kike: stuff

Implemented a lot of the channel stuff and other stuff as well.

1 files changed, 682 insertions, 102 deletions

diff --git a/src/kike.c b/src/kike.c
index e14a646..cda6984 100644
--- a/src/kike.c
+++ b/src/kike.c
@@ -103,6 +103,7 @@ enum validation_result
 // 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
@@ -194,6 +195,25 @@ irc_validate_nickname (const char *nickname)
 	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
@@ -284,12 +304,7 @@ client_get_mode (struct client *self)
 	if (m & IRC_USER_MODE_RESTRICTED)          str_append_c (&mode, 'r');
 	if (m & IRC_USER_MODE_OPERATOR)            str_append_c (&mode, 'o');
 	if (m & IRC_USER_MODE_RX_SERVER_NOTICES)   str_append_c (&mode, 's');
-
-	if (mode.len)
-		return str_steal (&mode);
-
-	str_free (&mode);
-	return NULL;
+	return str_steal (&mode);
 }
 
 #define IRC_SUPPORTED_CHAN_MODES "ov" "imnqpst" "kl"
@@ -339,6 +354,9 @@ channel_init (struct channel *self)
 {
 	memset (self, 0, sizeof *self);
 
+	self->user_limit = -1;
+	self->topic = xstrdup ("");
+
 	str_vector_init (&self->ban_list);
 	str_vector_init (&self->exception_list);
 	str_vector_init (&self->invite_list);
@@ -363,6 +381,33 @@ channel_free (struct channel *self)
 	str_vector_free (&self->invite_list);
 }
 
+static char *
+channel_get_mode (struct channel *self, bool disclose_secrets)
+{
+	struct str mode;
+	str_init (&mode);
+
+	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');
+
+	if (self->user_limit != -1)
+		str_append_printf (&mode, " %ld", self->user_limit);
+
+	// XXX: is this correct?  Try it on an existing implementation.
+	if (self->key && disclose_secrets)
+		str_append_printf (&mode, " %s", self->key);
+	return str_steal (&mode);
+}
+
 struct server_context
 {
 	int listen_fd;                      ///< Listening socket FD
@@ -450,22 +495,7 @@ server_context_free (struct server_context *self)
 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 *);
-
-static void
-client_unregister (struct client *c, const char *reason)
-{
-	if (!c->registered)
-		return;
-
-	// TODO: multicast a `:prefix QUIT :reason' to all people present on all
-	//   channels we were on.
-	// TODO: remove ourselves from the channels, ...
-	str_map_set (&c->ctx->users, c->nickname, NULL);
-	free (c->nickname);
-	c->nickname = NULL;
-
-	c->registered = false;
-}
+static void client_unregister (struct client *, const char *);
 
 static void
 irc_try_finish_quit (struct server_context *ctx)
@@ -500,6 +530,8 @@ client_kill (struct client *c, const char *reason)
 static void
 irc_send_str (struct client *c, const struct str *s)
 {
+	hard_assert (c->initialized && !c->closing_link);
+
 	// TODO: kill the connection above some "SendQ" threshold (careful!)
 	str_append_data (&c->write_buffer, s->str,
 		s->len > IRC_MAX_MESSAGE_LENGTH ? IRC_MAX_MESSAGE_LENGTH : s->len);
@@ -591,12 +623,10 @@ static void
 on_irc_client_timeout_timer (void *user_data)
 {
 	struct client *c = user_data;
-	struct str reason;
-	str_init (&reason);
-	str_append_printf (&reason, "Ping timeout: >%u seconds",
-		c->ctx->ping_interval);
-	irc_close_link (c, reason.str);
-	str_free (&reason);
+	char *reason = xstrdup_printf
+		("Ping timeout: >%u seconds", c->ctx->ping_interval);
+	irc_close_link (c, reason);
+	free (reason);
 }
 
 static void
@@ -623,16 +653,31 @@ enum
 	IRC_RPL_CREATED               =   3,
 	IRC_RPL_MYINFO                =   4,
 
