_t i = 0; i < channels.len; i++)
+			if ((chan = str_map_find (&c->ctx->channels, channels.vector[i]))
+			 && (!(chan->modes & IRC_CHAN_MODE_SECRET)
+			 || channel_get_user (chan, c)))
+				irc_send_rpl_list (c, chan);
+		strv_free (&channels);
+	}
+	irc_send_reply (c, IRC_RPL_LISTEND);
+}
+
+static void
+irc_append_prefixes (struct client *c, struct channel_user *user,
+	struct str *output)
+{
+	struct str prefixes = str_make ();
+	if (user->modes & IRC_CHAN_MODE_OPERATOR)  str_append_c (&prefixes, '@');
+	if (user->modes & IRC_CHAN_MODE_VOICE)     str_append_c (&prefixes, '+');
+
+	if (prefixes.len)
+	{
+		if (c->caps_enabled & IRC_CAP_MULTI_PREFIX)
+			str_append   (output, prefixes.str);
+		else
+			str_append_c (output, prefixes.str[0]);
+	}
+	str_free (&prefixes);
+}
+
+static char *
+irc_make_rpl_namreply_item
+	(struct client *c, struct client *target, struct channel_user *user)
+{
+	struct str result = str_make ();
+
+	if (user)
+		irc_append_prefixes (c, user, &result);
+
+	str_append (&result, target->nickname);
+	if (c->caps_enabled & IRC_CAP_USERHOST_IN_NAMES)
+		str_append_printf (&result,
+			"!%s@%s", target->username, target->hostname);
+	return str_steal (&result);
+}
+
+static void
+irc_send_rpl_namreply (struct client *c, const struct channel *chan,
+	struct str_map *used_nicks)
+{
+	char type = '=';
+	if (chan->modes & IRC_CHAN_MODE_SECRET)
+		type = '@';
+	else if (chan->modes & IRC_CHAN_MODE_PRIVATE)
+		type = '*';
+
+	bool on_channel = channel_get_user (chan, c);
+	struct strv nicks = strv_make ();
+	for (struct channel_user *iter = chan->users; iter; iter = iter->next)
+	{
+		if (!on_channel && (iter->c->mode & IRC_USER_MODE_INVISIBLE))
+			continue;
+		if (used_nicks)
+			str_map_set (used_nicks, iter->c->nickname, (void *) 1);
+		strv_append_owned (&nicks,
+			irc_make_rpl_namreply_item (c, iter->c, iter));
+	}
+
+	irc_send_reply_vector (c, IRC_RPL_NAMREPLY,
+		nicks.vector, type, chan->name, "");
+	strv_free (&nicks);
+}
+
+static void
+irc_send_disassociated_names (struct client *c, struct str_map *used)
+{
+	struct strv nicks = strv_make ();
+	struct str_map_iter iter = str_map_iter_make (&c->ctx->users);
+	struct client *target;
+	while ((target = str_map_iter_next (&iter)))
+	{
+		if ((target->mode & IRC_USER_MODE_INVISIBLE)
+		 || str_map_find (used, target->nickname))
+			continue;
+		strv_append_owned (&nicks,
+			irc_make_rpl_namreply_item (c, target, NULL));
+	}
+
+	if (nicks.len)
+		irc_send_reply_vector (c, IRC_RPL_NAMREPLY,
+			nicks.vector, '*', "*", "");
+	strv_free (&nicks);
+}
+
+static void
+irc_handle_names (const struct irc_message *msg, struct client *c)
+{
+	if (msg->params.len > 1 && !irc_is_this_me (c->ctx, msg->params.vector[1]))
+		RETURN_WITH_REPLY (c, IRC_ERR_NOSUCHSERVER, msg->params.vector[1]);
+
+	struct channel *chan;
+	if (msg->params.len == 0)
+	{
+		struct str_map used = str_map_make (NULL);
+		used.key_xfrm = irc_strxfrm;
+
+		struct str_map_iter iter = str_map_iter_make (&c->ctx->channels);
+		while ((chan = str_map_iter_next (&iter)))
+			if (!(chan->modes & (IRC_CHAN_MODE_PRIVATE | IRC_CHAN_MODE_SECRET))
+			 || channel_get_user (chan, c))
+				irc_send_rpl_namreply (c, chan, &used);
+
+		// Also send all visible users we haven't listed yet
+		irc_send_disassociated_names (c, &used);
+		str_map_free (&used);
+
+		irc_send_reply (c, IRC_RPL_ENDOFNAMES, "*");
+	}
+	else
+	{
+		struct strv channels = strv_make ();
+		cstr_split (msg->params.vector[0], ",", true, &channels);
+		for (size_t i = 0; i < channels.len; i++)
+			if ((chan = str_map_find (&c->ctx->channels, channels.vector[i]))
+			 && (!(chan->modes & IRC_CHAN_MODE_SECRET)
+			 || channel_get_user (chan, c)))
+			{
+				irc_send_rpl_namreply (c, chan, NULL);
+				irc_send_reply (c, IRC_RPL_ENDOFNAMES, channels.vector[i]);
+			}
+		strv_free (&channels);
+	}
+}
+
+static void
+irc_send_rpl_whoreply (struct client *c, const struct channel *chan,
+	const struct client *target)
+{
+	struct str chars = str_make ();
+	str_append_c (&chars, target->away_message ? 'G' : 'H');
+	if (target->mode & IRC_USER_MODE_OPERATOR)
+		str_append_c (&chars, '*');
+
+	struct channel_user *user;
+	if (chan && (user = channel_get_user (chan, target)))
+		irc_append_prefixes (c, user, &chars);
+
+	irc_send_reply (c, IRC_RPL_WHOREPLY, chan ? chan->name : "*",
+		target->username, target->hostname, target->ctx->server_name,
+		target->nickname, chars.str, 0 /* hop count */, target->realname);
+	str_free (&chars);
+}
+
+static void
+irc_match_send_rpl_whoreply (struct client *c, struct client *target,
+	const char *mask)
+{
+	bool is_roommate = false;
+	struct str_map_iter iter = str_map_iter_make (&c->ctx->channels);
+	struct channel *chan;
+	while ((chan = str_map_iter_next (&iter)))
+		if (channel_get_user (chan, target) && channel_get_user (chan, c))
+		{
+			is_roommate = true;
+			break;
+		}
+	if ((target->mode & IRC_USER_MODE_INVISIBLE) && !is_roommate)
+		return;
+
+	if (irc_fnmatch (mask, target->hostname)
+	 && irc_fnmatch (mask, target->nickname)
+	 && irc_fnmatch (mask, target->realname)
+	 && irc_fnmatch (mask, c->ctx->server_name))
+		return;
+
+	// Try to find a channel they're on that's visible to us
+	struct channel *user_chan = NULL;
+	iter = str_map_iter_make (&c->ctx->channels);
+	while ((chan = str_map_iter_next (&iter)))
+		if (channel_get_user (chan, target)
+		 && (!(chan->modes & (IRC_CHAN_MODE_PRIVATE | IRC_CHAN_MODE_SECRET))
+			|| channel_get_user (chan, c)))
+		{
+			user_chan = chan;
+			break;
+		}
+	irc_send_rpl_whoreply (c, user_chan, target);
+}
+
+static void
+irc_handle_who (const struct irc_message *msg, struct client *c)
+{
+	bool only_ops = msg->params.len > 1 && !strcmp (msg->params.vector[1], "o");
+
+	const char *shown_mask = msg->params.vector[0], *used_mask;
+	if (!shown_mask)
+		used_mask = shown_mask = "*";
+	else if (!strcmp (shown_mask, "0"))
+		used_mask = "*";
+	else
+		used_mask = shown_mask;
+
+	struct channel *chan;
+	if ((chan = str_map_find (&c->ctx->channels, used_mask)))
+	{
+		bool on_chan = !!channel_get_user (chan, c);
+		if (on_chan || !(chan->modes & IRC_CHAN_MODE_SECRET))
+			for (struct channel_user *iter = chan->users;
+				iter; iter = iter->next)
+			{
+				if ((on_chan || !(iter->c->mode & IRC_USER_MODE_INVISIBLE))
+				 && (!only_ops || (iter->c->mode & IRC_USER_MODE_OPERATOR)))
+					irc_send_rpl_whoreply (c, chan, iter->c);
+			}
+	}
+	else
+	{
+		struct str_map_iter iter = str_map_iter_make (&c->ctx->users);
+		struct client *target;
+		while ((target = str_map_iter_next (&iter)))
+			if (!only_ops || (target->mode & IRC_USER_MODE_OPERATOR))
+				irc_match_send_rpl_whoreply (c, target, used_mask);
+	}
+	irc_send_reply (c, IRC_RPL_ENDOFWHO, shown_mask);
+}
+
+static void
+irc_send_whois_reply (struct client *c, const struct client *target)
+{
+	const char *nick = target->nickname;
+	irc_send_reply (c, IRC_RPL_WHOISUSER, nick,
+		target->username, target->hostname, target->realname);
+	irc_send_reply (c, IRC_RPL_WHOISSERVER, nick, target->ctx->server_name,
+		str_map_find (&c->ctx->config, "server_info"));
+	if (target->mode & IRC_USER_MODE_OPERATOR)
+		irc_send_reply (c, IRC_RPL_WHOISOPERATOR, nick);
+	irc_send_reply (c, IRC_RPL_WHOISIDLE, nick,
+		(int) (time (NULL) - target->last_active));
+	if (target->away_message)
+		irc_send_reply (c, IRC_RPL_AWAY, nick, target->away_message);
+
+	struct strv channels = strv_make ();
+
+	struct str_map_iter iter = str_map_iter_make (&c->ctx->channels);
+	struct channel *chan;
+	struct channel_user *channel_user;
+	while ((chan = str_map_iter_next (&iter)))
+		if ((channel_user = channel_get_user (chan, target))
+		 && (!(chan->modes & (IRC_CHAN_MODE_PRIVATE | IRC_CHAN_MODE_SECRET))
+			|| channel_get_user (chan, c)))
+		{
+			struct str item = str_make ();
+			if (channel_user->modes & IRC_CHAN_MODE_OPERATOR)
+				str_append_c (&item, '@');
+			else if (channel_user->modes & IRC_CHAN_MODE_VOICE)
+				str_append_c (&item, '+');
+			str_append (&item, chan->name);
+			strv_append_owned (&channels, str_steal (&item));
+		}
+
+	irc_send_reply_vector (c, IRC_RPL_WHOISCHANNELS, channels.vector, nick, "");
+	strv_free (&channels);
+
+	irc_send_reply (c, IRC_RPL_ENDOFWHOIS, nick);
+}
+
+static void
+irc_handle_whois (const struct irc_message *msg, struct client *c)
+{
+	if (msg->params.len < 1)
+		RETURN_WITH_REPLY (c, IRC_ERR_NEEDMOREPARAMS, msg->command);
+	if (msg->params.len > 1 && !irc_is_this_me (c->ctx, msg->params.vector[0]))
+		RETURN_WITH_REPLY (c, IRC_ERR_NOSUCHSERVER, msg->params.vector[0]);
+
+	struct strv masks = strv_make ();
+	const char *masks_str = msg->params.vector[msg->params.len > 1];
+	cstr_split (masks_str, ",", true, &masks);
+	for (size_t i = 0; i < masks.len; i++)
+	{
+		const char *mask = masks.vector[i];
+		struct client *target;
+		if (!strpbrk (mask, "*?"))
