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, 2063 insertions, 0 deletions

diff --git a/xB.c b/xB.c
new file mode 100644
index 0000000..9e36040
--- /dev/null
+++ b/xB.c
@@ -0,0 +1,2063 @@
+/*
+ * xB.c: a modular IRC bot
+ *
+ * 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 "xB"
+
+#include "common.c"
+
+// --- Configuration (application-specific) ------------------------------------
+
+static struct simple_config_item g_config_table[] =
+{
+	{ "nickname",        "xB",              "IRC nickname"                   },
+	{ "username",        "bot",             "IRC user name"                  },
+	{ "realname",        "xB IRC bot",      "IRC real name/e-mail"           },
+
+	{ "irc_host",        NULL,              "Address of the IRC server"      },
+	{ "irc_port",        "6667",            "Port of the IRC server"         },
+	{ "tls",             "off",             "Whether to use TLS"             },
+	{ "tls_cert",        NULL,              "Client TLS certificate (PEM)"   },
+	{ "tls_verify",      "on",              "Whether to verify certificates" },
+	{ "tls_ca_file",     NULL,              "OpenSSL CA bundle file"         },
+	{ "tls_ca_path",     NULL,              "OpenSSL CA bundle path"         },
+	{ "autojoin",        NULL,              "Channels to join on start"      },
+	{ "reconnect",       "on",              "Whether to reconnect on error"  },
+	{ "reconnect_delay", "5",               "Time between reconnecting"      },
+
+	{ "socks_host",      NULL,              "Address of a SOCKS 4a/5 proxy"  },
+	{ "socks_port",      "1080",            "SOCKS port number"              },
+	{ "socks_username",  NULL,              "SOCKS auth. username"           },
+	{ "socks_password",  NULL,              "SOCKS auth. password"           },
+
+	{ "prefix",          ":",               "The prefix for bot commands"    },
+	{ "admin",           NULL,              "Host mask for administrators"   },
+	{ "plugins",         NULL,              "The plugins to load on startup" },
+	{ "plugin_dir",      NULL,              "Plugin search path override"    },
+	{ "recover",         "on",              "Whether to re-launch on crash"  },
+
+	{ NULL,              NULL,              NULL                             }
+};
+
+// --- Application data --------------------------------------------------------
+
+struct plugin
+{
+	LIST_HEADER (struct plugin)
+	struct bot_context *ctx;            ///< Parent context
+
+	char *name;                         ///< Plugin identifier
+	pid_t pid;                          ///< PID of the plugin process
+
+	bool is_zombie;                     ///< Whether the child is a zombie
+	bool initialized;                   ///< Ready to exchange IRC messages
+	struct str queued_output;           ///< Output queued up until initialized
+
+	// Since we're doing non-blocking I/O, we need to queue up data so that
+	// we don't stall on plugins unnecessarily.
+
+	int read_fd;                        ///< The read end of the comm. pipe
+	int write_fd;                       ///< The write end of the comm. pipe
+
+	struct poller_fd read_event;        ///< Read FD event
+	struct poller_fd write_event;       ///< Write FD event
+
+	struct str read_buffer;             ///< Unprocessed input
+	struct str write_buffer;            ///< Output yet to be sent out
+};
+
+static struct plugin *
+plugin_new (void)
+{
+	struct plugin *self = xcalloc (1, sizeof *self);
+	self->pid = -1;
+	self->queued_output = str_make ();
+
+	self->read_fd = -1;
+	self->read_buffer = str_make ();
+	self->write_fd = -1;
+	self->write_buffer = str_make ();
+	return self;
+}
+
+static void
+plugin_destroy (struct plugin *self)
+{
+	soft_assert (self->pid == -1);
+	free (self->name);
+
+	str_free (&self->read_buffer);
+	if (!soft_assert (self->read_fd == -1))
+		xclose (self->read_fd);
+
+	str_free (&self->write_buffer);
+	if (!soft_assert (self->write_fd == -1))
+		xclose (self->write_fd);
+
+	if (!self->initialized)
+		str_free (&self->queued_output);
+
+	free (self);
+}
+
+// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+
+struct bot_context
+{
+	struct str_map config;              ///< User configuration
+	regex_t *admin_re;                  ///< Regex to match our administrator
+	bool reconnect;                     ///< Whether to reconnect on conn. fail.
+	unsigned long reconnect_delay;      ///< Reconnect delay in seconds
+
+	int irc_fd;                         ///< Socket FD of the server
+	struct str read_buffer;             ///< Input yet to be processed
+	struct poller_fd irc_event;         ///< IRC FD event
+	bool irc_registered;                ///< Whether we may send messages now
+
+	struct poller_fd signal_event;      ///< Signal FD event
+	struct poller_timer ping_tmr;       ///< We should send a ping
+	struct poller_timer timeout_tmr;    ///< Connection seems to be dead
+	struct poller_timer reconnect_tmr;  ///< We should reconnect now
+
+	SSL_CTX *ssl_ctx;                   ///< SSL context
+	SSL *ssl;                           ///< SSL connection
+
+	struct plugin *plugins;             ///< Linked list of plugins
+	struct str_map plugins_by_name;     ///< Indexes @em plugins by their name
+
+	struct poller poller;               ///< Manages polled descriptors
+	bool quitting;                      ///< User requested quitting
+	bool polling;                       ///< The event loop is running
+};
+
+static void on_irc_ping_timeout (void *user_data);
+static void on_irc_timeout (void *user_data);
+static void on_irc_reconnect_timeout (void *user_data);
+
+static void
+bot_context_init (struct bot_context *self)
+{
+	self->config = str_map_make (free);
+	simple_config_load_defaults (&self->config, g_config_table);
+	self->admin_re = NULL;
+
+	self->irc_fd = -1;
+	self->read_buffer = str_make ();
+	self->irc_registered = false;
+
+	self->ssl = NULL;
+	self->ssl_ctx = NULL;
+
+	self->plugins = NULL;
+	self->plugins_by_name = str_map_make (NULL);
+
+	poller_init (&self->poller);
+	self->quitting = false;
+	self->polling = false;
+
+	self->timeout_tmr = poller_timer_make (&self->poller);
+	self->timeout_tmr.dispatcher = on_irc_timeout;
+	self->timeout_tmr.user_data = self;
+
+	self->ping_tmr = poller_timer_make (&self->poller);
+	self->ping_tmr.dispatcher = on_irc_ping_timeout;
+	self->ping_tmr.user_data = self;
+
+	self->reconnect_tmr = poller_timer_make (&self->poller);
+	self->reconnect_tmr.dispatcher = on_irc_reconnect_timeout;
+	self->reconnect_tmr.user_data = self;
+}
+
+static void
+bot_context_free (struct bot_context *self)
+{
+	str_map_free (&self->config);
+	if (self->admin_re)
+		regex_free (self->admin_re);
+	str_free (&self->read_buffer);
+
+	// TODO: terminate the plugins properly before this is called
+	LIST_FOR_EACH (struct plugin, link, self->plugins)
+		plugin_destroy (link);
+
+	if (self->irc_fd != -1)
+	{
+		poller_fd_reset (&self->irc_event);
+		xclose (self->irc_fd);
+	}
+	if (self->ssl)
+		SSL_free (self->ssl);
+	if (self->ssl_ctx)
+		SSL_CTX_free (self->ssl_ctx);
+
+	str_map_free (&self->plugins_by_name);
+	poller_free (&self->poller);
+}
+
+static void
+irc_shutdown (struct bot_context *ctx)
+{
+	// TODO: set a timer after which we cut the connection?
+	// Generally non-critical
+	if (ctx->ssl)
+		soft_assert (SSL_shutdown (ctx->ssl) != -1);
+	else
+		soft_assert (shutdown (ctx->irc_fd, SHUT_WR) == 0);
+}
+
+static void
+try_finish_quit (struct bot_context *ctx)
+{
+	if (ctx->quitting && ctx->irc_fd == -1 && !ctx->plugins)
+		ctx->polling = false;
+}
+
+static bool plugin_zombify (struct plugin *);
+
+static void
+initiate_quit (struct bot_context *ctx)
+{
+	// Initiate bringing down of the two things that block our shutdown:
+	// a/ the IRC socket, b/ our child processes:
+
+	for (struct plugin *plugin = ctx->plugins;
+		plugin; plugin = plugin->next)
+		plugin_zombify (plugin);
+	if (ctx->irc_fd != -1)
+		irc_shutdown (ctx);
+
+	ctx->quitting = true;
+	try_finish_quit (ctx);
+}
+
+static bool irc_send (struct bot_context *ctx,
+	const char *format, ...) ATTRIBUTE_PRINTF (2, 3);
+
+static bool
+irc_send (struct bot_context *ctx, const char *format, ...)
