path: root/rpc/comms/ipc_windows.go

// +build windows

package comms

import (
    "fmt"
    "io"
    "net"
    "os"
    "sync"
    "syscall"
    "time"
    "unsafe"

    "github.com/ethereum/go-ethereum/logger"
    "github.com/ethereum/go-ethereum/logger/glog"
    "github.com/ethereum/go-ethereum/rpc/codec"
    "github.com/ethereum/go-ethereum/rpc/shared"
)

var (
    modkernel32 = syscall.NewLazyDLL("kernel32.dll")

    procCreateNamedPipeW    = modkernel32.NewProc("CreateNamedPipeW")
    procConnectNamedPipe    = modkernel32.NewProc("ConnectNamedPipe")
    procDisconnectNamedPipe = modkernel32.NewProc("DisconnectNamedPipe")
    procWaitNamedPipeW      = modkernel32.NewProc("WaitNamedPipeW")
    procCreateEventW        = modkernel32.NewProc("CreateEventW")
    procGetOverlappedResult = modkernel32.NewProc("GetOverlappedResult")
    procCancelIoEx          = modkernel32.NewProc("CancelIoEx")
)

func createNamedPipe(name *uint16, openMode uint32, pipeMode uint32, maxInstances uint32, outBufSize uint32, inBufSize uint32, defaultTimeout uint32, sa *syscall.SecurityAttributes) (handle syscall.Handle, err error) {
    r0, _, e1 := syscall.Syscall9(procCreateNamedPipeW.Addr(), 8, uintptr(unsafe.Pointer(name)), uintptr(openMode), uintptr(pipeMode), uintptr(maxInstances), uintptr(outBufSize), uintptr(inBufSize), uintptr(defaultTimeout), uintptr(unsafe.Pointer(sa)), 0)
    handle = syscall.Handle(r0)
    if handle == syscall.InvalidHandle {
        if e1 != 0 {
            err = error(e1)
        } else {
            err = syscall.EINVAL
        }
    }
    return
}

func cancelIoEx(handle syscall.Handle, overlapped *syscall.Overlapped) (err error) {
    r1, _, e1 := syscall.Syscall(procCancelIoEx.Addr(), 2, uintptr(handle), uintptr(unsafe.Pointer(overlapped)), 0)
    if r1 == 0 {
        if e1 != 0 {
            err = error(e1)
        } else {
            err = syscall.EINVAL
        }
    }
    return
}

func connectNamedPipe(handle syscall.Handle, overlapped *syscall.Overlapped) (err error) {
    r1, _, e1 := syscall.Syscall(procConnectNamedPipe.Addr(), 2, uintptr(handle), uintptr(unsafe.Pointer(overlapped)), 0)
    if r1 == 0 {
        if e1 != 0 {
            err = error(e1)
        } else {
            err = syscall.EINVAL
        }
    }
    return
}

func disconnectNamedPipe(handle syscall.Handle) (err error) {
    r1, _, e1 := syscall.Syscall(procDisconnectNamedPipe.Addr(), 1, uintptr(handle), 0, 0)
    if r1 == 0 {
        if e1 != 0 {
            err = error(e1)
        } else {
            err = syscall.EINVAL
        }
    }
    return
}

func waitNamedPipe(name *uint16, timeout uint32) (err error) {
    r1, _, e1 := syscall.Syscall(procWaitNamedPipeW.Addr(), 2, uintptr(unsafe.Pointer(name)), uintptr(timeout), 0)
    if r1 == 0 {
        if e1 != 0 {
            err = error(e1)
        } else {
            err = syscall.EINVAL
        }
    }
    return
}

func createEvent(sa *syscall.SecurityAttributes, manualReset bool, initialState bool, name *uint16) (handle syscall.Handle, err error) {
    var _p0 uint32
    if manualReset {
        _p0 = 1
    } else {
        _p0 = 0
    }
    var _p1 uint32
    if initialState {
        _p1 = 1
    } else {
        _p1 = 0
    }
    r0, _, e1 := syscall.Syscall6(procCreateEventW.Addr(), 4, uintptr(unsafe.Pointer(sa)), uintptr(_p0), uintptr(_p1), uintptr(unsafe.Pointer(name)), 0, 0)
    handle = syscall.Handle(r0)
    if handle == syscall.InvalidHandle {
        if e1 != 0 {
            err = error(e1)
        } else {
            err = syscall.EINVAL
        }
    }
    return
}