+		{
+			if (!(target = str_map_find (&c->ctx->users, mask)))
+				irc_send_reply (c, IRC_ERR_NOSUCHNICK, mask);
+			else
+				irc_send_whois_reply (c, target);
+		}
+		else
+		{
+			struct str_map_iter iter = str_map_iter_make (&c->ctx->users);
+			bool found = false;
+			while ((target = str_map_iter_next (&iter)))
+				if (!irc_fnmatch (mask, target->nickname))
+				{
+					irc_send_whois_reply (c, target);
+					found = true;
+				}
+			if (!found)
+				irc_send_reply (c, IRC_ERR_NOSUCHNICK, mask);
+		}
+	}
+	strv_free (&masks);
+}
+
+static void
+irc_handle_whowas (const struct irc_message *msg, struct client *c)
+{
+	if (msg->params.len < 1)
+		RETURN_WITH_REPLY (c, IRC_ERR_NEEDMOREPARAMS, msg->command);
+	if (msg->params.len > 2 && !irc_is_this_me (c->ctx, msg->params.vector[2]))
+		RETURN_WITH_REPLY (c, IRC_ERR_NOSUCHSERVER, msg->params.vector[2]);
+	// The "count" parameter is ignored, we only store one entry for a nick
+
+	struct strv nicks = strv_make ();
+	cstr_split (msg->params.vector[0], ",", true, &nicks);
+
+	for (size_t i = 0; i < nicks.len; i++)
+	{
+		const char *nick = nicks.vector[i];
+		struct whowas_info *info = str_map_find (&c->ctx->whowas, nick);
+		if (!info)
+			irc_send_reply (c, IRC_ERR_WASNOSUCHNICK, nick);
+		else
+		{
+			irc_send_reply (c, IRC_RPL_WHOWASUSER, nick,
+				info->username, info->hostname, info->realname);
+			irc_send_reply (c, IRC_RPL_WHOISSERVER, nick, c->ctx->server_name,
+				str_map_find (&c->ctx->config, "server_info"));
+		}
+		irc_send_reply (c, IRC_RPL_ENDOFWHOWAS, nick);
+	}
+	strv_free (&nicks);
+}
+
+static void
+irc_send_rpl_topic (struct client *c, struct channel *chan)
+{
+	if (!*chan->topic)
+		irc_send_reply (c, IRC_RPL_NOTOPIC, chan->name);
+	else
+	{
+		irc_send_reply (c, IRC_RPL_TOPIC, chan->name, chan->topic);
+		irc_send_reply (c, IRC_RPL_TOPICWHOTIME,
+			chan->name, chan->topic_who, (long long) chan->topic_time);
+	}
+}
+
+static void
+irc_handle_topic (const struct irc_message *msg, struct client *c)
+{
+	if (msg->params.len < 1)
+		RETURN_WITH_REPLY (c, IRC_ERR_NEEDMOREPARAMS, msg->command);
+
+	const char *target = msg->params.vector[0];
+	struct channel *chan = str_map_find (&c->ctx->channels, target);
+	if (!chan)
+		RETURN_WITH_REPLY (c, IRC_ERR_NOSUCHCHANNEL, target);
+
+	if (msg->params.len < 2)
+	{
+		irc_send_rpl_topic (c, chan);
+		return;
+	}
+
+	struct channel_user *user = channel_get_user (chan, c);
+	if (!user)
+		RETURN_WITH_REPLY (c, IRC_ERR_NOTONCHANNEL, target);
+
+	if ((chan->modes & IRC_CHAN_MODE_PROTECTED_TOPIC)
+	 && !(user->modes & IRC_CHAN_MODE_OPERATOR))
+		RETURN_WITH_REPLY (c, IRC_ERR_CHANOPRIVSNEEDED, target);
+
+	cstr_set (&chan->topic, xstrdup (msg->params.vector[1]));
+	cstr_set (&chan->topic_who, xstrdup_printf
+		("%s!%s@%s", c->nickname, c->username, c->hostname));
+	chan->topic_time = time (NULL);
+
+	char *message = xstrdup_printf (":%s!%s@%s TOPIC %s :%s",
+		c->nickname, c->username, c->hostname, target, chan->topic);
+	irc_channel_multicast (chan, message, NULL);
+	free (message);
+}
+
+static void
+irc_try_part (struct client *c, const char *channel_name, const char *reason)
+{
+	if (!reason)
+		reason = c->nickname;
+
+	struct channel *chan;
+	if (!(chan = str_map_find (&c->ctx->channels, channel_name)))
+		RETURN_WITH_REPLY (c, IRC_ERR_NOSUCHCHANNEL, channel_name);
+
+	struct channel_user *user;
+	if (!(user = channel_get_user (chan, c)))
+		RETURN_WITH_REPLY (c, IRC_ERR_NOTONCHANNEL, channel_name);
+
+	char *message = xstrdup_printf (":%s!%s@%s PART %s :%s",
+		c->nickname, c->username, c->hostname, channel_name, reason);
+	if (!(chan->modes & IRC_CHAN_MODE_QUIET))
+		irc_channel_multicast (chan, message, NULL);
+	else
+		client_send (c, "%s", message);
+	free (message);
+
+	channel_remove_user (chan, user);
+	irc_channel_destroy_if_empty (c->ctx, chan);
+}
+
+static void
+irc_part_all_channels (struct client *c)
+{
+	// We have to be careful here, the channel might get destroyed
+	struct str_map_unset_iter iter =
+		str_map_unset_iter_make (&c->ctx->channels);
+
+	struct channel *chan;
+	while ((chan = str_map_unset_iter_next (&iter)))
+		if (channel_get_user (chan, c))
+			irc_try_part (c, chan->name, NULL);
+	str_map_unset_iter_free (&iter);
+}
+
+static void
+irc_handle_part (const struct irc_message *msg, struct client *c)
+{
+	if (msg->params.len < 1)
+		RETURN_WITH_REPLY (c, IRC_ERR_NEEDMOREPARAMS, msg->command);
+
+	const char *reason = msg->params.len > 1 ? msg->params.vector[1] : NULL;
+	struct strv channels = strv_make ();
+	cstr_split (msg->params.vector[0], ",", true, &channels);
+	for (size_t i = 0; i < channels.len; i++)
+		irc_try_part (c, channels.vector[i], reason);
+	strv_free (&channels);
+}
+
+static void
+irc_try_kick (struct client *c, const char *channel_name, const char *nick,
+	const char *reason)
+{
+	struct channel *chan;
+	if (!(chan = str_map_find (&c->ctx->channels, channel_name)))
+		RETURN_WITH_REPLY (c, IRC_ERR_NOSUCHCHANNEL, channel_name);
+
+	struct channel_user *user;
+	if (!(user = channel_get_user (chan, c)))
+		RETURN_WITH_REPLY (c, IRC_ERR_NOTONCHANNEL, channel_name);
+	if (!(user->modes & IRC_CHAN_MODE_OPERATOR))
+		RETURN_WITH_REPLY (c, IRC_ERR_CHANOPRIVSNEEDED, channel_name);
+
+	struct client *client;
+	if (!(client = str_map_find (&c->ctx->users, nick))
+	 || !(user = channel_get_user (chan, client)))
+		RETURN_WITH_REPLY (c, IRC_ERR_USERNOTINCHANNEL, nick, channel_name);
+
+	char *message = xstrdup_printf (":%s!%s@%s KICK %s %s :%s",
+		c->nickname, c->username, c->hostname, channel_name, nick, reason);
+	if (!(chan->modes & IRC_CHAN_MODE_QUIET))
+		irc_channel_multicast (chan, message, NULL);
+	else
+		client_send (c, "%s", message);
+	free (message);
+
+	channel_remove_user (chan, user);
+	irc_channel_destroy_if_empty (c->ctx, chan);
+}
+
+static void
+irc_handle_kick (const struct irc_message *msg, struct client *c)
+{
+	if (msg->params.len < 2)
+		RETURN_WITH_REPLY (c, IRC_ERR_NEEDMOREPARAMS, msg->command);
+
+	const char *reason = c->nickname;
+	if (msg->params.len > 2)
+		reason = msg->params.vector[2];
+
+	struct strv channels = strv_make ();
+	cstr_split (msg->params.vector[0], ",", true, &channels);
+	struct strv users = strv_make ();
+	cstr_split (msg->params.vector[1], ",", true, &users);
+
+	if (channels.len == 1)
+		for (size_t i = 0; i < users.len; i++)
+			irc_try_kick (c, channels.vector[0], users.vector[i], reason);