+	IRC_RPL_UMODEIS               = 221,
 	IRC_RPL_LUSERCLIENT           = 251,
 	IRC_RPL_LUSEROP               = 252,
 	IRC_RPL_LUSERUNKNOWN          = 253,
 	IRC_RPL_LUSERCHANNELS         = 254,
 	IRC_RPL_LUSERME               = 255,
 
+	IRC_RPL_AWAY                  = 301,
 	IRC_RPL_USERHOST              = 302,
+	IRC_RPL_UNAWAY                = 305,
+	IRC_RPL_NOWAWAY               = 306,
 	IRC_RPL_LIST                  = 322,
 	IRC_RPL_LISTEND               = 323,
+	IRC_RPL_CHANNELMODEIS         = 324,
+	IRC_RPL_NOTOPIC               = 331,
+	IRC_RPL_TOPIC                 = 332,
+	IRC_RPL_INVITELIST            = 346,
+	IRC_RPL_ENDOFINVITELIST       = 347,
+	IRC_RPL_EXCEPTLIST            = 348,
+	IRC_RPL_ENDOFEXCEPTLIST       = 349,
 	IRC_RPL_VERSION               = 351,
+	IRC_RPL_NAMREPLY              = 353,
+	IRC_RPL_ENDOFNAMES            = 366,
+	IRC_RPL_BANLIST               = 367,
+	IRC_RPL_ENDOFBANLIST          = 368,
 	IRC_RPL_MOTD                  = 372,
 	IRC_RPL_MOTDSTART             = 375,
 	IRC_RPL_ENDOFMOTD             = 376,
@@ -640,6 +685,8 @@ enum
 
 	IRC_ERR_NOSUCHNICK            = 401,
 	IRC_ERR_NOSUCHSERVER          = 402,
+	IRC_ERR_NOSUCHCHANNEL         = 403,
+	IRC_ERR_CANNOTSENDTOCHAN      = 404,
 	IRC_ERR_NOORIGIN              = 409,
 	IRC_ERR_NORECIPIENT           = 411,
 	IRC_ERR_NOTEXTTOSEND          = 412,
@@ -648,9 +695,20 @@ enum
 	IRC_ERR_NONICKNAMEGIVEN       = 431,
 	IRC_ERR_ERRONEOUSNICKNAME     = 432,
 	IRC_ERR_NICKNAMEINUSE         = 433,
+	IRC_ERR_NOTONCHANNEL          = 442,
+	IRC_ERR_SUMMONDISABLED        = 445,
+	IRC_ERR_USERSDISABLED         = 446,
 	IRC_ERR_NOTREGISTERED         = 451,
 	IRC_ERR_NEEDMOREPARAMS        = 461,
-	IRC_ERR_ALREADYREGISTERED     = 462
+	IRC_ERR_ALREADYREGISTERED     = 462,
+	IRC_ERR_CHANNELISFULL         = 471,
+	IRC_ERR_INVITEONLYCHAN        = 473,
+	IRC_ERR_BANNEDFROMCHAN        = 474,
+	IRC_ERR_BADCHANNELKEY         = 475,
+	IRC_ERR_BADCHANMASK           = 476,
+	IRC_ERR_CHANOPRIVSNEEDED      = 482,
+
+	IRC_ERR_USERSDONTMATCH        = 502
 };
 
 static const char *g_default_replies[] =
@@ -660,16 +718,31 @@ static const char *g_default_replies[] =
 	[IRC_RPL_CREATED] = ":This server was created %s",
 	[IRC_RPL_MYINFO] = "%s %s %s %s",
 