+{
+	va_list ap;
+
+	if (g_debug_mode)
+	{
+		fputs ("[IRC] <== \"", stderr);
+		va_start (ap, format);
+		vfprintf (stderr, format, ap);
+		va_end (ap);
+		fputs ("\"\n", stderr);
+	}
+
+	if (!soft_assert (ctx->irc_fd != -1))
+		return false;
+
+	va_start (ap, format);
+	struct str str = str_make ();
+	str_append_vprintf (&str, format, ap);
+	str_append (&str, "\r\n");
+	va_end (ap);
+
+	bool result = true;
+	if (ctx->ssl)
+	{
+		// TODO: call SSL_get_error() to detect if a clean shutdown has occured
+		ERR_clear_error ();
+		if (SSL_write (ctx->ssl, str.str, str.len) != (int) str.len)
+		{
+			print_debug ("%s: %s: %s", __func__, "SSL_write",
+				xerr_describe_error ());
+			result = false;
+		}
+	}
+	else if (write (ctx->irc_fd, str.str, str.len) != (ssize_t) str.len)
+	{
+		print_debug ("%s: %s: %s", __func__, "write", strerror (errno));
+		result = false;
+	}
+
+	str_free (&str);
+	return result;
+}
+
+static bool
+irc_get_boolean_from_config
+	(struct bot_context *ctx, const char *name, bool *value, struct error **e)
+{
+	const char *str = str_map_find (&ctx->config, name);
+	hard_assert (str != NULL);
+
+	if (set_boolean_if_valid (value, str))
+		return true;
+
+	return error_set (e, "invalid configuration value for `%s'", name);
+}
+
+static bool
+irc_initialize_ca_set (SSL_CTX *ssl_ctx, const char *file, const char *path,
+	struct error **e)
+{
+	ERR_clear_error ();
+
+	if (file || path)
+	{
+		if (SSL_CTX_load_verify_locations (ssl_ctx, file, path))
+			return true;
+
+		return error_set (e, "%s: %s",
+			"failed to set locations for the CA certificate bundle",
+			xerr_describe_error ());
+	}
+
+	if (!SSL_CTX_set_default_verify_paths (ssl_ctx))
+		return error_set (e, "%s: %s",
+			"couldn't load the default CA certificate bundle",
+			xerr_describe_error ());
+	return true;
+}
+
+static bool
+irc_initialize_ca (struct bot_context *ctx, struct error **e)
+{
+	const char *ca_file = str_map_find (&ctx->config, "tls_ca_file");
+	const char *ca_path = str_map_find (&ctx->config, "tls_ca_path");
+
+	char *full_file = ca_file
+		? resolve_filename (ca_file, resolve_relative_config_filename) : NULL;
+	char *full_path = ca_path
+		? resolve_filename (ca_path, resolve_relative_config_filename) : NULL;
+
+	bool ok = false;
+	if      (ca_file && !full_file)
+		error_set (e, "couldn't find the CA bundle file");
+	else if (ca_path && !full_path)
+		error_set (e, "couldn't find the CA bundle path");
+	else
+		ok = irc_initialize_ca_set (ctx->ssl_ctx, full_file, full_path, e);
+
+	free (full_file);
+	free (full_path);
+	return ok;
+}
+
+static bool
+irc_initialize_ssl_ctx (struct bot_context *ctx, struct error **e)
+{
+	// Disable deprecated protocols (see RFC 7568)
+	SSL_CTX_set_options (ctx->ssl_ctx, SSL_OP_NO_SSLv2 | SSL_OP_NO_SSLv3);
+
+	bool verify;
+	if (!irc_get_boolean_from_config (ctx, "tls_verify", &verify, e))
+		return false;
+	SSL_CTX_set_verify (ctx->ssl_ctx,
+		verify ? SSL_VERIFY_PEER : SSL_VERIFY_NONE, NULL);
+
+	struct error *error = NULL;
+	if (!irc_initialize_ca (ctx, &error))
+	{
+		if (verify)
+		{
+			error_propagate (e, error);
+			return false;
+		}
+
+		// Only inform the user if we're not actually verifying
+		print_warning ("%s", error->message);
+		error_free (error);
+	}
+	return true;
+}
+
+static bool
+irc_initialize_tls (struct bot_context *ctx, struct error **e)
+{
+	const char *error_info = NULL;
+	ctx->ssl_ctx = SSL_CTX_new (SSLv23_client_method ());
+	if (!ctx->ssl_ctx)
+		goto error_ssl_1;
+	if (!irc_initialize_ssl_ctx (ctx, e))
+		goto error_ssl_2;
+
+	ctx->ssl = SSL_new (ctx->ssl_ctx);
+	if (!ctx->ssl)
+		goto error_ssl_2;
+
+	const char *tls_cert = str_map_find (&ctx->config, "tls_cert");
+	if (tls_cert)
+	{
+		char *path = resolve_filename
+			(tls_cert, resolve_relative_config_filename);
+		if (!path)
+			print_error ("%s: %s", "cannot open file", tls_cert);
+		// XXX: perhaps we should read the file ourselves for better messages
+		else if (!SSL_use_certificate_file (ctx->ssl, path, SSL_FILETYPE_PEM)
+			|| !SSL_use_PrivateKey_file (ctx->ssl, path, SSL_FILETYPE_PEM))
+			print_error ("%s: %s", "setting the TLS client certificate failed",
+				xerr_describe_error ());
+		free (path);
+	}
+
+	SSL_set_connect_state (ctx->ssl);
+	if (!SSL_set_fd (ctx->ssl, ctx->irc_fd))
+		goto error_ssl_3;
+	// Avoid SSL_write() returning SSL_ERROR_WANT_READ
+	SSL_set_mode (ctx->ssl, SSL_MODE_AUTO_RETRY);
+
+	switch (xssl_get_error (ctx->ssl, SSL_connect (ctx->ssl), &error_info))
+	{
+	case SSL_ERROR_NONE:
+		return true;
+	case SSL_ERROR_ZERO_RETURN:
+		error_info = "server closed the connection";
+	default:
+		break;
+	}
+
+error_ssl_3:
+	SSL_free (ctx->ssl);
+	ctx->ssl = NULL;
+error_ssl_2:
+	SSL_CTX_free (ctx->ssl_ctx);
+	ctx->ssl_ctx = NULL;
+error_ssl_1:
+	if (!error_info)
+		error_info = xerr_describe_error ();
+	return error_set (e, "%s: %s", "could not initialize TLS", error_info);
+}
+
+static bool
+irc_establish_connection (struct bot_context *ctx,
+	const char *host, const char *port, struct error **e)
+{
+	struct addrinfo gai_hints, *gai_result, *gai_iter;
+	memset (&gai_hints, 0, sizeof gai_hints);
+	gai_hints.ai_socktype = SOCK_STREAM;
+
+	int err = getaddrinfo (host, port, &gai_hints, &gai_result);
+	if (err)
+		return error_set (e, "%s: %s: %s", "connection failed",
+			"getaddrinfo", gai_strerror (err));
+
+	int sockfd;
+	for (gai_iter = gai_result; gai_iter; gai_iter = gai_iter->ai_next)
+	{
+		sockfd = socket (gai_iter->ai_family,
+			gai_iter->ai_socktype, gai_iter->ai_protocol);
+		if (sockfd == -1)
+			continue;
+		set_cloexec (sockfd);
+
+		int yes = 1;
+		soft_assert (setsockopt (sockfd, SOL_SOCKET, SO_KEEPALIVE,
+			&yes, sizeof yes) != -1);
+
+		const char *real_host = host;
+
+		// Let's try to resolve the address back into a real hostname;
+		// we don't really need this, so we can let it quietly fail
+		char buf[NI_MAXHOST];
+		err = getnameinfo (gai_iter->ai_addr, gai_iter->ai_addrlen,
+			buf, sizeof buf, NULL, 0, 0);
+		if (err)
+			print_debug ("%s: %s", "getnameinfo", gai_strerror (err));
+		else
+			real_host = buf;
+
+		// XXX: we shouldn't mix these statuses with `struct error'; choose 1!
