128 lines
2.7 KiB
Go
128 lines
2.7 KiB
Go
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package packp
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import (
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"bufio"
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"bytes"
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"errors"
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"fmt"
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"io"
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"gopkg.in/src-d/go-git.v4/plumbing"
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"gopkg.in/src-d/go-git.v4/plumbing/format/pktline"
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)
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const ackLineLen = 44
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// ServerResponse object acknowledgement from upload-pack service
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type ServerResponse struct {
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ACKs []plumbing.Hash
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}
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// Decode decodes the response into the struct, isMultiACK should be true, if
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// the request was done with multi_ack or multi_ack_detailed capabilities.
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func (r *ServerResponse) Decode(reader *bufio.Reader, isMultiACK bool) error {
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// TODO: implement support for multi_ack or multi_ack_detailed responses
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if isMultiACK {
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return errors.New("multi_ack and multi_ack_detailed are not supported")
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}
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s := pktline.NewScanner(reader)
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for s.Scan() {
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line := s.Bytes()
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if err := r.decodeLine(line); err != nil {
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return err
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}
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// we need to detect when the end of a response header and the beginning
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// of a packfile header happened, some requests to the git daemon
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// produces a duplicate ACK header even when multi_ack is not supported.
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stop, err := r.stopReading(reader)
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if err != nil {
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return err
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}
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if stop {
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break
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}
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}
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return s.Err()
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}
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// stopReading detects when a valid command such as ACK or NAK is found to be
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// read in the buffer without moving the read pointer.
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func (r *ServerResponse) stopReading(reader *bufio.Reader) (bool, error) {
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ahead, err := reader.Peek(7)
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if err == io.EOF {
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return true, nil
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}
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if err != nil {
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return false, err
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}
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if len(ahead) > 4 && r.isValidCommand(ahead[0:3]) {
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return false, nil
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}
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if len(ahead) == 7 && r.isValidCommand(ahead[4:]) {
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return false, nil
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}
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return true, nil
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}
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func (r *ServerResponse) isValidCommand(b []byte) bool {
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commands := [][]byte{ack, nak}
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for _, c := range commands {
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if bytes.Equal(b, c) {
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return true
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}
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}
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return false
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}
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func (r *ServerResponse) decodeLine(line []byte) error {
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if len(line) == 0 {
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return fmt.Errorf("unexpected flush")
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}
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if bytes.Equal(line[0:3], ack) {
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return r.decodeACKLine(line)
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}
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if bytes.Equal(line[0:3], nak) {
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return nil
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}
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return fmt.Errorf("unexpected content %q", string(line))
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}
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func (r *ServerResponse) decodeACKLine(line []byte) error {
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if len(line) < ackLineLen {
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return fmt.Errorf("malformed ACK %q", line)
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}
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sp := bytes.Index(line, []byte(" "))
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h := plumbing.NewHash(string(line[sp+1 : sp+41]))
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r.ACKs = append(r.ACKs, h)
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return nil
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}
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// Encode encodes the ServerResponse into a writer.
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func (r *ServerResponse) Encode(w io.Writer) error {
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if len(r.ACKs) > 1 {
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return errors.New("multi_ack and multi_ack_detailed are not supported")
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}
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e := pktline.NewEncoder(w)
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if len(r.ACKs) == 0 {
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return e.Encodef("%s\n", nak)
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}
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return e.Encodef("%s %s\n", ack, r.ACKs[0].String())
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}
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