# nim-eth # Copyright (c) 2018-2021 Status Research & Development GmbH # Licensed and distributed under either of # * MIT license (license terms in the root directory or at https://opensource.org/licenses/MIT). # * Apache v2 license (license terms in the root directory or at https://www.apache.org/licenses/LICENSE-2.0). # at your option. This file may not be copied, modified, or distributed except according to those terms. {.push raises: [Defect].} import std/times, chronos, stint, nimcrypto/keccak, chronicles, bearssl, stew/[objects, results], ".."/[keys, rlp], "."/[kademlia, enode] export Node, results logScope: topics = "discovery" const # UDP packet constants. MAC_SIZE = 256 div 8 # 32 SIG_SIZE = 520 div 8 # 65 HEAD_SIZE = MAC_SIZE + SIG_SIZE # 97 EXPIRATION = 60 # let messages expire after N secondes PROTO_VERSION = 4 type DiscoveryProtocol* = ref object privKey: PrivateKey address: Address bootstrapNodes*: seq[Node] thisNode*: Node kademlia*: KademliaProtocol[DiscoveryProtocol] transp: DatagramTransport CommandId = enum cmdPing = 1 cmdPong = 2 cmdFindNode = 3 cmdNeighbours = 4 DiscProtocolError* = object of CatchableError DiscResult*[T] = Result[T, cstring] const MinListLen: array[CommandId, int] = [4, 3, 2, 2] proc append*(w: var RlpWriter, a: IpAddress) = case a.family of IpAddressFamily.IPv6: w.append(a.address_v6) of IpAddressFamily.IPv4: w.append(a.address_v4) proc append(w: var RlpWriter, p: Port) = w.append(p.int) proc append(w: var RlpWriter, pk: PublicKey) = w.append(pk.toRaw()) proc append(w: var RlpWriter, h: MDigest[256]) = w.append(h.data) proc pack(cmdId: CommandId, payload: openArray[byte], pk: PrivateKey): seq[byte] = ## Create and sign a UDP message to be sent to a remote node. ## ## See https://github.com/ethereum/devp2p/blob/master/rlpx.md#node-discovery for information on ## how UDP packets are structured. # TODO: There is a lot of unneeded allocations here let encodedData = @[cmdId.byte] & @payload let signature = @(pk.sign(encodedData).toRaw()) let msgHash = keccak256.digest(signature & encodedData) result = @(msgHash.data) & signature & encodedData proc validateMsgHash(msg: openArray[byte]): DiscResult[MDigest[256]] = if msg.len > HEAD_SIZE: var ret: MDigest[256] ret.data[0 .. ^1] = msg.toOpenArray(0, ret.data.high) if ret == keccak256.digest(msg.toOpenArray(MAC_SIZE, msg.high)): ok(ret) else: err("disc: invalid message hash") else: err("disc: msg missing hash") proc recoverMsgPublicKey(msg: openArray[byte]): DiscResult[PublicKey] = if msg.len <= HEAD_SIZE: return err("disc: can't get public key") let sig = ? Signature.fromRaw(msg.toOpenArray(MAC_SIZE, HEAD_SIZE)) recover(sig, msg.toOpenArray(HEAD_SIZE, msg.high)) proc unpack(msg: openArray[byte]): tuple[cmdId: CommandId, payload: seq[byte]] {.raises: [DiscProtocolError, Defect].} = # Check against possible RangeError if msg[HEAD_SIZE].int < CommandId.low.ord or msg[HEAD_SIZE].int > CommandId.high.ord: raise newException(DiscProtocolError, "Unsupported packet id") result = (cmdId: msg[HEAD_SIZE].CommandId, payload: msg[HEAD_SIZE + 1 .. ^1]) proc expiration(): uint32 = result = uint32(epochTime() + EXPIRATION) # Wire protocol proc send(d: DiscoveryProtocol, n: Node, data: seq[byte]) {.raises: [Defect].} = let ta = initTAddress(n.node.address.ip, n.node.address.udpPort) let f = d.transp.sendTo(ta, data) f.callback = proc(data: pointer) {.gcsafe.} = if f.failed: debug "Discovery send failed", msg = f.readError.msg proc sendPing*(d: DiscoveryProtocol, n: Node): seq[byte] {.raises: [Defect].} = let payload = rlp.encode((PROTO_VERSION, d.address, n.node.address, expiration())) let msg = pack(cmdPing, payload, d.privKey) result = msg[0 ..