+		char *address = format_host_port_pair (real_host, port);
+		print_status ("connecting to %s...", address);
+		free (address);
+
+		if (!connect (sockfd, gai_iter->ai_addr, gai_iter->ai_addrlen))
+			break;
+
+		xclose (sockfd);
+	}
+
+	freeaddrinfo (gai_result);
+
+	if (!gai_iter)
+		return error_set (e, "connection failed");
+
+	ctx->irc_fd = sockfd;
+	return true;
+}
+
+// --- Signals -----------------------------------------------------------------
+
+static int g_signal_pipe[2];            ///< A pipe used to signal... signals
+
+static struct strv
+	g_original_argv,                    ///< Original program arguments
+	g_recovery_env;                     ///< Environment for re-exec recovery
+
+/// Program termination has been requested by a signal
+static volatile sig_atomic_t g_termination_requested;
+
+/// Points to startup reason location within `g_recovery_environment'
+static char **g_startup_reason_location;
+/// The environment variable used to pass the startup reason when re-executing
+static const char g_startup_reason_str[] = "STARTUP_REASON";
+
+static void
+sigchld_handler (int signum)
+{
+	(void) signum;
+
+	int original_errno = errno;
+	// Just so that the read end of the pipe wakes up the poller.
+	// NOTE: Linux has signalfd() and eventfd(), and the BSD's have kqueue.
+	//   All of them are better than this approach, although platform-specific.
+	if (write (g_signal_pipe[1], "c", 1) == -1)
+		soft_assert (errno == EAGAIN);
+	errno = original_errno;
+}
+
+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);
+
+	struct sigaction sa;
+	sa.sa_flags = SA_RESTART;
+	sa.sa_handler = sigchld_handler;
+	sigemptyset (&sa.sa_mask);
+
+	if (sigaction (SIGCHLD, &sa, NULL) == -1)
+		exit_fatal ("sigaction: %s", strerror (errno));
+
+	signal (SIGPIPE, SIG_IGN);
+
+	sa.sa_handler = sigterm_handler;
+	if (sigaction (SIGINT, &sa, NULL) == -1
+	 || sigaction (SIGTERM, &sa, NULL) == -1)
+		exit_fatal ("sigaction: %s", strerror (errno));
+}
+
+static void
+translate_signal_info (int no, const char **name, int code, const char **reason)
+{
+	if (code == SI_USER)         *reason = "signal sent by kill()";
+	if (code == SI_QUEUE)        *reason = "signal sent by sigqueue()";
+
+	switch (no)
+	{
+	case SIGILL:
+		*name = "SIGILL";
+		if (code == ILL_ILLOPC)  *reason = "illegal opcode";
+		if (code == ILL_ILLOPN)  *reason = "illegal operand";
+		if (code == ILL_ILLADR)  *reason = "illegal addressing mode";
+		if (code == ILL_ILLTRP)  *reason = "illegal trap";
+		if (code == ILL_PRVOPC)  *reason = "privileged opcode";
+		if (code == ILL_PRVREG)  *reason = "privileged register";
+		if (code == ILL_COPROC)  *reason = "coprocessor error";
+		if (code == ILL_BADSTK)  *reason = "internal stack error";
+		break;
+	case SIGFPE:
+		*name = "SIGFPE";
+		if (code == FPE_INTDIV)  *reason = "integer divide by zero";
+		if (code == FPE_INTOVF)  *reason = "integer overflow";
+		if (code == FPE_FLTDIV)  *reason = "floating-point divide by zero";
+		if (code == FPE_FLTOVF)  *reason = "floating-point overflow";
+		if (code == FPE_FLTUND)  *reason = "floating-point underflow";
+		if (code == FPE_FLTRES)  *reason = "floating-point inexact result";
+		if (code == FPE_FLTINV)  *reason = "invalid floating-point operation";
+		if (code == FPE_FLTSUB)  *reason = "subscript out of range";
+		break;
+	case SIGSEGV:
+		*name = "SIGSEGV";
+		if (code == SEGV_MAPERR)
+			*reason = "address not mapped to object";
+		if (code == SEGV_ACCERR)
+			*reason = "invalid permissions for mapped object";
+		break;
+	case SIGBUS:
+		*name = "SIGBUS";
+		if (code == BUS_ADRALN)  *reason = "invalid address alignment";
+		if (code == BUS_ADRERR)  *reason = "nonexistent physical address";
+		if (code == BUS_OBJERR)  *reason = "object-specific hardware error";
+		break;
+	default:
+		*name = NULL;
+	}
+}
+
+static void
+recovery_handler (int signum, siginfo_t *info, void *context)
+{
+	(void) context;
+
+	// TODO: maybe try to force a core dump like this: if (fork() == 0) return;
+	// TODO: maybe we could even send "\r\nQUIT :reason\r\n" to the server. >_>
+	//   As long as we're not connected via TLS, that is.
+
+	const char *signal_name = NULL, *reason = NULL;
+	translate_signal_info (signum, &signal_name, info->si_code, &reason);
+
+	char buf[128], numbuf[8];
+	if (!signal_name)
+	{
+		snprintf (numbuf, sizeof numbuf, "%d", signum);
+		signal_name = numbuf;
+	}
+
+	if (reason)
+		snprintf (buf, sizeof buf, "%s=%s: %s: %s", g_startup_reason_str,
+			"signal received", signal_name, reason);
+	else
+		snprintf (buf, sizeof buf, "%s=%s: %s", g_startup_reason_str,
+			"signal received", signal_name);
+	*g_startup_reason_location = buf;
+
+	// Avoid annoying resource intensive infinite loops by sleeping for a bit
+	(void) sleep (1);
+
+	// TODO: maybe pregenerate the path, see the following for some other ways
+	//   that would be illegal to do from within a signal handler:
+	//     http://stackoverflow.com/a/1024937
+	//     http://stackoverflow.com/q/799679
+	//   Especially if we change the current working directory in the program.
+	//
+	//   Note that I can just overwrite g_orig_argv[0].
+
+	// NOTE: our children will read EOF on the read ends of their pipes as a
+	//   a result of O_CLOEXEC.  That should be enough to make them terminate.
+
+	char **argv = g_original_argv.vector, **argp = g_recovery_env.vector;
+	execve ("/proc/self/exe",        argv, argp);  // Linux
+	execve ("/proc/curproc/file",    argv, argp);  // BSD
+	execve ("/proc/curproc/exe",     argv, argp);  // BSD
+	execve ("/proc/self/path/a.out", argv, argp);  // Solaris
+	execve (argv[0],                 argv, argp);  // unreliable fallback
+
+	// Let's just crash
+	perror ("execve");
+	signal (signum, SIG_DFL);
+	raise (signum);
+}
+
+static void
+prepare_recovery_environment (void)
+{
+	g_recovery_env = strv_make ();
+	strv_append_vector (&g_recovery_env, environ);
+
+	// Prepare a location within the environment where we will put the startup
+	// (or maybe rather restart) reason in case of an irrecoverable error.
+	char **iter;
+	for (iter = g_recovery_env.vector; *iter; iter++)
+	{
+		const size_t len = sizeof g_startup_reason_str - 1;
+		if (!strncmp (*iter, g_startup_reason_str, len) && (*iter)[len] == '=')
+			break;
+	}
+
+	if (*iter)
+		g_startup_reason_location = iter;
+	else
+	{
+		g_startup_reason_location = g_recovery_env.vector + g_recovery_env.len;
+		strv_append (&g_recovery_env, "");
+	}
+}
+
+static bool
+setup_recovery_handler (struct bot_context *ctx, struct error **e)
+{
+	bool recover;
+	if (!irc_get_boolean_from_config (ctx, "recover", &recover, e))
+		return false;
+	if (!recover)
+		return true;
+
+	// Make sure these signals aren't blocked, otherwise we would be unable
+	// to handle them, making the critical conditions fatal.
+	sigset_t mask;
+	sigemptyset (&mask);
+	sigaddset (&mask, SIGSEGV);
+	sigaddset (&mask, SIGBUS);
+	sigaddset (&mask, SIGFPE);
+	sigaddset (&mask, SIGILL);
+	sigprocmask (SIG_UNBLOCK, &mask, NULL);
+
+	struct sigaction sa;
+	sa.sa_flags = SA_SIGINFO;
+	sa.sa_sigaction = recovery_handler;
+	sigemptyset (&sa.sa_mask);
+
+	prepare_recovery_environment ();
+
+	// TODO: also handle SIGABRT... or avoid doing abort() in the first place?
