Update enrs in buckets and replacement caches and fix empty ENR list in AuthResponse

eth/p2p/discoveryv5/encoding.nim

@@ -103,9 +103,10 @@ proc encodeAuthHeader*(rng: var BrHmacDrbgContext,
   var resp = AuthResponse(version: 5)
   let ln = c.localNode
 
-  # TODO: What goes over the wire now in case of no updated ENR?
   if challenge.recordSeq < ln.record.seqNum:
     resp.record = ln.record
+  # else:
+  # an uninitialized record which will get encoded as an empty rlp list.
 
   let ephKeys = KeyPair.random(rng)
   let signature = signIDNonce(c.privKey, challenge.idNonce,
@@ -118,7 +119,7 @@ proc encodeAuthHeader*(rng: var BrHmacDrbgContext,
   let respRlp = rlp.encode(resp)
 
   var zeroNonce: array[gcmNonceSize, byte]
-  let respEnc = encryptGCM(secrets.authRespKey, zeroNonce, respRLP, [])
+  let respEnc = encryptGCM(secrets.authRespKey, zeroNonce, respRlp, [])
 
   let header = AuthHeader(auth: nonce, idNonce: challenge.idNonce,
     scheme: authSchemeName, ephemeralKey: ephKeys.pubkey.toRaw,

eth/p2p/discoveryv5/enr.nim

@@ -450,11 +450,8 @@ proc `$`(f: Field): string =
 
 proc `$`*(r: Record): string =
   result = "("
-  var first = true
+  result &= $r.seqNum
   for (k, v) in r.pairs:
-    if first:
-      first = false
-    else:
     result &= ", "
     result &= k
     result &= ": "
@@ -472,4 +469,7 @@ proc read*(rlp: var Rlp, T: typedesc[Record]):
   rlp.skipElem()
 
 proc append*(rlpWriter: var RlpWriter, value: Record) =
+  if value.raw.len > 0:
     rlpWriter.appendRawBytes(value.raw)
+  else:
+    rlpWriter.startList(0)

eth/p2p/discoveryv5/routing_table.nim

@@ -110,6 +110,9 @@ proc add(k: KBucket, n: Node): Node =
   k.lastUpdated = epochTime()
   let nodeIdx = k.nodes.find(n)
   if nodeIdx != -1:
+    if k.nodes[nodeIdx].record.seqNum < n.record.seqNum:
+      # In case of a newer record, it gets replaced.
+      k.nodes[nodeIdx].record = n.record
     return nil
   elif k.len < BUCKET_SIZE:
     k.nodes.add(n)
@@ -126,6 +129,9 @@ proc addReplacement(k: KBucket, n: Node) =
   ## to the tail.
   let nodeIdx = k.replacementCache.find(n)
   if nodeIdx != -1:
+    if k.replacementCache[nodeIdx].record.seqNum <= n.record.seqNum:
+      # In case the record sequence number is higher or the same, the node gets
+      # moved to the tail.
       k.replacementCache.delete(nodeIdx)
       k.replacementCache.add(n)
   else:

tests/p2p/test_enr.nim

@@ -10,7 +10,7 @@ suite "ENR":
     var pk = PrivateKey.fromHex(
       "5d2908f3f09ea1ff2e327c3f623159639b00af406e9009de5fd4b910fc34049d")[]
     var r = initRecord(123, pk, {"udp": 1234'u, "ip": [byte 5, 6, 7, 8]})[]
-    check($r == """(id: "v4", ip: 0x05060708, secp256k1: 0x02E51EFA66628CE09F689BC2B82F165A75A9DDECBB6A804BE15AC3FDF41F3B34E7, udp: 1234)""")
+    check($r == """(123, id: "v4", ip: 0x05060708, secp256k1: 0x02E51EFA66628CE09F689BC2B82F165A75A9DDECBB6A804BE15AC3FDF41F3B34E7, udp: 1234)""")
     let uri = r.toURI()
     var r2: Record
     let sigValid = r2.fromURI(uri)
@@ -22,7 +22,7 @@ suite "ENR":
     var pk = PrivateKey.fromHex(
       "5d2908f3f09ea1ff2e327c3f623159639b00af406e9009de5fd4b910fc34049d")[]
     var r = initRecord(123, pk, {"udp": 1234'u, "ip": [byte 5, 6, 7, 8]})[]
-    check($r == """(id: "v4", ip: 0x05060708, secp256k1: 0x02E51EFA66628CE09F689BC2B82F165A75A9DDECBB6A804BE15AC3FDF41F3B34E7, udp: 1234)""")
+    check($r == """(123, id: "v4", ip: 0x05060708, secp256k1: 0x02E51EFA66628CE09F689BC2B82F165A75A9DDECBB6A804BE15AC3FDF41F3B34E7, udp: 1234)""")
     let encoded = rlp.encode(r)
     let decoded = rlp.decode(encoded, enr.Record)
     check($decoded == $r)
@@ -44,7 +44,7 @@ suite "ENR":
     var r: Record
     let sigValid = r.fromBase64("-IS4QHCYrYZbAKWCBRlAy5zzaDZXJBGkcnh4MHcBFZntXNFrdvJjX04jRzjzCBOonrkTfj499SZuOh8R33Ls8RRcy5wBgmlkgnY0gmlwhH8AAAGJc2VjcDI1NmsxoQPKY0yuDUmstAHYpMa2_oxVtw0RW_QAdpzBQA8yWM0xOIN1ZHCCdl8")
     check(sigValid)
-    check($r == """(id: "v4", ip: 0x7F000001, secp256k1: 0x03CA634CAE0D49ACB401D8A4C6B6FE8C55B70D115BF400769CC1400F3258CD3138, udp: 30303)""")
+    check($r == """(1, id: "v4", ip: 0x7F000001, secp256k1: 0x03CA634CAE0D49ACB401D8A4C6B6FE8C55B70D115BF400769CC1400F3258CD3138, udp: 30303)""")
 
   test "Bad base64":
     var r: Record
@@ -146,13 +146,13 @@ suite "ENR":
                                  "z": [byte 0],
                                  "123": "abc",
                                  "a12": 1'u})[]
-    check $r == """(123: "abc", a12: 1, abc: 1234, id: "v4", secp256k1: 0x02E51EFA66628CE09F689BC2B82F165A75A9DDECBB6A804BE15AC3FDF41F3B34E7, z: 0x00)"""
+    check $r == """(123, 123: "abc", a12: 1, abc: 1234, id: "v4", secp256k1: 0x02E51EFA66628CE09F689BC2B82F165A75A9DDECBB6A804BE15AC3FDF41F3B34E7, z: 0x00)"""
 
     let newField = toFieldPair("test", 123'u)
     let newField2 = toFieldPair("zzz", 123'u)
     let updated = r.update(pk, [newField, newField2])
     check updated.isOk()
-    check $r == """(123: "abc", a12: 1, abc: 1234, id: "v4", secp256k1: 0x02E51EFA66628CE09F689BC2B82F165A75A9DDECBB6A804BE15AC3FDF41F3B34E7, test: 123, z: 0x00, zzz: 123)"""
+    check $r == """(124, 123: "abc", a12: 1, abc: 1234, id: "v4", secp256k1: 0x02E51EFA66628CE09F689BC2B82F165A75A9DDECBB6A804BE15AC3FDF41F3B34E7, test: 123, z: 0x00, zzz: 123)"""
 
   test "ENR update size too big":
     let pk = PrivateKey.fromHex(