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[official-gcc.git] / main / libgo / go / net / fd_windows.go

// 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
        ioSync  uint64
)

// CancelIo Windows API cancels all outstanding IO for a particular
// socket on current thread. To overcome that limitation, we run
// special goroutine, locked to OS single thread, that both starts
// and cancels IO. It means, there are 2 unavoidable thread switches
// for every IO.
// Some newer versions of Windows has new CancelIoEx API, that does
// not have that limitation and can be used from any thread. This
// package uses CancelIoEx API, if present, otherwise it fallback
// to CancelIo.

var (
        canCancelIO                               bool // determines if CancelIoEx API is present
        skipSyncNotif                             bool
        hasLoadSetFileCompletionNotificationModes bool
)

func sysInit() {
        var d syscall.WSAData
        e := syscall.WSAStartup(uint32(0x202), &d)
        if e != nil {
                initErr = os.NewSyscallError("WSAStartup", e)
        }
        canCancelIO = syscall.LoadCancelIoEx() == nil
        if syscall.LoadGetAddrInfo() == nil {
                lookupPort = newLookupPort
                lookupIP = newLookupIP
        }

        hasLoadSetFileCompletionNotificationModes = syscall.LoadSetFileCompletionNotificationModes() == nil
        if hasLoadSetFileCompletionNotificationModes {
                // It's not safe to use FILE_SKIP_COMPLETION_PORT_ON_SUCCESS if non IFS providers are installed:
                // http://support.microsoft.com/kb/2568167
                skipSyncNotif = true
                protos := [2]int32{syscall.IPPROTO_TCP, 0}
                var buf [32]syscall.WSAProtocolInfo
                len := uint32(unsafe.Sizeof(buf))
                n, err := syscall.WSAEnumProtocols(&protos[0], &buf[0], &len)
                if err != nil {
                        skipSyncNotif = false
                } else {
                        for i := int32(0); i < n; i++ {
                                if buf[i].ServiceFlags1&syscall.XP1_IFS_HANDLES == 0 {
                                        skipSyncNotif = false
                                        break
                                }
                        }
                }
        }
}

func closesocket(s syscall.Handle) error {
        return syscall.Closesocket(s)
}

func canUseConnectEx(net string) bool {
        switch net {
        case "udp", "udp4", "udp6", "ip", "ip4", "ip6":
                // ConnectEx windows API does not support connectionless sockets.
                return false
        }
        return syscall.LoadConnectEx() == nil
}

func dial(net string, ra Addr, dialer func(time.Time) (Conn, error), deadline time.Time) (Conn, error) {
        if !canUseConnectEx(net) {
                // Use the relatively inefficient goroutine-racing
                // implementation of DialTimeout.
                return dialChannel(net, ra, dialer, deadline)
        }
        return dialer(deadline)
}

// operation contains superset of data necessary to perform all async IO.
type operation struct {
        // Used by IOCP interface, it must be first field
        // of the struct, as our code rely on it.
        o syscall.Overlapped

        // fields used by runtime.netpoll
        runtimeCtx uintptr
        mode       int32
        errno      int32
        qty        uint32

        // fields used only by net package
        fd     *netFD
        errc   chan error
        buf    syscall.WSABuf
        sa     syscall.Sockaddr
        rsa    *syscall.RawSockaddrAny
        rsan   int32
        handle syscall.Handle
        flags  uint32
}

func (o *operation) InitBuf(buf []byte) {
        o.buf.Len = uint32(len(buf))
        o.buf.Buf = nil
        if len(buf) != 0 {
                o.buf.Buf = (*byte)(unsafe.Pointer(&buf[0]))
        }
}

// ioSrv executes net IO requests.
type ioSrv struct {
        req chan ioSrvReq
}

type ioSrvReq struct {
        o      *operation
        submit func(o *operation) error // if nil, cancel the operation
}

