+/*
+ * Yes, this function looks a little ugly.
+ * However, in some circumstances we may not have a userrec, so we need to do things this way.
+ * Returns 1 if colliding local client, 2 if colliding remote, 3 if colliding both.
+ * Sends SVSNICKs as appropriate and forces nickchanges too.
+ */
+int TreeSocket::DoCollision(userrec *u, time_t remotets, const char *remoteident, const char *remoteip, const char *remoteuid)
+{
+ /*
+ * Under old protocol rules, we would have had to kill both clients.
+ * Really, this sucks.
+ * These days, we have UID. And, so what we do is, force nick change client(s)
+ * involved according to timestamp rules.
+ *
+ * RULES:
+ * user@ip equal:
+ * Force nick change on OLDER timestamped client
+ * user@ip differ:
+ * Force nick change on NEWER timestamped client
+ * TS EQUAL:
+ * FNC both.
+ *
+ * This stops abusive use of collisions, simplifies problems with loops, and so on.
+ * -- w00t
+ */
+ bool bChangeLocal = true;
+ bool bChangeRemote = true;
+
+ /* for brevity, don't use the userrec */
+ time_t localts = u->age;
+ const char *localident = u->ident;
+ const char *localip = u->GetIPString();
+
+ /* mmk. let's do this again. */
+ if (remotets == localts)
+ {
+ /* equal. fuck them both! do nada, let the handler at the bottom figure this out. */
+ }
+ else
+ {
+ /* fuck. now it gets complex. */
+
+ /* first, let's see if ident@host matches. */
+ bool SamePerson = strcmp(localident, remoteident)
+ && !strcmp(localip, remoteip);
+
+ /*
+ * if ident@ip is equal, and theirs is newer, or
+ * ident@ip differ, and ours is newer
+ */
+ if((SamePerson && remotets < localts) ||
+ (!SamePerson && remotets > localts))
+ {
+ /* remote needs to change */
+ bChangeLocal = false;
+ }
+ else
+ {
+ /* ours needs to change */
+ bChangeRemote = false;
+ }
+ }
+
+
+ if (bChangeLocal)
+ {
+ u->ForceNickChange(u->uuid);
+
+ if (!bChangeRemote)
+ return 1;
+ }
+ if (bChangeRemote)
+ {
+ /*
+ * Cheat a little here. Instead of a dedicated command to change UID,
+ * use SVSNICK and accept their client with it's UID (as we know the SVSNICK will
+ * not fail under any circumstances -- UIDs are netwide exclusive).
+ *
+ * This means that each side of a collide will generate one extra NICK back to where
+ * they have just linked (and where it got the SVSNICK from), however, it will
+ * be dropped harmlessly as it will come in as :928AAAB NICK 928AAAB, and we already
+ * have 928AAAB's nick set to that.
+ * -- w00t
+ */
+ userrec *remote = this->Instance->FindUUID(remoteuid);
+
+ if (remote)
+ {
+ /* buh.. nick change collide. force change their nick. */
+ remote->ForceNickChange(remote->uuid);
+ }
+ else
+ {
+ /* user has not been introduced yet, just inform their server */
+ this->WriteLine(std::string(":")+this->Instance->Config->ServerName+" SVSNICK "+remoteuid+" " + remoteuid);
+ }
+
+ if (!bChangeRemote)
+ return 2;
+ }
+
+ return 3;
+}
+