make asyncSendMsg and asyncRecvMsg generic

This commit is contained in:
Christian Ulrich 2020-06-15 22:30:30 +02:00
parent ccd0a9983e
commit aca6888011
No known key found for this signature in database
GPG Key ID: 8241BE099775A097
1 changed files with 48 additions and 44 deletions

View File

@ -1,7 +1,12 @@
import asyncdispatch, threadpool, osproc, options
import asyncdispatch, threadpool, osproc
from net import
BufferSize
from os import
osLastError,
newOsError
from sequtils import
map,
foldl
from posix import
SOL_SOCKET,
SCM_RIGHTS,
@ -14,6 +19,7 @@ from posix import
SocketHandle,
CMSG_SPACE,
CMSG_FIRSTHDR,
CMSG_NXTHDR,
CMSG_LEN,
CMSG_DATA,
sendmsg,
@ -46,35 +52,39 @@ proc asyncExecCmd*(command: string): Future[int] =
addEvent(event, callback)
return future
type ControlMessage = object
level: int
msgType: int
data: string
proc asyncSendMsg*(fd: AsyncFD, data: string,
ancillaryData: Option[AsyncFD] = none(AsyncFD)): Future[void] =
cmsgs: seq[ControlMessage] = @[]): Future[void] =
var retFuture = newFuture[void]("asyncSendMsg")
proc cb(sock: AsyncFD): bool =
# FIXME: if file descriptor is given in ancillaryData, check if sock is a
# unix socket
result = true
# sendmsg needs an array of iovec structs as described in the writev(2) man
# page. The message is passed as a msghdr struct which may contain ancillary
# data, see sendmsg(2) man page. We use ancillary data exclusively for
# passing a file descriptor if one is given in ancillaryData.
# data, see sendmsg(2) man page.
var iovec = IOVec(iov_base: data.cstring,
iov_len: data.len.csize_t)
var msg = Tmsghdr(msg_iov: addr iovec,
msg_iovlen: 1)
if ancillaryData.isSome:
# assemble ancillary data, see cmsg(3) man page
let cmsgBufferLen = CMSG_SPACE(sizeof(AsyncFD).csize_t)
let cmsgBuffer = newString(cmsgBufferLen)
msg.msg_control = cmsgBuffer.cstring
msg.msg_controllen = cmsgBufferLen
let cmsg: ptr Tcmsghdr = CMSG_FIRSTHDR(addr msg)
cmsg.cmsg_len = CMSG_LEN(sizeof(AsyncFD).csize_t)
cmsg.cmsg_level = SOL_SOCKET
cmsg.cmsg_type = SCM_RIGHTS
var ancillaryFd = ancillaryData.get
copyMem(CMSG_DATA(cmsg), addr ancillaryFd, sizeof(AsyncFD))
var cmsgBuf: string
if cmsgs.len > 0:
proc space(c: ControlMessage): csize_t = CMSG_SPACE(c.data.len.csize_t)
let cmsgBufLen = cmsgs.map(space).foldl(a + b, 0.csize_t)
cmsgBuf = newString(cmsgBufLen)
msg.msg_control = cmsgBuf.cstring
msg.msg_controllen = cmsgBufLen
var cmsgHeader = CMSG_FIRSTHDR(addr msg)
for cmsg in cmsgs:
cmsgHeader.cmsg_len = CMSG_LEN(cmsg.data.len.csize_t)
cmsgHeader.cmsg_level = cmsg.level.int32
cmsgHeader.cmsg_type = cmsg.msgType.int32
copyMem(CMSG_DATA(cmsgHeader), cmsg.data.cstring, cmsg.data.len)
cmsgHeader = CMSG_NXTHDR(addr msg, cmsgHeader)
let res = sendmsg(sock.SocketHandle, addr msg, 0)
if res < 0:
@ -91,12 +101,11 @@ proc asyncSendMsg*(fd: AsyncFD, data: string,
addWrite(fd, cb)
return retFuture
proc asyncRecvMsg*(fd: AsyncFD,
size: int): Future[tuple[data: string,
ancillaryData: Option[AsyncFD]]] =
var retFuture =
newFuture[tuple[data: string,
ancillaryData: Option[AsyncFD]]]("asyncRecvMsg")
proc asyncRecvMsg*(fd: AsyncFD, size: int = BufferSize,
cmsgSize: int = BufferSize):
Future[tuple[data: string, cmsgs: seq[ControlMessage]]] =
var retFuture = newFuture[tuple[data: string,
cmsgs: seq[ControlMessage]]]("asyncRecvMsg")
proc cb(sock: AsyncFD): bool =
result = true
@ -104,16 +113,12 @@ proc asyncRecvMsg*(fd: AsyncFD,
var dataBuffer = newString(size)
var iovec = IOVec(iov_base: dataBuffer.cstring,
iov_len: dataBuffer.len.csize_t)
let cmsgBufferLen = CMSG_SPACE(sizeof(AsyncFD).csize_t)
let cmsgBuffer = newString(cmsgBufferLen)
var cmsgBuffer = newString(cmsgSize)
zeroMem(cmsgBuffer.cstring, cmsgBuffer.len)
var msg = Tmsghdr(msg_iov: addr iovec,
msg_iovlen: 1,
msg_control: cmsgBuffer.cstring,
msg_controllen: cmsgBufferLen)
let cmsg: ptr Tcmsghdr = CMSG_FIRSTHDR(addr msg)
cmsg.cmsg_len = 0
cmsg.cmsg_level = 0
cmsg.cmsg_type = 0
msg_control: addr cmsgBuffer[0],
msg_controllen: cmsgSize.csize_t)
let res = recvmsg(sock.SocketHandle, addr msg, 0)
if res < 0:
@ -126,20 +131,19 @@ proc asyncRecvMsg*(fd: AsyncFD,
result = false
return
var ancillaryData = none(AsyncFD)
if cmsg.cmsg_len > 0:
if cmsg.cmsg_len == CMSG_LEN(sizeof(AsyncFD).csize_t) and
cmsg.cmsg_level == SOL_SOCKET and
cmsg.cmsg_type == SCM_RIGHTS:
var ancillaryFd: AsyncFD
copyMem(addr ancillaryFd, CMSG_DATA(cmsg), sizeof(AsyncFD))
ancillaryData = some(ancillaryFd)
else:
retFuture.fail(newException(ValueError, "unexpected ancillary data"))
return
var cmsgs = newSeq[ControlMessage]()
var cmsgHeader = CMSG_FIRSTHDR(addr msg)
while cmsgHeader != nil:
let dataLen = cmsgHeader.cmsg_len - sizeof(Tcmsghdr).csize_t
var cmsg = ControlMessage(level: cmsgHeader.cmsg_level,
msgType: cmsgHeader.cmsg_type,
data: newString(dataLen))
copyMem(cmsg.data.cstring, CMSG_DATA(cmsgHeader), cmsgHeader.cmsg_len)
cmsgs.add(cmsg)
cmsgHeader = CMSG_NXTHDR(addr msg, cmsgHeader)
dataBuffer.setLen(res)
retFuture.complete((dataBuffer, ancillaryData))
retFuture.complete((dataBuffer, cmsgs))
addRead(fd, cb)
return retFuture