nim-eth/eth/p2p/p2p_protocol_dsl.nim

1039 lines
33 KiB
Nim

{.push raises: [].}
import
std/[options, sequtils],
stew/shims/macros, chronos, faststreams/outputs
type
MessageKind* = enum
msgHandshake
msgNotification
msgRequest
msgResponse
Message* = ref object
id*: int
ident*: NimNode
kind*: MessageKind
procDef*: NimNode
timeoutParam*: NimNode
recName*: NimNode
strongRecName*: NimNode
recBody*: NimNode
protocol*: P2PProtocol
response*: Message
userHandler*: NimNode
initResponderCall*: NimNode
outputParamDef*: NimNode
Request* = ref object
queries*: seq[Message]
response*: Message
SendProc* = object
## A `SendProc` is a proc used to send a single P2P message.
## If it's a Request, then the return type will be a Future
## of the respective Response type. All send procs also have
## an automatically inserted `timeout` parameter.
msg*: Message
## The message being implemented
def*: NimNode
## The definition of the proc
peerParam*: NimNode
## Cached ident for the peer param
msgParams*: seq[NimNode]
## Cached param ident for all values that must be written
## on the wire. The automatically inserted `timeout` is not
## included.
timeoutParam*: NimNode
## Cached ident for the timeout parameter
extraDefs*: NimNode
## The response procs have extra templates that must become
## part of the generated code
P2PProtocol* = ref object
# Settings
name*: string
version*: int
timeouts*: int64
useRequestIds*: bool
useSingleRecordInlining*: bool
rlpxName*: string
outgoingRequestDecorator*: NimNode
incomingRequestDecorator*: NimNode
incomingRequestThunkDecorator*: NimNode
incomingResponseDecorator*: NimNode
incomingResponseThunkDecorator*: NimNode
PeerStateType*: NimNode
NetworkStateType*: NimNode
backend*: Backend
# Cached properties
nameIdent*: NimNode
protocolInfoVar*: NimNode
# All messages
messages*: seq[Message]
# Messages by type:
handshake*: Message
notifications*: seq[Message]
requests*: seq[Request]
# Output procs
outSendProcs*: NimNode
outRecvProcs*: NimNode
outProcRegistrations*: NimNode
# Event handlers
onPeerConnected*: NimNode
onPeerDisconnected*: NimNode
Backend* = ref object
# Code generators
implementMsg*: proc (msg: Message)
implementProtocolInit*: proc (protocol: P2PProtocol): NimNode
afterProtocolInit*: proc (protocol: P2PProtocol)
# Bound symbols to the back-end run-time types and procs
PeerType*: NimNode
NetworkType*: NimNode
SerializationFormat*: NimNode
ResponderType*: NimNode
RequestResultsWrapper*: NimNode
ReqIdType*: NimNode
registerProtocol*: NimNode
setEventHandlers*: NimNode
BackendFactory* = proc (p: P2PProtocol): Backend
P2PBackendError* = object of CatchableError
InvalidMsgError* = object of P2PBackendError
const
defaultReqTimeout = 10.seconds
tracingEnabled = defined(p2pdump)
let
# Variable names affecting the public interface of the library:
reqIdVar* {.compileTime.} = ident "reqId"
# XXX: Binding the int type causes instantiation failure for some reason
ReqIdType* {.compileTime.} = ident "int"
peerVar* {.compileTime.} = ident "peer"
responseVar* {.compileTime.} = ident "response"
streamVar* {.compileTime.} = ident "stream"
protocolVar* {.compileTime.} = ident "protocol"
deadlineVar* {.compileTime.} = ident "deadline"
timeoutVar* {.compileTime.} = ident "timeout"
perProtocolMsgIdVar* {.compileTime.} = ident "perProtocolMsgId"
currentProtocolSym* {.compileTime.} = ident "CurrentProtocol"
resultIdent* {.compileTime.} = ident "result"
# Locally used symbols:
Option {.compileTime.} = ident "Option"
