m_spanningtree Add optional expected nick TS parameter to SVSNICK

Drop SVSNICK if the expected nick TS is present and it does not match the user's nick timestamp

1 files changed, 23 insertions, 0 deletions

diff --git a/src/modules/m_spanningtree/svsnick.cpp b/src/modules/m_spanningtree/svsnick.cpp
index 8689f71ac..bb21fc54d 100644
--- a/src/modules/m_spanningtree/svsnick.cpp
+++ b/src/modules/m_spanningtree/svsnick.cpp
@@ -29,6 +29,29 @@ CmdResult CommandSVSNick::Handle(User* user, std::vector<std::string>& parameter
 
 	if (u && IS_LOCAL(u))
 	{
+		// The 4th parameter is optional and it is the expected nick TS of the target user. If this parameter is
+		// present and it doesn't match the user's nick TS, the SVSNICK is not acted upon.
+		// This makes it possible to detect the case when services wants to change the nick of a user, but the
+		// user changes their nick before the SVSNICK arrives, making the SVSNICK nick change (usually to a guest nick)
+		// unnecessary. Consider the following for example:
+		//
+		// 1. test changes nick to Attila which is protected by services
+		// 2. Services SVSNICKs the user to Guest12345
+		// 3. Attila changes nick to Attila_ which isn't protected by services
+		// 4. SVSNICK arrives
+		// 5. Attila_ gets his nick changed to Guest12345 unnecessarily
+		//
+		// In this case when the SVSNICK is processed the target has already changed his nick to something
+		// which isn't protected, so changing the nick again to a Guest nick is not desired.
+		// However, if the expected nick TS parameter is present in the SVSNICK then the nick change in step 5
+		// won't happen because the timestamps won't match.
+		if (parameters.size() > 3)
+		{
+			time_t ExpectedTS = ConvToInt(parameters[3]);
+			if (u->age != ExpectedTS)
+				return CMD_FAILURE; // Ignore SVSNICK
+		}
+
 		std::string nick = parameters[1];
 		if (isdigit(nick[0]))
 			nick = u->uuid;