package packp import ( "bytes" "encoding/hex" "fmt" "io" "strconv" "time" "github.com/go-git/go-git/v5/plumbing" "github.com/go-git/go-git/v5/plumbing/format/pktline" ) // Decode reads the next upload-request form its input and // stores it in the UploadRequest. func (u *UploadRequest) Decode(r io.Reader) error { d := newUlReqDecoder(r) return d.Decode(u) } type ulReqDecoder struct { s *pktline.Scanner // a pkt-line scanner from the input stream line []byte // current pkt-line contents, use parser.nextLine() to make it advance nLine int // current pkt-line number for debugging, begins at 1 err error // sticky error, use the parser.error() method to fill this out data *UploadRequest // parsed data is stored here } func newUlReqDecoder(r io.Reader) *ulReqDecoder { return &ulReqDecoder{ s: pktline.NewScanner(r), } } func (d *ulReqDecoder) Decode(v *UploadRequest) error { d.data = v for state := d.decodeFirstWant; state != nil; { state = state() } return d.err } // fills out the parser stiky error func (d *ulReqDecoder) error(format string, a ...interface{}) { msg := fmt.Sprintf( "pkt-line %d: %s", d.nLine, fmt.Sprintf(format, a...), ) d.err = NewErrUnexpectedData(msg, d.line) } // Reads a new pkt-line from the scanner, makes its payload available as // p.line and increments p.nLine. A successful invocation returns true, // otherwise, false is returned and the sticky error is filled out // accordingly. Trims eols at the end of the payloads. func (d *ulReqDecoder) nextLine() bool { d.nLine++ if !d.s.Scan() { if d.err = d.s.Err(); d.err != nil { return false } d.error("EOF") return false } d.line = d.s.Bytes() d.line = bytes.TrimSuffix(d.line, eol) return true } // Expected format: want [ capabilities] func (d *ulReqDecoder) decodeFirstWant() stateFn { if ok := d.nextLine(); !ok { return nil } if !bytes.HasPrefix(d.line, want) { d.error("missing 'want ' prefix") return nil } d.line = bytes.TrimPrefix(d.line, want) hash, ok := d.readHash() if !ok { return nil } d.data.Wants = append(d.data.Wants, hash) return d.decodeCaps } func (d *ulReqDecoder) readHash() (plumbing.Hash, bool) { if len(d.line) < hashSize { d.err = fmt.Errorf("malformed hash: %v", d.line) return plumbing.ZeroHash, false } var hash plumbing.Hash if _, err := hex.Decode(hash[:], d.line[:hashSize]); err != nil { d.error("invalid hash text: %s", err) return plumbing.ZeroHash, false } d.line = d.line[hashSize:] return hash, true } // Expected format: sp cap1 sp cap2 sp cap3... func (d *ulReqDecoder) decodeCaps() stateFn { d.line = bytes.TrimPrefix(d.line, sp) if err := d.data.Capabilities.Decode(d.line); err != nil { d.error("invalid capabilities: %s", err) } return d.decodeOtherWants } // Expected format: want func (d *ulReqDecoder) decodeOtherWants() stateFn { if ok := d.nextLine(); !ok { return nil } if bytes.HasPrefix(d.line, shallow) { return d.decodeShallow } if bytes.HasPrefix(d.line, deepen) { return d.decodeDeepen } if len(d.line) == 0 { return nil } if !bytes.HasPrefix(d.line, want) { d.error("unexpected payload while expecting a want: %q", d.line) return nil } d.line = bytes.TrimPrefix(d.line, want) hash, ok := d.readHash() if !ok { return nil } d.data.Wants = append(d.data.Wants, hash) return d.decodeOtherWants } // Expected format: shallow func (d *ulReqDecoder) decodeShallow() stateFn { if bytes.HasPrefix(d.line, deepen) { return d.decodeDeepen } if len(d.line) == 0 { return nil } if !bytes.HasPrefix(d.line, shallow) { d.error("unexpected payload while expecting a shallow: %q", d.line) return nil } d.line = bytes.TrimPrefix(d.line, shallow) hash, ok := d.readHash() if !ok { return nil } d.data.Shallows = append(d.data.Shallows, hash) if ok := d.nextLine(); !ok { return nil } return d.decodeShallow } // Expected format: deepen / deepen-since
    / deepen-not func (d *ulReqDecoder) decodeDeepen() stateFn { if bytes.HasPrefix(d.line, deepenCommits) { return d.decodeDeepenCommits } if bytes.HasPrefix(d.line, deepenSince) { return d.decodeDeepenSince } if bytes.HasPrefix(d.line, deepenReference) { return d.decodeDeepenReference } if len(d.line) == 0 { return nil } d.error("unexpected deepen specification: %q", d.line) return nil } func (d *ulReqDecoder) decodeDeepenCommits() stateFn { d.line = bytes.TrimPrefix(d.line, deepenCommits) var n int if n, d.err = strconv.Atoi(string(d.line)); d.err != nil { return nil } if n < 0 { d.err = fmt.Errorf("negative depth") return nil } d.data.Depth = DepthCommits(n) return d.decodeFlush } func (d *ulReqDecoder) decodeDeepenSince() stateFn { d.line = bytes.TrimPrefix(d.line, deepenSince) var secs int64 secs, d.err = strconv.ParseInt(string(d.line), 10, 64) if d.err != nil { return nil } t := time.Unix(secs, 0).UTC() d.data.Depth = DepthSince(t) return d.decodeFlush } func (d *ulReqDecoder) decodeDeepenReference() stateFn { d.line = bytes.TrimPrefix(d.line, deepenReference) d.data.Depth = DepthReference(string(d.line)) return d.decodeFlush } func (d *ulReqDecoder) decodeFlush() stateFn { if ok := d.nextLine(); !ok { return nil } if len(d.line) != 0 { d.err = fmt.Errorf("unexpected payload while expecting a flush-pkt: %q", d.line) } return nil }