From 130c64f33a493074a64d4e2af2ae57091f5a480e Mon Sep 17 00:00:00 2001
From: Dmitriy Ryajov <dryajov@gmail.com>
Date: Fri, 5 Jun 2020 18:17:05 -0600
Subject: [PATCH] don't return nil in dial (#205)

* dont return nil in dial

* don't crash on pubsub send
---
 libp2p.nimble                          |  2 +-
 libp2p/protocols/pubsub/pubsubpeer.nim | 14 ++++++++------
 libp2p/standard_setup.nim              |  2 +-
 libp2p/switch.nim                      |  3 +--
 4 files changed, 11 insertions(+), 10 deletions(-)

diff --git a/libp2p.nimble b/libp2p.nimble
index e6a685d63..73ebfa361 100644
--- a/libp2p.nimble
+++ b/libp2p.nimble
@@ -14,7 +14,7 @@ requires "nim >= 1.2.0",
          "chronos >= 2.3.8",
          "metrics",
          "secp256k1",
-         "stew"
+         "stew >= 0.1.0"
 
 proc runTest(filename: string, verify: bool = true, sign: bool = true) =
   var excstr: string = "nim c -r --opt:speed -d:debug --verbosity:0 --hints:off"
diff --git a/libp2p/protocols/pubsub/pubsubpeer.nim b/libp2p/protocols/pubsub/pubsubpeer.nim
index 73324e1e6..95688e03c 100644
--- a/libp2p/protocols/pubsub/pubsubpeer.nim
+++ b/libp2p/protocols/pubsub/pubsubpeer.nim
@@ -48,8 +48,9 @@ proc isConnected*(p: PubSubPeer): bool =
 
 proc `conn=`*(p: PubSubPeer, conn: Connection) =
   trace "attaching send connection for peer", peer = p.id
-  p.sendConn = conn
-  p.onConnect.fire()
+  if not(isNil(conn)):
+    p.sendConn = conn
+    p.onConnect.fire()
 
 proc recvObservers(p: PubSubPeer, msg: var RPCMsg) =
   # trigger hooks
@@ -113,10 +114,11 @@ proc send*(p: PubSubPeer, msgs: seq[RPCMsg]) {.async.} =
         trace "about to send message", peer = p.id,
                                        encoded = digest
         await p.onConnect.wait()
-        trace "sending encoded msgs to peer", peer = p.id,
-                                              encoded = encoded.buffer.shortLog
-        await p.sendConn.writeLp(encoded.buffer)
-        p.sentRpcCache.put(digest)
+        if p.isConnected: # this can happen if the remote disconnected
+          trace "sending encoded msgs to peer", peer = p.id,
+                                                encoded = encoded.buffer.shortLog
+          await p.sendConn.writeLp(encoded.buffer)
+          p.sentRpcCache.put(digest)
       except CatchableError as exc:
         trace "unable to send to remote", exc = exc.msg
         p.sendConn = nil
diff --git a/libp2p/standard_setup.nim b/libp2p/standard_setup.nim
index 240bf33ce..9d167801f 100644
--- a/libp2p/standard_setup.nim
+++ b/libp2p/standard_setup.nim
@@ -45,7 +45,7 @@ proc newStandardSwitch*(privKey = none(PrivateKey),
     muxers = {MplexCodec: mplexProvider}.toTable
     identify = newIdentify(peerInfo)
 
-  var 
+  var
     secureManagerInstances: seq[Secure]
   for sec in secureManagers:
     case sec
diff --git a/libp2p/switch.nim b/libp2p/switch.nim
index 5d0281b94..7f317a479 100644
--- a/libp2p/switch.nim
+++ b/libp2p/switch.nim
@@ -282,8 +282,7 @@ proc dial*(s: Switch,
     trace "Attempting to select remote", proto = proto
 
   if not await s.ms.select(result, proto):
-    warn "Unable to select sub-protocol", proto = proto
-    return nil
+    raise newException(CatchableError, "Unable to select sub-protocol " & proto)
 
 proc mount*[T: LPProtocol](s: Switch, proto: T) {.gcsafe.} =
   if isNil(proto.handler):