Future {.compileTime.} = ident "Future"
Void {.compileTime.} = ident "void"
writeField {.compileTime.} = ident "writeField"
PROTO {.compileTime.} = ident "PROTO"
MSG {.compileTime.} = ident "MSG"
template Opt(T): auto = newTree(nnkBracketExpr, Option, T)
template Fut(T): auto = newTree(nnkBracketExpr, Future, T)
proc initFuture*[T](loc: var Future[T]) =
loc = newFuture[T]()
proc isRlpx*(p: P2PProtocol): bool =
p.rlpxName.len > 0
template applyDecorator(p: NimNode, decorator: NimNode) =
if decorator.kind != nnkNilLit:
p.pragma.insert(0, decorator)
when tracingEnabled:
proc logSentMsgFields(peer: NimNode,
protocolInfo: NimNode,
msgName: string,
fields: openArray[NimNode]): NimNode =
## This generates the tracing code inserted in the message sending procs
## `fields` contains all the params that were serialized in the message
let
tracer = ident "tracer"
tracerStream = ident "tracerStream"
logMsgEventImpl = ident "logMsgEventImpl"
result = quote do:
var `tracerStream` = memoryOutput()
var `tracer` = JsonWriter.init(`tracerStream`)
beginRecord(`tracer`)
for f in fields:
result.add newCall(writeField, tracer, newLit($f), f)
result.add quote do:
endRecord(`tracer`)
`logMsgEventImpl`("outgoing_msg", `peer`,
`protocolInfo`, `msgName`,
getOutput(`tracerStream`, string))
proc createPeerState[Peer, ProtocolState](peer: Peer): RootRef =
var res = new ProtocolState
mixin initProtocolState
initProtocolState(res, peer)
return cast[RootRef](res)
proc createNetworkState[NetworkNode, NetworkState](network: NetworkNode): RootRef {.gcsafe.} =
var res = new NetworkState
mixin initProtocolState
initProtocolState(res, network)
return cast[RootRef](res)
proc expectBlockWithProcs*(n: NimNode): seq[NimNode] =
template helperName: auto = $n[0]
if n.len != 2 or n[1].kind != nnkStmtList:
error(helperName & " expects a block", n)
for p in n[1]:
if p.kind == nnkProcDef:
result.add p
elif p.kind == nnkCommentStmt:
continue
else:
error(helperName & " expects a proc definition.", p)
proc nameOrNil*(procDef: NimNode): NimNode =
if procDef != nil:
procDef.name
else:
newNilLit()
proc isOutputParamName(paramName: NimNode): bool =
eqIdent(paramName, "output") or eqIdent(paramName, "response")
proc isOutputParam(param: NimNode): bool =
param.len > 0 and param[0].skipPragma.isOutputParamName
proc getOutputParam(procDef: NimNode): NimNode =
let params = procDef.params
for i in countdown(params.len - 1, 1):
let param = params[i]
if isOutputParam(param):
return param
proc outputParam*(msg: Message): NimNode =
case msg.kind
of msgRequest:
outputParam(msg.response)
of msgResponse:
msg.outputParamDef
else:
raiseAssert "Only requests (and the attached responses) can have output parameters"
proc outputParamIdent*(msg: Message): NimNode =
let outputParam = msg.outputParam
if outputParam != nil:
return outputParam[0].skipPragma
proc outputParamType*(msg: Message): NimNode =
let outputParam = msg.outputParam
if outputParam != nil:
return outputParam[1]
proc refreshParam(n: NimNode): NimNode =
result = copyNimTree(n)
if n.kind == nnkIdentDefs:
for i in 0..<n.len-2:
if n[i].kind == nnkSym:
result[i] = genSym(symKind(n[i]), $n[i])
iterator typedInputParams(procDef: NimNode, skip = 0): (NimNode, NimNode) =
for paramName, paramType in typedParams(procDef, skip):
if not isOutputParamName(paramName):
yield (paramName, paramType)
proc copyInputParams(params: NimNode): NimNode =
result = newTree(params.kind)
for param in params:
if not isOutputParam(param):