+	[IRC_RPL_UMODEIS] = "+%s",
 	[IRC_RPL_LUSERCLIENT] = ":There are %d users and %d services on %d servers",
 	[IRC_RPL_LUSEROP] = "%d :operator(s) online",
 	[IRC_RPL_LUSERUNKNOWN] = "%d :unknown connection(s)",
 	[IRC_RPL_LUSERCHANNELS] = "%d :channels formed",
 	[IRC_RPL_LUSERME] = ":I have %d clients and %d servers",
 
+	[IRC_RPL_AWAY] = "%s :%s",
 	[IRC_RPL_USERHOST] = ":%s",
+	[IRC_RPL_UNAWAY] = ":You are no longer marked as being away",
+	[IRC_RPL_NOWAWAY] = ":You have been marked as being away",
 	[IRC_RPL_LIST] = "%s %d :%s",
 	[IRC_RPL_LISTEND] = ":End of LIST",
+	[IRC_RPL_CHANNELMODEIS] = "%s +%s",
+	[IRC_RPL_NOTOPIC] = "%s :No topic is set",
+	[IRC_RPL_TOPIC] = "%s :%s",
+	[IRC_RPL_INVITELIST] = "%s %s",
+	[IRC_RPL_ENDOFINVITELIST] = "%s :End of channel invite list",
+	[IRC_RPL_EXCEPTLIST] = "%s %s",
+	[IRC_RPL_ENDOFEXCEPTLIST] = "%s :End of channel exception list",
 	[IRC_RPL_VERSION] = "%s.%d %s :%s",
+	[IRC_RPL_NAMREPLY] = "%c %s :%s",
+	[IRC_RPL_ENDOFNAMES] = "%s :End of NAMES list",
+	[IRC_RPL_BANLIST] = "%s %s",
+	[IRC_RPL_ENDOFBANLIST] = "%s :End of channel ban list",
 	[IRC_RPL_MOTD] = ":- %s",
 	[IRC_RPL_MOTDSTART] = ":- %s Message of the day - ",
 	[IRC_RPL_ENDOFMOTD] = ":End of MOTD command",
@@ -677,6 +750,8 @@ static const char *g_default_replies[] =
 
 	[IRC_ERR_NOSUCHNICK] = "%s :No such nick/channel",
 	[IRC_ERR_NOSUCHSERVER] = "%s :No such server",
+	[IRC_ERR_NOSUCHCHANNEL] = "%s :No such channel",
+	[IRC_ERR_CANNOTSENDTOCHAN] = "%s :Cannot send to channel",
 	[IRC_ERR_NOORIGIN] = ":No origin specified",
 	[IRC_ERR_NORECIPIENT] = ":No recipient given (%s)",
 	[IRC_ERR_NOTEXTTOSEND] = ":No text to send",
@@ -685,9 +760,20 @@ static const char *g_default_replies[] =
 	[IRC_ERR_NONICKNAMEGIVEN] = ":No nickname given",
 	[IRC_ERR_ERRONEOUSNICKNAME] = "%s :Erroneous nickname",
 	[IRC_ERR_NICKNAMEINUSE] = "%s :Nickname is already in use",
+	[IRC_ERR_NOTONCHANNEL] = "%s :You're not on that channel",
+	[IRC_ERR_SUMMONDISABLED] = ":SUMMON has been disabled",
+	[IRC_ERR_USERSDISABLED] = ":USERS has been disabled",
 	[IRC_ERR_NOTREGISTERED] = ":You have not registered",
 	[IRC_ERR_NEEDMOREPARAMS] = "%s :Not enough parameters",
 	[IRC_ERR_ALREADYREGISTERED] = ":Unauthorized command (already registered)",
+	[IRC_ERR_CHANNELISFULL] = "%s :Cannot join channel (+l)",
+	[IRC_ERR_INVITEONLYCHAN] = "%s :Cannot join channel (+i)",
+	[IRC_ERR_BANNEDFROMCHAN] = "%s :Cannot join channel (+b)",
+	[IRC_ERR_BADCHANNELKEY] = "%s :Cannot join channel (+k)",
+	[IRC_ERR_BADCHANMASK] = "%s :Bad Channel Mask",
+	[IRC_ERR_CHANOPRIVSNEEDED] = "%s :You're not channel operator",
+
+	[IRC_ERR_USERSDONTMATCH] = ":Cannot change mode for other users",
 };
 
