import macros, tables, algorithm, deques, hashes, options, typetraits, std_shims/macros_shim, chronicles, nimcrypto, chronos, eth/[rlp, common, keys, async_utils], private/p2p_types, kademlia, auth, rlpxcrypt, enode when useSnappy: import snappy const devp2pSnappyVersion* = 5 logScope: topics = "rlpx" const devp2pVersion* = 4 defaultReqTimeout = milliseconds(10000) maxMsgSize = 1024 * 1024 include p2p_tracing when tracingEnabled: import eth/common/eth_types_json_serialization export # XXX: This is a work-around for a Nim issue. # See a more detailed comment in p2p_tracing.nim init, writeValue, getOutput var gProtocols: seq[ProtocolInfo] gDevp2pInfo: ProtocolInfo # The variables above are immutable RTTI information. We need to tell # Nim to not consider them GcSafe violations: template allProtocols*: auto = {.gcsafe.}: gProtocols template devp2pInfo: auto = {.gcsafe.}: gDevp2pInfo chronicles.formatIt(Peer): $(it.remote) proc disconnect*(peer: Peer, reason: DisconnectionReason, notifyOtherPeer = false) {.gcsafe, async.} template raisePeerDisconnected(msg: string, r: DisconnectionReason) = var e = newException(PeerDisconnected, msg) e.reason = r raise e proc disconnectAndRaise(peer: Peer, reason: DisconnectionReason, msg: string) {.async.} = let r = reason await peer.disconnect(r) raisePeerDisconnected(msg, r) # Dispatcher # proc hash(d: Dispatcher): int = hash(d.protocolOffsets) proc `==`(lhs, rhs: Dispatcher): bool = lhs.activeProtocols == rhs.activeProtocols proc describeProtocols(d: Dispatcher): string = result = "" for protocol in d.activeProtocols: if result.len != 0: result.add(',') for c in protocol.name: result.add(c) proc numProtocols(d: Dispatcher): int = d.activeProtocols.len proc getDispatcher(node: EthereumNode, otherPeerCapabilities: openarray[Capability]): Dispatcher = # TODO: sub-optimal solution until progress is made here: # https://github.com/nim-lang/Nim/issues/7457 # We should be able to find an existing dispatcher without allocating a new one new result newSeq(result.protocolOffsets, allProtocols.len) result.protocolOffsets.fill -1 var nextUserMsgId = 0x10 for localProtocol in node.protocols: let idx = localProtocol.index block findMatchingProtocol: for remoteCapability in otherPeerCapabilities: if localProtocol.name == remoteCapability.name and localProtocol.version == remoteCapability.version: result.protocolOffsets[idx] = nextUserMsgId nextUserMsgId += localProtocol.messages.len break findMatchingProtocol template copyTo(src, dest; index: int) = for i in 0 ..< src.len: dest[index + i] = addr src[i] result.messages = newSeq[ptr MessageInfo](nextUserMsgId) devp2pInfo.messages.copyTo(result.messages, 0) for localProtocol in node.protocols: let idx = localProtocol.index if result.protocolOffsets[idx] != -1: result.activeProtocols.add localProtocol localProtocol.messages.copyTo(result.messages, result.protocolOffsets[idx]) proc getMsgName*(peer: Peer, msgId: int): string = if not peer.dispatcher.isNil and msgId < peer.dispatcher.messages.len: return peer.dispatcher.messages[msgId].name else: return case msgId of 0: "hello" of 1: "disconnect" of 2: "ping" of 3: "pong" else: $msgId proc getMsgMetadata*(peer: Peer, msgId: int): (ProtocolInfo, ptr MessageInfo) = doAssert msgId >= 0 if msgId <= devp2pInfo.messages[^1].id: return (devp2pInfo, addr devp2pInfo.messages[msgId]) if msgId < peer.dispatcher.messages.len: for i in 0 ..< allProtocols.len: let offset = peer.dispatcher.protocolOffsets[i] if offset != -1 and offset + allProtocols[i].messages[^1].id >= msgId: return (allProtocols[i], peer.dispatcher.messages[msgId]) # Protocol info objects # proc initProtocol(name: string, version: int, peerInit: PeerStateInitializer, networkInit: NetworkStateInitializer): ProtocolInfoObj = result.name = name result.version = version result.messages = @[] result.peerStateInitializer = peerInit result.networkStateInitializer = networkInit proc setEventHandlers(p: ProtocolInfo, handshake: HandshakeStep, disconnectHandler: DisconnectionHandler) = p.handshake = handshake p.disconnectHandler = disconnectHandler func asCapability*(p: ProtocolInfo): Capability = result.name = p.name result.version = p.version func nameStr*(p: ProtocolInfo): string = result = newStringOfCap(3) for c in p.name: result.add(c) # XXX: this used to be inline, but inline procs # cannot be passed to closure params proc cmp*(lhs, rhs: ProtocolInfo): int = for i in 0..2: if lhs.name[i] != rhs.name[i]: return int16(lhs.name[i]) - int16(rhs.name[i]) return 0 proc messagePrinter[MsgType](msg: pointer): string {.gcsafe.} = result = "" # TODO: uncommenting the line below increases the compile-time # tremendously (for reasons not yet known) # result = $(cast[ptr MsgType](msg)[]) proc nextMsgResolver[MsgType](msgData: Rlp, future: FutureBase) {.gcsafe.} = var reader = msgData Future[MsgType](future).complete reader.readRecordType(MsgType, MsgType.rlpFieldsCount > 1) proc requestResolver[MsgType](msg: pointer, future: FutureBase) {.gcsafe.} = var f = Future[Option[MsgType]](future) if not f.finished: if msg != nil: f.complete some(cast[ptr MsgType](msg)[]) else: f.complete none(MsgType) else: # This future was already resolved, but let's do some sanity checks # here. The only reasonable explanation is that the request should # have timed out. if msg != nil: if f.read.isSome: doAssert false, "trying to resolve a request twice" else: doAssert false, "trying to resolve a timed out request with a value" else: try: if not f.read.isSome: doAssert false, "a request timed out twice" except: debug "Exception in requestResolver()", exc = getCurrentException().name, err = getCurrentExceptionMsg() raise proc registerMsg(protocol: ProtocolInfo, id: int, name: string, thunk: MessageHandler, printer: MessageContentPrinter, requestResolver: RequestResolver, nextMsgResolver: NextMsgResolver) = if protocol.messages.len <= id: protocol.messages.setLen(id + 1) protocol.messages[id] = MessageInfo(id: id, name: name, thunk: thunk, printer: printer, requestResolver: requestResolver, nextMsgResolver: nextMsgResolver) proc registerProtocol(protocol: ProtocolInfo) = # TODO: This can be done at compile-time in the future if protocol.version > 0: let pos = lowerBound(gProtocols, protocol) gProtocols.insert(protocol, pos) for i in 0 ..