`enterList` now returns a bool

eth/p2p/discoveryv5/encoding.nim

@@ -158,31 +158,42 @@ proc decryptGCM(key: array[16, byte], nonce, ct, authData: openarray[byte]): seq
     result = @[]
   dctx.clear()
 
-proc decodePacketBody(typ: byte, body: openarray[byte], res: var Packet): bool =
-  if typ >= PacketKind.low.byte and typ <= PacketKind.high.byte:
-    let kind = cast[PacketKind](typ)
-    res = Packet(kind: kind)
-    var rlp = rlpFromBytes(@body.toRange)
-    rlp.enterList()
+type
+  DecodePacketResult = enum
+    decodingSuccessful
+    invalidPacketPayload
+    invalidPacketType
+    unsupportedPacketType
+
+proc decodePacketBody(typ: byte,
+                      body: openarray[byte],
+                      res: var Packet): DecodePacketResult =
+  if typ < PacketKind.low.byte or typ > PacketKind.high.byte:
+    return invalidPacketType
+
+  let kind = cast[PacketKind](typ)
+  res = Packet(kind: kind)
+  var rlp = rlpFromBytes(@body.toRange)
+  if rlp.enterList:
     res.reqId = rlp.read(RequestId)
 
     proc decode[T](rlp: var Rlp, v: var T) {.inline, nimcall.} =
       for k, v in v.fieldPairs:
         v = rlp.read(typeof(v))
 
-    template decode(k: untyped) =
-      if k == kind:
-        decode(rlp, res.k)
-        result = true
+    case kind
+    of unused: return invalidPacketPayload
+    of ping: rlp.decode(res.ping)
+    of pong: rlp.decode(res.pong)
+    of findNode: rlp.decode(res.findNode)
+    of nodes: rlp.decode(res.nodes)
+    of regtopic, ticket, regconfirmation, topicquery:
+      # TODO Implement these packet types
+      return unsupportedPacketType
 
-    decode(ping)
-    decode(pong)
-    decode(findNode)
-    decode(nodes)
+    return decodingSuccessful
   else:
-    debug "unknown packet type ", typ
-
-  return true
+    return invalidPacketPayload
 
 proc decodeAuthResp(c: Codec, fromId: NodeId, head: AuthHeader,
     challenge: Whoareyou, secrets: var HandshakeSecrets, newNode: var Node): bool =
@@ -215,6 +226,8 @@ proc decodeEncrypted*(c: var Codec,
   var r = rlpFromBytes(input[32 .. ^1])
   var auth: AuthHeader
   var readKey: array[16, byte]
+  logScope: sender = $fromAddr
+
   if r.isList:
     # Handshake - rlp list indicates auth-header
 
@@ -258,7 +271,12 @@ proc decodeEncrypted*(c: var Codec,
 
   let body = decryptGCM(readKey, auth.auth, bodyEnc.toOpenArray, input[0 .. 31].toOpenArray)
   if body.len > 1:
-    result = decodePacketBody(body[0], body.toOpenArray(1, body.high), packet)
+    let status = decodePacketBody(body[0], body.toOpenArray(1, body.high), packet)
+    if status == decodingSuccessful:
+      return true
+    else:
+      debug "Failed to decode discovery packet", reason = status
+      return false
 
 proc newRequestId*(): RequestId =
   if randomBytes(addr result, sizeof(result)) != sizeof(result):

eth/p2p/discoveryv5/enr.nim

@@ -195,7 +195,8 @@ proc verifySignatureV4(r: Record, sigData: openarray[byte], content: seq[byte]):
 proc verifySignature(r: Record): bool =
   var rlp = rlpFromBytes(r.raw.toRange)
   let sz = rlp.listLen
-  rlp.enterList()
+  if not rlp.enterList:
+    return false
   let sigData = rlp.read(Bytes)
   let content = block:
     var writer = initRlpList(sz - 1)
@@ -219,12 +220,16 @@ proc fromBytesAux(r: var Record): bool =
     return false
 
   var rlp = rlpFromBytes(r.raw.toRange)
+  if not rlp.isList:
+    return false
+
   let sz = rlp.listLen
   if sz < minRlpListLen or sz mod 2 != 0:
     # Wrong rlp object
     return false
 