// 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.
// It is used only when the CancelIoEx API is unavailable.
func (s *ioSrv) ProcessRemoteIO() {
        runtime.LockOSThread()
        defer runtime.UnlockOSThread()
        for r := range s.req {
                if r.submit != nil {
                        r.o.errc <- r.submit(r.o)
                } else {
                        r.o.errc <- syscall.CancelIo(r.o.fd.sysfd)
                }
        }
}

// ExecIO executes a single IO operation o. It submits and cancels
// IO in the current thread for systems where Windows CancelIoEx API
// is available. Alternatively, it passes the request onto
// runtime netpoll and waits for completion or cancels request.
func (s *ioSrv) ExecIO(o *operation, name string, submit func(o *operation) error) (int, error) {
        fd := o.fd
        // Notify runtime netpoll about starting IO.
        err := fd.pd.Prepare(int(o.mode))
        if err != nil {
                return 0, &OpError{name, fd.net, fd.laddr, err}
        }
        // Start IO.
        if canCancelIO {
                err = submit(o)
        } else {
                // Send request to a special dedicated thread,
                // so it can stop the IO with CancelIO later.
                s.req <- ioSrvReq{o, submit}
                err = <-o.errc
        }
        switch err {
        case nil:
                // IO completed immediately
                if o.fd.skipSyncNotif {
                        // No completion message will follow, so return immediately.
                        return int(o.qty), nil
                }
                // 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{name, fd.net, fd.laddr, err}
        }
        // Wait for our request to complete.
        err = fd.pd.Wait(int(o.mode))
        if err == nil {
                // All is good. Extract our IO results and return.
                if o.errno != 0 {
                        err = syscall.Errno(o.errno)
                        return 0, &OpError{name, fd.net, fd.laddr, err}
                }
                return int(o.qty), nil
        }
        // IO is interrupted by "close" or "timeout"
        netpollErr := err
        switch netpollErr {
        case errClosing, errTimeout:
                // will deal with those.
        default:
                panic("net: unexpected runtime.netpoll error: " + netpollErr.Error())
        }
        // Cancel our request.
        if canCancelIO {
                err := syscall.CancelIoEx(fd.sysfd, &o.o)
                // Assuming ERROR_NOT_FOUND is returned, if IO is completed.
                if err != nil && err != syscall.ERROR_NOT_FOUND {
                        // TODO(brainman): maybe do something else, but panic.
                        panic(err)
                }
        } else {
                s.req <- ioSrvReq{o, nil}
                <-o.errc
        }
        // Wait for cancellation to complete.
        fd.pd.WaitCanceled(int(o.mode))
        if o.errno != 0 {
                err = syscall.Errno(o.errno)
                if err == syscall.ERROR_OPERATION_ABORTED { // IO Canceled
                        err = netpollErr
                }
                return 0, &OpError{name, fd.net, fd.laddr, err}
        }
        // We issued cancellation request. But, it seems, IO operation succeeded
        // before cancellation request run. We need to treat IO operation as
        // succeeded (the bytes are actually sent/recv from network).
        return int(o.qty), nil
}

// Start helper goroutines.
var rsrv, wsrv *ioSrv
var onceStartServer sync.Once

func startServer() {
        rsrv = new(ioSrv)
        wsrv = new(ioSrv)
        if !canCancelIO {
                // Only CancelIo API is available. Lets start two special goroutines
                // locked to an OS thread, that both starts and cancels IO. One will
                // process read requests, while other will do writes.
                rsrv.req = make(chan ioSrvReq)
                go rsrv.ProcessRemoteIO()
                wsrv.req = make(chan ioSrvReq)
                go wsrv.ProcessRemoteIO()
        }
}

// Network file descriptor.
type netFD struct {
        // locking/lifetime of sysfd + serialize access to Read and Write methods
        fdmu fdMutex