< gProtocols.len: gProtocols[i].index = i else: gDevp2pInfo = protocol # Message composition and encryption # proc perPeerMsgIdImpl(peer: Peer, proto: ProtocolInfo, msgId: int): int {.inline.} = result = msgId if not peer.dispatcher.isNil: result += peer.dispatcher.protocolOffsets[proto.index] template getPeer(peer: Peer): auto = peer template getPeer(response: Response): auto = Peer(response) template getPeer(response: ResponseWithId): auto = response.peer proc supports*(peer: Peer, proto: ProtocolInfo): bool {.inline.} = peer.dispatcher.protocolOffsets[proto.index] != -1 proc supports*(peer: Peer, Protocol: type): bool {.inline.} = ## Checks whether a Peer supports a particular protocol peer.supports(Protocol.protocolInfo) template perPeerMsgId(peer: Peer, MsgType: type): int = perPeerMsgIdImpl(peer, MsgType.msgProtocol.protocolInfo, MsgType.msgId) proc writeMsgId(p: ProtocolInfo, msgId: int, peer: Peer, rlpOut: var RlpWriter) = let baseMsgId = peer.dispatcher.protocolOffsets[p.index] doAssert baseMsgId != -1 rlpOut.append(baseMsgId + msgId) proc invokeThunk*(peer: Peer, msgId: int, msgData: var Rlp): Future[void] = template invalidIdError: untyped = raise newException(ValueError, "RLPx message with an invalid id " & $msgId & " on a connection supporting " & peer.dispatcher.describeProtocols) if msgId >= peer.dispatcher.messages.len: invalidIdError() let thunk = peer.dispatcher.messages[msgId].thunk if thunk == nil: invalidIdError() return thunk(peer, msgId, msgData) proc linkSendFailureToReqFuture[S, R](sendFut: Future[S], resFut: Future[R]) = sendFut.addCallback() do (arg: pointer): if not sendFut.error.isNil: resFut.fail(sendFut.error) template compressMsg(peer: Peer, data: Bytes): Bytes = when useSnappy: if peer.snappyEnabled: snappy.compress(data) else: data else: data proc sendMsg*(peer: Peer, data: Bytes) {.gcsafe, async.} = try: var cipherText = encryptMsg(peer.compressMsg(data), peer.secretsState) discard await peer.transport.write(cipherText) except: await peer.disconnect(TcpError) # this is usually a "(32) Broken pipe": # FIXME: this exception should be caught somewhere in addMsgHandler() and # sending should be retried a few times raise proc send*[Msg](peer: Peer, msg: Msg): Future[void] = logSentMsg(peer, msg) var rlpWriter = initRlpWriter() rlpWriter.append perPeerMsgId(peer, Msg) rlpWriter.appendRecordType(msg, Msg.rlpFieldsCount > 1) peer.sendMsg rlpWriter.finish proc registerRequest*(peer: Peer, timeout: Duration, responseFuture: FutureBase, responseMsgId: int): int = inc peer.lastReqId result = peer.lastReqId let timeoutAt = Moment.fromNow(timeout) let req = OutstandingRequest(id: result, future: responseFuture, timeoutAt: timeoutAt) peer.outstandingRequests[responseMsgId].addLast req doAssert(not peer.dispatcher.isNil) let requestResolver = peer.dispatcher.messages[responseMsgId].requestResolver proc timeoutExpired(udata: pointer) = requestResolver(nil, responseFuture) addTimer(timeoutAt, timeoutExpired, nil) proc resolveResponseFuture(peer: Peer, msgId: int, msg: pointer, reqId: int) = logScope: msg = peer.dispatcher.messages[msgId].name msgContents = peer.dispatcher.messages[msgId].printer(msg) receivedReqId = reqId remotePeer = peer.remote template resolve(future) = (peer.dispatcher.messages[msgId].requestResolver)(msg, future) template outstandingReqs: auto = peer.outstandingRequests[msgId] if reqId == -1: # XXX: This is a response from an ETH-like protocol that doesn't feature # request IDs. Handling the response is quite tricky here because this may # be a late response to an already timed out request or a valid response # from a more recent one. # # We can increase the robustness by recording enough features of the # request so we can recognize the matching response, but this is not very # easy to do because our peers are allowed to send partial responses. # # A more generally robust approach is to maintain a set of the wanted # data items and then to periodically look for items that have been # requested long time ago, but are still missing. New requests can be # issues for such items potentially from another random peer. var expiredRequests = 0 for req in outstandingReqs: if not req.future.finished: break inc expiredRequests outstandingReqs.shrink(fromFirst = expiredRequests) if outstandingReqs.len > 0: let oldestReq = outstandingReqs.popFirst resolve oldestReq.future else: trace "late or duplicate reply for a RLPx request" else: # TODO: This is not completely sound because we are still using a global # `reqId` sequence (the problem is that we might get a response ID that # matches a request ID for a different type of request). To make the code # correct, we can use a separate sequence per response type, but we have # to first verify that the other Ethereum clients are supporting this # correctly (because then, we'll be reusing the same reqIds for different # types of requests). Alternatively, we can assign a separate interval in # the `reqId` space for each type of response. if reqId > peer.lastReqId: warn "RLPx response without a matching request" return var idx = 0 while idx < outstandingReqs.len: template req: auto = outstandingReqs()[idx] if req.future.finished: doAssert req.timeoutAt <= Moment.now() # Here we'll remove the expired request by swapping # it with the last one in the deque (if necessary): if idx != outstandingReqs.len - 1: req = outstandingReqs.popLast continue else: outstandingReqs.shrink(fromLast = 1) # This was the last item, so we don't have any # more work to do: return if req.id == reqId: resolve req.future # Here we'll remove the found request by swapping # it with the last one in the deque (if necessary): if idx != outstandingReqs.len - 1: req = outstandingReqs.popLast else: outstandingReqs.shrink(fromLast = 1) return inc idx debug "late or duplicate reply for a RLPx request" proc recvMsg*(peer: Peer): Future[tuple[msgId: int, msgData: Rlp]] {.async.