Increase packet size of utp over discv5 (#1042)

* Increase packet size of utp over discv5

fluffy/fluffy.nim

@@ -111,8 +111,9 @@ proc run(config: PortalConf) {.raises: [CatchableError, Defect].} =
 
   # One instance of UtpDiscv5Protocol is shared over all the PortalStreams.
   let
+    maxPayloadSize = uint32(discv5MaxSize - talkReqOverhead - utpHeaderOverhead)
     socketConfig = SocketConfig.init(
-      incomingSocketReceiveTimeout = none(Duration))
+      incomingSocketReceiveTimeout = none(Duration), payloadSize = maxPayloadSize)
     streamTransport = UtpDiscv5Protocol.new(
       d,
       utpProtocolId,
@@ -123,7 +124,6 @@ proc run(config: PortalConf) {.raises: [CatchableError, Defect].} =
         stateNetwork.portalProtocol.stream,
         historyNetwork.portalProtocol.stream]),
       socketConfig)
-
   stateNetwork.setStreamTransport(streamTransport)
   historyNetwork.setStreamTransport(streamTransport)
 

fluffy/network/wire/portal_stream.nim

@@ -22,6 +22,18 @@ const
   utpProtocolId* = "utp".toBytes()
   defaultConnectionTimeout = 5.seconds
   defaultReadTimeout = 2.seconds
+  # TalkReq message is used as transport message
+  talkReqOverhead* =
+    16 + # IV size
+    55 + # header size
+    1 + # talkReq msg id
+    3 + # rlp encoding outer list, max length will be encoded in 2 bytes
+    9 + # request id (max = 8) + 1 byte from rlp encoding byte string
+    3 + # rlp encoding response byte string, max length in 2 bytes
+    16 + # HMAC
+    len(utpProtocolId) + 1 # + 1 is necessary due to rlp encoding of those bytes
+  utpHeaderOverhead* = 20
+  discv5MaxSize* = 1280
 
 type
   ContentRequest = object