Start working on #450

libp2p/builders.nim

@@ -28,6 +28,8 @@ type
     maxConnsPerPeer: int
     protoVersion: Option[string]
     agentVersion: Option[string]
+    externalAddress: Option[MultiAddress]
+    addressProvider: Option[CurrentAddressProvider]
 
 proc init*(_: type[SwitchBuilder]): SwitchBuilder =
   SwitchBuilder(
@@ -104,6 +106,14 @@ proc withAgentVersion*(b: SwitchBuilder, agentVersion: string): SwitchBuilder =
   b.agentVersion = some(agentVersion)
   b
 
+proc withExternalAddress*(b: SwitchBuilder, address: MultiAddress): SwitchBuilder =
+  b.externalAddress = some(address)
+  b
+
+proc withAddressProvider*(b: SwitchBuilder, provider: CurrentAddressProvider): SwitchBuilder =
+  b.addressProvider = some(provider)
+  b
+
 proc build*(b: SwitchBuilder): Switch =
   let
     inTimeout = b.inTimeout
@@ -134,8 +144,13 @@ proc build*(b: SwitchBuilder): Switch =
         transports &= Transport(TcpTransport.init(b.tcpTransportFlags.get()))
       transports
     muxers = {MplexCodec: mplexProvider}.toTable
-    identify = newIdentify(peerInfo)
+    identify = block:
-
+      if b.addressProvider.isSome():
+        newIdentify(peerInfo, b.addressProvider.get())
+      elif b.externalAddress.isSome():
+        newIdentify(peerInfo, proc(): MultiAddress = b.externalAddress.get())
+      else:
+        newIdentify(peerInfo)
   if b.secureManagers.len == 0:
     b.secureManagers &= SecureProtocol.Noise
 

libp2p/protocols/identify.nim

@@ -42,8 +42,13 @@ type
     agentVersion*: Option[string]
     protos*: seq[string]
 
+  CurrentAddressProvider* =
+    proc(): MultiAddress {.raises: [Defect], gcsafe.}
+
   Identify* = ref object of LPProtocol
     peerInfo*: PeerInfo
+    provider*: CurrentAddressProvider
+
 
 proc encodeMsg*(peerInfo: PeerInfo, observedAddr: Multiaddress): ProtoBuffer =
   result = initProtoBuffer()
@@ -101,16 +106,17 @@ proc decodeMsg*(buf: seq[byte]): Option[IdentifyInfo] =
     trace "decodeMsg: failed to decode received message"
     none[IdentifyInfo]()
 
-proc newIdentify*(peerInfo: PeerInfo): Identify =
+proc newIdentify*(peerInfo: PeerInfo, provider: CurrentAddressProvider = nil): Identify =
   new result
   result.peerInfo = peerInfo
+  result.provider = provider
   result.init()
 
 method init*(p: Identify) =
   proc handle(conn: Connection, proto: string) {.async, gcsafe, closure.} =
     try:
       trace "handling identify request", conn
-      var pb = encodeMsg(p.peerInfo, conn.observedAddr)
+      var pb = encodeMsg(p.peerInfo, (if not isNil(p.provider): p.provider() else: conn.observedAddr))
       await conn.writeLp(pb.buffer)
     except CancelledError as exc:
       raise exc
@@ -151,5 +157,5 @@ proc identify*(p: Identify,
 
 proc push*(p: Identify, conn: Connection) {.async.} =
   await conn.write(IdentifyPushCodec)
-  var pb = encodeMsg(p.peerInfo, conn.observedAddr)
+  var pb = encodeMsg(p.peerInfo, (if not isNil(p.provider): p.provider() else: conn.observedAddr))
   await conn.writeLp(pb.buffer)

tests/testidentify.nim

@@ -31,6 +31,7 @@ suite "Identify":
       msListen {.threadvar.}: MultistreamSelect
       msDial {.threadvar.}: MultistreamSelect
       conn {.threadvar.}: Connection
+      exposedAddr {.threadvar.}: MultiAddress
 
     asyncSetup:
       ma = Multiaddress.init("/ip4/0.0.0.0/tcp/0").tryGet()
@@ -41,7 +42,9 @@ suite "Identify":
       transport1 = TcpTransport.init()
       transport2 = TcpTransport.init()
 
-      identifyProto1 = newIdentify(remotePeerInfo)
+      exposedAddr = Multiaddress.init("/ip4/192.168.1.1/tcp/1337").get()
+
+      identifyProto1 = newIdentify(remotePeerInfo, proc(): MultiAddress = exposedAddr)
       identifyProto2 = newIdentify(remotePeerInfo)
 
       msListen = newMultistream()
@@ -92,6 +95,7 @@ suite "Identify":
 
       check id.pubKey.get() == remoteSecKey.getKey().get()
       check id.addrs[0] == ma
+      check id.observedAddr.get() == exposedAddr
       check id.protoVersion.get() == ProtoVersion
       check id.agentVersion.get() == customAgentVersion
       check id.protos == @["/test/proto1/1.0.0", "/test/proto2/1.0.0"]
@@ -117,3 +121,23 @@ suite "Identify":
         let pi2 = PeerInfo.init(PrivateKey.random(ECDSA, rng[]).get())
         discard await msDial.select(conn, IdentifyCodec)
         discard await identifyProto2.identify(conn, pi2)
+
+    asyncTest "external address provider":
+        msListen.addHandler(IdentifyCodec, identifyProto1)
+        serverFut = transport1.start(ma)
+        proc acceptHandler(): Future[void] {.async, gcsafe.} =
+          let c = await transport1.accept()
+          await msListen.handle(c)
+
+        acceptFut = acceptHandler()
+        conn = await transport2.dial(transport1.ma)
+
+        discard await msDial.select(conn, IdentifyCodec)
+        let id = await identifyProto2.identify(conn, remotePeerInfo)
+
+        check id.pubKey.get() == remoteSecKey.getKey().get()
+        check id.addrs[0] == ma
+        check id.observedAddr.get() == exposedAddr
+        check id.protoVersion.get() == ProtoVersion
+        check id.agentVersion.get() == AgentVersion
+        check id.protos == @["/test/proto1/1.0.0", "/test/proto2/1.0.0"]