 // XXX: this way we cannot typecheck the arguments, so we must be careful
@@ -709,15 +795,18 @@ irc_send_reply (struct client *c, int id, ...)
 	str_free (&tmp);
 }
 
+#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)
-	{
-		irc_send_reply (c, IRC_ERR_NOMOTD);
-		return;
-	}
+		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++)
@@ -725,13 +814,130 @@ irc_send_motd (struct client *c)
 	irc_send_reply (c, IRC_RPL_ENDOFMOTD);
 }
 
-static bool
-client_on_channel (struct client *c, const struct channel *chan)
+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 (!irc_strcmp (iter->nickname, c->nickname))
-			return true;
-	return false;
+			return iter;
+	return NULL;
+}
+
+static struct channel_user *
+channel_add_user (struct channel *chan, const struct client *c)
+{
+	size_t nick_len = strlen (c->nickname);
+	struct channel_user *link = xcalloc (1, sizeof *link + nick_len + 1);
+	memcpy (link->nickname, c->nickname, nick_len + 1);
+	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;
+}
+
+static void
+channel_destroy_if_empty (struct server_context *ctx, struct channel *chan)
+{
+	if (!chan->users)
+	{
+		str_map_set (&ctx->channels, chan->name, NULL);
+		channel_free (chan);
+		free (chan);
+	}
+}
+
+static bool
+client_in_mask_list (const struct client *c, const struct str_vector *mask)
+{
+	struct str client;
+	str_init (&client);
+	str_append_printf (&client, "%s!%s@%s",
+		c->nickname, c->username, c->hostname);
+	irc_strxfrm (client.str, client.str, client.len);
+	bool result = false;
+	for (size_t i = 0; i < mask->len; i++)
+		// FIXME: irc_strxfrm() for the mask (save in canonical format?)
+		if (!fnmatch (client.str, mask->vector[i], 0))
+		{
+			result = true;
+			break;
+		}
+	str_free (&client);
+	return result;
+}
+
+static void
+client_send_to_roommates (struct client *c, const char *message)
+{
+	struct str_map targets;
+	str_map_init (&targets);
+	targets.key_xfrm = irc_strxfrm;
+
+	struct str_map_iter iter;
+	str_map_iter_init (&iter, &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;
+
+		// When we're unregistering, the str_map_find() will return zero,
+		// which will prevent sending the QUIT message to ourselves.
+		for (struct channel_user *iter = chan->users; iter; iter = iter->next)
+			str_map_set (&targets, iter->nickname,
+				str_map_find (&c->ctx->users, iter->nickname));
+	}
+
+	str_map_iter_init (&iter, &targets);
+	struct client *target;
+	while ((target = str_map_iter_next (&iter)))
+		irc_send (target, "%s", message);
+}
+
+static void
+client_unregister (struct client *c, const char *reason)
+{
+	if (!c->registered)
+		return;
+
+	// Make the user effectively non-existent
+	str_map_set (&c->ctx->users, c->nickname, NULL);
+
+	char *message = xstrdup_printf (":%s!%s@%s QUIT :%s",
+		c->nickname, c->username, c->hostname, reason);
+	client_send_to_roommates (c, message);
+	free (message);
+
+	struct str_map_iter iter;
+	str_map_iter_init (&iter, &c->ctx->channels);
+	struct channel *chan;
+	while ((chan = str_map_iter_next (&iter)))
+	{
+		struct channel_user *user;
+		if (!(user = channel_get_user (chan, c)))
+			continue;
+		channel_remove_user (chan, user);
+		channel_destroy_if_empty (c->ctx, chan);
+	}
+
+	free (c->nickname);
+	c->nickname = NULL;
+	c->registered = false;
 }
 