< MAC_SIZE] trace ">>> ping ", n d.send(n, msg) proc sendPong*(d: DiscoveryProtocol, n: Node, token: MDigest[256]) = let payload = rlp.encode((n.node.address, token, expiration())) let msg = pack(cmdPong, payload, d.privKey) trace ">>> pong ", n d.send(n, msg) proc sendFindNode*(d: DiscoveryProtocol, n: Node, targetNodeId: NodeId) = var data: array[64, byte] data[32 .. ^1] = targetNodeId.toByteArrayBE() let payload = rlp.encode((data, expiration())) let msg = pack(cmdFindNode, payload, d.privKey) trace ">>> find_node to ", n#, ": ", msg.toHex() d.send(n, msg) proc sendNeighbours*(d: DiscoveryProtocol, node: Node, neighbours: seq[Node]) = const MAX_NEIGHBOURS_PER_PACKET = 12 # TODO: Implement a smarter way to compute it type Neighbour = tuple[ip: IpAddress, udpPort, tcpPort: Port, pk: PublicKey] var nodes = newSeqOfCap[Neighbour](MAX_NEIGHBOURS_PER_PACKET) shallow(nodes) template flush() = block: let payload = rlp.encode((nodes, expiration())) let msg = pack(cmdNeighbours, payload, d.privKey) trace "Neighbours to", node, nodes d.send(node, msg) nodes.setLen(0) for i, n in neighbours: nodes.add((n.node.address.ip, n.node.address.udpPort, n.node.address.tcpPort, n.node.pubkey)) if nodes.len == MAX_NEIGHBOURS_PER_PACKET: flush() if nodes.len != 0: flush() proc newDiscoveryProtocol*(privKey: PrivateKey, address: Address, bootstrapNodes: openArray[ENode], rng = newRng() ): DiscoveryProtocol = result.new() result.privKey = privKey result.address = address result.bootstrapNodes = newSeqOfCap[Node](bootstrapNodes.len) for n in bootstrapNodes: result.bootstrapNodes.add(newNode(n)) result.thisNode = newNode(privKey.toPublicKey(), address) result.kademlia = newKademliaProtocol(result.thisNode, result, rng = rng) proc recvPing(d: DiscoveryProtocol, node: Node, msgHash: MDigest[256]) {.raises: [ValueError, Defect].} = d.kademlia.recvPing(node, msgHash) proc recvPong(d: DiscoveryProtocol, node: Node, payload: seq[byte]) {.raises: [RlpError, Defect].} = let rlp = rlpFromBytes(payload) let tok = rlp.listElem(1).toBytes() d.kademlia.recvPong(node, tok) proc recvNeighbours(d: DiscoveryProtocol, node: Node, payload: seq[byte]) {.raises: [RlpError, Defect].} = let rlp = rlpFromBytes(payload) let neighboursList = rlp.listElem(0) let sz = neighboursList.listLen() var neighbours = newSeqOfCap[Node](16) for i in 0 ..< sz: let n = neighboursList.listElem(i) let ipBlob = n.listElem(0).toBytes var ip: IpAddress case ipBlob.len of 4: ip = IpAddress( family: IpAddressFamily.IPv4, address_v4: toArray(4, ipBlob)) of 16: ip = IpAddress( family: IpAddressFamily.IPv6, address_v6: toArray(16, ipBlob)) else: error "Wrong ip address length!" continue let udpPort = n.listElem(1).toInt(uint16).Port let tcpPort = n.listElem(2).toInt(uint16).Port let pk = PublicKey.fromRaw(n.listElem(3).toBytes) if pk.isErr: warn "Could not parse public key" continue neighbours.add(newNode(pk[], Address(ip: ip, udpPort: udpPort, tcpPort: tcpPort))) d.kademlia.recvNeighbours(node, neighbours) proc recvFindNode(d: DiscoveryProtocol, node: Node, payload: openArray[byte]) {.raises: [RlpError, ValueError, Defect].} = let rlp = rlpFromBytes(payload) trace "<<< find_node from ", node let rng = rlp.listElem(0).toBytes # Check for pubkey len if rng.len == 64: let nodeId = readUintBE[256](rng[32 .. ^1]) d.kademlia.recvFindNode(node, nodeId) else: trace "Invalid target public key received" proc expirationValid(cmdId: CommandId, rlpEncodedPayload: openArray[byte]): bool {.raises: [DiscProtocolError, RlpError].} = ## Can only raise `DiscProtocolError` and all of `RlpError` # Check if there is a payload if rlpEncodedPayload.len <= 0: raise newException(DiscProtocolError, "RLP stream is empty") let rlp = rlpFromBytes(rlpEncodedPayload) # Check payload is an RLP list and if the list has the minimum items required # for this packet type if rlp.isList and rlp.listLen >= MinListLen[cmdId]: # Expiration is always the last mandatory item of the list let expiration = rlp.listElem(MinListLen[cmdId] - 1).toInt(uint32) result = epochTime() <= expiration.float else: raise newException(DiscProtocolError, "Invalid RLP list for this packet id") proc receive*(d: DiscoveryProtocol, a: Address, msg: openArray[byte]) {.raises: [DiscProtocolError, RlpError, ValueError, Defect].