buildkit/session/grpchijack/dial.go

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package grpchijack
import (
"net"
"strings"
"sync"
"time"
controlapi "github.com/moby/buildkit/api/services/control"
"github.com/moby/buildkit/session"
"golang.org/x/net/context"
"google.golang.org/grpc"
"google.golang.org/grpc/metadata"
)
var bufPool = sync.Pool{
New: func() interface{} {
return make([]byte, 32*1<<10)
},
}
func Dialer(api controlapi.ControlClient) session.Dialer {
return func(ctx context.Context, proto string, meta map[string][]string) (net.Conn, error) {
meta = lowerHeaders(meta)
md := metadata.MD(meta)
ctx = metadata.NewOutgoingContext(context.Background(), md)
stream, err := api.Session(ctx)
if err != nil {
return nil, err
}
return streamToConn(stream), nil
}
}
func streamToConn(stream grpc.Stream) net.Conn {
return &conn{stream: stream, buf: make([]byte, 32*1<<10)}
}
type conn struct {
stream grpc.Stream
buf []byte
lastBuf []byte
}
func (c *conn) Read(b []byte) (int, error) {
if c.lastBuf != nil {
n := copy(b, c.lastBuf)
c.lastBuf = c.lastBuf[n:]
if len(c.lastBuf) == 0 {
c.lastBuf = nil
}
return n, nil
}
m := new(controlapi.BytesMessage)
m.Data = c.buf
if err := c.stream.RecvMsg(m); err != nil {
return 0, err
}
c.buf = m.Data[:cap(m.Data)]
n := copy(b, m.Data)
if n < len(m.Data) {
c.lastBuf = m.Data[n:]
}
return n, nil
}
func (c *conn) Write(b []byte) (int, error) {
m := &controlapi.BytesMessage{Data: b}
if err := c.stream.SendMsg(m); err != nil {
return 0, err
}
return len(b), nil
}
func (c *conn) Close() error {
if cs, ok := c.stream.(grpc.ClientStream); ok {
return cs.CloseSend()
}
return nil
}
func (c *conn) LocalAddr() net.Addr {
return dummyAddr{}
}
func (c *conn) RemoteAddr() net.Addr {
return dummyAddr{}
}
func (c *conn) SetDeadline(t time.Time) error {
return nil
}
func (c *conn) SetReadDeadline(t time.Time) error {
return nil
}
func (c *conn) SetWriteDeadline(t time.Time) error {
return nil
}
type dummyAddr struct {
}
func (d dummyAddr) Network() string {
return "tcp"
}
func (d dummyAddr) String() string {
return "localhost"
}
func lowerHeaders(in map[string][]string) map[string][]string {
out := map[string][]string{}
for k := range in {
out[strings.ToLower(k)] = in[k]
}
return out
}