+	if (sigaction (SIGSEGV, &sa, NULL) == -1
+	 || sigaction (SIGBUS,  &sa, NULL) == -1
+	 || sigaction (SIGFPE,  &sa, NULL) == -1
+	 || sigaction (SIGILL,  &sa, NULL) == -1)
+		print_error ("sigaction: %s", strerror (errno));
+	return true;
+}
+
+// --- Plugins -----------------------------------------------------------------
+
+/// The name of the special IRC command for interprocess communication
+static const char *plugin_ipc_command = "ZYKLONB";
+
+static struct plugin *
+plugin_find_by_pid (struct bot_context *ctx, pid_t pid)
+{
+	struct plugin *iter;
+	for (iter = ctx->plugins; iter; iter = iter->next)
+		if (iter->pid == pid)
+			return iter;
+	return NULL;
+}
+
+static bool
+plugin_zombify (struct plugin *plugin)
+{
+	if (plugin->is_zombie)
+		return false;
+
+	// FIXME: make sure that we don't remove entries from the poller while we
+	//   still may have stuff to read; maybe just check that the read pipe is
+	//   empty before closing it... and then on EOF check if `pid == -1' and
+	//   only then dispose of it (it'd be best to simulate that both of these
+	//   cases may happen).
+	poller_fd_reset (&plugin->write_event);
+
+	// TODO: try to flush the write buffer (non-blocking)?
+
+	// The plugin should terminate itself after it receives EOF.
+	xclose (plugin->write_fd);
+	plugin->write_fd = -1;
+
+	// Make it a pseudo-anonymous zombie.  In this state we process any
+	// remaining commands it attempts to send to us before it finally dies.
+	str_map_set (&plugin->ctx->plugins_by_name, plugin->name, NULL);
+	plugin->is_zombie = true;
+
+	// TODO: wait a few seconds and then send SIGKILL to the plugin
+	return true;
+}
+
+static void
+on_plugin_writable (const struct pollfd *fd, struct plugin *plugin)
+{
+	struct str *buf = &plugin->write_buffer;
+	size_t written_total = 0;
+
+	if (fd->revents & ~(POLLOUT | POLLHUP | POLLERR))
+		print_debug ("fd %d: unexpected revents: %d", fd->fd, fd->revents);
+
+	while (written_total != buf->len)
+	{
+		ssize_t n_written = write (fd->fd, buf->str + written_total,
+			buf->len - written_total);
+
+		if (n_written < 0)
+		{
+			if (errno == EAGAIN)
+				break;
+			if (errno == EINTR)
+				continue;
+
+			soft_assert (errno == EPIPE);
+			// Zombies shouldn't get dispatched for writability
+			hard_assert (!plugin->is_zombie);
+
+			print_debug ("%s: %s", "write", strerror (errno));
+			print_error ("failure on writing to plugin `%s',"
+				" therefore I'm unloading it", plugin->name);
+			plugin_zombify (plugin);
+			break;
+		}
+
+		// This may be equivalent to EAGAIN on some implementations
+		if (n_written == 0)
+			break;
+
+		written_total += n_written;
+	}
+
+	if (written_total != 0)
+		str_remove_slice (buf, 0, written_total);
+
+	if (buf->len == 0)
+		// Everything has been written, there's no need to end up in here again
+		poller_fd_reset (&plugin->write_event);
+}
+
+static void
+plugin_queue_write (struct plugin *plugin)
+{
+	if (plugin->is_zombie)
+		return;
+
+	// Don't let the write buffer grow indefinitely.  If there's a ton of data
+	// waiting to be processed by the plugin, it usually means there's something
+	// wrong with it (such as someone stopping the process).
+	if (plugin->write_buffer.len >= (1 << 20))
+	{
+		print_warning ("plugin `%s' does not seem to process messages fast"
+			" enough, I'm unloading it", plugin->name);
+		plugin_zombify (plugin);
+		return;
+	}
+	poller_fd_set (&plugin->write_event, POLLOUT);
+}
+
+static void
+plugin_send (struct plugin *plugin, const char *format, ...)
+	ATTRIBUTE_PRINTF (2, 3);
+
+static void
+plugin_send (struct plugin *plugin, const char *format, ...)
+{
+	va_list ap;
+
+	if (g_debug_mode)
+	{
+		fprintf (stderr, "[%s] <-- \"", plugin->name);
+		va_start (ap, format);
+		vfprintf (stderr, format, ap);
+		va_end (ap);
+		fputs ("\"\n", stderr);
+	}
+
+	va_start (ap, format);
+	str_append_vprintf (&plugin->write_buffer, format, ap);
+	va_end (ap);
+	str_append (&plugin->write_buffer, "\r\n");
+
+	plugin_queue_write (plugin);
+}
+
+static void
+plugin_process_ipc (struct plugin *plugin, const struct irc_message *msg)
+{
+	// Replies are sent in the order in which they came in, so there's
+	// no need to attach a special identifier to them.  It might be
+	// desirable in some cases, though.
+
+	if (msg->params.len < 1)
+		return;
+
+	const char *command = msg->params.vector[0];
+	if (!plugin->initialized && !strcasecmp (command, "register"))
+	{
+		// Register for relaying of IRC traffic
+		plugin->initialized = true;
+
+		// Flush any queued up traffic here.  The point of queuing it in
+		// the first place is so that we don't have to wait for plugin
+		// initialization during startup.
+		//
+		// Note that if we start filtering data coming to the plugins e.g.
+		// based on what it tells us upon registration, we might need to
+		// filter `queued_output' as well.
+		str_append_str (&plugin->write_buffer, &plugin->queued_output);
+		str_free (&plugin->queued_output);
+
+		// NOTE: this may trigger the buffer length check
+		plugin_queue_write (plugin);
+	}
+	else if (!strcasecmp (command, "get_config"))
+	{
+		if (msg->params.len < 2)
+			return;
+
+		const char *value =
+			str_map_find (&plugin->ctx->config, msg->params.vector[1]);
+		// TODO: escape the value (although there's no need to ATM)
+		plugin_send (plugin, "%s :%s",
+			plugin_ipc_command, value ? value : "");
+	}
+	else if (!strcasecmp (command, "print"))
+	{
+		if (msg->params.len < 2)
+			return;
+
+		printf ("%s\n", msg->params.vector[1]);
+	}
+}
+
+static void
+plugin_process_message (const struct irc_message *msg,
+	const char *raw, void *user_data)
+{
+	struct plugin *plugin = user_data;
+	struct bot_context *ctx = plugin->ctx;
+
+	if (g_debug_mode)
+		fprintf (stderr, "[%s] --> \"%s\"\n", plugin->name, raw);
+
+	if (!strcasecmp (msg->command, plugin_ipc_command))
+		plugin_process_ipc (plugin, msg);
+	else if (plugin->initialized && ctx->irc_registered)
+	{
+		// Pass everything else through to the IRC server
+		// XXX: when the server isn't ready yet, these messages get silently
+		//   discarded, which shouldn't pose a problem most of the time.
+		//   Perhaps we could send a "connected" notification on `register'
+		//   if `irc_ready' is true, or after it becomes true later, so that
+		//   plugins know when to start sending unprovoked IRC messages.
+		// XXX: another case is when the connection gets interrupted and the
+		//   plugin tries to send something back while we're reconnecting.
+		//   For that we might set up a global buffer that gets flushed out
+		//   after `irc_ready' becomes true.  Note that there is always some
+		//   chance of messages getting lost without us even noticing it.
+		irc_send (ctx, "%s", raw);
+	}
+}
+
+static void
+on_plugin_readable (const struct pollfd *fd, struct plugin *plugin)
+{
+	if (fd->revents & ~(POLLIN | POLLHUP | POLLERR))
+		print_debug ("fd %d: unexpected revents: %d", fd->fd, fd->revents);
+
+	// TODO: see if I can reuse irc_fill_read_buffer()
+	struct str *buf = &plugin->read_buffer;
+	while (true)
+	{
+		str_reserve (buf, 512 + 1);
+		ssize_t n_read = read (fd->fd, buf->str + buf->len,
+			buf->alloc - buf->len - 1);
+
+		if (n_read < 0)
+		{
+			if (errno == EAGAIN)
+				break;
+			if (soft_assert (errno == EINTR))
+				continue;
+
+			if (!plugin->is_zombie)
+			{
+				print_error ("failure on reading from plugin `%s',"
+					" therefore I'm unloading it", plugin->name);
+				plugin_zombify (plugin);
+			}
+			return;
+		}
+
+		// EOF; hopefully it will die soon (maybe it already has)
+		if (n_read == 0)
+			break;
+
+		buf->str[buf->len += n_read] = '\0';
+		if (buf->len >= (1 << 20))
+		{
+			// XXX: this isn't really the best flood prevention mechanism,
+			//   but it wasn't even supposed to be one.