} = # Note: export only needed for testing let msgHash = validateMsgHash(msg) if msgHash.isOk(): let remotePubkey = recoverMsgPublicKey(msg) if remotePubkey.isOk: let (cmdId, payload) = unpack(msg) if expirationValid(cmdId, payload): let node = newNode(remotePubkey[], a) case cmdId of cmdPing: d.recvPing(node, msgHash[]) of cmdPong: d.recvPong(node, payload) of cmdNeighbours: d.recvNeighbours(node, payload) of cmdFindNode: d.recvFindNode(node, payload) else: trace "Received msg already expired", cmdId, a else: notice "Wrong public key from ", a, err = remotePubkey.error else: notice "Wrong msg mac from ", a proc processClient(transp: DatagramTransport, raddr: TransportAddress): Future[void] {.async, raises: [Defect].} = var proto = getUserData[DiscoveryProtocol](transp) let buf = try: transp.getMessage() except TransportOsError as e: # This is likely to be local network connection issues. warn "Transport getMessage", exception = e.name, msg = e.msg return let a = Address(ip: raddr.address, udpPort: raddr.port, tcpPort: raddr.port) try: proto.receive(a, buf) except RlpError as e: debug "Receive failed", exc = e.name, err = e.msg except DiscProtocolError as e: debug "Receive failed", exc = e.name, err = e.msg except ValueError as e: debug "Receive failed", exc = e.name, err = e.msg proc open*(d: DiscoveryProtocol) {.raises: [Defect, CatchableError].} = # TODO allow binding to specific IP / IPv6 / etc let ta = initTAddress(IPv4_any(), d.address.udpPort) d.transp = newDatagramTransport(processClient, udata = d, local = ta) proc lookupRandom*(d: DiscoveryProtocol): Future[seq[Node]] = d.kademlia.lookupRandom() proc run(d: DiscoveryProtocol) {.async.} = while true: discard await d.lookupRandom() await sleepAsync(chronos.seconds(3)) trace "Discovered nodes", nodes = d.kademlia.nodesDiscovered proc bootstrap*(d: DiscoveryProtocol) {.async.} = await d.kademlia.bootstrap(d.bootstrapNodes) discard d.run() proc resolve*(d: DiscoveryProtocol, n: NodeId): Future[Node] = d.kademlia.resolve(n) proc randomNodes*(d: DiscoveryProtocol, count: int): seq[Node] = d.kademlia.randomNodes(count) when isMainModule: import logging, stew/byteutils const LOCAL_BOOTNODES = [ "enode://6456719e7267e061161c88720287a77b80718d2a3a4ff5daeba614d029dc77601b75e32190aed1c9b0b9ccb6fac3bcf000f48e54079fa79e339c25d8e9724226@127.0.0.1:30301" ] addHandler(newConsoleLogger()) block: let m = hexToSeqByte"79664bff52ee17327b4a2d8f97d8fb32c9244d719e5038eb4f6b64da19ca6d271d659c3ad9ad7861a928ca85f8d8debfbe6b7ade26ad778f2ae2ba712567fcbd55bc09eb3e74a893d6b180370b266f6aaf3fe58a0ad95f7435bf3ddf1db940d20102f2cb842edbd4d182944382765da0ab56fb9e64a85a597e6bb27c656b4f1afb7e06b0fd4e41ccde6dba69a3c4a150845aaa4de2" discard validateMsgHash(m).expect("valid hash") var remotePubkey = recoverMsgPublicKey(m).expect("valid key") let (cmdId, payload) = unpack(m) doAssert(payload == hexToSeqByte"f2cb842edbd4d182944382765da0ab56fb9e64a85a597e6bb27c656b4f1afb7e06b0fd4e41ccde6dba69a3c4a150845aaa4de2") doAssert(cmdId == cmdPong) doAssert(remotePubkey == PublicKey.fromHex( "78de8a0916848093c73790ead81d1928bec737d565119932b98c6b100d944b7a95e94f847f689fc723399d2e31129d182f7ef3863f2b4c820abbf3ab2722344d")[]) let privKey = PrivateKey.fromHex("a2b50376a79b1a8c8a3296485572bdfbf54708bb46d3c25d73d2723aaaf6a617")[] # echo privKey # block: # var b = @[1.byte, 2, 3] # let m = pack(cmdPing, b.initBytesRange, privKey) # let (remotePubkey, cmdId, payload) = unpack(m) # doAssert(remotePubkey.raw_key.toHex == privKey.public_key.raw_key.toHex) var bootnodes = newSeq[ENode]() for item in LOCAL_BOOTNODES: bootnodes.add(ENode.fromString(item)[]) let listenPort = Port(30310) var address = Address(udpPort: listenPort, tcpPort: listenPort) address.ip.family = IpAddressFamily.IPv4 let discovery = newDiscoveryProtocol(privkey, address, bootnodes) echo discovery.thisNode.node.pubkey echo "this_node.id: ", discovery.thisNode.id.toHex() discovery.open() proc test() {.async.} = {.gcsafe.}: await discovery.bootstrap() waitFor test()