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Diffstat (limited to 'formats/packp/pktline/scanner.go')
-rw-r--r-- | formats/packp/pktline/scanner.go | 133 |
1 files changed, 0 insertions, 133 deletions
diff --git a/formats/packp/pktline/scanner.go b/formats/packp/pktline/scanner.go deleted file mode 100644 index 3ce2adf..0000000 --- a/formats/packp/pktline/scanner.go +++ /dev/null @@ -1,133 +0,0 @@ -package pktline - -import ( - "errors" - "io" -) - -const ( - lenSize = 4 -) - -// ErrInvalidPktLen is returned by Err() when an invalid pkt-len is found. -var ErrInvalidPktLen = errors.New("invalid pkt-len found") - -// Scanner provides a convenient interface for reading the payloads of a -// series of pkt-lines. It takes an io.Reader providing the source, -// which then can be tokenized through repeated calls to the Scan -// method. -// -// After each Scan call, the Bytes method will return the payload of the -// corresponding pkt-line on a shared buffer, which will be 65516 bytes -// or smaller. Flush pkt-lines are represented by empty byte slices. -// -// Scanning stops at EOF or the first I/O error. -type Scanner struct { - r io.Reader // The reader provided by the client - err error // Sticky error - payload []byte // Last pkt-payload - len [lenSize]byte // Last pkt-len -} - -// NewScanner returns a new Scanner to read from r. -func NewScanner(r io.Reader) *Scanner { - return &Scanner{ - r: r, - } -} - -// Err returns the first error encountered by the Scanner. -func (s *Scanner) Err() error { - return s.err -} - -// Scan advances the Scanner to the next pkt-line, whose payload will -// then be available through the Bytes method. Scanning stops at EOF -// or the first I/O error. After Scan returns false, the Err method -// will return any error that occurred during scanning, except that if -// it was io.EOF, Err will return nil. -func (s *Scanner) Scan() bool { - var l int - l, s.err = s.readPayloadLen() - if s.err == io.EOF { - s.err = nil - return false - } - if s.err != nil { - return false - } - - if cap(s.payload) < l { - s.payload = make([]byte, 0, l) - } - - if _, s.err = io.ReadFull(s.r, s.payload[:l]); s.err != nil { - return false - } - s.payload = s.payload[:l] - - return true -} - -// Bytes returns the most recent payload generated by a call to Scan. -// The underlying array may point to data that will be overwritten by a -// subsequent call to Scan. It does no allocation. -func (s *Scanner) Bytes() []byte { - return s.payload -} - -// Method readPayloadLen returns the payload length by reading the -// pkt-len and substracting the pkt-len size. -func (s *Scanner) readPayloadLen() (int, error) { - if _, err := io.ReadFull(s.r, s.len[:]); err != nil { - if err == io.EOF { - return 0, err - } - return 0, ErrInvalidPktLen - } - - n, err := hexDecode(s.len) - if err != nil { - return 0, err - } - - switch { - case n == 0: - return 0, nil - case n <= lenSize: - return 0, ErrInvalidPktLen - case n > MaxPayloadSize+lenSize: - return 0, ErrInvalidPktLen - default: - return n - lenSize, nil - } -} - -// Turns the hexadecimal representation of a number in a byte slice into -// a number. This function substitute strconv.ParseUint(string(buf), 16, -// 16) and/or hex.Decode, to avoid generating new strings, thus helping the -// GC. -func hexDecode(buf [lenSize]byte) (int, error) { - var ret int - for i := 0; i < lenSize; i++ { - n, err := asciiHexToByte(buf[i]) - if err != nil { - return 0, ErrInvalidPktLen - } - ret = 16*ret + int(n) - } - return ret, nil -} - -// turns the hexadecimal ascii representation of a byte into its -// numerical value. Example: from 'b' to 11 (0xb). -func asciiHexToByte(b byte) (byte, error) { - switch { - case b >= '0' && b <= '9': - return b - '0', nil - case b >= 'a' && b <= 'f': - return b - 'a' + 10, nil - default: - return 0, ErrInvalidPktLen - } -} |