Avoid unnecessary rate limit message copy (#1067)

libp2p/protocols/pubsub/gossipsub.nim

@@ -398,34 +398,26 @@ proc validateAndRelay(g: GossipSub,
 proc dataAndTopicsIdSize(msgs: seq[Message]): int =
   msgs.mapIt(it.data.len + it.topicIds.mapIt(it.len).foldl(a + b, 0)).foldl(a + b, 0)
 
-proc rateLimit*(g: GossipSub, peer: PubSubPeer, rpcMsgOpt: Opt[RPCMsg], msgSize: int) {.async.} =
+proc messageOverhead(g: GossipSub, msg: RPCMsg, msgSize: int): int =
   # In this way we count even ignored fields by protobuf
+  let
+    payloadSize =
+      if g.verifySignature:
+        byteSize(msg.messages)
+      else:
+        dataAndTopicsIdSize(msg.messages)
+    controlSize = msg.control.withValue(control):
+      byteSize(control.ihave) + byteSize(control.iwant)
+    do: # no control message
+      0
 
-  var rmsg = rpcMsgOpt.valueOr:
-    peer.overheadRateLimitOpt.withValue(overheadRateLimit):
-      if not overheadRateLimit.tryConsume(msgSize):
-        libp2p_gossipsub_peers_rate_limit_hits.inc(labelValues = [peer.getAgent()]) # let's just measure at the beginning for test purposes.
-        debug "Peer sent a msg that couldn't be decoded and it's above rate limit.", peer, uselessAppBytesNum = msgSize
-        if g.parameters.disconnectPeerAboveRateLimit:
-          await g.disconnectPeer(peer)
-          raise newException(PeerRateLimitError, "Peer disconnected because it's above rate limit.")
-
-    raise newException(CatchableError, "Peer msg couldn't be decoded")
-
-  let usefulMsgBytesNum =
-    if g.verifySignature:
-      byteSize(rmsg.messages)
-    else:
-      dataAndTopicsIdSize(rmsg.messages)
-
-  var uselessAppBytesNum = msgSize - usefulMsgBytesNum
-  rmsg.control.withValue(control):
-    uselessAppBytesNum -= (byteSize(control.ihave) + byteSize(control.iwant))
+  msgSize - payloadSize - controlSize
 
+proc rateLimit*(g: GossipSub, peer: PubSubPeer, overhead: int) {.async.} =
   peer.overheadRateLimitOpt.withValue(overheadRateLimit):
-    if not overheadRateLimit.tryConsume(uselessAppBytesNum):
+    if not overheadRateLimit.tryConsume(overhead):
       libp2p_gossipsub_peers_rate_limit_hits.inc(labelValues = [peer.getAgent()]) # let's just measure at the beginning for test purposes.
-      debug "Peer sent too much useless application data and it's above rate limit.", peer, msgSize, uselessAppBytesNum, rmsg
+      debug "Peer sent too much useless application data and it's above rate limit.", peer, overhead
       if g.parameters.disconnectPeerAboveRateLimit:
         await g.disconnectPeer(peer)
         raise newException(PeerRateLimitError, "Peer disconnected because it's above rate limit.")
@@ -433,12 +425,11 @@ proc rateLimit*(g: GossipSub, peer: PubSubPeer, rpcMsgOpt: Opt[RPCMsg], msgSize:
 method rpcHandler*(g: GossipSub,
                   peer: PubSubPeer,
                   data: seq[byte]) {.async.} =
-
   let msgSize = data.len
   var rpcMsg = decodeRpcMsg(data).valueOr:
     debug "failed to decode msg from peer", peer, err = error
-    await rateLimit(g, peer, Opt.none(RPCMsg), msgSize)
-    return
+    await rateLimit(g, peer, msgSize)
+    raise newException(CatchableError, "Peer msg couldn't be decoded")
 
   when defined(libp2p_expensive_metrics):
     for m in rpcMsg.messages:
@@ -446,7 +437,7 @@ method rpcHandler*(g: GossipSub,
         libp2p_pubsub_received_messages.inc(labelValues = [$peer.peerId, t])
 
   trace "decoded msg from peer", peer, msg = rpcMsg.shortLog
-  await rateLimit(g, peer, Opt.some(rpcMsg), msgSize)
+  await rateLimit(g, peer, g.messageOverhead(rpcMsg, msgSize))
 
   # trigger hooks
   peer.recvObservers(rpcMsg)

tests/pubsub/testgossipinternal.nim

@@ -525,6 +525,17 @@ suite "GossipSub internal":
     await conn.close()
     await gossipSub.switch.stop()
 
+  asyncTest "invalid message bytes":
+    let gossipSub = TestGossipSub.init(newStandardSwitch())
+
+    let peerId = randomPeerId()
+    let peer = gossipSub.getPubSubPeer(peerId)
+
+    expect(CatchableError):
+      await gossipSub.rpcHandler(peer, @[byte 1, 2, 3])
+
+    await gossipSub.switch.stop()
+
   asyncTest "rebalanceMesh fail due to backoff":
     let gossipSub = TestGossipSub.init(newStandardSwitch())
     let topic = "foobar"