+	else
+		for (size_t i = 0; i < channels.len && i < users.len; i++)
+			irc_try_kick (c, channels.vector[i], users.vector[i], reason);
+
+	strv_free (&channels);
+	strv_free (&users);
+}
+
+static void
+irc_send_invite_notifications
+	(struct channel *chan, struct client *c, struct client *target)
+{
+	for (struct channel_user *iter = chan->users; iter; iter = iter->next)
+		if (iter->c != target && iter->c->caps_enabled & IRC_CAP_INVITE_NOTIFY)
+			client_send (iter->c, ":%s!%s@%s INVITE %s %s",
+				c->nickname, c->username, c->hostname,
+				target->nickname, chan->name);
+}
+
+static void
+irc_handle_invite (const struct irc_message *msg, struct client *c)
+{
+	if (msg->params.len < 2)
+		RETURN_WITH_REPLY (c, IRC_ERR_NEEDMOREPARAMS, msg->command);
+
+	const char *target       = msg->params.vector[0];
+	const char *channel_name = msg->params.vector[1];
+
+	struct client *client = str_map_find (&c->ctx->users, target);
+	if (!client)
+		RETURN_WITH_REPLY (c, IRC_ERR_NOSUCHNICK, target);
+
+	struct channel *chan = str_map_find (&c->ctx->channels, channel_name);
+	if (chan)
+	{
+		struct channel_user *inviting_user;
+		if (!(inviting_user = channel_get_user (chan, c)))
+			RETURN_WITH_REPLY (c, IRC_ERR_NOTONCHANNEL, channel_name);
+		if (channel_get_user (chan, client))
+			RETURN_WITH_REPLY (c, IRC_ERR_USERONCHANNEL, target, channel_name);
+
+		if ((inviting_user->modes & IRC_CHAN_MODE_OPERATOR))
+			str_map_set (&client->invites, channel_name, (void *) 1);
+		else if ((chan->modes & IRC_CHAN_MODE_INVITE_ONLY))
+			RETURN_WITH_REPLY (c, IRC_ERR_CHANOPRIVSNEEDED, channel_name);
+
+		// It's not specified when and how we should send out invite-notify
+		if (chan->modes & IRC_CHAN_MODE_INVITE_ONLY)
+			irc_send_invite_notifications (chan, c, client);
+	}
+
+	client_send (client, ":%s!%s@%s INVITE %s %s",
+		c->nickname, c->username, c->hostname, client->nickname, channel_name);
+	if (client->away_message)
+		irc_send_reply (c, IRC_RPL_AWAY,
+			client->nickname, client->away_message);
+	irc_send_reply (c, IRC_RPL_INVITING, client->nickname, channel_name);
+}
+
+static void
+irc_try_join (struct client *c, const char *channel_name, const char *key)
+{
+	struct channel *chan = str_map_find (&c->ctx->channels, channel_name);
+	unsigned user_mode = 0;
+	if (!chan)
+	{
+		if (irc_validate_channel_name (channel_name) != VALIDATION_OK)
+			RETURN_WITH_REPLY (c, IRC_ERR_BADCHANMASK, channel_name);
+		chan = irc_channel_create (c->ctx, channel_name);
+		user_mode = IRC_CHAN_MODE_OPERATOR;
+	}
+	else if (channel_get_user (chan, c))
+		return;
+
+	bool invited_by_chanop = !!str_map_find (&c->invites, channel_name);
+	if ((chan->modes & IRC_CHAN_MODE_INVITE_ONLY)
+	 && !client_in_mask_list (c, &chan->invite_list)
+	 && !invited_by_chanop)
+		RETURN_WITH_REPLY (c, IRC_ERR_INVITEONLYCHAN, channel_name);
+	if (chan->key && (!key || strcmp (key, chan->key)))
+		RETURN_WITH_REPLY (c, IRC_ERR_BADCHANNELKEY, channel_name);
+	if (chan->user_limit != -1
+	 && channel_user_count (chan) >= (size_t) chan->user_limit)
+		RETURN_WITH_REPLY (c, IRC_ERR_CHANNELISFULL, channel_name);
+	if (client_in_mask_list (c, &chan->ban_list)
+	 && !client_in_mask_list (c, &chan->exception_list)
+	 && !invited_by_chanop)
+		RETURN_WITH_REPLY (c, IRC_ERR_BANNEDFROMCHAN, channel_name);
+
+	// Destroy any invitation as there's no other way to get rid of it
+	str_map_set (&c->invites, channel_name, NULL);
+
+	channel_add_user (chan, c)->modes = user_mode;
+
+	char *message = xstrdup_printf (":%s!%s@%s JOIN %s",
+		c->nickname, c->username, c->hostname, channel_name);
+	if (!(chan->modes & IRC_CHAN_MODE_QUIET))
+		irc_channel_multicast (chan, message, NULL);
+	else
+		client_send (c, "%s", message);
+	free (message);
+
+	irc_send_rpl_topic (c, chan);
+	irc_send_rpl_namreply (c, chan, NULL);
+	irc_send_reply (c, IRC_RPL_ENDOFNAMES, chan->name);
+}
+
+static void
+irc_handle_join (const struct irc_message *msg, struct client *c)
+{
+	if (msg->params.len < 1)
+		RETURN_WITH_REPLY (c, IRC_ERR_NEEDMOREPARAMS, msg->command);
+
+	if (!strcmp (msg->params.vector[0], "0"))
+	{
+		irc_part_all_channels (c);
+		return;
+	}
+
+	struct strv channels = strv_make ();
+	cstr_split (msg->params.vector[0], ",", true, &channels);
+	struct strv keys = strv_make ();
+	if (msg->params.len > 1)
+		cstr_split (msg->params.vector[1], ",", true, &keys);
+
+	for (size_t i = 0; i < channels.len; i++)
+		irc_try_join (c, channels.vector[i],
+			i < keys.len ? keys.vector[i] : NULL);
+
+	strv_free (&channels);
+	strv_free (&keys);
+}
+
+static void
+irc_handle_summon (const struct irc_message *msg, struct client *c)
+{
+	(void) msg;
+	irc_send_reply (c, IRC_ERR_SUMMONDISABLED);
+}
+
+static void
+irc_handle_users (const struct irc_message *msg, struct client *c)
+{
+	(void) msg;
+	irc_send_reply (c, IRC_ERR_USERSDISABLED);
+}
+
+static void
+irc_handle_away (const struct irc_message *msg, struct client *c)
+{
+	if (msg->params.len < 1)
+	{
+		cstr_set (&c->away_message, NULL);
+		irc_send_reply (c, IRC_RPL_UNAWAY);
+	}
+	else
+	{
+		cstr_set (&c->away_message, xstrdup (msg->params.vector[0]));
+		irc_send_reply (c, IRC_RPL_NOWAWAY);
+	}
+}
+
+static void
+irc_handle_ison (const struct irc_message *msg, struct client *c)
+{
+	if (msg->params.len < 1)
+		RETURN_WITH_REPLY (c, IRC_ERR_NEEDMOREPARAMS, msg->command);
+
+	struct str result = str_make ();
+	const char *nick;
+	if (str_map_find (&c->ctx->users, (nick = msg->params.vector[0])))
+		str_append (&result, nick);
+	for (size_t i = 1; i < msg->params.len; i++)
+		if (str_map_find (&c->ctx->users, (nick = msg->params.vector[i])))
+			str_append_printf (&result, " %s", nick);
+
+	irc_send_reply (c, IRC_RPL_ISON, result.str);
+	str_free (&result);
+}
+
+static void
+irc_handle_admin (const struct irc_message *msg, struct client *c)
+{
+	if (msg->params.len > 0 && !irc_is_this_me (c->ctx, msg->params.vector[0]))
+		RETURN_WITH_REPLY (c, IRC_ERR_NOSUCHSERVER, msg->params.vector[0]);
+	irc_send_reply (c, IRC_ERR_NOADMININFO, c->ctx->server_name);
+}
+
+static void
+irc_handle_stats_links (struct client *c, const struct irc_message *msg)
+{
+	// There is only an "l" query in RFC 2812 but we cannot link,
+	// so instead we provide the "L" query giving information for all users
+	const char *filter = NULL;
+	if (msg->params.len > 1)
+		filter = msg->params.vector[1];
+