+			if (plugin->is_zombie)
+			{
+				print_error ("a zombie of plugin `%s' is trying to flood us,"
+					" therefore I'm killing it", plugin->name);
+				kill (plugin->pid, SIGKILL);
+			}
+			else
+			{
+				print_error ("plugin `%s' seems to spew out data frantically,"
+					" therefore I'm unloading it", plugin->name);
+				plugin_zombify (plugin);
+			}
+			return;
+		}
+	}
+
+	irc_process_buffer (buf, plugin_process_message, plugin);
+}
+
+static bool
+is_valid_plugin_name (const char *name)
+{
+	if (!*name)
+		return false;
+	for (const char *p = name; *p; p++)
+		if (!isgraph (*p) || *p == '/')
+			return false;
+	return true;
+}
+
+static char *
+plugin_resolve_relative_filename (const char *filename)
+{
+	struct strv paths = strv_make ();
+	get_xdg_data_dirs (&paths);
+	char *result = resolve_relative_filename_generic
+		(&paths, PROGRAM_NAME "/plugins/", filename);
+	strv_free (&paths);
+	return result;
+}
+
+static struct plugin *
+plugin_launch (struct bot_context *ctx, const char *name, struct error **e)
+{
+	char *path = NULL;
+	const char *plugin_dir = str_map_find (&ctx->config, "plugin_dir");
+	if (plugin_dir)
+	{
+		// resolve_relative_filename_generic() won't accept relative paths,
+		// so just keep the old behaviour and expect the file to exist.
+		// We could use resolve_filename() on "plugin_dir" with paths=getcwd().
+		path = xstrdup_printf ("%s/%s", plugin_dir, name);
+	}
+	else if (!(path = plugin_resolve_relative_filename (name)))
+	{
+		error_set (e, "plugin not found");
+		goto fail_0;
+	}
+
+	int stdin_pipe[2];
+	if (pipe (stdin_pipe) == -1)
+	{
+		error_set (e, "%s: %s", "pipe", strerror (errno));
+		goto fail_0;
+	}
+
+	int stdout_pipe[2];
+	if (pipe (stdout_pipe) == -1)
+	{
+		error_set (e, "%s: %s", "pipe", strerror (errno));
+		goto fail_1;
+	}
+
+	struct str work_dir = str_make ();
+	get_xdg_home_dir (&work_dir, "XDG_DATA_HOME", ".local/share");
+	str_append_printf (&work_dir, "/%s", PROGRAM_NAME);
+
+	if (!mkdir_with_parents (work_dir.str, e))
+		goto fail_2;
+
+	set_cloexec (stdin_pipe[1]);
+	set_cloexec (stdout_pipe[0]);
+
+	pid_t pid = fork ();
+	if (pid == -1)
+	{
+		error_set (e, "%s: %s", "fork", strerror (errno));
+		goto fail_2;
+	}
+
+	if (pid == 0)
+	{
+		// Redirect the child's stdin and stdout to the pipes
+		if (dup2 (stdin_pipe[0], STDIN_FILENO) == -1
+		 || dup2 (stdout_pipe[1], STDOUT_FILENO) == -1)
+		{
+			print_error ("%s: %s: %s", "failed to load the plugin",
+				"dup2", strerror (errno));
+			_exit (EXIT_FAILURE);
+		}
+		if (chdir (work_dir.str))
+		{
+			print_error ("%s: %s: %s", "failed to load the plugin",
+				"chdir", strerror (errno));
+			_exit (EXIT_FAILURE);
+		}
+
+		xclose (stdin_pipe[0]);
+		xclose (stdout_pipe[1]);
+
+		// Restore some of the signal handling
+		signal (SIGPIPE, SIG_DFL);
+
+		char *argv[] = { path, NULL };
+		execve (argv[0], argv, environ);
+
+		// We will collect the failure later via SIGCHLD
+		print_error ("%s: %s: %s", "failed to load the plugin",
+			"exec", strerror (errno));
+		_exit (EXIT_FAILURE);
+	}
+
+	str_free (&work_dir);
+	free (path);
+
+	xclose (stdin_pipe[0]);
+	xclose (stdout_pipe[1]);
+
+	struct plugin *plugin = plugin_new ();
+	plugin->ctx = ctx;
+	plugin->pid = pid;
+	plugin->name = xstrdup (name);
+	plugin->read_fd = stdout_pipe[0];
+	plugin->write_fd = stdin_pipe[1];
+	return plugin;
+
+fail_2:
+	str_free (&work_dir);
+	xclose (stdout_pipe[0]);
+	xclose (stdout_pipe[1]);
+fail_1:
+	xclose (stdin_pipe[0]);
+	xclose (stdin_pipe[1]);
+fail_0:
+	free (path);
+	return NULL;
+}
+
+static bool
+plugin_load (struct bot_context *ctx, const char *name, struct error **e)
+{
+	if (!is_valid_plugin_name (name))
+		return error_set (e, "invalid plugin name");
+	if (str_map_find (&ctx->plugins_by_name, name))
+		return error_set (e, "the plugin has already been loaded");
+
+	struct plugin *plugin;
+	if (!(plugin = plugin_launch (ctx, name, e)))
+		return false;
+
+	set_blocking (plugin->read_fd, false);
+	set_blocking (plugin->write_fd, false);
+
+	plugin->read_event = poller_fd_make (&ctx->poller, plugin->read_fd);
+	plugin->read_event.dispatcher = (poller_fd_fn) on_plugin_readable;
+	plugin->read_event.user_data = plugin;
+
+	plugin->write_event = poller_fd_make (&ctx->poller, plugin->write_fd);
+	plugin->write_event.dispatcher = (poller_fd_fn) on_plugin_writable;
+	plugin->write_event.user_data = plugin;
+
+	LIST_PREPEND (ctx->plugins, plugin);
+	str_map_set (&ctx->plugins_by_name, name, plugin);
+
+	poller_fd_set (&plugin->read_event, POLLIN);
+	return true;
+}
+
+static bool
+plugin_unload (struct bot_context *ctx, const char *name, struct error **e)
+{
+	struct plugin *plugin = str_map_find (&ctx->plugins_by_name, name);
+
+	if (!plugin)
+		return error_set (e, "no such plugin is loaded");
+
+	plugin_zombify (plugin);
+
+	// TODO: add a `kill zombies' command to forcefully get rid of processes
+	//   that do not understand the request.
+	return true;
+}
+
+static void
+plugin_load_all_from_config (struct bot_context *ctx)
+{
+	const char *plugin_list = str_map_find (&ctx->config, "plugins");
+	if (!plugin_list)
+		return;
+
+	struct strv plugins = strv_make ();
+	cstr_split (plugin_list, ",", true, &plugins);
+	for (size_t i = 0; i < plugins.len; i++)
+	{
+		char *name = cstr_strip_in_place (plugins.vector[i], " ");
+
+		struct error *e = NULL;
+		if (!plugin_load (ctx, name, &e))
+		{
+			print_error ("plugin `%s' failed to load: %s", name, e->message);
+			error_free (e);
+		}
+	}
+
+	strv_free (&plugins);
+}
+
+// --- Main program ------------------------------------------------------------
+
+static bool
+parse_bot_command (const char *s, const char *command, const char **following)
+{
+	size_t command_len = strlen (command);
+	if (strncasecmp (s, command, command_len))
+		return false;
+	s += command_len;
+
+	// Expect a word boundary, so that we don't respond to invalid things
+	if (isalnum (*s))
+		return false;
+
+	// Ignore any initial spaces; the rest is the command's argument
+	while (isblank (*s))
+		s++;
+	*following = s;
+	return true;
+}
+
+static void
+split_bot_command_argument_list (const char *arguments, struct strv *out)
+{
+	cstr_split (arguments, ",", true, out);
+	for (size_t i = 0; i < out->len; )
+	{
+		if (!*cstr_strip_in_place (out->vector[i], " \t"))
+			strv_remove (out, i);
+		else
+			i++;
+	}
+}
+
+static bool
+is_private_message (const struct irc_message *msg)
+{
+	hard_assert (msg->params.len);
+	return !strchr ("#&+!", *msg->params.vector[0]);
+}
+
+static bool
+is_sent_by_admin (struct bot_context *ctx, const struct irc_message *msg)
+{
+	// No administrator set -> everyone is an administrator
+	if (!ctx->admin_re)
+		return true;
+	return regexec (ctx->admin_re, msg->prefix, 0, NULL, 0) != REG_NOMATCH;
+}
+
+static void respond_to_user (struct bot_context *ctx, const struct
+	irc_message *msg, const char *format, ...) ATTRIBUTE_PRINTF (3, 4);
+
+static void
+respond_to_user (struct bot_context *ctx, const struct irc_message *msg,
+	const char *format, ...)