result.add param.refreshParam
proc chooseFieldType(n: NimNode): NimNode =
## Examines the parameter types used in the message signature
## and selects the corresponding field type for use in the
## message object type (i.e. `p2p.hello`).
##
## For now, only openArray types are remapped to sequences.
result = n
if n.kind == nnkBracketExpr and eqIdent(n[0], "openArray"):
result = n.copyNimTree
result[0] = ident("seq")
proc verifyStateType(t: NimNode): NimNode =
result = t[1]
if result.kind == nnkSym and $result == "nil":
return nil
if result.kind != nnkBracketExpr or $result[0] != "ref":
error $result & " must be a ref type"
proc processProtocolBody*(p: P2PProtocol, protocolBody: NimNode)
proc init*(T: type P2PProtocol, backendFactory: BackendFactory,
name: string, version: int, body: NimNode,
timeouts: int64, useRequestIds: bool, rlpxName: string,
outgoingRequestDecorator: NimNode,
incomingRequestDecorator: NimNode,
incomingRequestThunkDecorator: NimNode,
incomingResponseDecorator: NimNode,
incomingResponseThunkDecorator: NimNode,
peerState, networkState: NimNode): P2PProtocol =
result = P2PProtocol(
name: name,
version: version,
timeouts: timeouts,
useRequestIds: useRequestIds,
rlpxName: rlpxName,
outgoingRequestDecorator: outgoingRequestDecorator,
incomingRequestDecorator: incomingRequestDecorator,
incomingRequestThunkDecorator: incomingRequestThunkDecorator,
incomingResponseDecorator: incomingResponseDecorator,
incomingResponseThunkDecorator: incomingResponseThunkDecorator,
PeerStateType: verifyStateType peerState,
NetworkStateType: verifyStateType networkState,
nameIdent: ident(name),
protocolInfoVar: ident(name & "Protocol"),
outSendProcs: newStmtList(),
outRecvProcs: newStmtList(),
outProcRegistrations: newStmtList())
result.backend = backendFactory(result)
assert(not result.backend.implementProtocolInit.isNil)
if result.backend.ReqIdType.isNil:
result.backend.ReqIdType = ident "int"
result.processProtocolBody body
if not result.backend.afterProtocolInit.isNil:
result.backend.afterProtocolInit(result)
proc isFuture(t: NimNode): bool =
t.kind == nnkBracketExpr and eqIdent(t[0], "Future")
proc augmentUserHandler(p: P2PProtocol, userHandlerProc: NimNode, msgId = -1) =
## This procs adds a set of common helpers available in all messages handlers
## (e.g. `perProtocolMsgId`, `peer.state`, etc).
userHandlerProc.addPragma ident"gcsafe"
if p.isRlpx:
userHandlerProc.addPragma ident"async"
var
getState = ident"getState"
getNetworkState = ident"getNetworkState"
protocolInfoVar = p.protocolInfoVar
protocolNameIdent = p.nameIdent
PeerType = p.backend.PeerType
PeerStateType = p.PeerStateType
NetworkStateType = p.NetworkStateType
prelude = newStmtList()
userHandlerProc.body.insert 0, prelude
# 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])
prelude.add quote do:
type `currentProtocolSym` = `protocolNameIdent`
if msgId >= 0 and p.isRlpx:
prelude.add quote do:
const `perProtocolMsgIdVar` = `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 PeerStateType != nil:
prelude.add quote do:
template state(`peerVar`: `PeerType`): `PeerStateType` =
cast[`PeerStateType`](`getState`(`peerVar`, `protocolInfoVar`))
if NetworkStateType != nil:
prelude.add quote do:
template networkState(`peerVar`: `PeerType`): `NetworkStateType` =
cast[`NetworkStateType`](`getNetworkState`(`peerVar`.network, `protocolInfoVar`))
proc addPreludeDefs*(userHandlerProc: NimNode, definitions: NimNode) =
userHandlerProc.body[0].add definitions
proc eventHandlerToProc(p: P2PProtocol, doBlock: NimNode, handlerName: string): NimNode =