-  rlp.enterList()
+  # We already know we are working with a list
+  discard rlp.enterList()
   rlp.skipElem() # Skip signature
 
   r.seqNum = rlp.read(uint64)

eth/p2p/rlpx.nim

@@ -567,7 +567,7 @@ proc p2pProtocolBackendImpl*(protocol: P2PProtocol): Backend =
     read = bindSym("read", brForceOpen)
     checkedRlpRead = bindSym "checkedRlpRead"
     startList = bindSym "startList"
-    enterList = bindSym "enterList"
+    tryEnterList = bindSym "tryEnterList"
     finish = bindSym "finish"
 
     messagePrinter = bindSym "messagePrinter"
@@ -677,7 +677,7 @@ proc p2pProtocolBackendImpl*(protocol: P2PProtocol): Backend =
 
     let
       paramCount = paramsToWrite.len
-      readParamsPrelude = if paramCount > 1: newCall(enterList, receivedRlp)
+      readParamsPrelude = if paramCount > 1: newCall(tryEnterList, receivedRlp)
                           else: newStmtList()
 
     when tracingEnabled:

eth/p2p/rlpx_protocols/les/flow_control.nim

@@ -104,16 +104,18 @@ proc loadMessageStats*(network: LesNetwork,
 
     try:
       var statsRlp = rlpFromBytes(stats.toRange)
-      statsRlp.enterList
+      if not statsRlp.enterList:
+        notice "Found a corrupted LES stats record"
+        break readFromDB
 
       let version = statsRlp.read(int)
       if version != lesStatsVer:
-        notice "Found outdated LES stats record"
+        notice "Found an outdated LES stats record"
         break readFromDB
 
       statsRlp >> network.messageStats
       if network.messageStats.len <= les.messages[^1].id:
-        notice "Found incomplete LES stats record"
+        notice "Found an incomplete LES stats record"
         break readFromDB
 
       return true

eth/p2p/rlpx_protocols/waku_protocol.nim

@@ -147,10 +147,18 @@ proc append*(rlpWriter: var RlpWriter, value: StatusOptions) =
   rlpWriter.append(rlpFromBytes(bytes.toRange))
 
 proc read*(rlp: var Rlp, T: typedesc[StatusOptions]): T =
+  if not rlp.isList():
+    raise newException(RlpTypeMismatch,
+      "List expected, but the source RLP is not a list.")
+
   let sz = rlp.listLen()
-  rlp.enterList()
+  # We already know that we are working with a list
+  discard rlp.enterList()
   for i in 0 ..< sz:
-    rlp.enterList()
+    if not rlp.enterList():
+      raise newException(RlpTypeMismatch,
+        "List expected, but the source RLP is not a list.")
+
     var k: KeyKind
     try:
       k = rlp.read(KeyKind)

eth/rlp.nim

@@ -242,10 +242,16 @@ proc currentElemEnd*(self: Rlp): int =
   elif isBlob() or isList():
     result += payloadOffset() + payloadBytesCount()
 
-proc enterList*(self: var Rlp) =
+proc enterList*(self: var Rlp): bool =
   if not isList():
-    raise newException(RlpTypeMismatch, "List expected, but source RLP is not a list")
+    return false
+
   position += payloadOffset()
+  return true
+
+proc tryEnterList*(self: var Rlp) =
+  if not enterList():
+    raise newException(RlpTypeMismatch, "List expected, but source RLP is not a list")
 
 proc skipElem*(rlp: var Rlp) =
   rlp.position = rlp.currentElemEnd

eth/trie/hexary.nim

@@ -386,7 +386,8 @@ proc replaceValue(data: Rlp, key: NibblesRange, value: BytesRange): Bytes =
 
   # XXX: This can be optimized to a direct bitwise copy of the source RLP
   var iter = data
-  iter.enterList()
+  # We already know that we are working with a list
+  discard iter.enterList()
   for i in 0 ..< 16:
     r.append iter
     iter.skipElem
@@ -511,7 +512,8 @@ proc deleteAt(self: var HexaryTrie;
       else:
         var rlpRes = initRlpList(17)
         var iter = origRlp
-        iter.enterList
+        # We already know that we are working with a list
+        discard iter.enterList
         for i in 0 ..< 16:
           rlpRes.append iter
           iter.skipElem

tests/rlp/test_api_usage.nim

@@ -102,7 +102,7 @@ test "encode and decode lists":
   var list = rlpFromBytes encodeList(rlp.listELem(1), rlp.listELem(0)).toRange
 
   # test that iteration with enterList/skipElem works as expected
-  list.enterList
+  discard list.enterList # We alreay know that we are working with a list
   check list.toString == "Lorem ipsum dolor sit amet"
   list.skipElem