Make use of peer.connectionState in whisper and blockchain sync + add note in docs

doc/p2p.md

@@ -265,6 +265,10 @@ p2pProtocol les(version = 2):
     debug "peer disconnected", peer
 ```
 
+**Note:** Be aware that if currently one of the subprotocol `onPeerConnected`
+calls fails, the client will be disconnected as `UselessPeer` but no
+`onPeerDisconnect` calls are run.
+
 ### Checking the other peer's supported sub-protocols
 
 Upon establishing a connection, RLPx will automatically negotiate the list of

eth/p2p/blockchain_sync.nim

@@ -171,7 +171,8 @@ proc obtainBlocksFromPeer(syncCtx: SyncContext, peer: Peer) {.async.} =
     # no need to exit here, because the context might still have blocks to fetch
     # from this peer
 
-  while (let workItemIdx = syncCtx.availableWorkItem(); workItemIdx != -1):
+  while (let workItemIdx = syncCtx.availableWorkItem(); workItemIdx != -1 and
+         peer.connectionState notin {Disconnecting, Disconnected}):
     template workItem: auto = syncCtx.workQueue[workItemIdx]
     workItem.state = Requested
     trace "Requesting block headers", start = workItem.startIndex, count = workItem.numBlocks, peer

eth/p2p/rlpx_protocols/whisper_protocol.nim

@@ -704,7 +704,6 @@ type
     isLightNode*: bool
     trusted*: bool
     received: HashSet[Message]
-    running: bool
 
   WhisperNetwork = ref object
     queue*: Queue
@@ -768,10 +767,7 @@ p2pProtocol Whisper(version = whisperVersion,
     if not whisperNet.config.isLightNode:
       traceAsyncErrors peer.run()
 
-    debug "Whisper peer initialized"
-
-  onPeerDisconnected do (peer: Peer, reason: DisconnectionReason) {.gcsafe.}:
-     peer.state.running = false
+    debug "Whisper peer initialized", peer
 
   proc status(peer: Peer,
               protocolVersion: uint,
@@ -890,12 +886,7 @@ proc processQueue(peer: Peer) =
   traceAsyncErrors peer.messages(envelopes)
 
 proc run(peer: Peer) {.async.} =
-  var
-    whisperPeer = peer.state(Whisper)
-    whisperNet = peer.networkState(Whisper)
-
-  whisperPeer.running = true
-  while whisperPeer.running:
+  while peer.connectionState notin {Disconnecting, Disconnected}:
     peer.processQueue()
     await sleepAsync(messageInterval)