func getOverlappedResult(handle syscall.Handle, overlapped *syscall.Overlapped, transferred *uint32, wait bool) (err error) {
    var _p0 uint32
    if wait {
        _p0 = 1
    } else {
        _p0 = 0
    }
    r1, _, e1 := syscall.Syscall6(procGetOverlappedResult.Addr(), 4, uintptr(handle), uintptr(unsafe.Pointer(overlapped)), uintptr(unsafe.Pointer(transferred)), uintptr(_p0), 0, 0)
    if r1 == 0 {
        if e1 != 0 {
            err = error(e1)
        } else {
            err = syscall.EINVAL
        }
    }
    return
}

const (
    // openMode
    pipe_access_duplex   = 0x3
    pipe_access_inbound  = 0x1
    pipe_access_outbound = 0x2

    // openMode write flags
    file_flag_first_pipe_instance = 0x00080000
    file_flag_write_through       = 0x80000000
    file_flag_overlapped          = 0x40000000

    // openMode ACL flags
    write_dac              = 0x00040000
    write_owner            = 0x00080000
    access_system_security = 0x01000000

    // pipeMode
    pipe_type_byte    = 0x0
    pipe_type_message = 0x4

    // pipeMode read mode flags
    pipe_readmode_byte    = 0x0
    pipe_readmode_message = 0x2

    // pipeMode wait mode flags
    pipe_wait   = 0x0
    pipe_nowait = 0x1

    // pipeMode remote-client mode flags
    pipe_accept_remote_clients = 0x0
    pipe_reject_remote_clients = 0x8

    pipe_unlimited_instances = 255

    nmpwait_wait_forever = 0xFFFFFFFF

    // the two not-an-errors below occur if a client connects to the pipe between
    // the server's CreateNamedPipe and ConnectNamedPipe calls.
    error_no_data        syscall.Errno = 0xE8
    error_pipe_connected syscall.Errno = 0x217
    error_pipe_busy      syscall.Errno = 0xE7
    error_sem_timeout    syscall.Errno = 0x79

    error_bad_pathname syscall.Errno = 0xA1
    error_invalid_name syscall.Errno = 0x7B

    error_io_incomplete syscall.Errno = 0x3e4
)

var _ net.Conn = (*PipeConn)(nil)
var _ net.Listener = (*PipeListener)(nil)

// ErrClosed is the error returned by PipeListener.Accept when Close is called
// on the PipeListener.
var ErrClosed = PipeError{"Pipe has been closed.", false}

// PipeError is an error related to a call to a pipe
type PipeError struct {
    msg     string
    timeout bool
}

// Error implements the error interface
func (e PipeError) Error() string {
    return e.msg
}

// Timeout implements net.AddrError.Timeout()
func (e PipeError) Timeout() bool {
    return e.timeout
}

// Temporary implements net.AddrError.Temporary()
func (e PipeError) Temporary() bool {
    return false
}

// Dial connects to a named pipe with the given address. If the specified pipe is not available,
// it will wait indefinitely for the pipe to become available.
//
// The address must be of the form \\.\\pipe\<name> for local pipes and \\<computer>\pipe\<name>
// for remote pipes.
//
// Dial will return a PipeError if you pass in a badly formatted pipe name.
//
// Examples:
//   // local pipe
//   conn, err := Dial(`\\.\pipe\mypipename`)
//
//   // remote pipe
//   conn, err := Dial(`\\othercomp\pipe\mypipename`)
func Dial(address string) (*PipeConn, error) {
    for {
        conn, err := dial(address, nmpwait_wait_forever)
        if err == nil {
            return conn, nil
        }
        if isPipeNotReady(err) {
            <-time.After(100 * time.Millisecond)
            continue
        }
        return nil, err
    }
}

// DialTimeout acts like Dial, but will time out after the duration of timeout
func DialTimeout(address string, timeout time.Duration) (*PipeConn, error) {
    deadline := time.Now().Add(timeout)

    now := time.Now()
    for now.Before(deadline) {
        millis := uint32(deadline.Sub(now) / time.Millisecond)
        conn, err := dial(address, millis)
        if err == nil {
            return conn, nil
        }
        if err == error_sem_timeout {
            // This is WaitNamedPipe's timeout error, so we know we're done
            return nil, PipeError{fmt.Sprintf(
                "Timed out waiting for pipe '%s' to come available", address), true}
        }
        if isPipeNotReady(err) {
            left := deadline.Sub(time.Now())
            retry := 100 * time.Millisecond
            if left > retry {
                <-time.After(retry)
            } else {
                <-time.After(left - time.Millisecond)
            }
            now = time.Now()
            continue
        }
        return nil, err
    }
    return nil, PipeError{fmt.Sprintf(
        "Timed out waiting for pipe '%s' to come available", address), true}
}

