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// Copyright 2010 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package net
import (
"errors"
"io"
"os"
"runtime"
"sync"
"syscall"
"time"
"unsafe"
)
var initErr error
func init() {
var d syscall.WSAData
e := syscall.WSAStartup(uint32(0x202), &d)
if e != nil {
initErr = os.NewSyscallError("WSAStartup", e)
}
}
func closesocket(s syscall.Handle) error {
return syscall.Closesocket(s)
}
// Interface for all io operations.
type anOpIface interface {
Op() *anOp
Name() string
Submit() error
}
// IO completion result parameters.
type ioResult struct {
qty uint32
err error
}
// anOp implements functionality common to all io operations.
type anOp struct {
// Used by IOCP interface, it must be first field
// of the struct, as our code rely on it.
o syscall.Overlapped
resultc chan ioResult
errnoc chan error
fd *netFD
}
func (o *anOp) Init(fd *netFD, mode int) {
o.fd = fd
var i int
if mode == 'r' {
i = 0
} else {
i = 1
}
if fd.resultc[i] == nil {
fd.resultc[i] = make(chan ioResult, 1)
}
o.resultc = fd.resultc[i]
if fd.errnoc[i] == nil {
fd.errnoc[i] = make(chan error)
}
o.errnoc = fd.errnoc[i]
}
func (o *anOp) Op() *anOp {
return o
}
// bufOp is used by io operations that read / write
// data from / to client buffer.
type bufOp struct {
anOp
buf syscall.WSABuf
}
func (o *bufOp) Init(fd *netFD, buf []byte, mode int) {
o.anOp.Init(fd, mode)
o.buf.Len = uint32(len(buf))
if len(buf) == 0 {
o.buf.Buf = nil
} else {
o.buf.Buf = (*byte)(unsafe.Pointer(&buf[0]))
}
}
// resultSrv will retrieve all io completion results from
// iocp and send them to the correspondent waiting client
// goroutine via channel supplied in the request.
type resultSrv struct {
iocp syscall.Handle
}
func (s *resultSrv) Run() {
var o *syscall.Overlapped
var key uint32
var r ioResult
for {
r.err = syscall.GetQueuedCompletionStatus(s.iocp, &(r.qty), &key, &o, syscall.INFINITE)
switch {
case r.err == nil:
// Dequeued successfully completed io packet.
case r.err == syscall.Errno(syscall.WAIT_TIMEOUT) && o == nil:
// Wait has timed out (should not happen now, but might be used in the future).
panic("GetQueuedCompletionStatus timed out")
case o == nil:
// Failed to dequeue anything -> report the error.
panic("GetQueuedCompletionStatus failed " + r.err.Error())
default:
// Dequeued failed io packet.
}
(*anOp)(unsafe.Pointer(o)).resultc <- r
}
}
// ioSrv executes net io requests.
type ioSrv struct {
submchan chan anOpIface // submit io requests
canchan chan anOpIface // cancel io requests
}
// ProcessRemoteIO will execute submit io requests on behalf
// of other goroutines, all on a single os thread, so it can
// cancel them later. Results of all operations will be sent
// back to their requesters via channel supplied in request.
func (s *ioSrv) ProcessRemoteIO() {
runtime.LockOSThread()
defer runtime.UnlockOSThread()
for {
select {
case o := <-s.submchan:
o.Op().errnoc <- o.Submit()
case o := <-s.canchan:
o.Op().errnoc <- syscall.CancelIo(syscall.Handle(o.Op().fd.sysfd))
}
}
}
// ExecIO executes a single io operation. It either executes it
// inline, or, if a deadline is employed, passes the request onto
// a special goroutine and waits for completion or cancels request.