} = ## This procs awaits the next complete RLPx message in the TCP stream var headerBytes: array[32, byte] await peer.transport.readExactly(addr headerBytes[0], 32) var msgSize: int if decryptHeaderAndGetMsgSize(peer.secretsState, headerBytes, msgSize) != RlpxStatus.Success: await peer.disconnectAndRaise(BreachOfProtocol, "Cannot decrypt RLPx frame header") if msgSize > maxMsgSize: await peer.disconnectAndRaise(BreachOfProtocol, "RLPx message exceeds maximum size") let remainingBytes = encryptedLength(msgSize) - 32 # TODO: Migrate this to a thread-local seq # JACEK: # or pass it in, allowing the caller to choose - they'll likely be in a # better position to decide if buffer should be reused or not. this will # also be useuful for chunked messages where part of the buffer may have # been processed and needs filling in var encryptedBytes = newSeq[byte](remainingBytes) await peer.transport.readExactly(addr encryptedBytes[0], len(encryptedBytes)) let decryptedMaxLength = decryptedLength(msgSize) var decryptedBytes = newSeq[byte](decryptedMaxLength) decryptedBytesCount = 0 if decryptBody(peer.secretsState, encryptedBytes, msgSize, decryptedBytes, decryptedBytesCount) != RlpxStatus.Success: await peer.disconnectAndRaise(BreachOfProtocol, "Cannot decrypt RLPx frame body") decryptedBytes.setLen(decryptedBytesCount) when useSnappy: if peer.snappyEnabled: decryptedBytes = snappy.uncompress(decryptedBytes) if decryptedBytes.len == 0: await peer.disconnectAndRaise(BreachOfProtocol, "Snappy uncompress encountered malformed data") var rlp = rlpFromBytes(decryptedBytes.toRange) try: let msgid = rlp.read(int) return (msgId, rlp) except RlpError: await peer.disconnectAndRaise(BreachOfProtocol, "Cannot read RLPx message id") proc checkedRlpRead(peer: Peer, r: var Rlp, MsgType: type): auto {.inline.} = let tmp = r when defined(release): return r.read(MsgType) else: try: return r.read(MsgType) except: # echo "Failed rlp.read:", tmp.inspect debug "Failed rlp.read", peer = peer, msg = MsgType.name, exception = getCurrentExceptionMsg() # dataHex = r.rawData.toSeq().toHex() raise proc waitSingleMsg(peer: Peer, MsgType: type): Future[MsgType] {.async.} = let wantedId = peer.perPeerMsgId(MsgType) while true: var (nextMsgId, nextMsgData) = await peer.recvMsg() if nextMsgId == wantedId: try: result = checkedRlpRead(peer, nextMsgData, MsgType) logReceivedMsg(peer, result) return except RlpError: await peer.disconnectAndRaise(BreachOfProtocol, "Invalid RLPx message body") elif nextMsgId == 1: # p2p.disconnect let reason = DisconnectionReason nextMsgData.listElem(0).toInt(uint32) await peer.disconnect(reason) raisePeerDisconnected("Unexpected disconnect", reason) else: warn "Dropped RLPX message", msg = peer.dispatcher.messages[nextMsgId].name include p2p_backends_helpers proc nextMsg*(peer: Peer, MsgType: type): Future[MsgType] = ## This procs awaits a specific RLPx message. ## Any messages received while waiting will be dispatched to their ## respective handlers. The designated message handler will also run ## to completion before the future returned by `nextMsg` is resolved. let wantedId = peer.perPeerMsgId(MsgType) let f = peer.awaitedMessages[wantedId] if not f.isNil: return Future[MsgType](f) initFuture result peer.awaitedMessages[wantedId] = result # Known fatal errors are handled inside dispatchMessages. # Errors we are currently unaware of are caught in the dispatchMessages # callback. There they will be logged if CatchableError and quit on Defect. # Non fatal errors such as the current CatchableError could be moved and # handled a layer lower for clarity (and consistency), as also the actual # message handler code as the TODO mentions already. proc dispatchMessages*(peer: Peer) {.async.} = while true: var msgId: int var msgData: Rlp try: (msgId, msgData) = await peer.recvMsg() except TransportIncompleteError: trace "Connection dropped, ending dispatchMessages loop", peer # This can happen during the rlpx connection setup or at any point after. # Because this code does not know, a disconnect needs to be done. await peer.disconnect(ClientQuitting) return if msgId == 1: # p2p.disconnect await peer.transport.closeWait() let reason = msgData.listElem(0).toInt(uint32).DisconnectionReason await peer.disconnect(reason) break try: await peer.invokeThunk(msgId, msgData) except RlpError: debug "RlpError, ending dispatchMessages loop", peer, err = getCurrentExceptionMsg() await peer.disconnect(BreachOfProtocol, true) return except CatchableError: warn "Error while handling RLPx message", peer, msg = peer.getMsgName(msgId), err = getCurrentExceptionMsg() # TODO: Hmm, this can be safely moved into the message handler thunk. # The documentation will need to be updated, explaning the fact that # nextMsg will be resolved only if the message handler has executed # successfully. if peer.awaitedMessages[msgId] != nil: let msgInfo = peer.dispatcher.messages[msgId] try: (msgInfo.nextMsgResolver)(msgData, peer.awaitedMessages[msgId]) except: # TODO: Handling errors here must be investigated more carefully. # They also are supposed to be handled at the call-site where # `nextMsg` is used. debug "nextMsg resolver failed, ending dispatchMessages loop", peer, err = getCurrentExceptionMsg() await peer.disconnect(BreachOfProtocol, true) return peer.awaitedMessages[msgId] = nil macro p2pProtocolImpl(name: static[string], version: static[uint], body: untyped, # TODO Nim can't handle a proper duration paramter here timeout: static[int64] = defaultReqTimeout.milliseconds, useRequestIds: static[bool] = true, shortName: static[string] = "", outgoingRequestDecorator: untyped = nil, incomingRequestDecorator: untyped = nil, incomingRequestThunkDecorator: untyped = nil, incomingResponseDecorator: untyped = nil, incomingResponseThunkDecorator: untyped = nil, peerState = type(nil), networkState = type(nil)): untyped = ## The macro used to defined RLPx sub-protocols. See README. var # XXX: deal with a Nim bug causing the macro params to be # zero when they are captured by a closure: outgoingRequestDecorator = outgoingRequestDecorator incomingRequestDecorator = incomingRequestDecorator incomingRequestThunkDecorator = incomingRequestThunkDecorator incomingResponseDecorator = incomingResponseDecorator incomingResponseThunkDecorator = incomingResponseThunkDecorator useRequestIds = useRequestIds version = version defaultTimeout = timeout nextId = 0 protoName = name shortName = if shortName.len > 0: shortName else: protoName outTypes = newNimNode(nnkStmtList) outSendProcs = newNimNode(nnkStmtList) outRecvProcs = newNimNode(nnkStmtList) outProcRegistrations = newNimNode(nnkStmtList) protoNameIdent = ident(protoName) resultIdent = ident "result" perProtocolMsgId = ident"perProtocolMsgId" response = ident"response" currentProtocolSym = ident"CurrentProtocol" protocol = ident(protoName & "Protocol") isSubprotocol = version > 0'u peerState = verifyStateType peerState.getType networkState = verifyStateType networkState.getType handshake = newNilLit() disconnectHandler = newNilLit() Option = bindSym "Option" # XXX: Binding the int type causes instantiation failure for some reason # Int = bindSym "int" Int = ident "int" Peer = bindSym "Peer" Duration = bindSym "Duration" milliseconds = bindSym "milliseconds" createNetworkState = bindSym "createNetworkState" createPeerState = bindSym "createPeerState" finish = bindSym "finish" initRlpWriter = bindSym "initRlpWriter" enterList = bindSym "enterList" messagePrinter = bindSym "messagePrinter" initProtocol = bindSym "initProtocol" nextMsgResolver = bindSym "nextMsgResolver" append = bindSym("append", brForceOpen) read = bindSym("read", brForceOpen) registerRequest = bindSym "registerRequest" requestResolver = bindSym "requestResolver" resolveResponseFuture = bindSym "resolveResponseFuture" rlpFromBytes = bindSym "rlpFromBytes" checkedRlpRead = bindSym "checkedRlpRead" sendMsg = bindSym "sendMsg" startList = bindSym "startList" writeMsgId = bindSym "writeMsgId" getState = bindSym "getState" getNetworkState = bindSym "getNetworkState" perPeerMsgId = bindSym "perPeerMsgId" perPeerMsgIdImpl = bindSym "perPeerMsgIdImpl" linkSendFailureToReqFuture = bindSym "linkSendFailureToReqFuture" # By convention, all Ethereum protocol names must be abbreviated to 3 letters doAssert shortName.len == 3 template applyDecorator(p: NimNode, decorator: NimNode) = if decorator.kind != nnkNilLit: p.addPragma decorator proc augmentUserHandler(userHandlerProc: NimNode, msgId = -1, msgKind = rlpxNotification, extraDefinitions: NimNode = nil) = ## Turns a regular proc definition into an async proc and adds ## the helpers for accessing the peer and network protocol states. case msgKind of rlpxRequest: userHandlerProc.applyDecorator incomingRequestDecorator of rlpxResponse: userHandlerProc.applyDecorator incomingResponseDecorator else: discard userHandlerProc.addPragma ident"gcsafe" userHandlerProc.addPragma ident"async" # We allow the user handler to use `openarray` params, but we turn # those into sequences to make the `async` pragma happy. for i in 1 ..< userHandlerProc.params.len: var param = userHandlerProc.params[i] param[^2] = chooseFieldType(param[^2]) var userHandlerDefinitions = newStmtList() userHandlerDefinitions.add quote do: type `currentProtocolSym` = `protoNameIdent` if extraDefinitions != nil: userHandlerDefinitions.add extraDefinitions if msgId >= 0: userHandlerDefinitions.add quote do: const `perProtocolMsgId` = `msgId` # Define local accessors for the peer and the network protocol states # inside each user message handler proc (e.g. peer.state.foo = bar) if peerState != nil: userHandlerDefinitions.add quote do: template state(p: `Peer`): `peerState` = cast[`peerState`](`getState`(p, `protocol`)) if networkState != nil: userHandlerDefinitions.add quote do: template networkState(p: `Peer`): `networkState` = cast[`networkState`](`getNetworkState`(p.network, `protocol`)) userHandlerProc.body.insert 0, userHandlerDefinitions proc liftEventHandler(doBlock: NimNode, handlerName: string): NimNode = ## Turns a "named" do block to a regular async proc ## (e.g. onPeerConnected do ...) var fn = newTree(nnkProcDef) doBlock.copyChildrenTo(fn) result = genSym(nskProc, protoName & handlerName) fn.name = result augmentUserHandler fn outRecvProcs.add fn proc addMsgHandler(msgId: int, n: NimNode, msgKind = rlpxNotification, responseMsgId = -1, responseRecord: NimNode = nil): NimNode = if n[0].kind == nnkPostfix: macros.error("p2pProcotol procs are public by default. " & "Please remove the postfix `*`.", n) let msgIdent = n.name msgName = $n.name hasReqIds = useRequestIds and msgKind in {rlpxRequest, rlpxResponse} var userPragmas = n.pragma # variables used in the sending procs msgRecipient = ident"msgRecipient" sendTo = ident"sendTo" reqTimeout: NimNode rlpWriter = ident"writer" appendParams = newNimNode(nnkStmtList) paramsToWrite = newSeq[NimNode](0) reqId = ident"reqId" perPeerMsgIdVar = ident"perPeerMsgId" # variables used in the receiving procs msgSender = ident"msgSender" receivedRlp = ident"rlp" receivedMsg = ident"msg" readParams = newNimNode(nnkStmtList) readParamsPrelude = newNimNode(nnkStmtList) callResolvedResponseFuture = newNimNode(nnkStmtList) # nodes to store the user-supplied message handling proc if present userHandlerProc: NimNode = nil userHandlerCall: NimNode = nil awaitUserHandler = newStmtList() # a record type associated with the message msgRecord = newIdentNode(msgName & "Obj") msgRecordFields = newTree(nnkRecList) msgRecordBody = newTree(nnkObjectTy, newEmptyNode(), newEmptyNode(), msgRecordFields) result = msgRecord if hasReqIds: # Messages using request Ids readParams.add quote do: let `reqId` = `read`(`receivedRlp`, int) case msgKind of rlpxNotification: discard of rlpxRequest: # If the request proc has a default timeout specified, remove it from # the signature for now so we can generate the `thunk` proc without it. # The parameter will be added back later only for to the sender proc. # When the timeout is not specified, we use a default one. reqTimeout = popTimeoutParam(n) if reqTimeout == nil: reqTimeout = newTree(nnkIdentDefs, ident"timeout", Duration, newCall(milliseconds, newLit(defaultTimeout))) let reqToResponseOffset = responseMsgId - msgId let responseMsgId = quote do: `perPeerMsgIdVar` + `reqToResponseOffset` # Each request is registered so we can resolve it when the response # arrives. There are two types of protocols: LES-like protocols use # explicit `reqId` sent over the wire, while the ETH wire protocol # assumes there is one outstanding request at a time (if there are # multiple requests we'll resolve them in FIFO order). let registerRequestCall = newCall(registerRequest, msgRecipient, reqTimeout[0], resultIdent, responseMsgId) if hasReqIds: appendParams.add quote do: initFuture `resultIdent` let `reqId` = `registerRequestCall` paramsToWrite.add reqId else: appendParams.add quote do: initFuture `resultIdent` discard `registerRequestCall` of rlpxResponse: let reqIdVal = if hasReqIds: `reqId` else: newLit(-1) callResolvedResponseFuture.add quote do: `resolveResponseFuture`(`msgSender`, `perPeerMsgId`(`msgSender`, `msgRecord`), addr(`receivedMsg`), `reqIdVal`) if hasReqIds: paramsToWrite.add newDotExpr(sendTo, ident"id") if n.body.kind != nnkEmpty: # implement the receiving thunk proc that deserialzed the # message parameters and calls the user proc: userHandlerProc = n.copyNimTree userHandlerProc.name = genSym(nskProc, msgName) var extraDefs: NimNode if msgKind == rlpxRequest: let peer = userHandlerProc.params[1][0] if hasReqIds: extraDefs = quote do: let `response` = ResponseWithId[`responseRecord`](peer: `peer`, id: `reqId`) else: extraDefs = quote do: let `response` = Response[`responseRecord`](`peer`) augmentUserHandler userHandlerProc, msgId, msgKind, extraDefs # This is the call to the user supplied handled. Here we add only the # initial peer param, while the rest of the params will be added later. userHandlerCall = newCall(userHandlerProc.name, msgSender) if hasReqIds: userHandlerProc.params.insert(2, newIdentDefs(reqId, ident"int")) userHandlerCall.add reqId # When there is a user handler, it must be awaited in the thunk proc. # Above, by default `awaitUserHandler` is set to a no-op statement list. awaitUserHandler = newCall("await", userHandlerCall) outRecvProcs.add(userHandlerProc) for param, paramType in n.typedParams(skip = 1): # This is a fragment of the sending proc that # serializes each of the passed parameters: paramsToWrite.add param # Each message has a corresponding record type. # Here, we create its fields one by one: msgRecordFields.add newTree(nnkIdentDefs, newTree(nnkPostfix, ident("*"), param), # The fields are public chooseFieldType(paramType), # some types such as openarray # are automatically remapped newEmptyNode()) # The received RLP data is deserialized to a local variable of # the message-specific type. This is done field by field here: let msgNameLit = newLit(msgName) readParams.add quote do: `receivedMsg`.`param` = `checkedRlpRead`(`msgSender`, `receivedRlp`, `paramType`) # If there is user message handler, we'll place a call to it by # unpacking the fields of the received message: if userHandlerCall != nil: userHandlerCall.add newDotExpr(receivedMsg, param) let paramCount = paramsToWrite.len if paramCount > 1: readParamsPrelude.add newCall(enterList, receivedRlp) when tracingEnabled: readParams.add newCall(bindSym"logReceivedMsg", msgSender, receivedMsg) let thunkName = ident(msgName & "_thunk") var thunkProc = quote do: proc `thunkName`(`msgSender`: `Peer`, _: int, data: Rlp) {.gcsafe.} = var `receivedRlp` = data var `receivedMsg` {.noinit.}: `msgRecord` `readParamsPrelude` `readParams` `awaitUserHandler` `callResolvedResponseFuture` for p in userPragmas: thunkProc.addPragma p case msgKind of rlpxRequest: thunkProc.applyDecorator incomingRequestThunkDecorator of rlpxResponse: thunkProc.applyDecorator incomingResponseThunkDecorator else: discard thunkProc.addPragma ident"async" outRecvProcs.add thunkProc outTypes.add quote do: # This is a type featuring a single field for each message param: type `msgRecord`* = `msgRecordBody` # Add a helper template for accessing the message type: # e.g. p2p.hello: template `msgIdent`*(T: type `protoNameIdent`): type = `msgRecord` # Add a helper template for obtaining the message Id for # a particular message type: template msgId*(T: type `msgRecord`): int = `msgId` template msgProtocol*(T: type `msgRecord`): type = `protoNameIdent` var msgSendProc = n let msgSendProcName = n.name outSendProcs.add msgSendProc # TODO: check that the first param has the correct type msgSendProc.params[1][0] = sendTo msgSendProc.addPragma ident"gcsafe" # Add a timeout parameter for all request procs case msgKind of rlpxRequest: msgSendProc.params.add reqTimeout of rlpxResponse: # A response proc must be called with a response object that originates # from a certain request. Here we change the Peer parameter at position # 1 to the correct strongly-typed ResponseType. The incoming procs still # gets the normal Peer paramter. let ResponseTypeHead = if useRequestIds: bindSym"ResponseWithId" else: bindSym"Response" ResponseType = newTree(nnkBracketExpr, ResponseTypeHead, msgRecord) msgSendProc.params[1][1] = ResponseType outSendProcs.add quote do: template send*(r: `ResponseType`, args: varargs[untyped]): auto = `msgSendProcName`(r, args) else: discard # We change the return type of the sending proc to a Future. # If this is a request proc, the future will return the response record. let rt = if msgKind != rlpxRequest: ident"void" else: newTree(nnkBracketExpr, Option, responseRecord) msgSendProc.params[0] = newTree(nnkBracketExpr, ident("Future"), rt) let msgBytes = ident"msgBytes" let finalizeRequest = quote do: let `msgBytes` = `finish`(`rlpWriter`) var sendCall = newCall(sendMsg, msgRecipient, msgBytes) let senderEpilogue = if msgKind == rlpxRequest: # In RLPx requests, the returned future was allocated here and passed # to `registerRequest`. It's already assigned to the result variable # of the proc, so we just wait for the sending operation to complete # and we return in a normal way. (the waiting is done, so we can catch # any possible errors). quote: `linkSendFailureToReqFuture`(`sendCall`, `resultIdent`) else: # In normal RLPx messages, we are returning the future returned by the # `sendMsg` call. quote: return `sendCall` let perPeerMsgIdValue = if isSubprotocol: newCall(perPeerMsgIdImpl, msgRecipient, protocol, newLit(msgId)) else: newLit(msgId) if paramCount > 1: # In case there are more than 1 parameter, # the params must be wrapped in a list: appendParams = newStmtList( newCall(startList, rlpWriter, newLit(paramCount)), appendParams) for p in paramsToWrite: appendParams.add newCall(append, rlpWriter, p) # Make the send proc public msgSendProc.name = newTree(nnkPostfix, ident("*"), msgSendProc.name) let initWriter = quote do: var `rlpWriter` = `initRlpWriter`() const `perProtocolMsgId` = `msgId` let `perPeerMsgIdVar` = `perPeerMsgIdValue` `append`(`rlpWriter`, `perPeerMsgIdVar`) when tracingEnabled: appendParams.add logSentMsgFields(msgRecipient, protocol, msgId, paramsToWrite) # let paramCountNode = newLit(paramCount) msgSendProc.body = quote do: let `msgRecipient` = getPeer(`sendTo`) `initWriter` `appendParams` `finalizeRequest` `senderEpilogue` if msgKind == rlpxRequest: msgSendProc.applyDecorator outgoingRequestDecorator outProcRegistrations.add( newCall(bindSym("registerMsg"), protocol, newIntLitNode(msgId), newStrLitNode($n.name), thunkName, newTree(nnkBracketExpr, messagePrinter, msgRecord), newTree(nnkBracketExpr, requestResolver, msgRecord), newTree(nnkBracketExpr, nextMsgResolver, msgRecord))) outTypes.add quote do: # Create a type acting as a pseudo-object representing the protocol # (e.g. p2p) type `protoNameIdent`* = object if peerState != nil: outTypes.add quote do: template State*(P: type `protoNameIdent`): type = `peerState` if networkState != nil: outTypes.add quote do: template NetworkState*(P: type `protoNameIdent`): type = `networkState` for n in body: case n.kind of {nnkCall, nnkCommand}: if eqIdent(n[0], "nextID"): # By default message IDs are assigned in increasing order # `nextID` can be used to skip some of the numeric slots if n.len == 2 and n[1].kind == nnkIntLit: nextId = n[1].intVal.int else: macros.error("nextID expects a single int value", n) elif eqIdent(n[0], "requestResponse"): # `requestResponse` can be given a block of 2 or more procs. # The last one is considered to be a response message, while # all preceeding ones are requests triggering the response. # The system makes sure to automatically insert a hidden `reqId` # parameter used to discriminate the individual messages. block processReqResp: if n.len == 2 and n[1].kind == nnkStmtList: var procs = newSeq[NimNode](0) for def in n[1]: if def.kind == nnkProcDef: procs.add(def) if procs.len > 1: let responseMsgId = nextId + procs.len - 1 let responseRecord = addMsgHandler(responseMsgId, procs[^1], msgKind = rlpxResponse) for i in 0 .. procs.len - 2: discard addMsgHandler(nextId + i, procs[i], msgKind = rlpxRequest, responseMsgId = responseMsgId, responseRecord = responseRecord) inc nextId, procs.len # we got all the way to here, so everything is fine. # break the block so it doesn't reach the error call below break processReqResp macros.error("requestResponse expects a block with at least two proc definitions") elif eqIdent(n[0], "onPeerConnected"): handshake = liftEventHandler(n[1], "Handshake") elif eqIdent(n[0], "onPeerDisconnected"): disconnectHandler = liftEventHandler(n[1], "PeerDisconnect") else: macros.error(repr(n) & " is not a recognized call in P2P protocol definitions", n) of nnkProcDef: discard addMsgHandler(nextId, n) inc nextId of nnkCommentStmt: discard else: macros.error("illegal syntax in a P2P protocol definition", n) let peerInit = if peerState == nil: newNilLit() else: newTree(nnkBracketExpr, createPeerState, peerState) let netInit = if networkState == nil: newNilLit() else: newTree(nnkBracketExpr, createNetworkState, networkState) result = newNimNode(nnkStmtList) result.add outTypes result.add quote do: # One global variable per protocol holds the protocol run-time data var p = `initProtocol`(`shortName`, `version`, `peerInit`, `netInit`) var `protocol` = addr p # The protocol run-time data is available as a pseudo-field # (e.g. `p2p.protocolInfo`) template protocolInfo*(P: type `protoNameIdent`): ProtocolInfo = `protocol` result.add outSendProcs, outRecvProcs, outProcRegistrations result.add quote do: setEventHandlers(`protocol`, `handshake`, `disconnectHandler`) result.add newCall(bindSym("registerProtocol"), protocol) when defined(debugRlpxProtocol) or defined(debugMacros): echo repr(result) macro p2pProtocol*(protocolOptions: untyped, body: untyped): untyped = let protoName = $(protocolOptions[0]) result = protocolOptions result[0] = bindSym"p2pProtocolImpl" result.add(newTree(nnkExprEqExpr, ident("name"), newLit(protoName))) result.add(newTree(nnkExprEqExpr, ident("body"), body)) p2pProtocol devp2p(version = 0, shortName = "p2p"): proc hello(peer: Peer, version: uint, clientId: string, capabilities: seq[Capability], listenPort: uint, nodeId: array[RawPublicKeySize, byte]) proc