## Turns a "named" do block to a regular async proc
## (e.g. onPeerConnected do ...)
result = newTree(nnkProcDef)
doBlock.copyChildrenTo(result)
result.name = ident(p.name & handlerName) # genSym(nskProc, p.name & handlerName)
p.augmentUserHandler result
proc addTimeoutParam(procDef: NimNode, defaultValue: int64) =
var
Duration = bindSym"Duration"
milliseconds = bindSym"milliseconds"
lastParam = procDef.params[^1]
procDef.params.add newTree(nnkIdentDefs,
timeoutVar,
Duration,
newCall(milliseconds, newLit(defaultValue)))
proc hasReqId*(msg: Message): bool =
msg.protocol.useRequestIds and msg.kind in {msgRequest, msgResponse}
proc ResponderType(msg: Message): NimNode =
var resp = if msg.kind == msgRequest: msg.response else: msg
newTree(nnkBracketExpr,
msg.protocol.backend.ResponderType, resp.strongRecName)
proc needsSingleParamInlining(msg: Message): bool =
msg.recBody.kind == nnkDistinctTy
proc newMsg(protocol: P2PProtocol, kind: MessageKind, id: int,
procDef: NimNode, response: Message = nil): Message =
if procDef[0].kind == nnkPostfix:
error("p2pProtocol procs are public by default. " &
"Please remove the postfix `*`.", procDef)
var
msgIdent = procDef.name
msgName = $msgIdent
recFields = newTree(nnkRecList)
recBody = newTree(nnkObjectTy, newEmptyNode(), newEmptyNode(), recFields)
strongRecName = ident(msgName & "Obj")
recName = strongRecName
for param, paramType in procDef.typedInputParams(skip = 1):
recFields.add newTree(nnkIdentDefs,
newTree(nnkPostfix, ident("*"), param), # The fields are public
chooseFieldType(paramType), # some types such as openArray
newEmptyNode()) # are automatically remapped
if recFields.len == 1 and protocol.useSingleRecordInlining:
# When we have a single parameter, it's treated as the transferred message
# type. `recName` will be resolved to the message type that's intended
# for serialization while `strongRecName` will be a distinct type over
# which overloads such as `msgId` can be defined. We must use a distinct
# type because otherwise Nim may see multiple overloads defined over the
# same request parameter type and this will be an ambiguity error.
recName = recFields[0][1]
recBody = newTree(nnkDistinctTy, recName)
result = Message(protocol: protocol,
id: id,
ident: msgIdent,
kind: kind,
procDef: procDef,
recName: recName,
strongRecName: strongRecName,
recBody: recBody,
response: response)
if procDef.body.kind != nnkEmpty:
var userHandler = copy procDef
protocol.augmentUserHandler userHandler, id
userHandler.name = ident(msgName & "UserHandler")
# Request and Response handlers get an extra `reqId` parameter if the
# protocol uses them:
if result.hasReqId:
userHandler.params.insert(2, newIdentDefs(reqIdVar, protocol.backend.ReqIdType))
# All request handlers get an automatically inserter `response` variable:
if kind == msgRequest and protocol.isRlpx:
assert response != nil
let
peerParam = userHandler.params[1][0]
ResponderType = result.ResponderType
initResponderCall = newCall(ident"init", ResponderType, peerParam)
if protocol.useRequestIds:
initResponderCall.add reqIdVar
userHandler.addPreludeDefs newVarStmt(responseVar, initResponderCall)
result.initResponderCall = initResponderCall
case kind
of msgRequest: userHandler.applyDecorator protocol.incomingRequestDecorator
of msgResponse: userHandler.applyDecorator protocol.incomingResponseDecorator
else: discard
result.userHandler = userHandler
protocol.outRecvProcs.add result.userHandler
protocol.messages.add result
proc isVoid(t: NimNode): bool =
t.kind == nnkEmpty or eqIdent(t, "void")
proc addMsg(p: P2PProtocol, id: int, procDef: NimNode) =
var
returnType = procDef.params[0]
hasReturnValue = not isVoid(returnType)
outputParam = procDef.getOutputParam()