+{
+	if (!soft_assert (msg->prefix && msg->params.len))
+		return;
+
+	char nick[strcspn (msg->prefix, "!") + 1];
+	strncpy (nick, msg->prefix, sizeof nick - 1);
+	nick[sizeof nick - 1] = '\0';
+
+	va_list ap;
+	struct str text = str_make ();
+	va_start (ap, format);
+	str_append_vprintf (&text, format, ap);
+	va_end (ap);
+
+	if (is_private_message (msg))
+		irc_send (ctx, "PRIVMSG %s :%s", nick, text.str);
+	else
+		irc_send (ctx, "PRIVMSG %s :%s: %s",
+			msg->params.vector[0], nick, text.str);
+
+	str_free (&text);
+}
+
+static void
+process_plugin_load (struct bot_context *ctx,
+	const struct irc_message *msg, const char *name)
+{
+	struct error *e = NULL;
+	if (plugin_load (ctx, name, &e))
+		respond_to_user (ctx, msg, "plugin `%s' queued for loading", name);
+	else
+	{
+		respond_to_user (ctx, msg, "plugin `%s' could not be loaded: %s",
+			name, e->message);
+		error_free (e);
+	}
+}
+
+static void
+process_plugin_unload (struct bot_context *ctx,
+	const struct irc_message *msg, const char *name)
+{
+	struct error *e = NULL;
+	if (plugin_unload (ctx, name, &e))
+		respond_to_user (ctx, msg, "plugin `%s' unloaded", name);
+	else
+	{
+		respond_to_user (ctx, msg, "plugin `%s' could not be unloaded: %s",
+			name, e->message);
+		error_free (e);
+	}
+}
+
+static void
+process_plugin_reload (struct bot_context *ctx,
+	const struct irc_message *msg, const char *name)
+{
+	// XXX: we might want to wait until the plugin terminates before we try
+	//   to reload it (so that it can save its configuration or whatever)
+
+	// So far the only error that can occur is that the plugin hasn't been
+	// loaded, which in this case doesn't really matter.
+	plugin_unload (ctx, name, NULL);
+
+	process_plugin_load (ctx, msg, name);
+}
+
+static char *
+make_status_report (struct bot_context *ctx)
+{
+	struct str report = str_make ();
+	const char *reason = getenv (g_startup_reason_str);
+	if (!reason)
+		reason = "launched normally";
+	str_append_printf (&report, "\x02startup reason:\x0f %s", reason);
+
+	size_t zombies = 0;
+	const char *prepend = "; \x02plugins:\x0f ";
+	for (struct plugin *plugin = ctx->plugins; plugin; plugin = plugin->next)
+	{
+		if (plugin->is_zombie)
+			zombies++;
+		else
+		{
+			str_append_printf (&report, "%s%s", prepend, plugin->name);
+			prepend = ", ";
+		}
+	}
+	if (!ctx->plugins)
+		str_append_printf (&report, "%s\x02none\x0f", prepend);
+
+	str_append_printf (&report, "; \x02zombies:\x0f %zu", zombies);
+	return str_steal (&report);
+}
+
+static void
+process_privmsg (struct bot_context *ctx, const struct irc_message *msg)
+{
+	if (!is_sent_by_admin (ctx, msg))
+		return;
+	if (msg->params.len < 2)
+		return;
+
+	const char *prefix = str_map_find (&ctx->config, "prefix");
+	hard_assert (prefix != NULL);  // We have a default value for this
+
+	// For us to recognize the command, it has to start with the prefix,
+	// with the exception of PM's sent directly to us.
+	const char *text = msg->params.vector[1];
+	if (!strncmp (text, prefix, strlen (prefix)))
+		text += strlen (prefix);
+	else if (!is_private_message (msg))
+		return;
+
+	const char *following;
+	struct strv list = strv_make ();
+
+	if (parse_bot_command (text, "quote", &following))
+		// This seems to replace tons of random stupid commands
+		irc_send (ctx, "%s", following);
+	else if (parse_bot_command (text, "quit", &following))
+	{
+		// We actually need this command (instead of just `quote') because we
+		// could try to reconnect to the server automatically otherwise.
+		if (*following)
+			irc_send (ctx, "QUIT :%s", following);
+		else
+			irc_send (ctx, "QUIT");
+		initiate_quit (ctx);
+	}
+	else if (parse_bot_command (text, "status", &following))
+	{
+		char *report = make_status_report (ctx);
+		respond_to_user (ctx, msg, "%s", report);
+		free (report);
+	}
+	else if (parse_bot_command (text, "load", &following))
+	{
+		split_bot_command_argument_list (following, &list);
+		for (size_t i = 0; i < list.len; i++)
+			process_plugin_load (ctx, msg, list.vector[i]);
+	}
+	else if (parse_bot_command (text, "reload", &following))
+	{
+		split_bot_command_argument_list (following, &list);
+		for (size_t i = 0; i < list.len; i++)
+			process_plugin_reload (ctx, msg, list.vector[i]);
+	}
+	else if (parse_bot_command (text, "unload", &following))
+	{
+		split_bot_command_argument_list (following, &list);
+		for (size_t i = 0; i < list.len; i++)
+			process_plugin_unload (ctx, msg, list.vector[i]);
+	}
+
+	strv_free (&list);
+}
+
+static void
+irc_forward_message_to_plugins (struct bot_context *ctx, const char *raw)
+{
+	// For consistency with plugin_process_message()
+	if (!ctx->irc_registered)
+		return;
+
+	for (struct plugin *plugin = ctx->plugins;
+		 plugin; plugin = plugin->next)
+	{
+		if (plugin->is_zombie)
+			continue;
+
+		if (plugin->initialized)
+			plugin_send (plugin, "%s", raw);
+		else
+			// TODO: make sure that this buffer doesn't get too large either
+			str_append_printf (&plugin->queued_output, "%s\r\n", raw);
+	}
+}
+
+static void
+irc_process_message (const struct irc_message *msg,
+	const char *raw, void *user_data)
+{
+	struct bot_context *ctx = user_data;
+	if (g_debug_mode)
+		fprintf (stderr, "[%s] ==> \"%s\"\n", "IRC", raw);
+
+	// This should be as minimal as possible, I don't want to have the whole bot
+	// written in C, especially when I have this overengineered plugin system.
+	// Therefore the very basic functionality only.
+	//
+	// I should probably even rip out the autojoin...