sendDisconnectMsg(peer: Peer, reason: DisconnectionReason) proc ping(peer: Peer) = discard peer.pong() proc pong(peer: Peer) = discard proc removePeer(network: EthereumNode, peer: Peer) = # It is necessary to check if peer.remote still exists. The connection might # have been dropped already from the peers side. # E.g. when receiving a p2p.disconnect message from a peer, a race will happen # between which side disconnects first. if network.peerPool != nil and not peer.remote.isNil: network.peerPool.connectedNodes.del(peer.remote) # Note: we need to do this check as disconnect (and thus removePeer) # currently can get called before the dispatcher is initialized. if not peer.dispatcher.isNil: for observer in network.peerPool.observers.values: if not observer.onPeerDisconnected.isNil: if observer.protocol.isNil or peer.supports(observer.protocol): observer.onPeerDisconnected(peer) proc callDisconnectHandlers(peer: Peer, reason: DisconnectionReason): Future[void] = var futures = newSeqOfCap[Future[void]](allProtocols.len) for protocol in peer.dispatcher.activeProtocols: if protocol.disconnectHandler != nil: futures.add((protocol.disconnectHandler)(peer, reason)) return all(futures) proc handshakeImpl[T](peer: Peer, sendFut: Future[void], responseFut: Future[T], timeout: Duration): Future[T] {.async.} = sendFut.addCallback do (arg: pointer) {.gcsafe.}: if sendFut.failed: debug "Handshake message not delivered", peer doAssert timeout.milliseconds > 0 yield responseFut or sleepAsync(timeout) if not responseFut.finished: discard disconnectAndRaise(peer, BreachOfProtocol, "Protocol handshake was not received in time.") elif responseFut.failed: raise responseFut.error else: return responseFut.read proc handshakeImpl(peer: Peer, sendFut: Future[void], timeout: Duration, HandshakeType: type): Future[HandshakeType] = handshakeImpl(peer, sendFut, nextMsg(peer, HandshakeType), timeout) macro handshake*(peer: Peer, timeout: untyped, sendCall: untyped): untyped = let msgName = $sendCall[0] msgType = newDotExpr(ident"CurrentProtocol", ident(msgName)) sendCall.insert(1, peer) result = newCall(bindSym"handshakeImpl", peer, sendCall, timeout, msgType) proc disconnect*(peer: Peer, reason: DisconnectionReason, notifyOtherPeer = false) {.async.} = if peer.connectionState notin {Disconnecting, Disconnected}: peer.connectionState = Disconnecting if notifyOtherPeer and not peer.transport.closed: var fut = peer.sendDisconnectMsg(reason) yield fut if fut.failed: debug "Failed to delived disconnect message", peer if not peer.dispatcher.isNil: # In case of `CatchableError` in any of the handlers, this will be logged. # Other handlers will still execute. # In case of `Defect` in any of the handlers, program will quit. traceAwaitErrors callDisconnectHandlers(peer, reason) logDisconnectedPeer peer peer.connectionState = Disconnected removePeer(peer.network, peer) proc validatePubKeyInHello(msg: devp2p.hello, pubKey: PublicKey): bool = var pk: PublicKey recoverPublicKey(msg.nodeId, pk) == EthKeysStatus.Success and pk == pubKey proc checkUselessPeer(peer: Peer) {.inline.} = if peer.dispatcher.numProtocols == 0: # XXX: Send disconnect + UselessPeer raise newException(UselessPeerError, "Useless peer") proc initPeerState*(peer: Peer, capabilities: openarray[Capability]) = peer.dispatcher = getDispatcher(peer.network, capabilities) checkUselessPeer(peer) # The dispatcher has determined our message ID sequence. # For each message ID, we allocate a potential slot for # tracking responses to requests. # (yes, some of the slots won't be used). peer.outstandingRequests.newSeq(peer.dispatcher.messages.len) for d in mitems(peer.outstandingRequests): d = initDeque[OutstandingRequest]() # Similarly, we need a bit of book-keeping data to keep track # of the potentially concurrent calls to `nextMsg`. peer.awaitedMessages.newSeq(peer.dispatcher.messages.len) peer.lastReqId = 0 # Initialize all the active protocol states newSeq(peer.protocolStates, allProtocols.len) for protocol in peer.dispatcher.activeProtocols: let peerStateInit = protocol.peerStateInitializer if peerStateInit != nil: peer.protocolStates[protocol.index] = peerStateInit(peer) proc postHelloSteps(peer: Peer, h: devp2p.hello) {.async.} = initPeerState(peer, h.capabilities) # Please note that the ordering of operations here is important! # # We must first start all handshake procedures and give them a # chance to send any initial packages they might require over # the network and to yield on their `nextMsg` waits. # var subProtocolsHandshakes = newSeqOfCap[Future[void]](allProtocols.len) for protocol in peer.dispatcher.activeProtocols: if protocol.handshake != nil: subProtocolsHandshakes.add((protocol.handshake)(peer)) # The `dispatchMesssages` loop must be started after this. # Otherwise, we risk that some of the handshake packets sent by # the other peer may arrrive too early and be processed before # the handshake code got a change to wait for them. # var messageProcessingLoop = peer.dispatchMessages() messageProcessingLoop.callback = proc(p: pointer) {.gcsafe.} = if messageProcessingLoop.failed: debug "Ending dispatchMessages loop", peer, err = messageProcessingLoop.error.msg traceAsyncErrors peer.disconnect(ClientQuitting) # The handshake may involve multiple async steps, so we wait # here for all of them to finish. # await all(subProtocolsHandshakes) peer.connectionState = Connected template `^`(arr): auto = # passes a stack array with a matching `arrLen` # variable as an open array arr.toOpenArray(0, `arr Len` - 1) proc check(status: AuthStatus) = if status != AuthStatus.Success: raise newException(CatchableError, "Error: " & $status) proc initSecretState(hs: var Handshake, authMsg, ackMsg: openarray[byte], p: Peer) = var secrets: ConnectionSecret check hs.getSecrets(authMsg, ackMsg, secrets) initSecretState(secrets, p.secretsState) burnMem(secrets) template checkSnappySupport(node: EthereumNode, handshake: Handshake, peer: Peer) = when useSnappy: peer.snappyEnabled = node.protocolVersion >= devp2pSnappyVersion.uint and handshake.version >= devp2pSnappyVersion.uint template getVersion(handshake: Handshake): uint = when useSnappy: handshake.version else: devp2pVersion template baseProtocolVersion(node: EthereumNode): untyped = when useSnappy: node.protocolVersion else: devp2pVersion template baseProtocolVersion(peer: Peer): uint = when useSnappy: if peer.snappyEnabled: devp2pSnappyVersion else: devp2pVersion else: devp2pVersion proc rlpxConnect*(node: EthereumNode, remote: Node): Future[Peer] {.async.