// isPipeNotReady checks the error to see if it indicates the pipe is not ready
func isPipeNotReady(err error) bool {
    // Pipe Busy means another client just grabbed the open pipe end,
    // and the server hasn't made a new one yet.
    // File Not Found means the server hasn't created the pipe yet.
    // Neither is a fatal error.

    return err == syscall.ERROR_FILE_NOT_FOUND || err == error_pipe_busy
}

// newOverlapped creates a structure used to track asynchronous
// I/O requests that have been issued.
func newOverlapped() (*syscall.Overlapped, error) {
    event, err := createEvent(nil, true, true, nil)
    if err != nil {
        return nil, err
    }
    return &syscall.Overlapped{HEvent: event}, nil
}

// waitForCompletion waits for an asynchronous I/O request referred to by overlapped to complete.
// This function returns the number of bytes transferred by the operation and an error code if
// applicable (nil otherwise).
func waitForCompletion(handle syscall.Handle, overlapped *syscall.Overlapped) (uint32, error) {
    _, err := syscall.WaitForSingleObject(overlapped.HEvent, syscall.INFINITE)
    if err != nil {
        return 0, err
    }
    var transferred uint32
    err = getOverlappedResult(handle, overlapped, &transferred, true)
    return transferred, err
}

// dial is a helper to initiate a connection to a named pipe that has been started by a server.
// The timeout is only enforced if the pipe server has already created the pipe, otherwise
// this function will return immediately.
func dial(address string, timeout uint32) (*PipeConn, error) {
    name, err := syscall.UTF16PtrFromString(string(address))
    if err != nil {
        return nil, err
    }
    // If at least one instance of the pipe has been created, this function
    // will wait timeout milliseconds for it to become available.
    // It will return immediately regardless of timeout, if no instances
    // of the named pipe have been created yet.
    // If this returns with no error, there is a pipe available.
    if err := waitNamedPipe(name, timeout); err != nil {
        if err == error_bad_pathname {
            // badly formatted pipe name
            return nil, badAddr(address)
        }
        return nil, err
    }
    pathp, err := syscall.UTF16PtrFromString(address)
    if err != nil {
        return nil, err
    }
    handle, err := syscall.CreateFile(pathp, syscall.GENERIC_READ|syscall.GENERIC_WRITE,
        uint32(syscall.FILE_SHARE_READ|syscall.FILE_SHARE_WRITE), nil, syscall.OPEN_EXISTING,
        syscall.FILE_FLAG_OVERLAPPED, 0)
    if err != nil {
        return nil, err
    }
    return &PipeConn{handle: handle, addr: PipeAddr(address)}, nil
}

// Listen returns a new PipeListener that will listen on a pipe with the given
// address. The address must be of the form \\.\pipe\<name>
//
// Listen will return a PipeError for an incorrectly formatted pipe name.
func Listen(address string) (*PipeListener, error) {
    handle, err := createPipe(address, true)
    if err == error_invalid_name {
        return nil, badAddr(address)
    }
    if err != nil {
        return nil, err
    }
    return &PipeListener{
        addr:   PipeAddr(address),
        handle: handle,
    }, nil
}

// PipeListener is a named pipe listener. Clients should typically
// use variables of type net.Listener instead of assuming named pipe.
type PipeListener struct {
    addr   PipeAddr
    handle syscall.Handle
    closed bool

    // acceptHandle contains the current handle waiting for
    // an incoming connection or nil.
    acceptHandle syscall.Handle
    // acceptOverlapped is set before waiting on a connection.
    // If not waiting, it is nil.
    acceptOverlapped *syscall.Overlapped
    // acceptMutex protects the handle and overlapped structure.
    acceptMutex sync.Mutex
}

// Accept implements the Accept method in the net.Listener interface; it
// waits for the next call and returns a generic net.Conn.
func (l *PipeListener) Accept() (net.Conn, error) {
    c, err := l.AcceptPipe()
    for err == error_no_data {
        // Ignore clients that connect and immediately disconnect.
        c, err = l.AcceptPipe()
    }
    if err != nil {
        return nil, err
    }
    return c, nil
}

// AcceptPipe accepts the next incoming call and returns the new connection.
// It might return an error if a client connected and immediately cancelled
// the connection.
func (l *PipeListener) AcceptPipe() (*PipeConn, error) {
    if l == nil || l.addr == "" || l.closed {
        return nil, syscall.EINVAL
    }