+
+	irc_forward_message_to_plugins (ctx, raw);
+
+	if (!strcasecmp (msg->command, "PING"))
+	{
+		if (msg->params.len)
+			irc_send (ctx, "PONG :%s", msg->params.vector[0]);
+		else
+			irc_send (ctx, "PONG");
+	}
+	else if (!ctx->irc_registered && !strcasecmp (msg->command, "001"))
+	{
+		print_status ("successfully connected");
+		ctx->irc_registered = true;
+
+		const char *autojoin = str_map_find (&ctx->config, "autojoin");
+		if (autojoin)
+			irc_send (ctx, "JOIN :%s", autojoin);
+	}
+	else if (!strcasecmp (msg->command, "PRIVMSG"))
+		process_privmsg (ctx, msg);
+}
+
+enum irc_read_result
+{
+	IRC_READ_OK,                        ///< Some data were read successfully
+	IRC_READ_EOF,                       ///< The server has closed connection
+	IRC_READ_AGAIN,                     ///< No more data at the moment
+	IRC_READ_ERROR                      ///< General connection failure
+};
+
+static enum irc_read_result
+irc_fill_read_buffer_tls (struct bot_context *ctx, struct str *buf)
+{
+	int n_read;
+start:
+	ERR_clear_error ();
+	n_read = SSL_read (ctx->ssl, buf->str + buf->len,
+		buf->alloc - buf->len - 1 /* null byte */);
+
+	const char *error_info = NULL;
+	switch (xssl_get_error (ctx->ssl, n_read, &error_info))
+	{
+	case SSL_ERROR_NONE:
+		buf->str[buf->len += n_read] = '\0';
+		return IRC_READ_OK;
+	case SSL_ERROR_ZERO_RETURN:
+		return IRC_READ_EOF;
+	case SSL_ERROR_WANT_READ:
+		return IRC_READ_AGAIN;
+	case SSL_ERROR_WANT_WRITE:
+	{
+		// Let it finish the handshake as we don't poll for writability;
+		// any errors are to be collected by SSL_read() in the next iteration
+		struct pollfd pfd = { .fd = ctx->irc_fd, .events = POLLOUT };
+		soft_assert (poll (&pfd, 1, 0) > 0);
+		goto start;
+	}
+	case XSSL_ERROR_TRY_AGAIN:
+		goto start;
+	default:
+		print_debug ("%s: %s: %s", __func__, "SSL_read", error_info);
+		return IRC_READ_ERROR;
+	}
+}
+
+static enum irc_read_result
+irc_fill_read_buffer (struct bot_context *ctx, struct str *buf)
+{
+	ssize_t n_read;
+start:
+	n_read = recv (ctx->irc_fd, buf->str + buf->len,
+		buf->alloc - buf->len - 1 /* null byte */, 0);
+
+	if (n_read > 0)
+	{
+		buf->str[buf->len += n_read] = '\0';
+		return IRC_READ_OK;
+	}
+	if (n_read == 0)
+		return IRC_READ_EOF;
+
+	if (errno == EAGAIN)
+		return IRC_READ_AGAIN;
+	if (errno == EINTR)
+		goto start;
+
+	print_debug ("%s: %s: %s", __func__, "recv", strerror (errno));
+	return IRC_READ_ERROR;
+}
+
+static bool irc_connect (struct bot_context *, struct error **);
+static void irc_queue_reconnect (struct bot_context *);
+
+static void
+irc_cancel_timers (struct bot_context *ctx)
+{
+	poller_timer_reset (&ctx->timeout_tmr);
+	poller_timer_reset (&ctx->ping_tmr);
+	poller_timer_reset (&ctx->reconnect_tmr);
+}
+
+static void
+on_irc_reconnect_timeout (void *user_data)
+{
+	struct bot_context *ctx = user_data;
+
+	struct error *e = NULL;
+	if (irc_connect (ctx, &e))
+	{
+		// TODO: inform plugins about the new connection
+		return;
+	}
+
+	print_error ("%s", e->message);
+	error_free (e);
+	irc_queue_reconnect (ctx);
+}
+
+static void
+irc_queue_reconnect (struct bot_context *ctx)
+{
+	hard_assert (ctx->irc_fd == -1);
+	print_status ("trying to reconnect in %ld seconds...",
+		ctx->reconnect_delay);
+	poller_timer_set (&ctx->reconnect_tmr, ctx->reconnect_delay * 1000);
+}
+
+static void
+on_irc_disconnected (struct bot_context *ctx)
+{
+	// Get rid of the dead socket and related things
+	if (ctx->ssl)
+	{
+		SSL_free (ctx->ssl);
+		ctx->ssl = NULL;
+		SSL_CTX_free (ctx->ssl_ctx);
+		ctx->ssl_ctx = NULL;
+	}
+
+	poller_fd_reset (&ctx->irc_event);
+	xclose (ctx->irc_fd);
+	ctx->irc_fd = -1;
+	ctx->irc_registered = false;
+
+	// TODO: inform plugins about the disconnect event
+
+	// All of our timers have lost their meaning now
+	irc_cancel_timers (ctx);
+
+	if (ctx->quitting)
+		try_finish_quit (ctx);
+	else if (!ctx->reconnect)
+		initiate_quit (ctx);
+	else
+		irc_queue_reconnect (ctx);
+}
+
+static void
+on_irc_ping_timeout (void *user_data)
+{
+	struct bot_context *ctx = user_data;
+	print_error ("connection timeout");
+	on_irc_disconnected (ctx);
+}
+
+static void
+on_irc_timeout (void *user_data)
+{
+	// Provoke a response from the server
+	struct bot_context *ctx = user_data;
+	irc_send (ctx, "PING :%s",
+		(char *) str_map_find (&ctx->config, "nickname"));
+}
+
+static void
+irc_reset_connection_timeouts (struct bot_context *ctx)
+{
+	irc_cancel_timers (ctx);
+	poller_timer_set (&ctx->timeout_tmr, 3 * 60 * 1000);
+	poller_timer_set (&ctx->ping_tmr, (3 * 60 + 30) * 1000);
+}
+
+static void
+on_irc_readable (const struct pollfd *fd, struct bot_context *ctx)
+{
+	if (fd->revents & ~(POLLIN | POLLHUP | POLLERR))
+		print_debug ("fd %d: unexpected revents: %d", fd->fd, fd->revents);
+
+	(void) set_blocking (ctx->irc_fd, false);
+
+	struct str *buf = &ctx->read_buffer;
+	enum irc_read_result (*fill_buffer)(struct bot_context *, struct str *)
+		= ctx->ssl
+		? irc_fill_read_buffer_tls
+		: irc_fill_read_buffer;
+	bool disconnected = false;
+	while (true)
+	{
+		str_reserve (buf, 512);
+		switch (fill_buffer (ctx, buf))
+		{
+		case IRC_READ_AGAIN:
+			goto end;
+		case IRC_READ_ERROR:
+			print_error ("reading from the IRC server failed");
+			disconnected = true;
+			goto end;
+		case IRC_READ_EOF:
+			print_status ("the IRC server closed the connection");
+			disconnected = true;
+			goto end;
+		case IRC_READ_OK:
+			break;
+		}
+
+		if (buf->len >= (1 << 20))
+		{
+			print_error ("the IRC server seems to spew out data frantically");
+			irc_shutdown (ctx);
+			goto end;
+		}
+	}
+end:
+	(void) set_blocking (ctx->irc_fd, true);
+	irc_process_buffer (buf, irc_process_message, ctx);
+
+	if (disconnected)
+		on_irc_disconnected (ctx);
+	else
+		irc_reset_connection_timeouts (ctx);
+}
+
+// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+
+// The bot is currently mostly synchronous (which also makes it shorter),
+// however our current SOCKS code is not, hence we must wrap it.
+
+struct irc_socks_data
+{
+	struct bot_context *ctx;            ///< Bot context
+	struct poller inner_poller;         ///< Special inner poller
+	bool polling;                       ///< Inner poller is no longer needed
+	struct socks_connector connector;   ///< SOCKS connector
+	bool succeeded;                     ///< Were we successful in connecting?
+};
+
+static void
+irc_on_socks_connected (void *user_data, int socket, const char *hostname)
+{
+	(void) hostname;
+
+	struct irc_socks_data *data = user_data;
+	data->ctx->irc_fd = socket;
+	data->succeeded = true;
+	data->polling = false;
+}
+
+static void
+irc_on_socks_failure (void *user_data)
+{
+	struct irc_socks_data *data = user_data;
+	data->succeeded = false;
+	data->polling = false;
+}
+
+static void
+irc_on_socks_connecting (void *user_data,
+	const char *address, const char *via, const char *version)
+{
+	(void) user_data;
+	print_status ("connecting to %s via %s (%s)...", address, via, version);
+}
+
+static void
+irc_on_socks_error (void *user_data, const char *error)
+{
+	(void) user_data;
+	print_error ("%s: %s", "SOCKS connection failed", error);
+}
+
+static bool
+irc_establish_connection_socks (struct bot_context *ctx,
+	const char *socks_host, const char *socks_port,
+	const char *host, const char *service, struct error **e)
+{
+	struct irc_socks_data data;
+	struct poller *poller = &data.inner_poller;
+	struct socks_connector *connector = &data.connector;
+
+	data.ctx = ctx;
+	poller_init (poller);
+	data.polling = true;
+	socks_connector_init (connector, poller);
+	data.succeeded = false;
+
+	connector->on_connected  = irc_on_socks_connected;
+	connector->on_connecting = irc_on_socks_connecting;
+	connector->on_error      = irc_on_socks_error;
+	connector->on_failure    = irc_on_socks_failure;
+	connector->user_data     = &data;
+
+	if (socks_connector_add_target (connector, host, service, e))
+	{
+		socks_connector_run (connector, socks_host, socks_port,
+			str_map_find (&ctx->config, "socks_username"),
+			str_map_find (&ctx->config, "socks_password"));
+		while (data.polling)
+			poller_run (poller);
+		if (!data.succeeded)
+			error_set (e, "connection failed");
+	}
+
+	socks_connector_free (connector);
+	poller_free (poller);
+	return data.succeeded;
+}
+
+// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+
+static bool
+irc_connect (struct bot_context *ctx, struct error **e)
+{
+	const char *irc_host = str_map_find (&ctx->config, "irc_host");
+	const char *irc_port = str_map_find (&ctx->config, "irc_port");
+	const char *socks_host = str_map_find (&ctx->config, "socks_host");
+	const char *socks_port = str_map_find (&ctx->config, "socks_port");
+
+	const char *nickname = str_map_find (&ctx->config, "nickname");
+	const char *username = str_map_find (&ctx->config, "username");
+	const char *realname = str_map_find (&ctx->config, "realname");
+
+	// We have a default value for these
+	hard_assert (irc_port && socks_port);
+	hard_assert (nickname && username && realname);
+
+	// TODO: again, get rid of `struct error' in here.  The question is: how
+	//   do we tell our caller that he should not try to reconnect?