+	for (struct client *iter = c->ctx->clients; iter; iter = iter->next)
+	{
+		if (filter && irc_strcmp (iter->nickname, filter))
+			continue;
+		irc_send_reply (c, IRC_RPL_STATSLINKINFO,
+			iter->address,           // linkname
+			iter->write_buffer.len,  // sendq
+			iter->n_sent_messages,     iter->sent_bytes     / 1024,
+			iter->n_received_messages, iter->received_bytes / 1024,
+			(long long) (time (NULL) - iter->opened));
+	}
+}
+
+static void
+irc_handle_stats_commands (struct client *c)
+{
+	struct str_map_iter iter = str_map_iter_make (&c->ctx->handlers);
+	struct irc_command *handler;
+	while ((handler = str_map_iter_next (&iter)))
+	{
+		if (!handler->n_received)
+			continue;
+		irc_send_reply (c, IRC_RPL_STATSCOMMANDS, handler->name,
+			handler->n_received, handler->bytes_received, (size_t) 0);
+	}
+}
+
+static void
+irc_handle_stats_uptime (struct client *c)
+{
+	time_t uptime = time (NULL) - c->ctx->started;
+
+	int days  =  uptime                   / 60 / 60 / 24;
+	int hours = (uptime % (60 * 60 * 24)) / 60 / 60;
+	int mins  = (uptime % (60 * 60))      / 60;
+	int secs  =  uptime %  60;
+
+	irc_send_reply (c, IRC_RPL_STATSUPTIME, days, hours, mins, secs);
+}
+
+static void
+irc_handle_stats (const struct irc_message *msg, struct client *c)
+{
+	char query = 0;
+	if (msg->params.len > 0)
+		query = *msg->params.vector[0];
+	if (msg->params.len > 1 && !irc_is_this_me (c->ctx, msg->params.vector[1]))
+		RETURN_WITH_REPLY (c, IRC_ERR_NOSUCHSERVER, msg->params.vector[1]);
+	if (!(c->mode & IRC_USER_MODE_OPERATOR))
+		RETURN_WITH_REPLY (c, IRC_ERR_NOPRIVILEGES);
+
+	switch (query)
+	{
+	case 'L': irc_handle_stats_links    (c, msg); break;
+	case 'm': irc_handle_stats_commands (c);      break;
+	case 'u': irc_handle_stats_uptime   (c);      break;
+	}
+
+	irc_send_reply (c, IRC_RPL_ENDOFSTATS, query ? query : '*');
+}
+
+static void
+irc_handle_links (const struct irc_message *msg, struct client *c)
+{
+	if (msg->params.len > 1 && !irc_is_this_me (c->ctx, msg->params.vector[0]))
+		RETURN_WITH_REPLY (c, IRC_ERR_NOSUCHSERVER, msg->params.vector[0]);
+
+	const char *mask = "*";
+	if (msg->params.len > 0)
+		mask = msg->params.vector[msg->params.len > 1];
+
+	if (!irc_fnmatch (mask, c->ctx->server_name))
+		irc_send_reply (c, IRC_RPL_LINKS, mask,
+			c->ctx->server_name, 0 /* hop count */,
+			str_map_find (&c->ctx->config, "server_info"));
+	irc_send_reply (c, IRC_RPL_ENDOFLINKS, mask);
+}
+
+static void
+irc_handle_kill (const struct irc_message *msg, struct client *c)
+{
+	if (msg->params.len < 2)
+		RETURN_WITH_REPLY (c, IRC_ERR_NEEDMOREPARAMS, msg->command);
+	if (!(c->mode & IRC_USER_MODE_OPERATOR))
+		RETURN_WITH_REPLY (c, IRC_ERR_NOPRIVILEGES);
+
+	struct client *target;
+	if (!(target = str_map_find (&c->ctx->users, msg->params.vector[0])))
+		RETURN_WITH_REPLY (c, IRC_ERR_NOSUCHNICK, msg->params.vector[0]);
+
+	client_send (target, ":%s!%s@%s KILL %s :%s",
+		c->nickname, c->username, c->hostname,
+		target->nickname, msg->params.vector[1]);
+
+	char *reason = xstrdup_printf ("Killed by %s: %s",
+		c->nickname, msg->params.vector[1]);
+	client_close_link (target, reason);
+	free (reason);
+}
+
+static void
+irc_handle_die (const struct irc_message *msg, struct client *c)
+{
+	(void) msg;
+
+	if (!(c->mode & IRC_USER_MODE_OPERATOR))
+		RETURN_WITH_REPLY (c, IRC_ERR_NOPRIVILEGES);
+	if (!c->ctx->quitting)
+		irc_initiate_quit (c->ctx);
+}
+
+// -----------------------------------------------------------------------------
+
+static void
+irc_register_handlers (struct server_context *ctx)
+{
+	// TODO: add an index for IRC_ERR_NOSUCHSERVER validation?
+	// TODO: add a minimal parameter count?
+	// TODO: add a field for oper-only commands?
+	static struct irc_command message_handlers[] =
+	{
+		{ "CAP",      false, irc_handle_cap,      0, 0 },
+		{ "PASS",     false, irc_handle_pass,     0, 0 },
+		{ "NICK",     false, irc_handle_nick,     0, 0 },
+		{ "USER",     false, irc_handle_user,     0, 0 },
+
+		{ "USERHOST", true,  irc_handle_userhost, 0, 0 },
+		{ "LUSERS",   true,  irc_handle_lusers,   0, 0 },
+		{ "MOTD",     true,  irc_handle_motd,     0, 0 },
+		{ "PING",     true,  irc_handle_ping,     0, 0 },
+		{ "PONG",     false, irc_handle_pong,     0, 0 },
+		{ "QUIT",     false, irc_handle_quit,     0, 0 },
+		{ "TIME",     true,  irc_handle_time,     0, 0 },
+		{ "VERSION",  true,  irc_handle_version,  0, 0 },
+		{ "USERS",    true,  irc_handle_users,    0, 0 },
+		{ "SUMMON",   true,  irc_handle_summon,   0, 0 },
+		{ "AWAY",     true,  irc_handle_away,     0, 0 },
+		{ "ADMIN",    true,  irc_handle_admin,    0, 0 },
+		{ "STATS",    true,  irc_handle_stats,    0, 0 },
+		{ "LINKS",    true,  irc_handle_links,    0, 0 },
+
+		{ "MODE",     true,  irc_handle_mode,     0, 0 },
+		{ "PRIVMSG",  true,  irc_handle_privmsg,  0, 0 },
+		{ "NOTICE",   true,  irc_handle_notice,   0, 0 },
+		{ "JOIN",     true,  irc_handle_join,     0, 0 },
+		{ "PART",     true,  irc_handle_part,     0, 0 },
+		{ "KICK",     true,  irc_handle_kick,     0, 0 },
+		{ "INVITE",   true,  irc_handle_invite,   0, 0 },
+		{ "TOPIC",    true,  irc_handle_topic,    0, 0 },
+		{ "LIST",     true,  irc_handle_list,     0, 0 },
+		{ "NAMES",    true,  irc_handle_names,    0, 0 },
+		{ "WHO",      true,  irc_handle_who,      0, 0 },
+		{ "WHOIS",    true,  irc_handle_whois,    0, 0 },
+		{ "WHOWAS",   true,  irc_handle_whowas,   0, 0 },
+		{ "ISON",     true,  irc_handle_ison,     0, 0 },
+
+		{ "KILL",     true,  irc_handle_kill,     0, 0 },
+		{ "DIE",      true,  irc_handle_die,      0, 0 },
+	};
+
+	for (size_t i = 0; i < N_ELEMENTS (message_handlers); i++)
+	{
+		const struct irc_command *cmd = &message_handlers[i];
+		str_map_set (&ctx->handlers, cmd->name, (void *) cmd);
+	}
+}
+
+static void
+irc_process_message (const struct irc_message *msg,
+	const char *raw, void *user_data)
+{
+	struct client *c = user_data;
+	if (c->closing_link)
+		return;
+
+	c->n_received_messages++;
+	c->received_bytes += strlen (raw) + 2;
+
+	if (!flood_detector_check (&c->antiflood))
+	{
+		client_close_link (c, "Excess flood");
+		return;
+	}
+
+	struct irc_command *cmd = str_map_find (&c->ctx->handlers, msg->command);
+	if (!cmd)
+		irc_send_reply (c, IRC_ERR_UNKNOWNCOMMAND, msg->command);
+	else
+	{
+		cmd->n_received++;
+		cmd->bytes_received += strlen (raw) + 2;
+
+		if (cmd->requires_registration && !c->registered)
