Handle edge cases relating to IRCd-sent account names.

modules/protocol/solanum.cpp

@@ -318,12 +318,32 @@ struct IRCDMessageEncap final
 		if (params[1] == "LOGIN" || params[1] == "SU")
 		{
 			User *u = source.GetUser();
-			NickCore *nc = NickCore::Find(params[2]);
-
-			if (!u || !nc)
+			if (!u)
 				return;
 
-			u->Login(nc);
+			// If we're bursting then then the user was probably logged in
+			// during a previous connection.
+			auto *na = NickAlias::Find(params[2]);
+			if (!na)
+			{
+				// Nick has been dropped, force the IRCd to deauth them.
+				IRCD->SendLogout(u);
+				return;
+			}
+
+			NickCore *nc = na->nc;
+			if (na == nc->na)
+			{
+				// User is logged into their display nick.
+				u->Login(nc);
+			}
+			else
+			{
+				// User is logged into a non-display nick, their display has
+				// probably expired due to a config change so reauthenticate
+				// them as their new display nick.
+				u->Identify(nc->na);
+			}
 		}
 		// Received: :42XAAAAAE ENCAP * CERTFP :3f122a9cc7811dbad3566bf2cec3009007c0868f
 		else if (params[1] == "CERTFP")