 static void
@@ -754,7 +960,7 @@ irc_send_lusers (struct client *c)
 	struct channel *chan;
 	while ((chan = str_map_iter_next (&iter)))
 		if (!(chan->modes & IRC_CHAN_MODE_SECRET)
-		 || client_on_channel (c, chan))
+		 || channel_get_user (chan, c))
 			n_channels++;
 
 	irc_send_reply (c, IRC_RPL_LUSERCLIENT,
@@ -795,7 +1001,7 @@ irc_try_finish_registration (struct client *c)
 	irc_send_motd (c);
 
 	char *mode = client_get_mode (c);
-	if (mode)
+	if (*mode)
 		irc_send (c, ":%s MODE %s :+%s", c->nickname, c->nickname, mode);
 	free (mode);
 }
@@ -816,54 +1022,45 @@ irc_handle_nick (const struct irc_message *msg, struct client *c)
 {
 	struct server_context *ctx = c->ctx;
 
-	if (c->registered)
-	{
-		irc_send_reply (c, IRC_ERR_ALREADYREGISTERED);
-		return;
-	}
 	if (msg->params.len < 1)
-	{
-		irc_send_reply (c, IRC_ERR_NONICKNAMEGIVEN);
-		return;
-	}
+		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);
+
+	if (c->registered)
 	{
-		irc_send_reply (c, IRC_ERR_ERRONEOUSNICKNAME, nickname);
-		return;
+		char *message = xstrdup_printf (":%s!%s@%s NICK :%s",
+			c->nickname, c->username, c->hostname, nickname);
+		client_send_to_roommates (c, message);
+		free (message);
 	}
+
+	// Release the old nickname and allocate a new one
 	if (c->nickname)
 	{
 		str_map_set (&ctx->users, c->nickname, NULL);
 		free (c->nickname);
 	}
-	if (str_map_find (&ctx->users, nickname))
-	{
-		irc_send_reply (c, IRC_ERR_NICKNAMEINUSE, nickname);
-		return;
-	}
-
-	// Allocate the nickname
 	c->nickname = xstrdup (nickname);
 	str_map_set (&ctx->users, nickname, c);
 
-	irc_try_finish_registration (c);
+	if (!c->registered)
+		irc_try_finish_registration (c);
 }
 
 static void
 irc_handle_user (const struct irc_message *msg, struct client *c)
 {
 	if (c->registered)
-	{
-		irc_send_reply (c, IRC_ERR_ALREADYREGISTERED);
-		return;
-	}
+		RETURN_WITH_REPLY (c, IRC_ERR_ALREADYREGISTERED);
 	if (msg->params.len < 4)
-	{
-		irc_send_reply (c, IRC_ERR_NEEDMOREPARAMS, msg->command);
-		return;
-	}
+		RETURN_WITH_REPLY (c, IRC_ERR_NEEDMOREPARAMS, msg->command);
 
 	const char *username = msg->params.vector[0];
 	const char *mode     = msg->params.vector[1];
@@ -892,10 +1089,7 @@ static void
 irc_handle_userhost (const struct irc_message *msg, struct client *c)
 {
 	if (msg->params.len < 1)
-	{
-		irc_send_reply (c, IRC_ERR_NEEDMOREPARAMS, msg->command);
-		return;
-	}
+		RETURN_WITH_REPLY (c, IRC_ERR_NEEDMOREPARAMS, msg->command);
 
