fix: code review

mix/config.nim

@@ -15,5 +15,5 @@ const
   surbSize* = headerSize + k + addrSize
     # Size of a surb packet inside the message payload
   surbLenSize* = 1 # Size of the field storing the number of surbs
-  surbIdLen* = 16 # Size of the identifier used when sending a message with surb
+  surbIdLen* = k # Size of the identifier used when sending a message with surb
   defaultSurbs* = uint8(4) # Default number of SURBs to send

mix/entry_connection.nim

@@ -241,7 +241,7 @@ proc new*(
 ): T {.raises: [].} =
   let params = params.get(MixParameters())
   let expectReply = params.expectReply.get(false)
-  let surbs =
+  let numSurbs =
     if expectReply:
       params.numSurbs.get(defaultSurbs)
     else:
@@ -271,7 +271,7 @@ proc new*(
           (Opt.none(PeerId), Opt.some(MixDestination.init(dest.peerId, dest.address)))
 
       await srcMix.anonymizeLocalProtocolSend(
-        instance.incoming, msg, codec, peerId, destination, surbs
+        instance.incoming, msg, codec, peerId, destination, numSurbs
       )
     except CatchableError as e:
       error "Error during execution of anonymizeLocalProtocolSend: ", err = e.msg

mix/mix_protocol.nim

@@ -220,7 +220,7 @@ proc handleMixNodeConnection(
           await nextHopConn.close()
         except CatchableError as e:
           error "Failed to close outgoing stream: ", err = e.msg
-      mix_messages_error.inc(labelValues = ["Intermediate", "DAIL_FAILED"])
+      mix_messages_error.inc(labelValues = ["Intermediate", "DIAL_FAILED"])
   of Duplicate:
     mix_messages_error.inc(labelValues = ["Intermediate/Exit", "DUPLICATE"])
     discard

mix/serialization.nim

@@ -184,8 +184,9 @@ type
 proc serializeMessageWithSURBs*(
     msg: seq[byte], surbs: seq[SURB]
 ): Result[seq[byte], string] =
-  if surbs.len > high(int8):
+  if surbs.len > (messageSize - surbLenSize - 1) div surbSize:
     return err("too many SURBs")
+
   let surbBytes =
     surbs.mapIt(?it.hop.serialize() & ?it.header.serialize() & it.key).concat()
   ok(byte(surbs.len) & surbBytes & msg)
@@ -211,6 +212,10 @@ proc extractSURBs*(msg: seq[byte]): Result[(seq[SURB], seq[byte]), string] =
   var offset = 0
   let surbsLenBytes = ?readBytes(msg, offset, 1)
   let surbsLen = int(surbsLenBytes[0])
+
+  if surbsLen > (messageSize - surbLenSize - 1) div surbSize:
+    return err("too many SURBs")
+
   var surbs: seq[SURB] = newSeq[SURB](surbsLen)
   for i in 0 ..< surbsLen:
     let hopBytes = ?readBytes(msg, offset, addrSize)