if outputParam != nil:
if hasReturnValue:
error "A request proc should either use a return value or an output parameter"
returnType = outputParam[1]
hasReturnValue = true
if hasReturnValue:
let
responseIdent = ident($procDef.name & "Response")
response = Message(protocol: p,
id: -1, # TODO: Implement the message IDs in RLPx-specific way
ident: responseIdent,
kind: msgResponse,
recName: returnType,
strongRecName: returnType,
recBody: returnType,
outputParamDef: outputParam)
p.messages.add response
let msg = p.newMsg(msgRequest, id, procDef, response = response)
p.requests.add Request(queries: @[msg], response: response)
else:
p.notifications.add p.newMsg(msgNotification, id, procDef)
proc identWithExportMarker*(msg: Message): NimNode =
newTree(nnkPostfix, ident("*"), msg.ident)
proc requestResultType*(msg: Message): NimNode =
let
protocol = msg.protocol
backend = protocol.backend
responseRec = msg.response.recName
var wrapperType = backend.RequestResultsWrapper
if wrapperType != nil:
if eqIdent(wrapperType, "void"):
return responseRec
else:
return newTree(nnkBracketExpr, wrapperType, responseRec)
else:
return newTree(nnkBracketExpr, Option, responseRec)
proc createSendProc*(msg: Message,
procType = nnkProcDef,
isRawSender = false,
nameSuffix = ""): SendProc =
# TODO: file an issue:
# macros.newProc and macros.params doesn't work with nnkMacroDef
let
nameSuffix = if nameSuffix.len == 0: (if isRawSender: "RawSender" else: "")
else: nameSuffix
name = if nameSuffix.len == 0: msg.identWithExportMarker
else: ident($msg.ident & nameSuffix)
pragmas = if procType == nnkProcDef: newTree(nnkPragma, ident"gcsafe")
else: newEmptyNode()
var def = newNimNode(procType).add(
name,
newEmptyNode(),
newEmptyNode(),
copyInputParams msg.procDef.params,
pragmas,
newEmptyNode(),
newStmtList()) ## body
if procType == nnkProcDef:
for p in msg.procDef.pragma:
if not eqIdent(p, "async"):
def.addPragma p
result.msg = msg
result.def = def
for param, paramType in def.typedInputParams():
if result.peerParam.isNil:
result.peerParam = param
else:
result.msgParams.add param
case msg.kind
of msgHandshake, msgRequest:
# Add a timeout parameter for all request procs
def.addTimeoutParam(msg.protocol.timeouts)
of msgResponse:
if msg.ResponderType != nil:
# 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 ResponderType. The incoming procs still
# gets the normal Peer parameter.
let
ResponderType = msg.ResponderType
sendProcName = msg.ident
def[3][1][1] = ResponderType
# We create a helper that enables the `response.send()` syntax
# inside the user handler of the request proc:
result.extraDefs = quote do:
template send*(r: `ResponderType`, args: varargs[untyped]): auto =
`sendProcName`(r, args)
of msgNotification:
discard
def[3][0] = if procType == nnkMacroDef:
ident "untyped"
elif msg.kind == msgRequest and not isRawSender:
Fut(msg.requestResultType)
elif msg.kind == msgHandshake and not isRawSender:
Fut(msg.recName)
else:
Fut(Void)
proc setBody*(sendProc: SendProc, body: NimNode) =
var
msg = sendProc.msg
protocol = msg.protocol
def = sendProc.def
# TODO: macros.body triggers an assertion error when the proc type is nnkMacroDef
def[6] = body
if msg.kind == msgRequest:
def.applyDecorator protocol.outgoingRequestDecorator
msg.protocol.outSendProcs.add def
if sendProc.extraDefs != nil:
msg.protocol.outSendProcs.add sendProc.extraDefs
proc writeParamsAsRecord*(params: openArray[NimNode],
outputStream, Format, RecordType: NimNode): NimNode =
if params.len == 0:
return newStmtList()
var
appendParams = newStmtList()
recordWriterCtx = ident "recordWriterCtx"
writer = ident "writer"
for param in params:
appendParams.add newCall(writeField,
writer, recordWriterCtx,
newLit($param), param)