+			irc_send_reply (c, IRC_ERR_NOTREGISTERED);
+		else
+			cmd->handler (msg, c);
+	}
+}
+
+// --- Network I/O -------------------------------------------------------------
+
+static bool
+irc_try_read (struct client *c)
+{
+	struct str *buf = &c->read_buffer;
+	ssize_t n_read;
+
+	while (true)
+	{
+		str_reserve (buf, 512);
+		n_read = read (c->socket_fd, buf->str + buf->len,
+			buf->alloc - buf->len - 1 /* null byte */);
+
+		if (n_read > 0)
+		{
+			buf->str[buf->len += n_read] = '\0';
+			// TODO: discard characters above the 512 character limit
+			irc_process_buffer (buf, irc_process_message, c);
+			continue;
+		}
+		if (n_read == 0)
+		{
+			client_kill (c, NULL);
+			return false;
+		}
+
+		if (errno == EAGAIN)
+			return true;
+		if (errno == EINTR)
+			continue;
+
+		print_debug ("%s: %s: %s", __func__, "read", strerror (errno));
+		client_kill (c, strerror (errno));
+		return false;
+	}
+}
+
+static bool
+irc_try_read_tls (struct client *c)
+{
+	if (c->ssl_tx_want_rx)
+		return true;
+
+	struct str *buf = &c->read_buffer;
+	c->ssl_rx_want_tx = false;
+	while (true)
+	{
+		str_reserve (buf, 512);
+		ERR_clear_error ();
+		int n_read = SSL_read (c->ssl, buf->str + buf->len,
+			buf->alloc - buf->len - 1 /* null byte */);
+
+		const char *error_info = NULL;
+		switch (xssl_get_error (c->ssl, n_read, &error_info))
+		{
+		case SSL_ERROR_NONE:
+			buf->str[buf->len += n_read] = '\0';
+			// TODO: discard characters above the 512 character limit
+			irc_process_buffer (buf, irc_process_message, c);
+			continue;
+		case SSL_ERROR_ZERO_RETURN:
+			client_kill (c, NULL);
+			return false;
+		case SSL_ERROR_WANT_READ:
+			return true;
+		case SSL_ERROR_WANT_WRITE:
+			c->ssl_rx_want_tx = true;
+			return true;
+		case XSSL_ERROR_TRY_AGAIN:
+			continue;
+		default:
+			print_debug ("%s: %s: %s", __func__, "SSL_read", error_info);
+			client_kill (c, error_info);
+			return false;
+		}
+	}
+}
+
+static bool
+irc_try_write (struct client *c)
+{
+	struct str *buf = &c->write_buffer;
+	ssize_t n_written;
+
+	while (buf->len)
+	{
+		n_written = write (c->socket_fd, buf->str, buf->len);
+		if (n_written >= 0)
+		{
+			str_remove_slice (buf, 0, n_written);
+			continue;
+		}
+
+		if (errno == EAGAIN)
+			return true;
+		if (errno == EINTR)
+			continue;
+
+		print_debug ("%s: %s: %s", __func__, "write", strerror (errno));
+		client_kill (c, strerror (errno));
+		return false;
+	}
+	return true;
+}
+
+static bool
+irc_try_write_tls (struct client *c)
+{
+	if (c->ssl_rx_want_tx)
+		return true;
+
+	struct str *buf = &c->write_buffer;
+	c->ssl_tx_want_rx = false;
+	while (buf->len)
+	{
+		ERR_clear_error ();
+		int n_written = SSL_write (c->ssl, buf->str, buf->len);
+
+		const char *error_info = NULL;
+		switch (xssl_get_error (c->ssl, n_written, &error_info))
+		{
+		case SSL_ERROR_NONE:
+			str_remove_slice (buf, 0, n_written);
+			continue;
+		case SSL_ERROR_ZERO_RETURN:
+			client_kill (c, NULL);
+			return false;
+		case SSL_ERROR_WANT_WRITE:
+			return true;
+		case SSL_ERROR_WANT_READ:
+			c->ssl_tx_want_rx = true;
+			return true;
+		case XSSL_ERROR_TRY_AGAIN:
+			continue;
+		default:
+			print_debug ("%s: %s: %s", __func__, "SSL_write", error_info);
+			client_kill (c, error_info);
+			return false;
+		}
+	}
+	return true;
+}
+
+// -----------------------------------------------------------------------------
+
+static bool
+irc_autodetect_tls (struct client *c)
+{
+	// Trivial SSL/TLS autodetection.  The first block of data returned by
+	// recv() must be at least three bytes long for this to work reliably,
+	// but that should not pose a problem in practice.
+	//
+	// SSL2:      1xxx xxxx | xxxx xxxx |    <1>
+	//               (message length)  (client hello)
+	// SSL3/TLS:    <22>    |    <3>    | xxxx xxxx
+	//           (handshake)|  (protocol version)
+	//
+	// Such byte sequences should never occur at the beginning of regular IRC
+	// communication, which usually begins with USER/NICK/PASS/SERVICE.
+
+	char buf[3];
+start:
+	switch (recv (c->socket_fd, buf, sizeof buf, MSG_PEEK))
+	{
+	case 3:
+		if ((buf[0] & 0x80) && buf[2] == 1)
+			return true;
+		// Fall-through
+	case 2:
+		if (buf[0] == 22 && buf[1] == 3)
+			return true;
+		break;
+	case 1:
+		if (buf[0] == 22)
+			return true;
+		break;
+	case 0:
+		break;
+	default:
+		if (errno == EINTR)
+			goto start;
+	}
+	return false;
+}
+
+static bool
+client_initialize_tls (struct client *c)
+{
+	const char *error_info = NULL;
+	if (!c->ctx->ssl_ctx)
+	{
+		error_info = "TLS support disabled";
+		goto error_ssl_1;
+	}
+
+	ERR_clear_error ();
+
+	c->ssl = SSL_new (c->ctx->ssl_ctx);
+	if (!c->ssl)
+		goto error_ssl_2;
+	if (!SSL_set_fd (c->ssl, c->socket_fd))
+		goto error_ssl_3;
+
+	SSL_set_accept_state (c->ssl);
+	return true;
+
+error_ssl_3:
+	SSL_free (c->ssl);
+	c->ssl = NULL;
+error_ssl_2:
+	error_info = xerr_describe_error ();
+error_ssl_1:
+	print_debug ("could not initialize TLS for %s: %s", c->address, error_info);
+	return false;
+}
+
+// -----------------------------------------------------------------------------
+
+static void
+on_client_ready (const struct pollfd *pfd, void *user_data)
+{
+	struct client *c = user_data;
+	if (!c->initialized)
+	{
+		hard_assert (pfd->events == POLLIN);
+		if (irc_autodetect_tls (c) && !client_initialize_tls (c))
+		{
+			client_kill (c, NULL);
+			return;
+		}
+		c->initialized = true;
+		client_set_ping_timer (c);
+	}
+
+	if (c->ssl)
+	{
+		// Reads may want to write, writes may want to read, poll() may
+		// return unexpected things in `revents'... let's try both
+		if (!irc_try_read_tls (c) || !irc_try_write_tls (c))
+			return;
+	}
+	else if (!irc_try_read (c) || !irc_try_write (c))
+		return;
+
+	client_update_poller (c, pfd);
+
+	// The purpose of the `closing_link' state is to transfer the `ERROR'
+	if (c->closing_link && !c->half_closed && !c->write_buffer.len)
+	{
+		// To make sure the client has received our ERROR message, we must
+		// first half-close the connection, otherwise it could happen that they
+		// receive a RST from our TCP stack first when we receive further data
+
+		// We only send the "close notify" alert if libssl can write to the
+		// socket at this moment.  All the other data has been already written,
+		// though, and the client will receive a TCP half-close as usual, so
+		// it's not that important if the alert actually gets through.