+	if (!irc_host)
+		return error_set (e, "no hostname specified in configuration");
+
+	bool use_tls;
+	if (!irc_get_boolean_from_config (ctx, "tls", &use_tls, e))
+		return false;
+
+	bool connected = socks_host
+		? irc_establish_connection_socks (ctx,
+			socks_host, socks_port, irc_host, irc_port, e)
+		: irc_establish_connection (ctx, irc_host, irc_port, e);
+	if (!connected)
+		return false;
+
+	if (use_tls && !irc_initialize_tls (ctx, e))
+	{
+		xclose (ctx->irc_fd);
+		ctx->irc_fd = -1;
+		return false;
+	}
+	print_status ("connection established");
+
+	ctx->irc_event = poller_fd_make (&ctx->poller, ctx->irc_fd);
+	ctx->irc_event.dispatcher = (poller_fd_fn) on_irc_readable;
+	ctx->irc_event.user_data = ctx;
+
+	// TODO: in exec try: 1/ set blocking, 2/ setsockopt() SO_LINGER,
+	//   (struct linger) { .l_onoff = true; .l_linger = 1 /* 1s should do */; }
+	//   3/ /* O_CLOEXEC */  But only if the QUIT message proves unreliable.
+	poller_fd_set (&ctx->irc_event, POLLIN);
+	irc_reset_connection_timeouts (ctx);
+
+	irc_send (ctx, "NICK %s", nickname);
+	irc_send (ctx, "USER %s 8 * :%s", username, realname);
+	return true;
+}
+
+static bool
+parse_config (struct bot_context *ctx, struct error **e)
+{
+	if (!irc_get_boolean_from_config (ctx, "reconnect", &ctx->reconnect, e))
+		return false;
+
+	const char *delay_str = str_map_find (&ctx->config, "reconnect_delay");
+	hard_assert (delay_str != NULL);  // We have a default value for this
+	if (!xstrtoul (&ctx->reconnect_delay, delay_str, 10))
+	{
+		return error_set (e,
+			"invalid configuration value for `%s'", "reconnect_delay");
+	}
+
+	hard_assert (!ctx->admin_re);
+	const char *admin = str_map_find (&ctx->config, "admin");
+	if (!admin)
+		return true;
+
+	struct error *error = NULL;
+	ctx->admin_re = regex_compile (admin, REG_EXTENDED | REG_NOSUB, &error);
+	if (!error)
+		return true;
+
+	error_set (e, "invalid configuration value for `%s': %s",
+		"admin", error->message);
+	error_free (error);
+	return false;
+}
+
+static void
+on_plugin_death (struct plugin *plugin, int status)
+{
+	struct bot_context *ctx = plugin->ctx;
+
+	// TODO: callbacks on children death, so that we may tell the user
+	//       "plugin `name' died"; use `status'
+	if (!plugin->is_zombie && WIFSIGNALED (status))
+	{
+		const char *notes = "";
+#ifdef WCOREDUMP
+		if (WCOREDUMP (status))
+			notes = " (core dumped)";
+#endif
+		print_warning ("Plugin `%s' died from signal %d%s",
+			plugin->name, WTERMSIG (status), notes);
+	}
+
+	// Let's go through the zombie state to simplify things a bit
+	// TODO: might not be a completely bad idea to restart the plugin
+	plugin_zombify (plugin);
+
+	plugin->pid = -1;
+
+	// In theory we could close `read_fd', set `read_event->closed' to true
+	// and expect epoll to no longer return events for the descriptor, as
+	// all the pipe ends should be closed by then (the child is dead, so its
+	// pipe FDs have been closed [assuming it hasn't forked without closing
+	// the descriptors, which would be evil], and we would have closed all
+	// of our FDs for this pipe as well).  In practice that doesn't work.
+	poller_fd_reset (&plugin->read_event);
+
+	xclose (plugin->read_fd);
+	plugin->read_fd = -1;
+
+	LIST_UNLINK (ctx->plugins, plugin);
+	plugin_destroy (plugin);
+
+	// Living child processes block us from quitting
+	try_finish_quit (ctx);
+}
+
+static bool
+try_reap_plugin (struct bot_context *ctx)
+{
+	int status;
+	pid_t zombie = waitpid (-1, &status, WNOHANG);
+
+	if (zombie == -1)
+	{
+		// No children to wait on
+		if (errno == ECHILD)
+			return false;
+
+		hard_assert (errno == EINTR);
+		return true;
+	}
+
+	if (zombie == 0)
+		return false;
+
+	struct plugin *plugin = plugin_find_by_pid (ctx, zombie);
+	// XXX: re-exec if something has died that we don't recognize?
+	if (soft_assert (plugin != NULL))
+		on_plugin_death (plugin, status);
+	return true;
+}
+
+static void
+kill_all_zombies (struct bot_context *ctx)
+{
+	for (struct plugin *plugin = ctx->plugins; plugin; plugin = plugin->next)
+	{
+		if (!plugin->is_zombie)
+			continue;
+
+		print_status ("forcefully killing a zombie of `%s' (PID %d)",
+			plugin->name, (int) plugin->pid);
+		kill (plugin->pid, SIGKILL);
+	}
+}
+
+static void
+on_signal_pipe_readable (const struct pollfd *fd, struct bot_context *ctx)
+{
+	char dummy;
+	(void) read (fd->fd, &dummy, 1);
+
+	if (g_termination_requested)
+	{
+		g_termination_requested = false;
+		if (!ctx->quitting)
+		{
+			// There may be a timer set to reconnect to the server
+			irc_cancel_timers (ctx);
+
+			if (ctx->irc_fd != -1)
+				irc_send (ctx, "QUIT :Terminated by signal");
+			initiate_quit (ctx);
+		}
+		else
+			// Disregard proper termination, just kill all the children
+			kill_all_zombies (ctx);
+	}
+
+	// Reap all dead children (since the signal pipe may overflow etc. we run
+	// waitpid() in a loop to return all the zombies it knows about).
+	while (try_reap_plugin (ctx))
+		;
+}
+
+int
+main (int argc, char *argv[])
+{
+	g_original_argv = strv_make ();
+	strv_append_vector (&g_original_argv, argv);
+
+	static const struct opt opts[] =
+	{
+		{ 'd', "debug", NULL, 0, "run in debug mode" },
+		{ '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, "Modular IRC bot.");
+
+	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 bot_context ctx;
+	bot_context_init (&ctx);
+
+	struct error *e = NULL;
+	if (!simple_config_update_from_file (&ctx.config, &e)
+	 || !setup_recovery_handler (&ctx, &e))
+	{
+		print_error ("%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 OpenBSD >= 201605
+	// cpath is for creating the plugin home directory
+	if (pledge ("stdio rpath cpath inet proc exec", NULL))
+		exit_fatal ("%s: %s", "pledge", strerror (errno));
+#endif
+
+	plugin_load_all_from_config (&ctx);
+	if (!parse_config (&ctx, &e)
+	 || !irc_connect (&ctx, &e))
+	{
+		print_error ("%s", e->message);
+		error_free (e);
+		exit (EXIT_FAILURE);
+	}
+
+	// TODO: clean re-exec support; to save the state I can either use argv,
+	//   argp, or I can create a temporary file, unlink it and use the FD
+	//   (mkstemp() on a `struct str' constructed from XDG_RUNTIME_DIR, TMPDIR
+	//   or /tmp as a last resort + PROGRAM_NAME + ".XXXXXX" -> unlink();
+	//   remember to use O_CREAT | O_EXCL).  The state needs to be versioned.
+	//   Unfortunately I cannot de/serialize SSL state.
+
+	ctx.polling = true;
+	while (ctx.polling)
+		poller_run (&ctx.poller);
+
+	bot_context_free (&ctx);
+	strv_free (&g_original_argv);
+	return EXIT_SUCCESS;
+}
+