// deadline is unix nanos.
func (s *ioSrv) ExecIO(oi anOpIface, deadline int64) (int, error) {
var err error
o := oi.Op()
if deadline != 0 {
// Send request to a special dedicated thread,
// so it can stop the io with CancelIO later.
s.submchan <- oi
err = <-o.errnoc
} else {
err = oi.Submit()
}
switch err {
case nil:
// IO completed immediately, but we need to get our completion message anyway.
case syscall.ERROR_IO_PENDING:
// IO started, and we have to wait for its completion.
err = nil
default:
return 0, &OpError{oi.Name(), o.fd.net, o.fd.laddr, err}
}
// Wait for our request to complete.
var r ioResult
if deadline != 0 {
dt := deadline - time.Now().UnixNano()
if dt < 1 {
dt = 1
}
timer := time.NewTimer(time.Duration(dt) * time.Nanosecond)
defer timer.Stop()
select {
case r = <-o.resultc:
case <-timer.C:
s.canchan <- oi
<-o.errnoc
r = <-o.resultc
if r.err == syscall.ERROR_OPERATION_ABORTED { // IO Canceled
r.err = syscall.EWOULDBLOCK
}
}
} else {
r = <-o.resultc
}
if r.err != nil {
err = &OpError{oi.Name(), o.fd.net, o.fd.laddr, r.err}
}
return int(r.qty), err
}
// Start helper goroutines.
var resultsrv *resultSrv
var iosrv *ioSrv
var onceStartServer sync.Once
func startServer() {
resultsrv = new(resultSrv)
var err error
resultsrv.iocp, err = syscall.CreateIoCompletionPort(syscall.InvalidHandle, 0, 0, 1)
if err != nil {
panic("CreateIoCompletionPort: " + err.Error())
}
go resultsrv.Run()
iosrv = new(ioSrv)
iosrv.submchan = make(chan anOpIface)
iosrv.canchan = make(chan anOpIface)
go iosrv.ProcessRemoteIO()
}
// Network file descriptor.
type netFD struct {
// locking/lifetime of sysfd
sysmu sync.Mutex
sysref int
closing bool
// immutable until Close
sysfd syscall.Handle
family int
sotype int
isConnected bool
net string
laddr Addr
raddr Addr
resultc [2]chan ioResult // read/write completion results
errnoc [2]chan error // read/write submit or cancel operation errors
// owned by client
rdeadline int64
rio sync.Mutex
wdeadline int64
wio sync.Mutex
}
func allocFD(fd syscall.Handle, family, sotype int, net string) *netFD {
netfd := &netFD{
sysfd: fd,
family: family,
sotype: sotype,
net: net,
}
runtime.SetFinalizer(netfd, (*netFD).Close)
return netfd
}
func newFD(fd syscall.Handle, family, proto int, net string) (*netFD, error) {
if initErr != nil {
return nil, initErr
}
onceStartServer.Do(startServer)
// Associate our socket with resultsrv.iocp.
if _, err := syscall.CreateIoCompletionPort(syscall.Handle(fd), resultsrv.iocp, 0, 0); err != nil {
return nil, err
}
return allocFD(fd, family, proto, net), nil
}
func (fd *netFD) setAddr(laddr, raddr Addr) {
fd.laddr = laddr
fd.raddr = raddr
}
func (fd *netFD) connect(ra syscall.Sockaddr) error {
return syscall.Connect(fd.sysfd, ra)
}
var errClosing = errors.New("use of closed network connection")
// Add a reference to this fd.
// If closing==true, mark the fd as closing.
// Returns an error if the fd cannot be used.
func (fd *netFD) incref(closing bool) error {
if fd == nil {
return errClosing
}
fd.sysmu.Lock()
if fd.closing {
fd.sysmu.Unlock()
return errClosing
}
fd.sysref++
if closing {
fd.closing = true
}
closing = fd.closing
fd.sysmu.Unlock()
return nil
}
// Remove a reference to this FD and close if we've been asked to do so (and
// there are no references left.
func (fd *netFD) decref() {
fd.sysmu.Lock()
fd.sysref--
// NOTE(rsc): On Unix we check fd.sysref == 0 here before closing,
// but on Windows we have no way to wake up the blocked I/O other
// than closing the socket (or calling Shutdown, which breaks other
// programs that might have a reference to the socket). So there is
// a small race here that we might close fd.sysfd and then some other
// goroutine might start a read of fd.sysfd (having read it before we
// write InvalidHandle to it), which might refer to some other file
// if the specific handle value gets reused. I think handle values on
// Windows are not reused as aggressively as file descriptors on Unix,
// so this might be tolerable.