    // the first time we call accept, the handle will have been created by the Listen
    // call. This is to prevent race conditions where the client thinks the server
    // isn't listening because it hasn't actually called create yet. After the first time, we'll
    // have to create a new handle each time
    handle := l.handle
    if handle == 0 {
        var err error
        handle, err = createPipe(string(l.addr), false)
        if err != nil {
            return nil, err
        }
    } else {
        l.handle = 0
    }

    overlapped, err := newOverlapped()
    if err != nil {
        return nil, err
    }
    defer syscall.CloseHandle(overlapped.HEvent)
    if err := connectNamedPipe(handle, overlapped); err != nil && err != error_pipe_connected {
        if err == error_io_incomplete || err == syscall.ERROR_IO_PENDING {
            l.acceptMutex.Lock()
            l.acceptOverlapped = overlapped
            l.acceptHandle = handle
            l.acceptMutex.Unlock()
            defer func() {
                l.acceptMutex.Lock()
                l.acceptOverlapped = nil
                l.acceptHandle = 0
                l.acceptMutex.Unlock()
            }()

            _, err = waitForCompletion(handle, overlapped)
        }
        if err == syscall.ERROR_OPERATION_ABORTED {
            // Return error compatible to net.Listener.Accept() in case the
            // listener was closed.
            return nil, ErrClosed
        }
        if err != nil {
            return nil, err
        }
    }
    return &PipeConn{handle: handle, addr: l.addr}, nil
}

// Close stops listening on the address.
// Already Accepted connections are not closed.
func (l *PipeListener) Close() error {
    if l.closed {
        return nil
    }
    l.closed = true
    if l.handle != 0 {
        err := disconnectNamedPipe(l.handle)
        if err != nil {
            return err
        }
        err = syscall.CloseHandle(l.handle)
        if err != nil {
            return err
        }
        l.handle = 0
    }
    l.acceptMutex.Lock()
    defer l.acceptMutex.Unlock()
    if l.acceptOverlapped != nil && l.acceptHandle != 0 {
        // Cancel the pending IO. This call does not block, so it is safe
        // to hold onto the mutex above.
        if err := cancelIoEx(l.acceptHandle, l.acceptOverlapped); err != nil {
            return err
        }
        err := syscall.CloseHandle(l.acceptOverlapped.HEvent)
        if err != nil {
            return err
        }
        l.acceptOverlapped.HEvent = 0
        err = syscall.CloseHandle(l.acceptHandle)
        if err != nil {
            return err
        }
        l.acceptHandle = 0
    }
    return nil
}

// Addr returns the listener's network address, a PipeAddr.
func (l *PipeListener) Addr() net.Addr { return l.addr }

// PipeConn is the implementation of the net.Conn interface for named pipe connections.
type PipeConn struct {
    handle syscall.Handle
    addr   PipeAddr

    // these aren't actually used yet
    readDeadline  *time.Time
    writeDeadline *time.Time
}

type iodata struct {
    n   uint32
    err error
}

// completeRequest looks at iodata to see if a request is pending. If so, it waits for it to either complete or to
// abort due to hitting the specified deadline. Deadline may be set to nil to wait forever. If no request is pending,
// the content of iodata is returned.
func (c *PipeConn) completeRequest(data iodata, deadline *time.Time, overlapped *syscall.Overlapped) (int, error) {
    if data.err == error_io_incomplete || data.err == syscall.ERROR_IO_PENDING {
        var timer <-chan time.Time
        if deadline != nil {
            if timeDiff := deadline.Sub(time.Now()); timeDiff > 0 {
                timer = time.After(timeDiff)
            }
        }
        done := make(chan iodata)
        go func() {
            n, err := waitForCompletion(c.handle, overlapped)
            done <- iodata{n, err}
        }()
        select {
        case data = <-done:
        case <-timer:
            syscall.CancelIoEx(c.handle, overlapped)
            data = iodata{0, timeout(c.addr.String())}
        }
    }
    // Windows will produce ERROR_BROKEN_PIPE upon closing
    // a handle on the other end of a connection. Go RPC
    // expects an io.EOF error in this case.
    if data.err == syscall.ERROR_BROKEN_PIPE {
        data.err = io.EOF
    }
    return int(data.n), data.err
}

