Allow plugins to intercept client-to-server chat messages

3 files changed, 33 insertions, 4 deletions

diff --git a/chat.go b/chat.go
index 2a8cda4..0578cb2 100644
--- a/chat.go
+++ b/chat.go
@@ -81,5 +81,13 @@ func onChatMsg(cc *ClientConn, cmd *mt.ToSrvChatMsg) (string, bool) {
 		return cmd.Handler(cc, args...), true
 	}
 
-	return "", false
+	onChatMsgMu.RLock()
+	defer onChatMsgMu.RUnlock()
+
+	msg := cmd.Msg
+	for _, handler := range onChatMsgs {
+		msg = handler(cc, msg)
+	}
+
+	return msg, msg == ""
 }
diff --git a/plugin_chat.go b/plugin_chat.go
new file mode 100644
index 0000000..a21526f
--- /dev/null
+++ b/plugin_chat.go
@@ -0,0 +1,21 @@
+package proxy
+
+import "sync"
+
+var (
+	onChatMsgs  []func(*ClientConn, string) string
+	onChatMsgMu sync.RWMutex
+)
+
+// RegisterOnChatMsg registers a handler that is called
+// when a client sends a chat message that is not a proxy command.
+// The returned string overrides the original message.
+// Later handlers will receive the modified message.
+// Handlers are called in registration order.
+// If the final message is empty, it is not forwarded to the upstream server.
+func RegisterOnChatMsg(handler func(*ClientConn, string) string) {
+	onChatMsgMu.Lock()
+	defer onChatMsgMu.Unlock()
+
+	onChatMsgs = append(onChatMsgs, handler)
+}
diff --git a/process.go b/process.go
index b7623b5..88c999f 100644
--- a/process.go
+++ b/process.go
@@ -462,6 +462,7 @@ func (cc *ClientConn) process(pkt mt.Pkt) {
 		go func(done chan<- struct{}) {
 			result, isCmd := onChatMsg(cc, cmd)
 			if !isCmd {
+				cmd.Msg = result
 				forward(pkt)
 			} else if result != "" {
 				cc.SendChatMsg(result)
@@ -474,9 +475,8 @@ func (cc *ClientConn) process(pkt mt.Pkt) {
 			select {
 			case <-done:
 			case <-time.After(ChatCmdTimeout):
-				cmdName := strings.Split(cmd.Msg, " ")[0]
-				cc.Log("<-", "timeout command", cmd.Msg)
-				cc.SendChatMsg("Command", cmdName, "is taking suspiciously long to execute.")
+				cc.Log("<-", "timeout chat msg", cmd.Msg)
+				cc.SendChatMsg("Proxy chat message processing timeout.")
 			}
 		}(done)