if fd.closing && fd.sysfd != syscall.InvalidHandle {
// In case the user has set linger, switch to blocking mode so
// the close blocks. As long as this doesn't happen often, we
// can handle the extra OS processes. Otherwise we'll need to
// use the resultsrv for Close too. Sigh.
syscall.SetNonblock(fd.sysfd, false)
closesocket(fd.sysfd)
fd.sysfd = syscall.InvalidHandle
// no need for a finalizer anymore
runtime.SetFinalizer(fd, nil)
}
fd.sysmu.Unlock()
}
func (fd *netFD) Close() error {
if err := fd.incref(true); err != nil {
return err
}
fd.decref()
return nil
}
func (fd *netFD) shutdown(how int) error {
if fd == nil || fd.sysfd == syscall.InvalidHandle {
return syscall.EINVAL
}
err := syscall.Shutdown(fd.sysfd, how)
if err != nil {
return &OpError{"shutdown", fd.net, fd.laddr, err}
}
return nil
}
func (fd *netFD) CloseRead() error {
return fd.shutdown(syscall.SHUT_RD)
}
func (fd *netFD) CloseWrite() error {
return fd.shutdown(syscall.SHUT_WR)
}
// Read from network.
type readOp struct {
bufOp
}
func (o *readOp) Submit() error {
var d, f uint32
return syscall.WSARecv(syscall.Handle(o.fd.sysfd), &o.buf, 1, &d, &f, &o.o, nil)
}
func (o *readOp) Name() string {
return "WSARecv"
}
func (fd *netFD) Read(buf []byte) (int, error) {
if fd == nil {
return 0, syscall.EINVAL
}
fd.rio.Lock()
defer fd.rio.Unlock()
if err := fd.incref(false); err != nil {
return 0, err
}
defer fd.decref()
if fd.sysfd == syscall.InvalidHandle {
return 0, syscall.EINVAL
}
var o readOp
o.Init(fd, buf, 'r')
n, err := iosrv.ExecIO(&o, fd.rdeadline)
if err == nil && n == 0 {
err = io.EOF
}
return n, err
}
// ReadFrom from network.
type readFromOp struct {
bufOp
rsa syscall.RawSockaddrAny
rsan int32
}
func (o *readFromOp) Submit() error {
var d, f uint32
return syscall.WSARecvFrom(o.fd.sysfd, &o.buf, 1, &d, &f, &o.rsa, &o.rsan, &o.o, nil)
}
func (o *readFromOp) Name() string {
return "WSARecvFrom"
}
func (fd *netFD) ReadFrom(buf []byte) (n int, sa syscall.Sockaddr, err error) {
if fd == nil {
return 0, nil, syscall.EINVAL
}
if len(buf) == 0 {
return 0, nil, nil
}
fd.rio.Lock()
defer fd.rio.Unlock()
if err := fd.incref(false); err != nil {
return 0, nil, err
}
defer fd.decref()
var o readFromOp
o.Init(fd, buf, 'r')
o.rsan = int32(unsafe.Sizeof(o.rsa))
n, err = iosrv.ExecIO(&o, fd.rdeadline)
if err != nil {
return 0, nil, err
}
sa, _ = o.rsa.Sockaddr()
return
}
// Write to network.
type writeOp struct {
bufOp
}
func (o *writeOp) Submit() error {
var d uint32
return syscall.WSASend(o.fd.sysfd, &o.buf, 1, &d, 0, &o.o, nil)
}
func (o *writeOp) Name() string {
return "WSASend"
}
func (fd *netFD) Write(buf []byte) (int, error) {
if fd == nil {
return 0, syscall.EINVAL
}
fd.wio.Lock()
defer fd.wio.Unlock()
if err := fd.incref(false); err != nil {
return 0, err
}
defer fd.decref()
var o writeOp
o.Init(fd, buf, 'w')
return iosrv.ExecIO(&o, fd.wdeadline)
}
// WriteTo to network.