+		if (c->ssl)
+			(void) SSL_shutdown (c->ssl);
+
+		// Either the shutdown succeeds, in which case we set a flag so that
+		// we don't retry this action and wait until we get an EOF, or it fails
+		// and we just kill the client straight away
+		if (!shutdown (c->socket_fd, SHUT_WR))
+			c->half_closed = true;
+		else
+			client_kill (c, NULL);
+	}
+}
+
+static void
+client_update_poller (struct client *c, const struct pollfd *pfd)
+{
+	// We must not poll for writing when the connection hasn't been initialized
+	int new_events = POLLIN;
+	if (c->ssl)
+	{
+		if (c->write_buffer.len || c->ssl_rx_want_tx)
+			new_events |= POLLOUT;
+
+		// While we're waiting for an opposite event, we ignore the original
+		if (c->ssl_rx_want_tx)  new_events &= ~POLLIN;
+		if (c->ssl_tx_want_rx)  new_events &= ~POLLOUT;
+	}
+	else if (c->initialized && c->write_buffer.len)
+		new_events |= POLLOUT;
+
+	hard_assert (new_events != 0);
+	if (!pfd || pfd->events != new_events)
+		poller_fd_set (&c->socket_event, new_events);
+}
+
+static void
+client_finish_connection (struct client *c)
+{
+	c->gni = NULL;
+
+	c->address = format_host_port_pair (c->hostname, c->port);
+	print_debug ("accepted connection from %s", c->address);
+
+	client_update_poller (c, NULL);
+	client_set_kill_timer (c);
+}
+
+static void
+on_client_gni_resolved (int result, char *host, char *port, void *user_data)
+{
+	struct client *c = user_data;
+
+	if (result)
+		print_debug ("%s: %s", "getnameinfo", gai_strerror (result));
+	else
+	{
+		cstr_set (&c->hostname, xstrdup (host));
+		(void) port;
+	}
+
+	poller_timer_reset (&c->gni_timer);
+	client_finish_connection (c);
+}
+
+static void
+on_client_gni_timer (struct client *c)
+{
+	async_cancel (&c->gni->async);
+	client_finish_connection (c);
+}
+
+static bool
+irc_try_fetch_client (struct server_context *ctx, int listen_fd)
+{
+	// XXX: `struct sockaddr_storage' is not the most portable thing
+	struct sockaddr_storage peer;
+	socklen_t peer_len = sizeof peer;
+
+	int fd = accept (listen_fd, (struct sockaddr *) &peer, &peer_len);
+	if (fd == -1)
+	{
+		if (errno == EAGAIN || errno == EWOULDBLOCK)
+			return false;
+		if (errno == EINTR)
+			return true;
+
+		if (errno == EBADF
+		 || errno == EINVAL
+		 || errno == ENOTSOCK
+		 || errno == EOPNOTSUPP)
+			print_fatal ("%s: %s", "accept", strerror (errno));
+
+		// OS kernels may return a wide range of unforeseeable errors.
+		// Assuming that they're either transient or caused by
+		// a connection that we've just extracted from the queue.
+		print_warning ("%s: %s", "accept", strerror (errno));
+		return true;
+	}
+
+	hard_assert (peer_len <= sizeof peer);
+	set_blocking (fd, false);
+
+	// A little bit questionable once the traffic gets high enough (IMO),
+	// but it reduces silly latencies that we don't need because we already
+	// do buffer our output
+	int yes = 1;
+	soft_assert (setsockopt (fd, IPPROTO_TCP, TCP_NODELAY,
+		&yes, sizeof yes) != -1);
+
+	if (ctx->max_connections != 0 && ctx->n_clients >= ctx->max_connections)
+	{
+		print_debug ("connection limit reached, refusing connection");
+		close (fd);
+		return true;
+	}
+
+	char host[NI_MAXHOST] = "unknown", port[NI_MAXSERV] = "unknown";
+	int err = getnameinfo ((struct sockaddr *) &peer, peer_len,
+		host, sizeof host, port, sizeof port, NI_NUMERICHOST | NI_NUMERICSERV);
+	if (err)
+		print_debug ("%s: %s", "getnameinfo", gai_strerror (err));
+
+	struct client *c = client_new ();
+	c->ctx = ctx;
+	c->opened = time (NULL);
+	c->socket_fd = fd;
+	c->hostname = xstrdup (host);
+	c->port = xstrdup (port);
+	c->last_active = time (NULL);
+	LIST_PREPEND (ctx->clients, c);
+	ctx->n_clients++;
+
+	c->socket_event = poller_fd_make (&c->ctx->poller, c->socket_fd);
+	c->socket_event.dispatcher = (poller_fd_fn) on_client_ready;
+	c->socket_event.user_data = c;
+
+	c->kill_timer = poller_timer_make (&c->ctx->poller);
+	c->kill_timer.dispatcher = (poller_timer_fn) on_client_kill_timer;
+	c->kill_timer.user_data = c;
+
+	c->timeout_timer = poller_timer_make (&c->ctx->poller);
+	c->timeout_timer.dispatcher = (poller_timer_fn) on_client_timeout_timer;
+	c->timeout_timer.user_data = c;
+
+	c->ping_timer = poller_timer_make (&c->ctx->poller);
+	c->ping_timer.dispatcher = (poller_timer_fn) on_client_ping_timer;
+	c->ping_timer.user_data = c;
+
+	// Resolve the client's hostname first; this is a blocking operation that
+	// depends on the network, so run it asynchronously with some timeout
+	c->gni = async_getnameinfo (&ctx->poller.common.async,
+		(const struct sockaddr *) &peer, peer_len, NI_NUMERICSERV);
+	c->gni->dispatcher = on_client_gni_resolved;
+	c->gni->user_data = c;
+
+	c->gni_timer = poller_timer_make (&c->ctx->poller);
+	c->gni_timer.dispatcher = (poller_timer_fn) on_client_gni_timer;
+	c->gni_timer.user_data = c;
+
+	poller_timer_set (&c->gni_timer, 5000);
+	return true;
+}
+
+static void
+on_irc_client_available (const struct pollfd *pfd, void *user_data)
+{
+	struct server_context *ctx = user_data;
+	while (irc_try_fetch_client (ctx, pfd->fd))
+		;
+}
+
+// --- Application setup -------------------------------------------------------
+
+static int
+irc_ssl_verify_callback (int verify_ok, X509_STORE_CTX *ctx)
+{
+	(void) verify_ok;
+	(void) ctx;
+
+	// RFC 5246: "If the client has sent a certificate with signing ability,
+	// a digitally-signed CertificateVerify message is sent to explicitly
+	// verify possession of the private key in the certificate."
+	//
+	// The handshake will fail if the client doesn't have a matching private
+	// key, see OpenSSL's tls_process_cert_verify(), and the CertificateVerify
+	// message cannot be skipped (except for a case where it doesn't matter).
+	// Thus we're fine checking just the cryptographic hash of the certificate.
+
+	// We only want to provide additional privileges based on the client's
+	// certificate, so let's not terminate the connection because of a failure
+	// (especially since self-signed certificates are likely to be used).
+	return 1;
+}
+
+static void
+irc_ssl_info_callback (const SSL *ssl, int where, int ret)
+{
+	// For debugging only; provides us with the most important information
+
+	struct str s = str_make ();
+	if (where & SSL_CB_LOOP)
+		str_append_printf (&s, "loop (%s) ",
+			SSL_state_string_long (ssl));
+	if (where & SSL_CB_EXIT)
+		str_append_printf (&s, "exit (%d in %s) ", ret,
+			SSL_state_string_long (ssl));
+
+	if (where & SSL_CB_READ)   str_append (&s, "read ");
+	if (where & SSL_CB_WRITE)  str_append (&s, "write ");
+
+	if (where & SSL_CB_ALERT)
+		str_append_printf (&s, "alert (%s: %s) ",
+			SSL_alert_type_string_long (ret),
+			SSL_alert_desc_string_long (ret));
+
+	if (where & SSL_CB_HANDSHAKE_START)  str_append (&s, "handshake start ");
+	if (where & SSL_CB_HANDSHAKE_DONE)   str_append (&s, "handshake done ");
+
+	print_debug ("ssl <%p> %s", ssl, s.str);
+	str_free (&s);
+}
+
+static bool
+irc_initialize_ssl_ctx (struct server_context *ctx,
+	const char *cert_path, const char *key_path, struct error **e)
+{
+	ERR_clear_error ();
+
+	ctx->ssl_ctx = SSL_CTX_new (SSLv23_server_method ());
+	if (!ctx->ssl_ctx)
+	{
+		error_set (e, "%s: %s", "could not initialize TLS",
+			xerr_describe_error ());
+		return false;
+	}
+	SSL_CTX_set_verify (ctx->ssl_ctx,
+		SSL_VERIFY_PEER | SSL_VERIFY_CLIENT_ONCE, irc_ssl_verify_callback);
+
+	if (g_debug_mode)
+		SSL_CTX_set_info_callback (ctx->ssl_ctx, irc_ssl_info_callback);
+
+	const unsigned char session_id_context[SSL_MAX_SSL_SESSION_ID_LENGTH]
+		= PROGRAM_NAME;
+	(void) SSL_CTX_set_session_id_context (ctx->ssl_ctx,
+		session_id_context, sizeof session_id_context);
+
+	// IRC is not particularly reconnect-heavy, prefer forward secrecy
+	SSL_CTX_set_session_cache_mode (ctx->ssl_ctx, SSL_SESS_CACHE_OFF);
+
+	// Gah, spare me your awkward semantics, I just want to push data!
