package packp
import (
"bytes"
"encoding/hex"
"errors"
"fmt"
"io"
"io/ioutil"
"github.com/go-git/go-git/v5/plumbing"
"github.com/go-git/go-git/v5/plumbing/format/pktline"
)
var (
shallowLineLength = len(shallow) + hashSize
minCommandLength = hashSize*2 + 2 + 1
minCommandAndCapsLength = minCommandLength + 1
)
var (
ErrEmpty = errors.New("empty update-request message")
errNoCommands = errors.New("unexpected EOF before any command")
errMissingCapabilitiesDelimiter = errors.New("capabilities delimiter not found")
)
func errMalformedRequest(reason string) error {
return fmt.Errorf("malformed request: %s", reason)
}
func errInvalidHashSize(got int) error {
return fmt.Errorf("invalid hash size: expected %d, got %d",
hashSize, got)
}
func errInvalidHash(err error) error {
return fmt.Errorf("invalid hash: %s", err.Error())
}
func errInvalidShallowLineLength(got int) error {
return errMalformedRequest(fmt.Sprintf(
"invalid shallow line length: expected %d, got %d",
shallowLineLength, got))
}
func errInvalidCommandCapabilitiesLineLength(got int) error {
return errMalformedRequest(fmt.Sprintf(
"invalid command and capabilities line length: expected at least %d, got %d",
minCommandAndCapsLength, got))
}
func errInvalidCommandLineLength(got int) error {
return errMalformedRequest(fmt.Sprintf(
"invalid command line length: expected at least %d, got %d",
minCommandLength, got))
}
func errInvalidShallowObjId(err error) error {
return errMalformedRequest(
fmt.Sprintf("invalid shallow object id: %s", err.Error()))
}
func errInvalidOldObjId(err error) error {
return errMalformedRequest(
fmt.Sprintf("invalid old object id: %s", err.Error()))
}
func errInvalidNewObjId(err error) error {
return errMalformedRequest(
fmt.Sprintf("invalid new object id: %s", err.Error()))
}
func errMalformedCommand(err error) error {
return errMalformedRequest(fmt.Sprintf(
"malformed command: %s", err.Error()))
}
// Decode reads the next update-request message form the reader and wr
func (req *ReferenceUpdateRequest) Decode(r io.Reader) error {
var rc io.ReadCloser
var ok bool
rc, ok = r.(io.ReadCloser)
if !ok {
rc = ioutil.NopCloser(r)
}
d := &updReqDecoder{r: rc, s: pktline.NewScanner(r)}
return d.Decode(req)
}
type updReqDecoder struct {
r io.ReadCloser
s *pktline.Scanner
req *ReferenceUpdateRequest
}
func (d *updReqDecoder) Decode(req *ReferenceUpdateRequest) error {
d.req = req
funcs := []func() error{
d.scanLine,
d.decodeShallow,
d.decodeCommandAndCapabilities,
d.decodeCommands,
d.setPackfile,
req.validate,
}
for _, f := range funcs {
if err := f(); err != nil {
return err
}
}
return nil
}
func (d *updReqDecoder) scanLine() error {
if ok := d.s.Scan(); !ok {
return d.scanErrorOr(ErrEmpty)
}
return nil
}
func (d *updReqDecoder) decodeShallow() error {
b := d.s.Bytes()
if !bytes.HasPrefix(b, shallowNoSp) {
return nil
}
if len(b) != shallowLineLength {
return errInvalidShallowLineLength(len(b))
}
h, err := parseHash(string(b[len(shallow):]))
if err != nil {
return errInvalidShallowObjId(err)
}
if ok := d.s.Scan(); !ok {
return d.scanErrorOr(errNoCommands)
}
d.req.Shallow = &h
return nil
}
func (d *updReqDecoder) decodeCommands() error {
for {
b := d.s.Bytes()
if bytes.Equal(b, pktline.Flush) {
return nil
}
c, err := parseCommand(b)
if err != nil {
return err
}
d.req.Commands = append(d.req.Commands, c)
if ok := d.s.Scan(); !ok {
return d.s.Err()
}
}
}
func (d *updReqDecoder) decodeCommandAndCapabilities() error {
b := d.s.Bytes()
i := bytes.IndexByte(b, 0)
if i == -1 {
return errMissingCapabilitiesDelimiter
}
if len(b) < minCommandAndCapsLength {
return errInvalidCommandCapabilitiesLineLength(len(b))
}
cmd, err := parseCommand(b[:i])
if err != nil {
return err
}
d.req.Commands = append(d.req.Commands, cmd)
if err := d.req.Capabilities.Decode(b[i+1:]); err != nil {
return err
}
if err := d.scanLine(); err != nil {
return err
}
return nil
}
func (d *updReqDecoder) setPackfile() error {
d.req.Packfile = d.r
return nil
}
func parseCommand(b []byte) (*Command, error) {
if len(b) < minCommandLength {
return nil, errInvalidCommandLineLength(len(b))
}
var (
os, ns string
n plumbing.ReferenceName
)
if _, err := fmt.Sscanf(string(b), "%s %s %s", &os, &ns, &n); err != nil {
return nil, errMalformedCommand(err)
}
oh, err := parseHash(os)
if err != nil {
return nil, errInvalidOldObjId(err)
}
nh, err := parseHash(ns)
if err != nil {
return nil, errInvalidNewObjId(err)
}
return &Command{Old: oh, New: nh, Name: n}, nil
}
func parseHash(s string) (plumbing.Hash, error) {
if len(s) != hashSize {
return plumbing.ZeroHash, errInvalidHashSize(len(s))
}
if _, err := hex.DecodeString(s); err != nil {
return plumbing.ZeroHash, errInvalidHash(err)
}
h := plumbing.NewHash(s)
return h, nil
}
func (d *updReqDecoder) scanErrorOr(origErr error) error {
if err := d.s.Err(); err != nil {
return err
}
return origErr
}