# TODO: this doesn't respect the `useSingleRecordInlining` option.
# Right now, it's not a problem because it's used only in the libp2p back-end
if params.len > 1:
result = quote do:
mixin init, writerType, beginRecord, endRecord
var `writer` = init(WriterType(`Format`), `outputStream`)
var `recordWriterCtx` = beginRecord(`writer`, `RecordType`)
`appendParams`
endRecord(`writer`, `recordWriterCtx`)
else:
let param = params[0]
result = quote do:
var `writer` = init(WriterType(`Format`), `outputStream`)
writeValue(`writer`, `param`)
proc useStandardBody*(sendProc: SendProc,
preSerializationStep: proc(stream: NimNode): NimNode,
postSerializationStep: proc(stream: NimNode): NimNode,
sendCallGenerator: proc (peer, bytes: NimNode): NimNode) =
let
msg = sendProc.msg
msgBytes = ident "msgBytes"
recipient = sendProc.peerParam
sendCall = sendCallGenerator(recipient, msgBytes)
if sendProc.msgParams.len == 0:
sendProc.setBody quote do:
var `msgBytes`: seq[byte]
`sendCall`
return
let
outputStream = ident "outputStream"
msgRecName = msg.recName
Format = msg.protocol.backend.SerializationFormat
preSerialization = if preSerializationStep.isNil: newStmtList()
else: preSerializationStep(outputStream)
serialization = writeParamsAsRecord(sendProc.msgParams,
outputStream, Format, msgRecName)
postSerialization = if postSerializationStep.isNil: newStmtList()
else: postSerializationStep(outputStream)
appendParams = newStmtList()
tracing = when not tracingEnabled:
newStmtList()
else:
logSentMsgFields(recipient,
msg.protocol.protocolInfoVar,
$msg.ident,
sendProc.msgParams)
sendProc.setBody quote do:
mixin init, WriterType, beginRecord, endRecord, getOutput
var `outputStream` = memoryOutput()
`preSerialization`
`serialization`
`postSerialization`
`tracing`
let `msgBytes` = getOutput(`outputStream`)
`sendCall`
proc correctSerializerProcParams(params: NimNode) =
# A serializer proc is just like a send proc, but:
# 1. it has a void return type
params[0] = ident "void"
# 2. The peer params is replaced with OutputStream
params[1] = newIdentDefs(streamVar, bindSym "OutputStream")
# 3. The timeout param is removed
params.del(params.len - 1)
proc createSerializer*(msg: Message, procType = nnkProcDef): NimNode =
var serializer = msg.createSendProc(procType, nameSuffix = "Serializer")
correctSerializerProcParams serializer.def.params
serializer.setBody writeParamsAsRecord(
serializer.msgParams,
streamVar,
msg.protocol.backend.SerializationFormat,
msg.recName)
return serializer.def
proc defineThunk*(msg: Message, thunk: NimNode) =
let protocol = msg.protocol
case msg.kind
of msgRequest: thunk.applyDecorator protocol.incomingRequestThunkDecorator
of msgResponse: thunk.applyDecorator protocol.incomingResponseThunkDecorator
else: discard
protocol.outRecvProcs.add thunk
proc genUserHandlerCall*(msg: Message, receivedMsg: NimNode,
leadingParams: openArray[NimNode],
outputParam: NimNode = nil): NimNode =
if msg.userHandler == nil:
return newStmtList()
result = newCall(msg.userHandler.name, leadingParams)
if msg.needsSingleParamInlining:
result.add receivedMsg
else:
var params = toSeq(msg.procDef.typedInputParams(skip = 1))
for p in params:
result.add newDotExpr(receivedMsg, p[0])
if outputParam != nil:
result.add outputParam
proc genAwaitUserHandler*(msg: Message, receivedMsg: NimNode,
leadingParams: openArray[NimNode],
outputParam: NimNode = nil): NimNode =
result = msg.genUserHandlerCall(receivedMsg, leadingParams, outputParam)
if result.len > 0: result = newCall("await", result)
proc appendAllInputParams*(node: NimNode, procDef: NimNode): NimNode =
