Transport hole punching (#873)

Co-authored-by: Tanguy <tanguy@status.im>

.pinned

@@ -1,6 +1,6 @@
 bearssl;https://github.com/status-im/nim-bearssl@#acf9645e328bdcab481cfda1c158e07ecd46bd7b
 chronicles;https://github.com/status-im/nim-chronicles@#32ac8679680ea699f7dbc046e8e0131cac97d41a
-chronos;https://github.com/status-im/nim-chronos@#f7835a192b45c37e97614d865141f21eea8c156e
+chronos;https://github.com/status-im/nim-chronos@#ab5a8c2e0f6941fe3debd61dff0293790079d1b0
 dnsclient;https://github.com/ba0f3/dnsclient.nim@#fcd7443634b950eaea574e5eaa00a628ae029823
 faststreams;https://github.com/status-im/nim-faststreams@#814f8927e1f356f39219f37f069b83066bcc893a
 httputils;https://github.com/status-im/nim-http-utils@#a85bd52ae0a956983ca6b3267c72961d2ec0245f

libp2p/protocols/connectivity/autonat/core.nim

@@ -58,6 +58,9 @@ type
     dial*: Option[AutonatDial]
     response*: Option[AutonatDialResponse]
 
+  NetworkReachability* {.pure.} = enum
+    Unknown, NotReachable, Reachable
+
 proc encode(p: AutonatPeerInfo): ProtoBuffer =
   result = initProtoBuffer()
   if p.id.isSome():

libp2p/protocols/connectivity/autonat/service.nim

@@ -44,9 +44,6 @@ type
     dialTimeout: Duration
     enableAddressMapper: bool
 
-  NetworkReachability* {.pure.} = enum
-    NotReachable, Reachable, Unknown
-
   StatusAndConfidenceHandler* = proc (networkReachability: NetworkReachability, confidence: Option[float]): Future[void]  {.gcsafe, raises: [Defect].}
 
 proc new*(

libp2p/transports/tcptransport.nim

@@ -42,13 +42,15 @@ type
     servers*: seq[StreamServer]
     clients: array[Direction, seq[StreamTransport]]
     flags: set[ServerFlags]
-    clientFlags: set[TransportFlags]
+    clientFlags: set[SocketFlags]
     acceptFuts: seq[Future[StreamTransport]]
 
   TcpTransportTracker* = ref object of TrackerBase
     opened*: uint64
     closed*: uint64
 
+  TcpTransportError* = object of transport.TransportError
+
 proc setupTcpTransportTracker(): TcpTransportTracker {.gcsafe, raises: [Defect].}
 
 proc getTcpTransportTracker(): TcpTransportTracker {.gcsafe.} =
@@ -136,13 +138,14 @@ proc new*(
       clientFlags:
         if ServerFlags.TcpNoDelay in flags:
           compilesOr:
-            {TransportFlags.TcpNoDelay}
+            {SocketFlags.TcpNoDelay}
           do:
             doAssert(false)
-            default(set[TransportFlags])
+            default(set[SocketFlags])
         else:
-          default(set[TransportFlags]),
-    upgrader: upgrade)
+          default(set[SocketFlags]),
+      upgrader: upgrade,
+      networkReachability: NetworkReachability.Unknown)
 
   return transport
 
@@ -165,6 +168,7 @@ method start*(
       trace "Invalid address detected, skipping!", address = ma
       continue
 
+    self.flags.incl(ServerFlags.ReusePort)
     let server = createStreamServer(
       ma = ma,
       flags = self.flags,
@@ -263,8 +267,13 @@ method dial*(
   ##
 
   trace "Dialing remote peer", address = $address
+  let transp =
+    if self.networkReachability == NetworkReachability.NotReachable and self.addrs.len > 0:
+      self.clientFlags.incl(SocketFlags.ReusePort)
+      await connect(address, flags = self.clientFlags, localAddress = Opt.some(self.addrs[0]))
+    else:
+      await connect(address, flags = self.clientFlags)
 
