Avoid dopplegangers, foreign address that have our client ID

diff --git a/client.go b/client.go
index ee238db934274a9111b5616e683822e9f00a2039..2746aedb124adbe17d6fb2e78b95f460ea434c3c 100644 (file)
--- a/client.go
+++ b/client.go
@@ -143,6 +143,10 @@ type Client struct {
        config          Config
        pruneTimer      *time.Timer
        extensionBytes  peerExtensionBytes
+       // Set of addresses that have our client ID. This intentionally will
+       // include ourselves if we end up trying to connect to our own address
+       // through legitimate channels.
+       dopplegangerAddrs map[string]struct{}
 
        torrentDataOpener TorrentDataOpener
 
@@ -480,6 +484,7 @@ func NewClient(cfg *Config) (cl *Client, err error) {
                torrentDataOpener: func(md *metainfo.Info) data.Data {
                        return filePkg.TorrentData(md, cfg.DataDir)
                },
+               dopplegangerAddrs: make(map[string]struct{}),
 
                quit:     make(chan struct{}),
                torrents: make(map[InfoHash]*torrent),
@@ -623,9 +628,10 @@ func (cl *Client) acceptConnections(l net.Listener, utp bool) {
                }
                acceptedConns.Add(1)
                cl.mu.RLock()
+               doppleganger := cl.dopplegangerAddr(conn.RemoteAddr().String())
                blockRange := cl.ipBlockRange(AddrIP(conn.RemoteAddr()))
                cl.mu.RUnlock()
-               if blockRange != nil {
+               if blockRange != nil || doppleganger {
                        inboundConnsBlocked.Add(1)
                        // log.Printf("inbound connection from %s blocked by %s", conn.RemoteAddr(), blockRange)
                        conn.Close()
@@ -708,6 +714,11 @@ func reducedDialTimeout(max time.Duration, halfOpenLimit int, pendingPeers int)
        return
 }
 
+func (me *Client) dopplegangerAddr(addr string) bool {
+       _, ok := me.dopplegangerAddrs[addr]
+       return ok
+}
+
 // Start the process of connecting to the given peer for the given torrent if
 // appropriate.
 func (me *Client) initiateConn(peer Peer, t *torrent) {
@@ -715,7 +726,7 @@ func (me *Client) initiateConn(peer Peer, t *torrent) {
                return
        }
        addr := net.JoinHostPort(peer.IP.String(), fmt.Sprintf("%d", peer.Port))
-       if t.addrActive(addr) {
+       if me.dopplegangerAddr(addr) || t.addrActive(addr) {
                duplicateConnsAvoided.Add(1)
                return
        }
@@ -1759,17 +1770,15 @@ func (me *Client) openNewConns(t *torrent) {
 }
 
 func (me *Client) addPeers(t *torrent, peers []Peer) {
-       blocked := 0
        for _, p := range peers {
+               if me.dopplegangerAddr(net.JoinHostPort(p.IP.String(), strconv.FormatInt(int64(p.Port), 10))) {
+                       continue
+               }
                if me.ipBlockRange(p.IP) != nil {
-                       blocked++
                        continue
                }
                t.addPeer(p)
        }
-       if blocked != 0 {
-               log.Printf("IP blocklist screened %d peers from being added", blocked)
-       }
        me.openNewConns(t)
 }