result = node
for p, _ in procDef.typedInputParams():
result.add p
proc paramNames*(procDef: NimNode, skipFirst = 0): seq[NimNode] =
result = newSeq[NimNode]()
for name, _ in procDef.typedParams(skip = skipFirst):
result.add name
proc netInit*(p: P2PProtocol): NimNode =
if p.NetworkStateType == nil:
newNilLit()
else:
newTree(nnkBracketExpr, bindSym"createNetworkState",
p.backend.NetworkType,
p.NetworkStateType)
proc createHandshakeTemplate*(msg: Message,
rawSendProc, handshakeImpl,
nextMsg: NimNode): SendProc =
let
handshakeExchanger = msg.createSendProc(procType = nnkTemplateDef)
forwardCall = newCall(rawSendProc).appendAllInputParams(handshakeExchanger.def)
peerValue = forwardCall[1]
msgRecName = msg.recName
forwardCall[1] = peerVar
forwardCall.del(forwardCall.len - 1)
let peerVar = genSym(nskLet ,"peer")
handshakeExchanger.setBody quote do:
let `peerVar` = `peerValue`
let sendingFuture = `forwardCall`
`handshakeImpl`(`peerVar`,
sendingFuture,
`nextMsg`(`peerVar`, `msgRecName`),
`timeoutVar`)
return handshakeExchanger
proc peerInit*(p: P2PProtocol): NimNode =
if p.PeerStateType == nil:
newNilLit()
else:
newTree(nnkBracketExpr, bindSym"createPeerState",
p.backend.PeerType,
p.PeerStateType)
proc processProtocolBody*(p: P2PProtocol, protocolBody: NimNode) =
## This procs handles all DSL statements valid inside a p2pProtocol.
##
## It will populate the protocol's fields such as:
## * handshake
## * requests
## * notifications
## * onPeerConnected
## * onPeerDisconnected
##
## All messages will have properly computed numeric IDs
##
var nextId = 0
for n in protocolBody:
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:
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 preceding ones are requests triggering the response.
# The system makes sure to automatically insert a hidden `reqId`
# parameter used to discriminate the individual messages.
let procs = expectBlockWithProcs(n)
if procs.len < 2:
error "requestResponse expects a block with at least two proc definitions"
var queries = newSeq[Message]()
let responseMsg = p.newMsg(msgResponse, nextId + procs.len - 1, procs[^1])
for i in 0 .. procs.len - 2:
queries.add p.newMsg(msgRequest, nextId + i, procs[i], response = responseMsg)
p.requests.add Request(queries: queries, response: responseMsg)
inc nextId, procs.len
elif eqIdent(n[0], "handshake"):
let procs = expectBlockWithProcs(n)
if procs.len != 1:
error "handshake expects a block with a single proc definition", n
if p.handshake != nil:
error "The handshake for the protocol is already defined", n
p.handshake = p.newMsg(msgHandshake, nextId, procs[0])
inc nextId
elif eqIdent(n[0], "onPeerConnected"):
p.onPeerConnected = p.eventHandlerToProc(n[1], "PeerConnected")
elif eqIdent(n[0], "onPeerDisconnected"):
p.onPeerDisconnected = p.eventHandlerToProc(n[1], "PeerDisconnected")
else:
error(repr(n) & " is not a recognized call in P2P protocol definitions", n)
of nnkProcDef, nnkIteratorDef:
p.addMsg(nextId, n)
inc nextId
of nnkCommentStmt:
discard
else:
error "Illegal syntax in a P2P protocol definition", n
proc genTypeSection*(p: P2PProtocol): NimNode =
var
protocolName = p.nameIdent
peerState = p.PeerStateType
networkState= p.NetworkStateType
result = newStmtList()
result.add quote do:
# Create a type acting as a pseudo-object representing the protocol
# (e.g. p2p)
type `protocolName`* = object
if peerState != nil:
result.add quote do:
template State*(`PROTO`: type `protocolName`): type = `peerState`
if networkState != nil:
result.add quote do:
template NetworkState*(`PROTO`: type `protocolName`): type = `networkState`