-  let transp = await connect(address, flags = self.clientFlags)
   try:
     let observedAddr = await getObservedAddr(transp)
     return await self.connHandler(transp, Opt.some(observedAddr), Direction.Out)

libp2p/transports/transport.nim

@@ -19,7 +19,10 @@ import ../stream/connection,
        ../multiaddress,
        ../multicodec,
        ../muxers/muxer,
-       ../upgrademngrs/upgrade
+       ../upgrademngrs/upgrade,
+       ../protocols/connectivity/autonat/core
+
+export core.NetworkReachability
 
 logScope:
   topics = "libp2p transport"
@@ -33,6 +36,7 @@ type
     addrs*: seq[MultiAddress]
     running*: bool
     upgrader*: Upgrade
+    networkReachability*: NetworkReachability
 
 proc newTransportClosedError*(parent: ref Exception = nil): ref LPError =
   newException(TransportClosedError,

libp2p/wire.nim

@@ -77,7 +77,8 @@ proc connect*(
   ma: MultiAddress,
   bufferSize = DefaultStreamBufferSize,
   child: StreamTransport = nil,
-  flags = default(set[TransportFlags])): Future[StreamTransport]
+  flags = default(set[SocketFlags]),
+  localAddress: Opt[MultiAddress] = Opt.none(MultiAddress)): Future[StreamTransport]
   {.raises: [Defect, LPError, MaInvalidAddress].} =
   ## Open new connection to remote peer with address ``ma`` and create
   ## new transport object ``StreamTransport`` for established connection.
@@ -90,7 +91,9 @@ proc connect*(
   let transportAddress = initTAddress(ma).tryGet()
 
   compilesOr:
-    return connect(transportAddress, bufferSize, child, flags)
+    return connect(transportAddress, bufferSize, child,
+      if localAddress.isSome(): initTAddress(localAddress.get()).tryGet() else : TransportAddress(),
+      flags)
   do:
     # support for older chronos versions
     return connect(transportAddress, bufferSize, child)

tests/testtcptransport.nim

@@ -7,6 +7,7 @@ import ../libp2p/[stream/connection,
                   transports/tcptransport,
                   upgrademngrs/upgrade,
                   multiaddress,
+                  multicodec,
                   errors,
                   wire]
 
@@ -125,6 +126,44 @@ suite "TCP transport":
     server.close()
     await server.join()
 
+  asyncTest "Starting with duplicate but zero ports addresses must NOT fail":
+    let ma = @[MultiAddress.init("/ip4/0.0.0.0/tcp/0").tryGet(),
+               MultiAddress.init("/ip4/0.0.0.0/tcp/0").tryGet()]
+
+    let transport: TcpTransport = TcpTransport.new(upgrade = Upgrade())
+
+    await transport.start(ma)
+    await transport.stop()
+
+  asyncTest "Bind to listening port when not reachable":
+    let ma = @[MultiAddress.init("/ip4/0.0.0.0/tcp/0").tryGet()]
+    let transport: TcpTransport = TcpTransport.new(upgrade = Upgrade())
+    await transport.start(ma)
+
+    let ma2 = @[MultiAddress.init("/ip4/0.0.0.0/tcp/0").tryGet()]
+    let transport2: TcpTransport = TcpTransport.new(upgrade = Upgrade())
+    await transport2.start(ma2)
+
+    let ma3 = @[MultiAddress.init("/ip4/0.0.0.0/tcp/0").tryGet()]
+    let transport3: TcpTransport = TcpTransport.new(upgrade = Upgrade())
+    await transport3.start(ma3)
+
+    let listeningPort = transport.addrs[0][multiCodec("tcp")].get()
+
+    let conn = await transport.dial(transport2.addrs[0])
+    let acceptedConn = await transport2.accept()
+    let acceptedPort = acceptedConn.observedAddr.get()[multiCodec("tcp")].get()
+    check listeningPort != acceptedPort
+
+    transport.networkReachability = NetworkReachability.NotReachable
+
+    let conn2 = await transport.dial(transport3.addrs[0])
+    let acceptedConn2 = await transport3.accept()
+    let acceptedPort2 = acceptedConn2.observedAddr.get()[multiCodec("tcp")].get()
+    check listeningPort == acceptedPort2
+
+    await allFutures(transport.stop(), transport2.stop(),  transport3.stop())
+
   proc transProvider(): Transport = TcpTransport.new(upgrade = Upgrade())
 
   commonTransportTest(