117 lines
2.5 KiB
Go
117 lines
2.5 KiB
Go
package wire
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import (
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"fmt"
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"io"
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"io/ioutil"
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"strconv"
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)
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// StatusCodes are returned by the server. If the code indicates failure, the
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// next message will be the error.
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type StatusCode string
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const (
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StatusSuccess StatusCode = "OKAY"
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StatusFailure = "FAIL"
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StatusNone = ""
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)
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func (status StatusCode) IsSuccess() bool {
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return status == StatusSuccess
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}
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/*
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Scanner reads tokens from a server.
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See Conn for more details.
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*/
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type Scanner interface {
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ReadStatus() (StatusCode, error)
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ReadMessage() ([]byte, error)
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ReadUntilEof() ([]byte, error)
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NewSyncScanner() SyncScanner
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Close() error
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}
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type realScanner struct {
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reader io.ReadCloser
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}
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func NewScanner(r io.ReadCloser) Scanner {
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return &realScanner{r}
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}
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func ReadMessageString(s Scanner) (string, error) {
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msg, err := s.ReadMessage()
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if err != nil {
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return string(msg), err
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}
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return string(msg), nil
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}
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func (s *realScanner) ReadStatus() (StatusCode, error) {
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status := make([]byte, 4)
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n, err := io.ReadFull(s.reader, status)
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if err != nil && err != io.ErrUnexpectedEOF {
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return "", err
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} else if err == io.ErrUnexpectedEOF {
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return StatusCode(status), incompleteMessage("status", n, 4)
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}
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return StatusCode(status), nil
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}
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func (s *realScanner) ReadMessage() ([]byte, error) {
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length, err := s.readLength()
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if err != nil {
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return nil, err
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}
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data := make([]byte, length)
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n, err := io.ReadFull(s.reader, data)
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if err != nil && err != io.ErrUnexpectedEOF {
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return data, fmt.Errorf("error reading message data: %v", err)
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} else if err == io.ErrUnexpectedEOF {
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return data, incompleteMessage("message data", n, length)
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}
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return data, nil
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}
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func (s *realScanner) ReadUntilEof() ([]byte, error) {
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return ioutil.ReadAll(s.reader)
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}
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func (s *realScanner) NewSyncScanner() SyncScanner {
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return NewSyncScanner(s.reader)
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}
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func (s *realScanner) Close() error {
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return s.reader.Close()
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}
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func (s *realScanner) readLength() (int, error) {
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lengthHex := make([]byte, 4)
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n, err := io.ReadFull(s.reader, lengthHex)
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if err != nil && err != io.ErrUnexpectedEOF {
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return 0, err
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} else if err == io.ErrUnexpectedEOF {
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return 0, incompleteMessage("length", n, 4)
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}
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length, err := strconv.ParseInt(string(lengthHex), 16, 64)
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if err != nil {
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return 0, fmt.Errorf("invalid hex length: %v", err)
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}
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// Clip the length to 255, as per the Google implementation.
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if length > MaxMessageLength {
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length = MaxMessageLength
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}
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return int(length), nil
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}
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var _ Scanner = &realScanner{}
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