        // immutable until Close
        sysfd         syscall.Handle
        family        int
        sotype        int
        isConnected   bool
        skipSyncNotif bool
        net           string
        laddr         Addr
        raddr         Addr

        rop operation // read operation
        wop operation // write operation

        // wait server
        pd pollDesc
}

func newFD(sysfd syscall.Handle, family, sotype int, net string) (*netFD, error) {
        if initErr != nil {
                return nil, initErr
        }
        onceStartServer.Do(startServer)
        return &netFD{sysfd: sysfd, family: family, sotype: sotype, net: net}, nil
}

func (fd *netFD) init() error {
        if err := fd.pd.Init(fd); err != nil {
                return err
        }
        if hasLoadSetFileCompletionNotificationModes {
                // We do not use events, so we can skip them always.
                flags := uint8(syscall.FILE_SKIP_SET_EVENT_ON_HANDLE)
                // It's not safe to skip completion notifications for UDP:
                // http://blogs.technet.com/b/winserverperformance/archive/2008/06/26/designing-applications-for-high-performance-part-iii.aspx
                if skipSyncNotif && fd.net == "tcp" {
                        flags |= syscall.FILE_SKIP_COMPLETION_PORT_ON_SUCCESS
                }
                err := syscall.SetFileCompletionNotificationModes(fd.sysfd, flags)
                if err == nil && flags&syscall.FILE_SKIP_COMPLETION_PORT_ON_SUCCESS != 0 {
                        fd.skipSyncNotif = true
                }
        }
        fd.rop.mode = 'r'
        fd.wop.mode = 'w'
        fd.rop.fd = fd
        fd.wop.fd = fd
        fd.rop.runtimeCtx = fd.pd.runtimeCtx
        fd.wop.runtimeCtx = fd.pd.runtimeCtx
        if !canCancelIO {
                fd.rop.errc = make(chan error)
                fd.wop.errc = make(chan error)
        }
        return nil
}

func (fd *netFD) setAddr(laddr, raddr Addr) {
        fd.laddr = laddr
        fd.raddr = raddr
        runtime.SetFinalizer(fd, (*netFD).Close)
}

func (fd *netFD) connect(la, ra syscall.Sockaddr) error {
        // Do not need to call fd.writeLock here,
        // because fd is not yet accessible to user,
        // so no concurrent operations are possible.
        if !canUseConnectEx(fd.net) {
                return syscall.Connect(fd.sysfd, ra)
        }
        // ConnectEx windows API requires an unconnected, previously bound socket.
        if la == nil {
                switch ra.(type) {
                case *syscall.SockaddrInet4:
                        la = &syscall.SockaddrInet4{}
                case *syscall.SockaddrInet6:
                        la = &syscall.SockaddrInet6{}
                default:
                        panic("unexpected type in connect")
                }
                if err := syscall.Bind(fd.sysfd, la); err != nil {
                        return err
                }
        }
        // Call ConnectEx API.
        o := &fd.wop
        o.sa = ra
        _, err := wsrv.ExecIO(o, "ConnectEx", func(o *operation) error {
                return syscall.ConnectEx(o.fd.sysfd, o.sa, nil, 0, nil, &o.o)
        })
        if err != nil {
                return err
        }
        // Refresh socket properties.
        return syscall.Setsockopt(fd.sysfd, syscall.SOL_SOCKET, syscall.SO_UPDATE_CONNECT_CONTEXT, (*byte)(unsafe.Pointer(&fd.sysfd)), int32(unsafe.Sizeof(fd.sysfd)))
}

func (fd *netFD) destroy() {
        if fd.sysfd == syscall.InvalidHandle {
                return
        }
        // Poller may want to unregister fd in readiness notification mechanism,
        // so this must be executed before closesocket.
        fd.pd.Close()
        closesocket(fd.sysfd)
        fd.sysfd = syscall.InvalidHandle
        // no need for a finalizer anymore
        runtime.SetFinalizer(fd, nil)
}

// Add a reference to this fd.
// Returns an error if the fd cannot be used.
func (fd *netFD) incref() error {
        if !fd.fdmu.Incref() {
                return errClosing
        }
        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() {
        if fd.fdmu.Decref() {
                fd.destroy()
        }
}