+	SSL_CTX_set_mode (ctx->ssl_ctx,
+		SSL_MODE_ACCEPT_MOVING_WRITE_BUFFER | SSL_MODE_ENABLE_PARTIAL_WRITE);
+
+	// Disable deprecated protocols (see RFC 7568)
+	SSL_CTX_set_options (ctx->ssl_ctx, SSL_OP_NO_SSLv2 | SSL_OP_NO_SSLv3);
+
+	// XXX: perhaps we should read the files ourselves for better messages
+	const char *ciphers = str_map_find (&ctx->config, "tls_ciphers");
+	if (!SSL_CTX_set_cipher_list (ctx->ssl_ctx, ciphers))
+		error_set (e, "failed to select any cipher from the cipher list");
+	else if (!SSL_CTX_use_certificate_chain_file (ctx->ssl_ctx, cert_path))
+		error_set (e, "%s: %s", "setting the TLS certificate failed",
+			xerr_describe_error ());
+	else if (!SSL_CTX_use_PrivateKey_file
+		(ctx->ssl_ctx, key_path, SSL_FILETYPE_PEM))
+		error_set (e, "%s: %s", "setting the TLS private key failed",
+			xerr_describe_error ());
+	else
+		// TODO: SSL_CTX_check_private_key()?  It has probably already been
+		//   checked by SSL_CTX_use_PrivateKey_file() above.
+		return true;
+
+	SSL_CTX_free (ctx->ssl_ctx);
+	ctx->ssl_ctx = NULL;
+	return false;
+}
+
+static bool
+irc_initialize_tls (struct server_context *ctx, struct error **e)
+{
+	const char *tls_cert = str_map_find (&ctx->config, "tls_cert");
+	const char *tls_key  = str_map_find (&ctx->config, "tls_key");
+
+	// Only try to enable SSL support if the user configures it; it is not
+	// a failure if no one has requested it.
+	if (!tls_cert && !tls_key)
+		return true;
+
+	if (!tls_cert)
+		error_set (e, "no TLS certificate set");
+	else if (!tls_key)
+		error_set (e, "no TLS private key set");
+	if (!tls_cert || !tls_key)
+		return false;
+
+	bool result = false;
+
+	char *cert_path = resolve_filename
+		(tls_cert, resolve_relative_config_filename);
+	char *key_path = resolve_filename
+		(tls_key, resolve_relative_config_filename);
+	if (!cert_path)
+		error_set (e, "%s: %s", "cannot open file", tls_cert);
+	else if (!key_path)
+		error_set (e, "%s: %s", "cannot open file", tls_key);
+	else
+		result = irc_initialize_ssl_ctx (ctx, cert_path, key_path, e);
+
+	free (cert_path);
+	free (key_path);
+	return result;
+}
+
+static bool
+irc_initialize_catalog (struct server_context *ctx, struct error **e)
+{
+	hard_assert (ctx->catalog == (nl_catd) -1);
+	const char *catalog = str_map_find (&ctx->config, "catalog");
+	if (!catalog)
+		return true;
+
+	char *path = resolve_filename (catalog, resolve_relative_config_filename);
+	if (!path)
+	{
+		error_set (e, "%s: %s", "cannot open file", catalog);
+		return false;
+	}
+	ctx->catalog = catopen (path, NL_CAT_LOCALE);
+	free (path);
+
+	if (ctx->catalog == (nl_catd) -1)
+	{
+		error_set (e, "%s: %s",
+			"failed reading the message catalog file", strerror (errno));
+		return false;
+	}
+	return true;
+}
+
+static bool
+irc_initialize_motd (struct server_context *ctx, struct error **e)
+{
+	hard_assert (ctx->motd.len == 0);
+	const char *motd = str_map_find (&ctx->config, "motd");
+	if (!motd)
+		return true;
+
+	char *path = resolve_filename (motd, resolve_relative_config_filename);
+	if (!path)
+	{
+		error_set (e, "%s: %s", "cannot open file", motd);
+		return false;
+	}
+	FILE *fp = fopen (path, "r");
+	free (path);
+
+	if (!fp)
+	{
+		error_set (e, "%s: %s",
+			"failed reading the MOTD file", strerror (errno));
+		return false;
+	}
+
+	struct str line = str_make ();
+	while (read_line (fp, &line))
+		strv_append_owned (&ctx->motd, str_steal (&line));
+	str_free (&line);
+
+	fclose (fp);
+	return true;
+}
+
+static bool
+irc_parse_config_unsigned (const char *name, const char *value, unsigned *out,
+	unsigned long min, unsigned long max, struct error **e)
+{
+	unsigned long ul;
+	hard_assert (value != NULL);
+	if (!xstrtoul (&ul, value, 10) || ul > max || ul < min)
+	{
+		error_set (e, "invalid configuration value for `%s': %s",
+			name, "the number is invalid or out of range");
+		return false;
+	}
+	*out = ul;
+	return true;
+}
+
+/// This function handles values that require validation before their first use,
+/// or some kind of a transformation (such as conversion to an integer) needs
+/// to be done before they can be used directly.
+static bool
+irc_parse_config (struct server_context *ctx, struct error **e)
+{
+#define PARSE_UNSIGNED(name, min, max)                                         \
+	irc_parse_config_unsigned (#name, str_map_find (&ctx->config, #name),      \
+		&ctx->name, min, max, e)
+
+	if (!PARSE_UNSIGNED (ping_interval,   1, UINT_MAX)
+	 || !PARSE_UNSIGNED (max_connections, 0, UINT_MAX))
+		return false;
+
+	bool result = true;
+	struct strv fingerprints = strv_make ();
+	const char *operators = str_map_find (&ctx->config, "operators");
+	if (operators)
+		cstr_split (operators, ",", true, &fingerprints);
+	for (size_t i = 0; i < fingerprints.len; i++)
+	{
+		const char *key = fingerprints.vector[i];
+		if (!irc_is_valid_fingerprint (key))
+		{
+			error_set (e, "invalid configuration value for `%s': %s",
+				"operators", "invalid fingerprint value");
+			result = false;
+			break;
+		}
+		str_map_set (&ctx->operators, key, (void *) 1);
+	}
+	strv_free (&fingerprints);
+	return result;
+}
+
+static bool
+irc_initialize_server_name (struct server_context *ctx, struct error **e)
+{
+	enum validation_result res;
+	const char *server_name = str_map_find (&ctx->config, "server_name");
+	if (server_name)
+	{
+		res = irc_validate_hostname (server_name);
+		if (res != VALIDATION_OK)
+		{
+			error_set (e, "invalid configuration value for `%s': %s",
+				"server_name", irc_validate_to_str (res));
+			return false;
+		}
+		ctx->server_name = xstrdup (server_name);
+	}
+	else
+	{
+		long host_name_max = sysconf (_SC_HOST_NAME_MAX);
+		if (host_name_max <= 0)
+			host_name_max = _POSIX_HOST_NAME_MAX;
+
+		char hostname[host_name_max + 1];
+		if (gethostname (hostname, sizeof hostname))
+		{
+			error_set (e, "%s: %s",
+				"getting the hostname failed", strerror (errno));
+			return false;
+		}
+		res = irc_validate_hostname (hostname);
+		if (res != VALIDATION_OK)
+		{
+			error_set (e,
+				"`%s' is not set and the hostname (`%s') cannot be used: %s",
+				"server_name", hostname, irc_validate_to_str (res));
+			return false;
+		}
+		ctx->server_name = xstrdup (hostname);
+	}
+	return true;
+}
+
+static bool
+irc_lock_pid_file (struct server_context *ctx, struct error **e)
+{
+	const char *path = str_map_find (&ctx->config, "pid_file");
+	if (!path)
+		return true;
+
+	char *resolved = resolve_filename (path, resolve_relative_runtime_filename);
+	bool result = lock_pid_file (resolved, e) != -1;
+	free (resolved);
+	return result;
+}
+
+static int
+irc_listen (struct addrinfo *gai_iter)
+{
+	int fd = socket (gai_iter->ai_family,
+		gai_iter->ai_socktype, gai_iter->ai_protocol);
+	if (fd == -1)
+		return -1;
+	set_cloexec (fd);
+
+	int yes = 1;
+	soft_assert (setsockopt (fd, SOL_SOCKET, SO_KEEPALIVE,
+		&yes, sizeof yes) != -1);
+	soft_assert (setsockopt (fd, SOL_SOCKET, SO_REUSEADDR,
+		&yes, sizeof yes) != -1);
+
+#if defined SOL_IPV6 && defined IPV6_V6ONLY
+	// Make NULL always bind to both IPv4 and IPv6, irrespectively of the order
+	// of results; only INADDR6_ANY seems to be affected by this
+	if (gai_iter->ai_family == AF_INET6)
+		soft_assert (setsockopt (fd, SOL_IPV6, IPV6_V6ONLY,
+			&yes, sizeof yes) != -1);
+#endif
+
+	char host[NI_MAXHOST], port[NI_MAXSERV];
+	host[0] = port[0] = '\0';
+	int err = getnameinfo (gai_iter->ai_addr, gai_iter->ai_addrlen,
+		host, sizeof host, port, sizeof port,