for msg in p.messages:
if msg.procDef == nil:
continue
let
msgId = msg.id
msgName = msg.ident
msgRecName = msg.recName
msgStrongRecName = msg.strongRecName
msgRecBody = msg.recBody
result.add quote do:
# This is a type featuring a single field for each message param:
type `msgStrongRecName`* = `msgRecBody`
# Add a helper template for accessing the message type:
# e.g. p2p.hello:
template `msgName`*(`PROTO`: type `protocolName`): type = `msgRecName`
# Add a helper template for obtaining the message Id for
# a particular message type:
template msgProtocol*(`MSG`: type `msgStrongRecName`): type = `protocolName`
template RecType*(`MSG`: type `msgStrongRecName`): untyped = `msgRecName`
if p.isRlpx:
result.add quote do:
template msgId*(`MSG`: type `msgStrongRecName`): int = `msgId`
proc genCode*(p: P2PProtocol): NimNode =
for msg in p.messages:
p.backend.implementMsg msg
result = newStmtList()
result.add p.genTypeSection()
let
protocolInfoVar = p.protocolInfoVar
protocolInfoVarObj = ident($protocolInfoVar & "Obj")
protocolName = p.nameIdent
protocolInit = p.backend.implementProtocolInit(p)
result.add quote do:
# One global variable per protocol holds the protocol run-time data
var `protocolInfoVarObj` = `protocolInit`
var `protocolInfoVar` = addr `protocolInfoVarObj`
# The protocol run-time data is available as a pseudo-field
# (e.g. `p2p.protocolInfo`)
template protocolInfo*(`PROTO`: type `protocolName`): auto = `protocolInfoVar`
result.add p.outSendProcs,
p.outRecvProcs,
p.outProcRegistrations
if p.onPeerConnected != nil: result.add p.onPeerConnected
if p.onPeerDisconnected != nil: result.add p.onPeerDisconnected
result.add newCall(p.backend.setEventHandlers,
protocolInfoVar,
nameOrNil p.onPeerConnected,
nameOrNil p.onPeerDisconnected)
result.add newCall(p.backend.registerProtocol, protocolInfoVar)
macro emitForSingleBackend(
name: static[string],
version: static[int],
backend: static[BackendFactory],
body: untyped,
# TODO Nim can't handle a proper duration parameter here
timeouts: static[int64] = defaultReqTimeout.milliseconds,
useRequestIds: static[bool] = true,
rlpxName: static[string] = "",
outgoingRequestDecorator: untyped = nil,
incomingRequestDecorator: untyped = nil,
incomingRequestThunkDecorator: untyped = nil,
incomingResponseDecorator: untyped = nil,
incomingResponseThunkDecorator: untyped = nil,
peerState = type(nil),
networkState = type(nil)): untyped =
var p = P2PProtocol.init(
backend,
name, version, body, timeouts,
useRequestIds, rlpxName,
outgoingRequestDecorator,
incomingRequestDecorator,
incomingRequestThunkDecorator,
incomingResponseDecorator,
incomingResponseThunkDecorator,
peerState.getType, networkState.getType)
result = p.genCode()
try:
result.storeMacroResult true
except IOError:
# IO error so the generated nim code might not be stored, don't sweat it.
discard
macro emitForAllBackends(backendSyms: typed, options: untyped, body: untyped): untyped =
let name = $(options[0])
var backends = newSeq[NimNode]()
if backendSyms.kind == nnkSym:
backends.add backendSyms
else:
for backend in backendSyms:
backends.add backend
result = newStmtList()
for backend in backends:
let call = copy options
call[0] = bindSym"emitForSingleBackend"
call.add newTree(nnkExprEqExpr, ident("name"), newLit(name))
call.add newTree(nnkExprEqExpr, ident("backend"), backend)
call.add newTree(nnkExprEqExpr, ident("body"), body)
result.add call
template p2pProtocol*(options: untyped, body: untyped) {.dirty.} =
bind emitForAllBackends
emitForAllBackends(p2pProtocolBackendImpl, options, body)