 	struct str reply;
 	str_init (&reply);
@@ -964,27 +1158,23 @@ irc_handle_pong (const struct irc_message *msg, struct client *c)
 static void
 irc_handle_quit (const struct irc_message *msg, struct client *c)
 {
-	struct str reason;
-	str_init (&reason);
-	str_append_printf (&reason, "Quit: %s",
+	char *reason = xstrdup_printf ("Quit: %s",
 		msg->params.len > 0 ? msg->params.vector[0] : c->nickname);
-	irc_close_link (c, reason.str);
-	str_free (&reason);
+	irc_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]))
-		irc_send_reply (c, IRC_ERR_NOSUCHSERVER, msg->params.vector[0]);
-	else
-	{
-		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);
-	}
+		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
@@ -998,27 +1188,126 @@ irc_handle_version (const struct irc_message *msg, struct client *c)
 }
 
 static void
-irc_handle_privmsg (const struct irc_message *msg, struct client *c)
+irc_channel_multicast (struct channel *chan, const char *message)
 {
-	if (msg->params.len < 1)
-		irc_send_reply (c, IRC_ERR_NORECIPIENT, msg->command);
-	else if (msg->params.len < 2 || !*msg->params.vector[1])
-		irc_send_reply (c, IRC_ERR_NOTEXTTOSEND);
+	for (struct channel_user *iter = chan->users; iter; iter = iter->next)
+	{
+		struct client *c = str_map_find (&chan->ctx->users, iter->nickname);
+		irc_send (c, "%s", message);
+	}
+}
+
+static void
+irc_send_channel_list (struct client *c, const char *channel_name,
+	const struct str_vector *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);
+}
+
+static bool
+irc_maybe_send_channel_list (struct client *c, struct channel *chan,
+	const char *mode_string)
+{
+	if (*mode_string == '+')
+		mode_string++;
+
+	if (!strcmp (mode_string, "b"))
+		irc_send_channel_list (c, chan->name, &chan->ban_list,
+			IRC_RPL_BANLIST, IRC_RPL_ENDOFBANLIST);
+	else if (!strcmp (mode_string, "e"))
+		irc_send_channel_list (c, chan->name, &chan->exception_list,
+			IRC_RPL_EXCEPTLIST, IRC_RPL_ENDOFEXCEPTLIST);
+	else if (!strcmp (mode_string, "I"))
+		irc_send_channel_list (c, chan->name, &chan->invite_list,
+			IRC_RPL_INVITELIST, IRC_RPL_ENDOFINVITELIST);
 	else
+		return false;
+	return true;
+}
+
+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);
+	if (client)
+	{
+		if (irc_strcmp (target, c->nickname))
+			RETURN_WITH_REPLY (c, IRC_ERR_USERSDONTMATCH);
+
+		char *mode = client_get_mode (client);
+		irc_send_reply (c, IRC_RPL_UMODEIS, mode);
+		free (mode);
+
+		// TODO: mode modification
+		return;
+	}
+
+	struct channel *chan = str_map_find (&c->ctx->channels, target);
+	if (chan)
 	{
-		const char *target = msg->params.vector[0];
-		const char *text   = msg->params.vector[1];
-		struct client *target_c = str_map_find (&c->ctx->users, target);
-		if (!target_c)
+		if (msg->params.len < 2)
 		{
-			irc_send_reply (c, IRC_ERR_NOSUCHNICK, target);
+			char *mode = channel_get_mode (chan, channel_get_user (chan, c));
+			irc_send_reply (c, IRC_RPL_CHANNELMODEIS, target, mode);
+			free (mode);
 			return;
 		}
+		if (msg->params.len < 3
+		 && irc_maybe_send_channel_list (c, chan, msg->params.vector[1]))
+			return;
+
+		// TODO: mode modification
+		return;
+	}
+
+	irc_send_reply (c, IRC_ERR_NOSUCHNICK, target);
+}
+
+static void
+irc_handle_privmsg (const struct irc_message *msg, struct client *c)
+{
+	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)
+	{
+		irc_send (client, ":%s!%s@%s PRIVMSG %s :%s",
+			c->nickname, c->username, c->hostname, target, text);
+		return;
+	}
 