type writeToOp struct {
bufOp
sa syscall.Sockaddr
}
func (o *writeToOp) Submit() error {
var d uint32
return syscall.WSASendto(o.fd.sysfd, &o.buf, 1, &d, 0, o.sa, &o.o, nil)
}
func (o *writeToOp) Name() string {
return "WSASendto"
}
func (fd *netFD) WriteTo(buf []byte, sa syscall.Sockaddr) (int, error) {
if fd == nil {
return 0, syscall.EINVAL
}
if len(buf) == 0 {
return 0, nil
}
fd.wio.Lock()
defer fd.wio.Unlock()
if err := fd.incref(false); err != nil {
return 0, err
}
defer fd.decref()
if fd.sysfd == syscall.InvalidHandle {
return 0, syscall.EINVAL
}
var o writeToOp
o.Init(fd, buf, 'w')
o.sa = sa
return iosrv.ExecIO(&o, fd.wdeadline)
}
// Accept new network connections.
type acceptOp struct {
anOp
newsock syscall.Handle
attrs [2]syscall.RawSockaddrAny // space for local and remote address only
}
func (o *acceptOp) Submit() error {
var d uint32
l := uint32(unsafe.Sizeof(o.attrs[0]))
return syscall.AcceptEx(o.fd.sysfd, o.newsock,
(*byte)(unsafe.Pointer(&o.attrs[0])), 0, l, l, &d, &o.o)
}
func (o *acceptOp) Name() string {
return "AcceptEx"
}
func (fd *netFD) accept(toAddr func(syscall.Sockaddr) Addr) (*netFD, error) {
if err := fd.incref(false); err != nil {
return nil, err
}
defer fd.decref()
// Get new socket.
// See ../syscall/exec.go for description of ForkLock.
syscall.ForkLock.RLock()
s, err := syscall.Socket(fd.family, fd.sotype, 0)
if err != nil {
syscall.ForkLock.RUnlock()
return nil, err
}
syscall.CloseOnExec(s)
syscall.ForkLock.RUnlock()
// Associate our new socket with IOCP.
onceStartServer.Do(startServer)
if _, err := syscall.CreateIoCompletionPort(s, resultsrv.iocp, 0, 0); err != nil {
return nil, &OpError{"CreateIoCompletionPort", fd.net, fd.laddr, err}
}
// Submit accept request.
var o acceptOp
o.Init(fd, 'r')
o.newsock = s
_, err = iosrv.ExecIO(&o, 0)
if err != nil {
closesocket(s)
return nil, err
}
// Inherit properties of the listening socket.
err = syscall.Setsockopt(s, syscall.SOL_SOCKET, syscall.SO_UPDATE_ACCEPT_CONTEXT, (*byte)(unsafe.Pointer(&fd.sysfd)), int32(unsafe.Sizeof(fd.sysfd)))
if err != nil {
closesocket(s)
return nil, err
}
// Get local and peer addr out of AcceptEx buffer.
var lrsa, rrsa *syscall.RawSockaddrAny
var llen, rlen int32
l := uint32(unsafe.Sizeof(*lrsa))
syscall.GetAcceptExSockaddrs((*byte)(unsafe.Pointer(&o.attrs[0])),
0, l, l, &lrsa, &llen, &rrsa, &rlen)
lsa, _ := lrsa.Sockaddr()
rsa, _ := rrsa.Sockaddr()
netfd := allocFD(s, fd.family, fd.sotype, fd.net)
netfd.setAddr(toAddr(lsa), toAddr(rsa))
return netfd, nil
}
// Unimplemented functions.
func (fd *netFD) dup() (*os.File, error) {
// TODO: Implement this
return nil, os.NewSyscallError("dup", syscall.EWINDOWS)
}
var errNoSupport = errors.New("address family not supported")
func (fd *netFD) ReadMsg(p []byte, oob []byte) (n, oobn, flags int, sa syscall.Sockaddr, err error) {
return 0, 0, 0, nil, errNoSupport
}
func (fd *netFD) WriteMsg(p []byte, oob []byte, sa syscall.Sockaddr) (n int, oobn int, err error) {
return 0, 0, errNoSupport
}