+		NI_NUMERICHOST | NI_NUMERICSERV);
+	if (err)
+		print_debug ("%s: %s", "getnameinfo", gai_strerror (err));
+
+	char *address = format_host_port_pair (host, port);
+	if (bind (fd, gai_iter->ai_addr, gai_iter->ai_addrlen))
+		print_error ("bind to %s failed: %s", address, strerror (errno));
+	else if (listen (fd, 16 /* arbitrary number */))
+		print_error ("listen on %s failed: %s", address, strerror (errno));
+	else
+	{
+		print_status ("listening on %s", address);
+		free (address);
+		return fd;
+	}
+
+	free (address);
+	xclose (fd);
+	return -1;
+}
+
+static void
+irc_listen_resolve (struct server_context *ctx,
+	const char *host, const char *port, struct addrinfo *gai_hints)
+{
+	struct addrinfo *gai_result, *gai_iter;
+	int err = getaddrinfo (host, port, gai_hints, &gai_result);
+	if (err)
+	{
+		char *address = format_host_port_pair (host, port);
+		print_error ("bind to %s failed: %s: %s",
+			address, "getaddrinfo", gai_strerror (err));
+		free (address);
+		return;
+	}
+
+	int fd;
+	for (gai_iter = gai_result; gai_iter; gai_iter = gai_iter->ai_next)
+	{
+		if (ctx->listen_len == ctx->listen_alloc)
+			break;
+
+		if ((fd = irc_listen (gai_iter)) == -1)
+			continue;
+		set_blocking (fd, false);
+
+		struct poller_fd *event = &ctx->listen_events[ctx->listen_len];
+		*event = poller_fd_make (&ctx->poller, fd);
+		event->dispatcher = (poller_fd_fn) on_irc_client_available;
+		event->user_data = ctx;
+
+		ctx->listen_fds[ctx->listen_len++] = fd;
+		poller_fd_set (event, POLLIN);
+	}
+	freeaddrinfo (gai_result);
+}
+
+static bool
+irc_setup_listen_fds (struct server_context *ctx, struct error **e)
+{
+	const char *bind_host = str_map_find (&ctx->config, "bind_host");
+	const char *bind_port = str_map_find (&ctx->config, "bind_port");
+	hard_assert (bind_port != NULL);  // We have a default value for this
+
+	struct addrinfo gai_hints;
+	memset (&gai_hints, 0, sizeof gai_hints);
+
+	gai_hints.ai_socktype = SOCK_STREAM;
+	gai_hints.ai_flags = AI_PASSIVE;
+
+	struct strv ports = strv_make ();
+	cstr_split (bind_port, ",", true, &ports);
+
+	// For C and simplicity's sake let's assume that the host will resolve
+	// to at most two different addresses: IPv4 and IPv6 in case it is NULL
+	ctx->listen_alloc = ports.len * 2;
+
+	ctx->listen_fds =
+		xcalloc (ctx->listen_alloc, sizeof *ctx->listen_fds);
+	ctx->listen_events =
+		xcalloc (ctx->listen_alloc, sizeof *ctx->listen_events);
+	for (size_t i = 0; i < ports.len; i++)
+		irc_listen_resolve (ctx, bind_host, ports.vector[i], &gai_hints);
+	strv_free (&ports);
+
+	if (!ctx->listen_len)
+	{
+		error_set (e, "%s: %s",
+			"network setup failed", "no ports to listen on");
+		return false;
+	}
+	return true;
+}
+
+// --- Main --------------------------------------------------------------------
+
+static void
+on_signal_pipe_readable (const struct pollfd *fd, struct server_context *ctx)
+{
+	char dummy;
+	(void) read (fd->fd, &dummy, 1);
+
+	if (g_termination_requested && !ctx->quitting)
+		irc_initiate_quit (ctx);
+}
+
+static void
+daemonize (struct server_context *ctx)
+{
+	print_status ("daemonizing...");
+
+	if (chdir ("/"))
+		exit_fatal ("%s: %s", "chdir", strerror (errno));
+
+	// Because of systemd, we need to exit the parent process _after_ writing
+	// a PID file, otherwise our grandchild would receive a SIGTERM
+	int sync_pipe[2];
+	if (pipe (sync_pipe))
+		exit_fatal ("%s: %s", "pipe", strerror (errno));
+
+	pid_t pid;
+	if ((pid = fork ()) < 0)
+		exit_fatal ("%s: %s", "fork", strerror (errno));
+	else if (pid)
+	{
+		// Wait until all write ends of the pipe are closed, which can mean
+		// either success or failure, we don't need to care
+		xclose (sync_pipe[PIPE_WRITE]);
+
+		char dummy;
+		if (read (sync_pipe[PIPE_READ], &dummy, 1) < 0)
+			exit_fatal ("%s: %s", "read", strerror (errno));
+
+		exit (EXIT_SUCCESS);
+	}
+
+	setsid ();
+	signal (SIGHUP, SIG_IGN);
+
+	if ((pid = fork ()) < 0)
+		exit_fatal ("%s: %s", "fork", strerror (errno));
+	else if (pid)
+		exit (EXIT_SUCCESS);
+
+	openlog (PROGRAM_NAME, LOG_NDELAY | LOG_NOWAIT | LOG_PID, 0);
+	g_log_message_real = log_message_syslog;
+
+	// Write the PID file (if so configured) and get rid of the pipe, so that
+	// the read() in our grandparent finally returns zero (no write ends)
+	struct error *e = NULL;
+	if (!irc_lock_pid_file (ctx, &e))
+		exit_fatal ("%s", e->message);
+
+	xclose (sync_pipe[PIPE_READ]);
+	xclose (sync_pipe[PIPE_WRITE]);
+
+	// XXX: we may close our own descriptors this way, crippling ourselves;
+	//   there is no real guarantee that we will start with all three
+	//   descriptors open.  In theory we could try to enumerate the descriptors
+	//   at the start of main().
+	for (int i = 0; i < 3; i++)
+		xclose (i);
+
+	int tty = open ("/dev/null", O_RDWR);
+	if (tty != 0 || dup (0) != 1 || dup (0) != 2)
+		exit_fatal ("failed to reopen FD's: %s", strerror (errno));
+
+	poller_post_fork (&ctx->poller);
+}
+
+int
+main (int argc, char *argv[])
+{
+	// Need to call this first as all string maps depend on it
+	siphash_wrapper_randomize ();
+
+	static const struct opt opts[] =
+	{
+		{ 'd', "debug", NULL, 0, "run in debug mode (do not daemonize)" },
+		{ 'h', "help", NULL, 0, "display this help and exit" },
+		{ 'V', "version", NULL, 0, "output version information and exit" },
+		{ 'w', "write-default-cfg", "FILENAME",
+		  OPT_OPTIONAL_ARG | OPT_LONG_ONLY,
+		  "write a default configuration file and exit" },
+		{ 0, NULL, NULL, 0, NULL }
+	};
+
+	struct opt_handler oh =
+		opt_handler_make (argc, argv, opts, NULL, "IRC daemon.");
+
+	int c;
+	while ((c = opt_handler_get (&oh)) != -1)
+	switch (c)
+	{
+	case 'd':
+		g_debug_mode = true;
+		break;
+	case 'h':
+		opt_handler_usage (&oh, stdout);
+		exit (EXIT_SUCCESS);
+	case 'V':
+		printf (PROGRAM_NAME " " PROGRAM_VERSION "\n");
+		exit (EXIT_SUCCESS);
+	case 'w':
+		call_simple_config_write_default (optarg, g_config_table);
+		exit (EXIT_SUCCESS);
+	default:
+		print_error ("wrong options");
+		opt_handler_usage (&oh, stderr);
+		exit (EXIT_FAILURE);
+	}
+
+	opt_handler_free (&oh);
+
+	print_status (PROGRAM_NAME " " PROGRAM_VERSION " starting");
+	setup_signal_handlers ();
+	init_openssl ();
+
+	struct server_context ctx;
+	server_context_init (&ctx);
+	ctx.started = time (NULL);
+	irc_register_handlers (&ctx);
+	irc_register_cap_handlers (&ctx);
+
+	struct error *e = NULL;
+	if (!simple_config_update_from_file (&ctx.config, &e))
+	{
+		print_error ("error loading configuration: %s", e->message);
+		error_free (e);
+		exit (EXIT_FAILURE);
+	}
+
+	ctx.signal_event = poller_fd_make (&ctx.poller, g_signal_pipe[0]);
+	ctx.signal_event.dispatcher = (poller_fd_fn) on_signal_pipe_readable;
+	ctx.signal_event.user_data = &ctx;
+	poller_fd_set (&ctx.signal_event, POLLIN);
+
+	if (!irc_initialize_tls (&ctx, &e)
+	 || !irc_initialize_server_name (&ctx, &e)
+	 || !irc_initialize_motd (&ctx, &e)
+	 || !irc_initialize_catalog (&ctx, &e)
+	 || !irc_parse_config (&ctx, &e)
+	 || !irc_setup_listen_fds (&ctx, &e))
+		exit_fatal ("%s", e->message);
+
+	if (!g_debug_mode)
+		daemonize (&ctx);
+	else if (!irc_lock_pid_file (&ctx, &e))
+		exit_fatal ("%s", e->message);
+
+#if OpenBSD >= 201605
+	// This won't be as simple once we decide to implement REHASH
+	if (pledge ("stdio inet dns", NULL))
+		exit_fatal ("%s: %s", "pledge", strerror (errno));
+#endif
+
+	ctx.polling = true;
+	while (ctx.polling)
+		poller_run (&ctx.poller);
+
+	server_context_free (&ctx);
+	return EXIT_SUCCESS;
+}