Implement modchannel plugin API between clients and proxy

2 files changed, 112 insertions, 0 deletions

diff --git a/plugin_modchan.go b/plugin_modchan.go
new file mode 100644
index 0000000..446a37f
--- /dev/null
+++ b/plugin_modchan.go
@@ -0,0 +1,96 @@
+package proxy
+
+import (
+	"sync"
+
+	"github.com/HimbeerserverDE/mt"
+)
+
+var (
+	modChanSubscribers  map[string][]*ClientConn
+	modChanSubscriberMu sync.RWMutex
+)
+
+var (
+	onCltModChanMsg     []func(string, *ClientConn, string) bool
+	onCltModChanMsgMu   sync.RWMutex
+	onCltModChanMsgOnce sync.Once
+)
+
+// SendModChanMsg sends a message to all subscribed clients on a modchannel.
+func SendModChanMsg(channel, msg string) {
+	modChanSubscriberMu.RLock()
+	defer modChanSubscriberMu.RUnlock()
+
+	subs, _ := modChanSubscribers[channel]
+	for _, cc := range subs {
+		cc.SendCmd(&mt.ToCltModChanMsg{
+			Channel: channel,
+			Msg:     msg,
+		})
+	}
+}
+
+// RegisterOnCltModChanMsg registers a handler that is called
+// when a client sends a message on a modchannel.
+// If any handler returns true, the message is not forwarded
+// to the upstream server.
+func RegisterOnCltModChanMsg(handler func(string, *ClientConn, string) bool) {
+	onCltModChanMsgMu.Lock()
+	defer onCltModChanMsgMu.Unlock()
+
+	onCltModChanMsg = append(onCltModChanMsg, handler)
+}
+
+func cltLeaveModChan(cc *ClientConn, channel string) {
+	modChanSubscriberMu.Lock()
+	defer modChanSubscriberMu.Unlock()
+
+	for i, sub := range modChanSubscribers[channel] {
+		if sub == cc {
+			modChanSubscribers[channel] = append(modChanSubscribers[channel][:i], modChanSubscribers[channel][i+1:]...)
+			break
+		}
+	}
+}
+
+func cltLeaveModChans(cc *ClientConn) {
+	modChanSubscriberMu.Lock()
+	defer modChanSubscriberMu.Unlock()
+
+	for ch := range modChanSubscribers {
+		for i, sub := range modChanSubscribers[ch] {
+			if sub == cc {
+				modChanSubscribers[ch] = append(modChanSubscribers[ch][:i], modChanSubscribers[ch][i+1:]...)
+				break
+			}
+		}
+	}
+}
+
+func handleCltModChanMsg(cc *ClientConn, cmd *mt.ToSrvMsgModChan) bool {
+	onCltModChanMsgMu.RLock()
+	defer onCltModChanMsgMu.RUnlock()
+
+	subs, _ := modChanSubscribers[cmd.Channel]
+	for _, sub := range subs {
+		sub.SendCmd(&mt.ToCltModChanMsg{
+			Channel: cmd.Channel,
+			Sender:  cc.Name(),
+			Msg:     cmd.Msg,
+		})
+	}
+
+	drop := false
+	for _, handler := range onCltModChanMsg {
+		if handler(cmd.Channel, cc, cmd.Msg) {
+			drop = true
+		}
+	}
+
+	return drop
+}
+
+func init() {
+	modChanSubscribers = make(map[string][]*ClientConn)
+}
diff --git a/process.go b/process.go
index a68238c..05b16fe 100644
--- a/process.go
+++ b/process.go
@@ -12,6 +12,10 @@ import (
 )
 
 func (cc *ClientConn) process(pkt mt.Pkt) {
+	defer func() {
+		cltLeaveModChans(cc)
+	}()
+
 	srv := cc.server()
 
 	forward := func(pkt mt.Pkt) {
@@ -484,6 +488,18 @@ func (cc *ClientConn) process(pkt mt.Pkt) {
 		if handleOnPlayerReceiveFields(cc, cmd) {
 			return
 		}
+	case *mt.ToSrvJoinModChan:
+		modChanSubscriberMu.Lock()
+		defer modChanSubscriberMu.Unlock()
+
+		subs, _ := modChanSubscribers[cmd.Channel]
+		modChanSubscribers[cmd.Channel] = append(subs, cc)
+	case *mt.ToSrvLeaveModChan:
+		cltLeaveModChan(cc, cmd.Channel)
+	case *mt.ToSrvMsgModChan:
+		if handleCltModChanMsg(cc, cmd) {
+			return
+		}
 	}
 
 	forward(pkt)