// Add a reference to this fd and lock for reading.
// Returns an error if the fd cannot be used.
func (fd *netFD) readLock() error {
        if !fd.fdmu.RWLock(true) {
                return errClosing
        }
        return nil
}

// Unlock for reading and remove a reference to this FD.
func (fd *netFD) readUnlock() {
        if fd.fdmu.RWUnlock(true) {
                fd.destroy()
        }
}

// Add a reference to this fd and lock for writing.
// Returns an error if the fd cannot be used.
func (fd *netFD) writeLock() error {
        if !fd.fdmu.RWLock(false) {
                return errClosing
        }
        return nil
}

// Unlock for writing and remove a reference to this FD.
func (fd *netFD) writeUnlock() {
        if fd.fdmu.RWUnlock(false) {
                fd.destroy()
        }
}

func (fd *netFD) Close() error {
        if !fd.fdmu.IncrefAndClose() {
                return errClosing
        }
        // unblock pending reader and writer
        fd.pd.Evict()
        fd.decref()
        return nil
}

func (fd *netFD) shutdown(how int) error {
        if err := fd.incref(); err != nil {
                return err
        }
        defer fd.decref()
        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)
}

func (fd *netFD) Read(buf []byte) (int, error) {
        if err := fd.readLock(); err != nil {
                return 0, err
        }
        defer fd.readUnlock()
        o := &fd.rop
        o.InitBuf(buf)
        n, err := rsrv.ExecIO(o, "WSARecv", func(o *operation) error {
                return syscall.WSARecv(o.fd.sysfd, &o.buf, 1, &o.qty, &o.flags, &o.o, nil)
        })
        if err == nil && n == 0 {
                err = io.EOF
        }
        if raceenabled {
                raceAcquire(unsafe.Pointer(&ioSync))
        }
        return n, err
}

func (fd *netFD) ReadFrom(buf []byte) (n int, sa syscall.Sockaddr, err error) {
        if len(buf) == 0 {
                return 0, nil, nil
        }
        if err := fd.readLock(); err != nil {
                return 0, nil, err
        }
        defer fd.readUnlock()
        o := &fd.rop
        o.InitBuf(buf)
        n, err = rsrv.ExecIO(o, "WSARecvFrom", func(o *operation) error {
                if o.rsa == nil {
                        o.rsa = new(syscall.RawSockaddrAny)
                }
                o.rsan = int32(unsafe.Sizeof(*o.rsa))
                return syscall.WSARecvFrom(o.fd.sysfd, &o.buf, 1, &o.qty, &o.flags, o.rsa, &o.rsan, &o.o, nil)
        })
        if err != nil {
                return 0, nil, err
        }
        sa, _ = o.rsa.Sockaddr()
        return
}

func (fd *netFD) Write(buf []byte) (int, error) {
        if err := fd.writeLock(); err != nil {
                return 0, err
        }
        defer fd.writeUnlock()
        if raceenabled {
                raceReleaseMerge(unsafe.Pointer(&ioSync))
        }
        o := &fd.wop
        o.InitBuf(buf)
        return wsrv.ExecIO(o, "WSASend", func(o *operation) error {
                return syscall.WSASend(o.fd.sysfd, &o.buf, 1, &o.qty, 0, &o.o, nil)
        })
}

func (fd *netFD) WriteTo(buf []byte, sa syscall.Sockaddr) (int, error) {
        if len(buf) == 0 {
                return 0, nil
        }
        if err := fd.writeLock(); err != nil {
                return 0, err
        }
        defer fd.writeUnlock()
        o := &fd.wop
        o.InitBuf(buf)
        o.sa = sa
        return wsrv.ExecIO(o, "WSASendto", func(o *operation) error {
                return syscall.WSASendto(o.fd.sysfd, &o.buf, 1, &o.qty, 0, o.sa, &o.o, nil)
        })
}

func (fd *netFD) acceptOne(toAddr func(syscall.Sockaddr) Addr, rawsa []syscall.RawSockaddrAny, o *operation) (*netFD, error) {
        // Get new socket.
        s, err := sysSocket(fd.family, fd.sotype, 0)
        if err != nil {
                return nil, &OpError{"socket", fd.net, fd.laddr, err}
        }