-		// TODO: channels
-		irc_send (target_c, ":%s!%s@%s PRIVMSG %s :%s",
+	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 PRIVMSG %s :%s",
 			c->nickname, c->username, c->hostname, target, text);
+		irc_channel_multicast (chan, message);
+		free (message);
+		return;
 	}
+
+	irc_send_reply (c, IRC_ERR_NOSUCHNICK, target);
 }
 
 static void
@@ -1036,10 +1325,7 @@ 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]))
-	{
-		irc_send_reply (c, IRC_ERR_NOSUCHSERVER, msg->params.vector[1]);
-		return;
-	}
+		RETURN_WITH_REPLY (c, IRC_ERR_NOSUCHSERVER, msg->params.vector[1]);
 
 	struct channel *chan;
 	if (msg->params.len == 0)
@@ -1048,7 +1334,7 @@ irc_handle_list (const struct irc_message *msg, struct client *c)
 		str_map_iter_init (&iter, &c->ctx->channels);
 		while ((chan = str_map_iter_next (&iter)))
 			if (!(chan->modes & (IRC_CHAN_MODE_PRIVATE | IRC_CHAN_MODE_SECRET))
-			 || client_on_channel (c, chan))
+			 || channel_get_user (chan, c))
 				irc_send_rpl_list (c, chan);
 	}
 	else
@@ -1059,13 +1345,298 @@ irc_handle_list (const struct irc_message *msg, struct client *c)
 		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)
-			 || client_on_channel (c, chan)))
+			 || channel_get_user (chan, c)))
 				irc_send_rpl_list (c, chan);
 		str_vector_free (&channels);
 	}
 	irc_send_reply (c, IRC_RPL_LISTEND);
 }
 
