diff options
Diffstat (limited to 'vendor/github.com/aws/aws-sdk-go/private/protocol/eventstream/decode.go')
-rw-r--r-- | vendor/github.com/aws/aws-sdk-go/private/protocol/eventstream/decode.go | 199 |
1 files changed, 199 insertions, 0 deletions
diff --git a/vendor/github.com/aws/aws-sdk-go/private/protocol/eventstream/decode.go b/vendor/github.com/aws/aws-sdk-go/private/protocol/eventstream/decode.go new file mode 100644 index 0000000..4b972b2 --- /dev/null +++ b/vendor/github.com/aws/aws-sdk-go/private/protocol/eventstream/decode.go @@ -0,0 +1,199 @@ +package eventstream + +import ( + "bytes" + "encoding/binary" + "encoding/hex" + "encoding/json" + "fmt" + "hash" + "hash/crc32" + "io" + + "github.com/aws/aws-sdk-go/aws" +) + +// Decoder provides decoding of an Event Stream messages. +type Decoder struct { + r io.Reader + logger aws.Logger +} + +// NewDecoder initializes and returns a Decoder for decoding event +// stream messages from the reader provided. +func NewDecoder(r io.Reader) *Decoder { + return &Decoder{ + r: r, + } +} + +// Decode attempts to decode a single message from the event stream reader. +// Will return the event stream message, or error if Decode fails to read +// the message from the stream. +func (d *Decoder) Decode(payloadBuf []byte) (m Message, err error) { + reader := d.r + if d.logger != nil { + debugMsgBuf := bytes.NewBuffer(nil) + reader = io.TeeReader(reader, debugMsgBuf) + defer func() { + logMessageDecode(d.logger, debugMsgBuf, m, err) + }() + } + + crc := crc32.New(crc32IEEETable) + hashReader := io.TeeReader(reader, crc) + + prelude, err := decodePrelude(hashReader, crc) + if err != nil { + return Message{}, err + } + + if prelude.HeadersLen > 0 { + lr := io.LimitReader(hashReader, int64(prelude.HeadersLen)) + m.Headers, err = decodeHeaders(lr) + if err != nil { + return Message{}, err + } + } + + if payloadLen := prelude.PayloadLen(); payloadLen > 0 { + buf, err := decodePayload(payloadBuf, io.LimitReader(hashReader, int64(payloadLen))) + if err != nil { + return Message{}, err + } + m.Payload = buf + } + + msgCRC := crc.Sum32() + if err := validateCRC(reader, msgCRC); err != nil { + return Message{}, err + } + + return m, nil +} + +// UseLogger specifies the Logger that that the decoder should use to log the +// message decode to. +func (d *Decoder) UseLogger(logger aws.Logger) { + d.logger = logger +} + +func logMessageDecode(logger aws.Logger, msgBuf *bytes.Buffer, msg Message, decodeErr error) { + w := bytes.NewBuffer(nil) + defer func() { logger.Log(w.String()) }() + + fmt.Fprintf(w, "Raw message:\n%s\n", + hex.Dump(msgBuf.Bytes())) + + if decodeErr != nil { + fmt.Fprintf(w, "Decode error: %v\n", decodeErr) + return + } + + rawMsg, err := msg.rawMessage() + if err != nil { + fmt.Fprintf(w, "failed to create raw message, %v\n", err) + return + } + + decodedMsg := decodedMessage{ + rawMessage: rawMsg, + Headers: decodedHeaders(msg.Headers), + } + + fmt.Fprintf(w, "Decoded message:\n") + encoder := json.NewEncoder(w) + if err := encoder.Encode(decodedMsg); err != nil { + fmt.Fprintf(w, "failed to generate decoded message, %v\n", err) + } +} + +func decodePrelude(r io.Reader, crc hash.Hash32) (messagePrelude, error) { + var p messagePrelude + + var err error + p.Length, err = decodeUint32(r) + if err != nil { + return messagePrelude{}, err + } + + p.HeadersLen, err = decodeUint32(r) + if err != nil { + return messagePrelude{}, err + } + + if err := p.ValidateLens(); err != nil { + return messagePrelude{}, err + } + + preludeCRC := crc.Sum32() + if err := validateCRC(r, preludeCRC); err != nil { + return messagePrelude{}, err + } + + p.PreludeCRC = preludeCRC + + return p, nil +} + +func decodePayload(buf []byte, r io.Reader) ([]byte, error) { + w := bytes.NewBuffer(buf[0:0]) + + _, err := io.Copy(w, r) + return w.Bytes(), err +} + +func decodeUint8(r io.Reader) (uint8, error) { + type byteReader interface { + ReadByte() (byte, error) + } + + if br, ok := r.(byteReader); ok { + v, err := br.ReadByte() + return uint8(v), err + } + + var b [1]byte + _, err := io.ReadFull(r, b[:]) + return uint8(b[0]), err +} +func decodeUint16(r io.Reader) (uint16, error) { + var b [2]byte + bs := b[:] + _, err := io.ReadFull(r, bs) + if err != nil { + return 0, err + } + return binary.BigEndian.Uint16(bs), nil +} +func decodeUint32(r io.Reader) (uint32, error) { + var b [4]byte + bs := b[:] + _, err := io.ReadFull(r, bs) + if err != nil { + return 0, err + } + return binary.BigEndian.Uint32(bs), nil +} +func decodeUint64(r io.Reader) (uint64, error) { + var b [8]byte + bs := b[:] + _, err := io.ReadFull(r, bs) + if err != nil { + return 0, err + } + return binary.BigEndian.Uint64(bs), nil +} + +func validateCRC(r io.Reader, expect uint32) error { + msgCRC, err := decodeUint32(r) + if err != nil { + return err + } + + if msgCRC != expect { + return ChecksumError{} + } + + return nil +} |