From 0f78dcdd577ae79b5ca26977bde118a421a999f5 Mon Sep 17 00:00:00 2001
From: Sadie Powell
Date: Sun, 28 Dec 2025 12:08:16 +0000
Subject: Avoid sending S2S tags to 1205 protocol servers.

---
 src/modules/m_spanningtree/compat.cpp | 21 ++++++++++++++++++++-
 1 file changed, 20 insertions(+), 1 deletion(-)

(limited to 'src/modules')

diff --git a/src/modules/m_spanningtree/compat.cpp b/src/modules/m_spanningtree/compat.cpp
index 8be5f8ec9..c41b8e45b 100644
--- a/src/modules/m_spanningtree/compat.cpp
+++ b/src/modules/m_spanningtree/compat.cpp
@@ -46,7 +46,26 @@ void TreeSocket::WriteLine(const std::string& original_line)
 
 	if (line[0] == '@') // Skip the tags.
 	{
-		cmdstart = NextToken(line, 0);
+		const auto tagend = NextToken(line, cmdstart);
+
+		auto tagsep = '@';
+		std::string newtags;
+		irc::sepstream ss(line.substr(cmdstart + 1, tagend - cmdstart - 1), ';');
+		for (std::string tag; ss.GetToken(tag); )
+		{
+			// Skip server tags.
+			if (tag[0] != '~')
+			{
+				newtags.push_back(tagsep);
+				newtags.append(tag);
+				tagsep = ';';
+			}
+		}
+		if (!newtags.empty())
+			newtags.push_back(' ');
+		line.replace(cmdstart, tagend - cmdstart + 1, newtags);
+
+		cmdstart = NextToken(line, cmdstart);
 		if (cmdstart != std::string::npos)
 			cmdstart++;
 	}
-- 
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