fix(relay): harden lifecycle and protocol handling

server/relay_protocol_gen.go

@@ -0,0 +1,43 @@
+// Code generated by scripts/generate_relay_protocol.py. DO NOT EDIT.
+
+package main
+
+const (
+	relayTypeCreate          = "create"
+	relayTypeJoin            = "join"
+	relayTypeBroadcast       = "broadcast"
+	relayTypeSendTo          = "sendTo"
+	relayTypePing            = "ping"
+	relayTypeCreated         = "created"
+	relayTypeJoined          = "joined"
+	relayTypePeerJoined      = "peerJoined"
+	relayTypePeerLeft        = "peerLeft"
+	relayTypeMessage         = "message"
+	relayTypeError           = "error"
+	relayTypePong            = "pong"
+	relayErrorRateLimited    = "rate_limited"
+	relayErrorInvalidMessage = "invalid_message"
+	relayErrorRoomExists     = "room_exists"
+	relayErrorRoomNotFound   = "room_not_found"
+	relayErrorRoomFull       = "room_full"
+	relayErrorNotInRoom      = "not_in_room"
+	relayErrorAlreadyInRoom  = "already_in_room"
+
+	maxRoomSize        = 8
+	maxMessageSize     = 65536
+	maxSessionIDLength = 64
+	maxPeerIDLength    = 128
+)
+
+func validRelayID(value string, maxLength int) bool {
+	if len(value) == 0 || len(value) > maxLength {
+		return false
+	}
+	for _, ch := range value {
+		if (ch < 'a' || ch > 'z') && (ch < 'A' || ch > 'Z') &&
+			(ch < '0' || ch > '9') && ch != '_' && ch != '-' {
+			return false
+		}
+	}
+	return true
+}