+static void
+irc_send_rpl_namreply (struct client *c, const struct channel *chan)
+{
+	struct str_vector nicks;
+	str_vector_init (&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);
+	for (struct channel_user *iter = chan->users; iter; iter = iter->next)
+	{
+		struct client *target = str_map_find (&c->ctx->users, iter->nickname);
+		if (!on_channel && (target->mode & IRC_USER_MODE_INVISIBLE))
+			continue;
+
+		struct str result;
+		str_init (&result);
+		if (iter->modes & IRC_CHAN_MODE_OPERATOR)
+			str_append_c (&result, '@');
+		else if (iter->modes & IRC_CHAN_MODE_VOICE)
+			str_append_c (&result, '+');
+		str_append (&result, target->nickname);
+		str_vector_add_owned (&nicks, str_steal (&result));
+	}
+
+	if (nicks.len)
+	{
+		char *reply = join_str_vector (&nicks, ' ');
+		irc_send_reply (c, IRC_RPL_NAMREPLY, type, chan->name, reply);
+		free (reply);
+	}
+	str_vector_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_iter iter;
+		str_map_iter_init (&iter, &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);
+
+		// TODO
+		// If no <channel> parameter is given, a list of all channels and their
+		// occupants is returned.  At the end of this list, a list of users who
+		// are visible but either not on any channel or not on a visible channel
+		// are listed as being on `channel' "*".
+		irc_send_reply (c, IRC_RPL_ENDOFNAMES, "*");
+	}
+	else
+	{
+		struct str_vector channels;
+		str_vector_init (&channels);
+		split_str_ignore_empty (msg->params.vector[0], ',', &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);
+				irc_send_reply (c, IRC_RPL_ENDOFNAMES, channels.vector[i]);
+			}
+		str_vector_free (&channels);
+	}
+}
+
+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);
+}
+
+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);
+
+	free (chan->topic);
+	chan->topic = xstrdup (msg->params.vector[1]);
+
+	char *message = xstrdup_printf (":%s!%s@%s TOPIC %s :%s",
+		c->nickname, c->username, c->hostname, target, chan->topic);
+	irc_channel_multicast (chan, message);
+	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);
+	else
+		irc_send (c, "%s", message);
+	free (message);
+
+	channel_remove_user (chan, user);
+	channel_destroy_if_empty (c->ctx, chan);
+}
+
+static void
+irc_part_all_channels (struct client *c)
+{
+	struct str_map_iter iter;
+	str_map_iter_init (&iter, &c->ctx->channels);
+	struct channel *chan = str_map_iter_next (&iter), *next;
+	while (chan)
+	{
+		// We have to be careful here, the channel might get destroyed
+		next = str_map_iter_next (&iter);
+		if (channel_get_user (chan, c))
+			irc_try_part (c, chan->name, NULL);
+		chan = next;
+	}
+}
+
+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 str_vector channels;
+	str_vector_init (&channels);
+	split_str_ignore_empty (msg->params.vector[0], ',', &channels);
+	for (size_t i = 0; i < channels.len; i++)
+		irc_try_part (c, channels.vector[i], reason);
+	str_vector_free (&channels);
+}
+
+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);
+		user_mode = IRC_CHAN_MODE_OPERATOR;
+
+		chan = xcalloc (1, sizeof *chan);
+		channel_init (chan);
+		str_map_set (&c->ctx->channels, channel_name, chan);
+
+		chan->ctx = c->ctx;
+		chan->name = xstrdup (channel_name);
+	}
+	else if (channel_get_user (chan, c))
+		return;
+
+	if ((chan->modes & IRC_CHAN_MODE_INVITE_ONLY)
+	 && !client_in_mask_list (c, &chan->invite_list))
+		// TODO: exceptions caused by INVITE
+		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))
+		RETURN_WITH_REPLY (c, IRC_ERR_BANNEDFROMCHAN, channel_name);
+
+	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);
+	else
+		irc_send (c, "%s", message);
+	free (message);
+
+	irc_send_rpl_topic (c, chan);
+	irc_send_rpl_namreply (c, chan);
+}
+
+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 str_vector channels;
+	struct str_vector keys;
+	str_vector_init (&channels);
+	str_vector_init (&keys);
+	split_str_ignore_empty (msg->params.vector[0], ',', &channels);
+	if (msg->params.len > 1)
+		split_str_ignore_empty (msg->params.vector[1], ',', &keys);
+
+	for (size_t i = 0; i < channels.len; i++)
+		irc_try_join (c, channels.vector[i],
+			i < keys.len ? keys.vector[i] : NULL);
+
+	str_vector_free (&channels);
+	str_vector_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)
+	{
+		free (c->away_message);
+		c->away_message = NULL;
+		irc_send_reply (c, IRC_RPL_UNAWAY);
+	}
+	else
+	{
+		free (c->away_message);
+		c->away_message = xstrdup (msg->params.vector[0]);
+		irc_send_reply (c, IRC_RPL_NOWAWAY);
+	}
+}
+
 // -----------------------------------------------------------------------------
 
 struct irc_command
@@ -1079,6 +1650,7 @@ 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: more commands, see RFC 2812 :!
 	static const struct irc_command message_handlers[] =
 	{
@@ -1094,9 +1666,17 @@ irc_register_handlers (struct server_context *ctx)
 		{ "QUIT",     false, irc_handle_quit     },
 		{ "TIME",     true,  irc_handle_time     },
 		{ "VERSION",  true,  irc_handle_version  },
+		{ "USERS",    true,  irc_handle_users    },
+		{ "SUMMON",   true,  irc_handle_summon   },
+		{ "AWAY",     true,  irc_handle_away     },
 
+		{ "MODE",     true,  irc_handle_mode     },
 		{ "PRIVMSG",  true,  irc_handle_privmsg  },
+		{ "JOIN",     true,  irc_handle_join     },
+		{ "PART",     true,  irc_handle_part     },
+		{ "TOPIC",    true,  irc_handle_topic    },
 		{ "LIST",     true,  irc_handle_list     },
+		{ "NAMES",    true,  irc_handle_names    },
 	};
 
 	for (size_t i = 0; i < N_ELEMENTS (message_handlers); i++)