1 files changed, 14 insertions, 3 deletions

diff --git a/ot_udp.c b/ot_udp.c
index 5bf9d52..4e760bb 100644
--- a/ot_udp.c
+++ b/ot_udp.c
@@ -105,10 +105,11 @@ int handle_udp6(int64_t serversocket, struct ot_workstruct *ws) {
        match, return an error packet */
     udp_make_connectionid(connid, remoteip, 1);
     if (inpacket[0] != connid[0] || inpacket[1] != connid[1]) {
-      const size_t s = sizeof("Connection ID missmatch.");
+      const char err_idmiss[] = "Connection ID missmatch.";
+      size_t s = sizeof(err_idmiss);
       outpacket[0]   = htonl(3);
       outpacket[1]   = inpacket[3];
-      memcpy(&outpacket[2], "Connection ID missmatch.", s);
+      memcpy(&outpacket[2], &err_idmiss[0], s);
       socket_send(serversocket, ws->outbuf, 8 + s, remoteip, remoteport);
       stats_issue_event(EVENT_CONNID_MISSMATCH, FLAG_UDP, 8 + s);
       return 1;
@@ -173,7 +174,17 @@ int handle_udp6(int64_t serversocket, struct ot_workstruct *ws) {
         numwant = max_peers;
 
       ws->reply      = ws->outbuf + 8;
-      ws->reply_size = 8 + add_peer_to_torrent_and_return_peers(FLAG_UDP, ws, numwant);
+      ws->reply_size = add_peer_to_torrent_and_return_peers(FLAG_UDP, ws, numwant);
+
+      if (!ws->reply_size) {
+        const char err_unauth[] = "Requested download is not authorized for use with this tracker.";
+        size_t s = sizeof(err_unauth);
+        outpacket[0]  = htonl(3);
+        memcpy(&outpacket[2], &err_unauth[0], s);
+        socket_send(serversocket, ws->outbuf, 8 + s, remoteip, remoteport);
+        return 1;
+      }
+      ws->reply_size += 8;
     }
 
     socket_send(serversocket, ws->outbuf, ws->reply_size, remoteip, remoteport);