diff options
Diffstat (limited to 'vendor/github.com/aws/aws-sdk-go/private/protocol/eventstream/encode.go')
-rw-r--r-- | vendor/github.com/aws/aws-sdk-go/private/protocol/eventstream/encode.go | 114 |
1 files changed, 114 insertions, 0 deletions
diff --git a/vendor/github.com/aws/aws-sdk-go/private/protocol/eventstream/encode.go b/vendor/github.com/aws/aws-sdk-go/private/protocol/eventstream/encode.go new file mode 100644 index 000000000..150a60981 --- /dev/null +++ b/vendor/github.com/aws/aws-sdk-go/private/protocol/eventstream/encode.go @@ -0,0 +1,114 @@ +package eventstream + +import ( + "bytes" + "encoding/binary" + "hash" + "hash/crc32" + "io" +) + +// Encoder provides EventStream message encoding. +type Encoder struct { + w io.Writer + + headersBuf *bytes.Buffer +} + +// NewEncoder initializes and returns an Encoder to encode Event Stream +// messages to an io.Writer. +func NewEncoder(w io.Writer) *Encoder { + return &Encoder{ + w: w, + headersBuf: bytes.NewBuffer(nil), + } +} + +// Encode encodes a single EventStream message to the io.Writer the Encoder +// was created with. An error is returned if writing the message fails. +func (e *Encoder) Encode(msg Message) error { + e.headersBuf.Reset() + + err := encodeHeaders(e.headersBuf, msg.Headers) + if err != nil { + return err + } + + crc := crc32.New(crc32IEEETable) + hashWriter := io.MultiWriter(e.w, crc) + + headersLen := uint32(e.headersBuf.Len()) + payloadLen := uint32(len(msg.Payload)) + + if err := encodePrelude(hashWriter, crc, headersLen, payloadLen); err != nil { + return err + } + + if headersLen > 0 { + if _, err := io.Copy(hashWriter, e.headersBuf); err != nil { + return err + } + } + + if payloadLen > 0 { + if _, err := hashWriter.Write(msg.Payload); err != nil { + return err + } + } + + msgCRC := crc.Sum32() + return binary.Write(e.w, binary.BigEndian, msgCRC) +} + +func encodePrelude(w io.Writer, crc hash.Hash32, headersLen, payloadLen uint32) error { + p := messagePrelude{ + Length: minMsgLen + headersLen + payloadLen, + HeadersLen: headersLen, + } + if err := p.ValidateLens(); err != nil { + return err + } + + err := binaryWriteFields(w, binary.BigEndian, + p.Length, + p.HeadersLen, + ) + if err != nil { + return err + } + + p.PreludeCRC = crc.Sum32() + err = binary.Write(w, binary.BigEndian, p.PreludeCRC) + if err != nil { + return err + } + + return nil +} + +func encodeHeaders(w io.Writer, headers Headers) error { + for _, h := range headers { + hn := headerName{ + Len: uint8(len(h.Name)), + } + copy(hn.Name[:hn.Len], h.Name) + if err := hn.encode(w); err != nil { + return err + } + + if err := h.Value.encode(w); err != nil { + return err + } + } + + return nil +} + +func binaryWriteFields(w io.Writer, order binary.ByteOrder, vs ...interface{}) error { + for _, v := range vs { + if err := binary.Write(w, order, v); err != nil { + return err + } + } + return nil +} |