Package hpack implements HPACK, a compression format for efficiently representing HTTP header fields in the context of HTTP/2.




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    var ErrInvalidHuffman = errors.New("hpack: invalid Huffman-encoded data")

      ErrInvalidHuffman is returned for errors found decoding Huffman-encoded strings.

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      var ErrStringLength = errors.New("hpack: string too long")

        ErrStringLength is returned by Decoder.Write when the max string length (as configured by Decoder.SetMaxStringLength) would be violated.


        func AppendHuffmanString

        func AppendHuffmanString(dst []byte, s string) []byte

          AppendHuffmanString appends s, as encoded in Huffman codes, to dst and returns the extended buffer.

          func HuffmanDecode

          func HuffmanDecode(w io.Writer, v []byte) (int, error)

            HuffmanDecode decodes the string in v and writes the expanded result to w, returning the number of bytes written to w and the Write call's return value. At most one Write call is made.

            func HuffmanDecodeToString

            func HuffmanDecodeToString(v []byte) (string, error)

              HuffmanDecodeToString decodes the string in v.

              func HuffmanEncodeLength

              func HuffmanEncodeLength(s string) uint64

                HuffmanEncodeLength returns the number of bytes required to encode s in Huffman codes. The result is round up to byte boundary.


                type Decoder

                type Decoder struct {
                	// contains filtered or unexported fields

                  A Decoder is the decoding context for incremental processing of header blocks.

                  func NewDecoder

                  func NewDecoder(maxDynamicTableSize uint32, emitFunc func(f HeaderField)) *Decoder

                    NewDecoder returns a new decoder with the provided maximum dynamic table size. The emitFunc will be called for each valid field parsed, in the same goroutine as calls to Write, before Write returns.

                    func (*Decoder) Close

                    func (d *Decoder) Close() error

                      Close declares that the decoding is complete and resets the Decoder to be reused again for a new header block. If there is any remaining data in the decoder's buffer, Close returns an error.

                      func (*Decoder) DecodeFull

                      func (d *Decoder) DecodeFull(p []byte) ([]HeaderField, error)

                        Decode decodes an entire block.

                        TODO: remove this method and make it incremental later? This is easier for debugging now.

                        func (*Decoder) EmitEnabled

                        func (d *Decoder) EmitEnabled() bool

                          EmitEnabled reports whether calls to the emitFunc provided to NewDecoder are currently enabled. The default is true.

                          func (*Decoder) SetAllowedMaxDynamicTableSize

                          func (d *Decoder) SetAllowedMaxDynamicTableSize(v uint32)

                            SetAllowedMaxDynamicTableSize sets the upper bound that the encoded stream (via dynamic table size updates) may set the maximum size to.

                            func (*Decoder) SetEmitEnabled

                            func (d *Decoder) SetEmitEnabled(v bool)

                              SetEmitEnabled controls whether the emitFunc provided to NewDecoder should be called. The default is true.

                              This facility exists to let servers enforce MAX_HEADER_LIST_SIZE while still decoding and keeping in-sync with decoder state, but without doing unnecessary decompression or generating unnecessary garbage for header fields past the limit.

                              func (*Decoder) SetEmitFunc

                              func (d *Decoder) SetEmitFunc(emitFunc func(f HeaderField))

                                SetEmitFunc changes the callback used when new header fields are decoded. It must be non-nil. It does not affect EmitEnabled.

                                func (*Decoder) SetMaxDynamicTableSize

                                func (d *Decoder) SetMaxDynamicTableSize(v uint32)

                                func (*Decoder) SetMaxStringLength

                                func (d *Decoder) SetMaxStringLength(n int)

                                  SetMaxStringLength sets the maximum size of a HeaderField name or value string. If a string exceeds this length (even after any decompression), Write will return ErrStringLength. A value of 0 means unlimited and is the default from NewDecoder.

                                  func (*Decoder) Write

                                  func (d *Decoder) Write(p []byte) (n int, err error)

                                  type DecodingError

                                  type DecodingError struct {
                                  	Err error

                                    A DecodingError is something the spec defines as a decoding error.

                                    func (DecodingError) Error

                                    func (de DecodingError) Error() string

                                    type Encoder

                                    type Encoder struct {
                                    	// contains filtered or unexported fields

                                    func NewEncoder

                                    func NewEncoder(w io.Writer) *Encoder

                                      NewEncoder returns a new Encoder which performs HPACK encoding. An encoded data is written to w.

                                      func (*Encoder) SetMaxDynamicTableSize

                                      func (e *Encoder) SetMaxDynamicTableSize(v uint32)

                                        SetMaxDynamicTableSize changes the dynamic header table size to v. The actual size is bounded by the value passed to SetMaxDynamicTableSizeLimit.

                                        func (*Encoder) SetMaxDynamicTableSizeLimit

                                        func (e *Encoder) SetMaxDynamicTableSizeLimit(v uint32)

                                          SetMaxDynamicTableSizeLimit changes the maximum value that can be specified in SetMaxDynamicTableSize to v. By default, it is set to 4096, which is the same size of the default dynamic header table size described in HPACK specification. If the current maximum dynamic header table size is strictly greater than v, "Header Table Size Update" will be done in the next WriteField call and the maximum dynamic header table size is truncated to v.

                                          func (*Encoder) WriteField

                                          func (e *Encoder) WriteField(f HeaderField) error

                                            WriteField encodes f into a single Write to e's underlying Writer. This function may also produce bytes for "Header Table Size Update" if necessary. If produced, it is done before encoding f.

                                            type HeaderField

                                            type HeaderField struct {
                                            	Name, Value string
                                            	// Sensitive means that this header field should never be
                                            	// indexed.
                                            	Sensitive bool

                                              A HeaderField is a name-value pair. Both the name and value are treated as opaque sequences of octets.

                                              func (HeaderField) IsPseudo

                                              func (hf HeaderField) IsPseudo() bool

                                                IsPseudo reports whether the header field is an http2 pseudo header. That is, it reports whether it starts with a colon. It is not otherwise guaranteed to be a valid pseudo header field, though.

                                                func (HeaderField) Size

                                                func (hf HeaderField) Size() uint32

                                                  Size returns the size of an entry per RFC 7541 section 4.1.

                                                  func (HeaderField) String

                                                  func (hf HeaderField) String() string

                                                  type InvalidIndexError

                                                  type InvalidIndexError int

                                                    An InvalidIndexError is returned when an encoder references a table entry before the static table or after the end of the dynamic table.

                                                    func (InvalidIndexError) Error

                                                    func (e InvalidIndexError) Error() string