        // Associate our new socket with IOCP.
        netfd, err := newFD(s, fd.family, fd.sotype, fd.net)
        if err != nil {
                closesocket(s)
                return nil, &OpError{"accept", fd.net, fd.laddr, err}
        }
        if err := netfd.init(); err != nil {
                fd.Close()
                return nil, err
        }

        // Submit accept request.
        o.handle = s
        o.rsan = int32(unsafe.Sizeof(rawsa[0]))
        _, err = rsrv.ExecIO(o, "AcceptEx", func(o *operation) error {
                return syscall.AcceptEx(o.fd.sysfd, o.handle, (*byte)(unsafe.Pointer(&rawsa[0])), 0, uint32(o.rsan), uint32(o.rsan), &o.qty, &o.o)
        })
        if err != nil {
                netfd.Close()
                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 {
                netfd.Close()
                return nil, &OpError{"Setsockopt", fd.net, fd.laddr, err}
        }

        return netfd, nil
}

func (fd *netFD) accept(toAddr func(syscall.Sockaddr) Addr) (*netFD, error) {
        if err := fd.readLock(); err != nil {
                return nil, err
        }
        defer fd.readUnlock()

        o := &fd.rop
        var netfd *netFD
        var err error
        var rawsa [2]syscall.RawSockaddrAny
        for {
                netfd, err = fd.acceptOne(toAddr, rawsa[:], o)
                if err == nil {
                        break
                }
                // Sometimes we see WSAECONNRESET and ERROR_NETNAME_DELETED is
                // returned here. These happen if connection reset is received
                // before AcceptEx could complete. These errors relate to new
                // connection, not to AcceptEx, so ignore broken connection and
                // try AcceptEx again for more connections.
                operr, ok := err.(*OpError)
                if !ok {
                        return nil, err
                }
                errno, ok := operr.Err.(syscall.Errno)
                if !ok {
                        return nil, err
                }
                switch errno {
                case syscall.ERROR_NETNAME_DELETED, syscall.WSAECONNRESET:
                        // ignore these and try again
                default:
                        return nil, err
                }
        }

        // Get local and peer addr out of AcceptEx buffer.
        var lrsa, rrsa *syscall.RawSockaddrAny
        var llen, rlen int32
        syscall.GetAcceptExSockaddrs((*byte)(unsafe.Pointer(&rawsa[0])),
                0, uint32(o.rsan), uint32(o.rsan), &lrsa, &llen, &rrsa, &rlen)
        lsa, _ := lrsa.Sockaddr()
        rsa, _ := rrsa.Sockaddr()

        netfd.setAddr(toAddr(lsa), toAddr(rsa))
        return netfd, nil
}

func skipRawSocketTests() (skip bool, skipmsg string, err error) {
        // From http://msdn.microsoft.com/en-us/library/windows/desktop/ms740548.aspx:
        // Note: To use a socket of type SOCK_RAW requires administrative privileges.
        // Users running Winsock applications that use raw sockets must be a member of
        // the Administrators group on the local computer, otherwise raw socket calls
        // will fail with an error code of WSAEACCES. On Windows Vista and later, access
        // for raw sockets is enforced at socket creation. In earlier versions of Windows,
        // access for raw sockets is enforced during other socket operations.
        s, err := syscall.Socket(syscall.AF_INET, syscall.SOCK_RAW, 0)
        if err == syscall.WSAEACCES {
                return true, "skipping test; no access to raw socket allowed", nil
        }
        if err != nil {
                return true, "", err
        }
        defer syscall.Closesocket(s)
        return false, "", 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
}