net_irc: Add private namespace channels to prevent relay collisions.

Add the ability for channels to exist in a "private"
per-user namespace, which allows a channel to be restricted
to a single user. This is mostly useful in conjunction
with private relays, to ensure that the channel is automatically
access restricted and also to prevent channel naming conflicts
between users/relays, since each such channel is unique by user,
thus avoiding naming collisions.

This extends the modeless channel prefix '+' for this purpose;
we still honor the modeless property of the channel, since modes
are not useful for private namespace channels.

configs/mod_slack.conf

@@ -17,12 +17,14 @@ cookie_ds=
                     ; If this user is on IRC but not in a relayed channel, the user will be automatically invited to channels with activity.
                     ; Messages posted from IRC will not be tagged with your username, so they will appear to be coming from you
                     ; (generally, it is appropriate to use a user token with this feature, as opposed to a bot token).
-                    ; Access to the channel itself is not inherently restricted, but other users cannot post over the relay (though they can to the IRC side),
+                    ; Access to the channel itself is not inherently restricted by default, but other users cannot post over the relay (though they can to the IRC side),
                     ; and if other members are present in the channel when a message is posted, they will be kicked.
-                    ; If you need to totally restrict access to the IRC channel, you will need to use ChanServ or the appropriate channel modes.
                     ; For example, the channel topic, if set on Slack, will be set as the IRC channel's topic, and is not private.
                     ; Additionally, since personal relays don't generally make sense to share between IRC users, it is recommended that
-                    ; you use the local channel prefix (&) instead of the network channel prefix (#).
+                    ; you use the modeless channel prefix (+) instead of the network channel prefix (#). +-prefixed channels in LBBS are "private namespace channels".
+                    ; These are treated specially in that the IRC channel exists in a namespace private to the specified user, so access is automatically restricted.
+                    ; It also prevents naming conflicts since the channels exist in separate namespaces; the channel +test for two different users refers to two different channels.
+                    ; If you do not use the + channel prefix, you can manually restrict channel access by normal mechanisms, e.g. using ChanServ or the appropriate channel modes.
 ;preservethreading=no ; If the first word of a message relayed from IRC to Slack consists of a thread ID followed by a colon,
                       ; then that message will be replied to "in thread" (without the thread ID prefixed). This allows transparently preserving Slack threading from IRC.
                       ; Default is 'no'.

include/net_irc.h

@@ -19,6 +19,19 @@
 #define PRIVATE_CHANNEL_PREFIX "*"
 #define SECRET_CHANNEL_PREFIX "@"
 
+/*! \brief RFC 2811 channel names namespace */
+/*! \note There is no real support for &, +,  and ! channels, as defined in the RFC; these are just defined here for completeness.
+ * Consequently, we hijack + (modeless channels) for private namespace channels (separate namespace per user),
+ * since we don't need modes for these anyways, and there's not much use for modeless channels otherwise.
+ * We can't use some other arbitrary prefix because IRC clients will just prefix # automatically
+ * if the channel name doesn't begin with one of the officially valid prefixes. */
+/* "Standard" channels */
+#define CHANNEL_NAME_PREFIX_NETWORK "#"
+#define CHANNEL_NAME_PREFIX_LOCAL "&"
+#define CHANNEL_NAME_PREFIX_MODELESS "+"
+/* "Safe" channels */
+#define CHANNEL_NAME_PREFIX_TIMESTAMPED "!"
+
 #define PREFIX_FOUNDER "~"
 #define PREFIX_ADMIN "&"
 #define PREFIX_OP "@"
@@ -164,9 +177,10 @@ int _irc_relay_send(const char *channel, enum channel_user_modes modes, const ch
  * \brief Set the channel topic (from a relay)
  * \param channel Channel name
  * \param topic Topic description
+ * \param ircuser Name of owner, for private namespace channels
  * \retval 0 on success, -1 on failure
  */
-int irc_relay_set_topic(const char *channel, const char *topic);
+int irc_relay_set_topic(const char *channel, const char *topic, const char *ircuser);
 
 #define irc_relay_raw_send(channel, msg) _irc_relay_raw_send(channel, msg, BBS_MODULE_SELF)
 

modules/mod_auth_mysql.c

@@ -327,7 +327,7 @@ static int make_user(const char *username, const char *password, const char *ful
 }
 
 /*! \note Sysop can always manually adjust the database if needed to override */
-#define USERNAME_RESERVED(u) (!strcasecmp(u, "root") || !strcasecmp(u, "sysop") || !strcasecmp(u, "bbs") || !strcasecmp(u, "ChanServ") || !strcasecmp(u, "NickServ") || !strcasecmp(u, "services") || !strcasecmp(u, "postmaster"))
+#define USERNAME_RESERVED(u) (!strcasecmp(u, "root") || !strcasecmp(u, "sysop") || !strcasecmp(u, "bbs") || !strcasecmp(u, "ChanServ") || !strcasecmp(u, "NickServ") || !strcasecmp(u, "MessageServ") || !strcasecmp(u, "services") || !strcasecmp(u, "postmaster") || !strcasecmp(u, "newsmaster") || !strcasecmp(u, "anonymous"))
 
 static int username_reserved(const char *username)
 {

modules/mod_slack.c

@@ -916,7 +916,7 @@ static int slack_send(struct irc_relay_message *rmsg)
 			if (!strlen_zero(cp->topic)) { /* The first time anybody joins, set the channel topic */
 				cp->used = 1; /* Only need to do this once */
 				/* XXX Note: Since anyone can join the channel, the channel topic may "leak" */
-				irc_relay_set_topic(channel, cp->topic);
+				irc_relay_set_topic(channel, cp->topic, relay->ircuser);
 			}
 		}
 		if (!relay->relaysystem) {