} = initTracing(devp2pInfo, node.protocols) new result result.network = node result.remote = remote let ta = initTAddress(remote.node.address.ip, remote.node.address.tcpPort) var ok = false try: result.transport = await connect(ta) var handshake = newHandshake({Initiator, EIP8}, int(node.baseProtocolVersion)) handshake.host = node.keys var authMsg: array[AuthMessageMaxEIP8, byte] var authMsgLen = 0 check authMessage(handshake, remote.node.pubkey, authMsg, authMsgLen) var res = result.transport.write(addr authMsg[0], authMsgLen) let initialSize = handshake.expectedLength var ackMsg = newSeqOfCap[byte](1024) ackMsg.setLen(initialSize) await result.transport.readExactly(addr ackMsg[0], len(ackMsg)) var ret = handshake.decodeAckMessage(ackMsg) if ret == AuthStatus.IncompleteError: ackMsg.setLen(handshake.expectedLength) await result.transport.readExactly(addr ackMsg[initialSize], len(ackMsg) - initialSize) ret = handshake.decodeAckMessage(ackMsg) check ret node.checkSnappySupport(handshake, result) initSecretState(handshake, ^authMsg, ackMsg, result) # if handshake.remoteHPubkey != remote.node.pubKey: # raise newException(Exception, "Remote pubkey is wrong") logConnectedPeer result var sendHelloFut = result.hello( handshake.getVersion(), node.clientId, node.capabilities, uint(node.address.tcpPort), node.keys.pubkey.getRaw()) var response = await result.handshakeImpl( sendHelloFut, result.waitSingleMsg(devp2p.hello), 10.seconds) if not validatePubKeyInHello(response, remote.node.pubKey): warn "Remote nodeId is not its public key" # XXX: Do we care? await postHelloSteps(result, response) ok = true except PeerDisconnected as e: if e.reason != TooManyPeers: debug "Unexpected disconnect during rlpxConnect", reason = e.reason except TransportIncompleteError: trace "Connection dropped in rlpxConnect", remote except UselessPeerError: trace "Disconnecting useless peer", peer = remote except RlpTypeMismatch: # Some peers report capabilities with names longer than 3 chars. We ignore # those for now. Maybe we should allow this though. debug "Rlp error in rlpxConnect" except TransportOsError: trace "TransportOsError", err = getCurrentExceptionMsg() except: error "Exception in rlpxConnect", remote, exc = getCurrentException().name, err = getCurrentExceptionMsg() result = nil raise if not ok: if not isNil(result.transport): result.transport.close() result = nil proc rlpxAccept*(node: EthereumNode, transport: StreamTransport): Future[Peer] {.async.} = initTracing(devp2pInfo, node.protocols) new result result.transport = transport result.network = node var handshake = newHandshake({Responder}) handshake.host = node.keys var ok = false try: let initialSize = handshake.expectedLength var authMsg = newSeqOfCap[byte](1024) authMsg.setLen(initialSize) await transport.readExactly(addr authMsg[0], len(authMsg)) var ret = handshake.decodeAuthMessage(authMsg) if ret == AuthStatus.IncompleteError: # Eip8 auth message is likely authMsg.setLen(handshake.expectedLength) await transport.readExactly(addr authMsg[initialSize], len(authMsg) - initialSize) ret = handshake.decodeAuthMessage(authMsg) check ret node.checkSnappySupport(handshake, result) handshake.version = uint8(result.baseProtocolVersion) var ackMsg: array[AckMessageMaxEIP8, byte] var ackMsgLen: int check handshake.ackMessage(ackMsg, ackMsgLen) var res = transport.write(addr ackMsg[0], ackMsgLen) initSecretState(handshake, authMsg, ^ackMsg, result) let listenPort = transport.localAddress().port logAcceptedPeer result var sendHelloFut = result.hello( result.baseProtocolVersion, node.clientId, node.capabilities, listenPort.uint, node.keys.pubkey.getRaw()) var response = await result.handshakeImpl( sendHelloFut, result.waitSingleMsg(devp2p.hello), 10.seconds) if not validatePubKeyInHello(response, handshake.remoteHPubkey): warn "A Remote nodeId is not its public key" # XXX: Do we care? let remote = transport.remoteAddress() let address = Address(ip: remote.address, tcpPort: remote.port, udpPort: remote.port) result.remote = newNode(initEnode(handshake.remoteHPubkey, address)) await postHelloSteps(result, response) ok = true except PeerDisconnected as e: if e.reason == AlreadyConnected: trace "Disconnect during rlpxAccept", reason = e.reason else: debug "Unexpected disconnect during rlpxAccept", reason = e.reason except TransportIncompleteError: trace "Connection dropped in rlpxAccept", remote = result.remote except UselessPeerError: trace "Disconnecting useless peer", peer = result.remote except: error "Exception in rlpxAccept", err = getCurrentExceptionMsg(), stackTrace = getCurrentException().getStackTrace() if not ok: if not isNil(result.transport): result.transport.close() result = nil raise when isMainModule: when false: # The assignments below can be used to investigate if the RLPx procs # are considered GcSafe. The short answer is that they aren't, because # they dispatch into user code that might use the GC. type GcSafeDispatchMsg = proc (peer: Peer, msgId: int, msgData: var Rlp) GcSafeRecvMsg = proc (peer: Peer): Future[tuple[msgId: int, msgData: Rlp]] {.gcsafe.} GcSafeAccept = proc (transport: StreamTransport, myKeys: KeyPair): Future[Peer] {.gcsafe.} var dispatchMsgPtr = invokeThunk recvMsgPtr: GcSafeRecvMsg = recvMsg acceptPtr: GcSafeAccept = rlpxAccept