// Read implements the net.Conn Read method.
func (c *PipeConn) Read(b []byte) (int, error) {
    // Use ReadFile() rather than Read() because the latter
    // contains a workaround that eats ERROR_BROKEN_PIPE.
    overlapped, err := newOverlapped()
    if err != nil {
        return 0, err
    }
    defer syscall.CloseHandle(overlapped.HEvent)
    var n uint32
    err = syscall.ReadFile(c.handle, b, &n, overlapped)
    return c.completeRequest(iodata{n, err}, c.readDeadline, overlapped)
}

// Write implements the net.Conn Write method.
func (c *PipeConn) Write(b []byte) (int, error) {
    overlapped, err := newOverlapped()
    if err != nil {
        return 0, err
    }
    defer syscall.CloseHandle(overlapped.HEvent)
    var n uint32
    err = syscall.WriteFile(c.handle, b, &n, overlapped)
    return c.completeRequest(iodata{n, err}, c.writeDeadline, overlapped)
}

// Close closes the connection.
func (c *PipeConn) Close() error {
    return syscall.CloseHandle(c.handle)
}

// LocalAddr returns the local network address.
func (c *PipeConn) LocalAddr() net.Addr {
    return c.addr
}

// RemoteAddr returns the remote network address.
func (c *PipeConn) RemoteAddr() net.Addr {
    // not sure what to do here, we don't have remote addr....
    return c.addr
}

// SetDeadline implements the net.Conn SetDeadline method.
// Note that timeouts are only supported on Windows Vista/Server 2008 and above
func (c *PipeConn) SetDeadline(t time.Time) error {
    c.SetReadDeadline(t)
    c.SetWriteDeadline(t)
    return nil
}

// SetReadDeadline implements the net.Conn SetReadDeadline method.
// Note that timeouts are only supported on Windows Vista/Server 2008 and above
func (c *PipeConn) SetReadDeadline(t time.Time) error {
    c.readDeadline = &t
    return nil
}

// SetWriteDeadline implements the net.Conn SetWriteDeadline method.
// Note that timeouts are only supported on Windows Vista/Server 2008 and above
func (c *PipeConn) SetWriteDeadline(t time.Time) error {
    c.writeDeadline = &t
    return nil
}

// PipeAddr represents the address of a named pipe.
type PipeAddr string

// Network returns the address's network name, "pipe".
func (a PipeAddr) Network() string { return "pipe" }

// String returns the address of the pipe
func (a PipeAddr) String() string {
    return string(a)
}

// createPipe is a helper function to make sure we always create pipes
// with the same arguments, since subsequent calls to create pipe need
// to use the same arguments as the first one. If first is set, fail
// if the pipe already exists.
func createPipe(address string, first bool) (syscall.Handle, error) {
    n, err := syscall.UTF16PtrFromString(address)
    if err != nil {
        return 0, err
    }
    mode := uint32(pipe_access_duplex | syscall.FILE_FLAG_OVERLAPPED)
    if first {
        mode |= file_flag_first_pipe_instance
    }
    return createNamedPipe(n,
        mode,
        pipe_type_byte,
        pipe_unlimited_instances,
        512, 512, 0, nil)
}

func badAddr(addr string) PipeError {
    return PipeError{fmt.Sprintf("Invalid pipe address '%s'.", addr), false}
}
func timeout(addr string) PipeError {
    return PipeError{fmt.Sprintf("Pipe IO timed out waiting for '%s'", addr), true}
}

func newIpcClient(cfg IpcConfig, codec codec.Codec) (*ipcClient, error) {
    c, err := Dial(cfg.Endpoint)
    if err != nil {
        return nil, err
    }

    return &ipcClient{cfg.Endpoint, c, codec, codec.New(c)}, nil
}

func (self *ipcClient) reconnect() error {
    c, err := Dial(self.endpoint)
    if err == nil {
        self.coder = self.codec.New(c)
    }
    return err
}

func startIpc(cfg IpcConfig, codec codec.Codec, api shared.EthereumApi) error {
    os.Remove(cfg.Endpoint) // in case it still exists from a previous run

    l, err := Listen(cfg.Endpoint)
    if err != nil {
        return err
    }
    os.Chmod(cfg.Endpoint, 0600)

    go func() {
        for {
            conn, err := l.Accept()
            if err != nil {
                glog.V(logger.Error).Infof("Error accepting ipc connection - %v\n", err)
                continue
            }

            id := newIpcConnId()
            glog.V(logger.Debug).Infof("New IPC connection with id %06d started\n", id)

            go handle(id, conn, api, codec)
        }

        os.Remove(cfg.Endpoint)
    }()

    glog.V(logger.Info).Infof("IPC service started (%s)\n", cfg.Endpoint)

    return nil
}