Add GossipSub ping (#912)

libp2p/protocols/pubsub/gossipsub.nim

@@ -156,6 +156,7 @@ method onNewPeer(g: GossipSub, peer: PubSubPeer) =
     peer.behaviourPenalty = stats.behaviourPenalty
 
   peer.iHaveBudget = IHavePeerBudget
+  peer.pingBudget = PingsPeerBudget
 
 method onPubSubPeerEvent*(p: GossipSub, peer: PubSubPeer, event: PubSubPeerEvent) {.gcsafe.} =
   case event.kind
@@ -352,6 +353,9 @@ proc validateAndRelay(g: GossipSub,
 method rpcHandler*(g: GossipSub,
                   peer: PubSubPeer,
                   rpcMsg: RPCMsg) {.async.} =
+  if rpcMsg.ping.len in 1..<64 and peer.pingBudget > 0:
+    g.send(peer, RPCMsg(pong: rpcMsg.ping))
+    peer.pingBudget.dec
   for i in 0..<min(g.topicsHigh, rpcMsg.subscriptions.len):
     template sub: untyped = rpcMsg.subscriptions[i]
     g.handleSubscribe(peer, sub.topic, sub.subscribe)

libp2p/protocols/pubsub/gossipsub/behavior.nim

@@ -644,6 +644,7 @@ proc onHeartbeat(g: GossipSub) {.raises: [].} =
         if peer.sentIHaves.len > g.parameters.historyLength:
           discard peer.sentIHaves.popLast()
         peer.iHaveBudget = IHavePeerBudget
+        peer.pingBudget = PingsPeerBudget
 
     var meshMetrics = MeshMetrics()
 

libp2p/protocols/pubsub/gossipsub/types.nim

@@ -45,6 +45,7 @@ const
 
 const
   BackoffSlackTime* = 2 # seconds
+  PingsPeerBudget* = 100 # maximum of 6.4kb/heartbeat (6.4kb/s with default 1 second/hb)
   IHavePeerBudget* = 10
   # the max amount of IHave to expose, not by spec, but go as example
   # rust sigp: https://github.com/sigp/rust-libp2p/blob/f53d02bc873fef2bf52cd31e3d5ce366a41d8a8c/protocols/gossipsub/src/config.rs#L572

libp2p/protocols/pubsub/pubsubpeer.nim

@@ -61,6 +61,7 @@ type
     score*: float64
     sentIHaves*: Deque[HashSet[MessageId]]
     iHaveBudget*: int
+    pingBudget*: int
     maxMessageSize: int
     appScore*: float64 # application specific score
     behaviourPenalty*: float64 # the eventual penalty score

libp2p/protocols/pubsub/rpc/messages.nim

@@ -62,6 +62,8 @@ type
       subscriptions*: seq[SubOpts]
       messages*: seq[Message]
       control*: Option[ControlMessage]
+      ping*: seq[byte]
+      pong*: seq[byte]
 
 func withSubs*(
     T: type RPCMsg, topics: openArray[string], subscribe: bool): T =

libp2p/protocols/pubsub/rpc/protobuf.nim

@@ -316,6 +316,12 @@ proc encodeRpcMsg*(msg: RPCMsg, anonymize: bool): seq[byte] =
     pb.write(2, item, anonymize)
   if msg.control.isSome():
     pb.write(3, msg.control.get())
+  # nim-libp2p extension, using fields which are unlikely to be used
+  # by other extensions
+  if msg.ping.len > 0:
+    pb.write(60, msg.ping)
+  if msg.pong.len > 0:
+    pb.write(61, msg.pong)
   if len(pb.buffer) > 0:
     pb.finish()
   pb.buffer
@@ -327,4 +333,6 @@ proc decodeRpcMsg*(msg: seq[byte]): ProtoResult[RPCMsg] {.inline.} =
   assign(rpcMsg.get().messages, ? pb.decodeMessages())
   assign(rpcMsg.get().subscriptions, ? pb.decodeSubscriptions())
   assign(rpcMsg.get().control, ? pb.decodeControl())
+  discard ? pb.getField(60, rpcMsg.get().ping)
+  discard ? pb.getField(61, rpcMsg.get().pong)
   rpcMsg