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author | Christopher Speller <crspeller@gmail.com> | 2016-10-03 16:03:15 -0400 |
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committer | GitHub <noreply@github.com> | 2016-10-03 16:03:15 -0400 |
commit | 8f91c777559748fa6e857d9fc1f4ae079a532813 (patch) | |
tree | 190f7cef373764a0d47a91045fdb486ee3d6781d /vendor/golang.org/x/net/http2/hpack/encode.go | |
parent | 5f8e5c401bd96cba9a98b2db02d72f9cbacb0103 (diff) | |
download | chat-8f91c777559748fa6e857d9fc1f4ae079a532813.tar.gz chat-8f91c777559748fa6e857d9fc1f4ae079a532813.tar.bz2 chat-8f91c777559748fa6e857d9fc1f4ae079a532813.zip |
Adding ability to serve TLS directly from Mattermost server (#4119)
Diffstat (limited to 'vendor/golang.org/x/net/http2/hpack/encode.go')
-rw-r--r-- | vendor/golang.org/x/net/http2/hpack/encode.go | 251 |
1 files changed, 251 insertions, 0 deletions
diff --git a/vendor/golang.org/x/net/http2/hpack/encode.go b/vendor/golang.org/x/net/http2/hpack/encode.go new file mode 100644 index 000000000..f9bb03398 --- /dev/null +++ b/vendor/golang.org/x/net/http2/hpack/encode.go @@ -0,0 +1,251 @@ +// Copyright 2014 The Go Authors. All rights reserved. +// Use of this source code is governed by a BSD-style +// license that can be found in the LICENSE file. + +package hpack + +import ( + "io" +) + +const ( + uint32Max = ^uint32(0) + initialHeaderTableSize = 4096 +) + +type Encoder struct { + dynTab dynamicTable + // minSize is the minimum table size set by + // SetMaxDynamicTableSize after the previous Header Table Size + // Update. + minSize uint32 + // maxSizeLimit is the maximum table size this encoder + // supports. This will protect the encoder from too large + // size. + maxSizeLimit uint32 + // tableSizeUpdate indicates whether "Header Table Size + // Update" is required. + tableSizeUpdate bool + w io.Writer + buf []byte +} + +// NewEncoder returns a new Encoder which performs HPACK encoding. An +// encoded data is written to w. +func NewEncoder(w io.Writer) *Encoder { + e := &Encoder{ + minSize: uint32Max, + maxSizeLimit: initialHeaderTableSize, + tableSizeUpdate: false, + w: w, + } + e.dynTab.setMaxSize(initialHeaderTableSize) + return e +} + +// 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. +func (e *Encoder) WriteField(f HeaderField) error { + e.buf = e.buf[:0] + + if e.tableSizeUpdate { + e.tableSizeUpdate = false + if e.minSize < e.dynTab.maxSize { + e.buf = appendTableSize(e.buf, e.minSize) + } + e.minSize = uint32Max + e.buf = appendTableSize(e.buf, e.dynTab.maxSize) + } + + idx, nameValueMatch := e.searchTable(f) + if nameValueMatch { + e.buf = appendIndexed(e.buf, idx) + } else { + indexing := e.shouldIndex(f) + if indexing { + e.dynTab.add(f) + } + + if idx == 0 { + e.buf = appendNewName(e.buf, f, indexing) + } else { + e.buf = appendIndexedName(e.buf, f, idx, indexing) + } + } + n, err := e.w.Write(e.buf) + if err == nil && n != len(e.buf) { + err = io.ErrShortWrite + } + return err +} + +// searchTable searches f in both stable and dynamic header tables. +// The static header table is searched first. Only when there is no +// exact match for both name and value, the dynamic header table is +// then searched. If there is no match, i is 0. If both name and value +// match, i is the matched index and nameValueMatch becomes true. If +// only name matches, i points to that index and nameValueMatch +// becomes false. +func (e *Encoder) searchTable(f HeaderField) (i uint64, nameValueMatch bool) { + for idx, hf := range staticTable { + if !constantTimeStringCompare(hf.Name, f.Name) { + continue + } + if i == 0 { + i = uint64(idx + 1) + } + if f.Sensitive { + continue + } + if !constantTimeStringCompare(hf.Value, f.Value) { + continue + } + i = uint64(idx + 1) + nameValueMatch = true + return + } + + j, nameValueMatch := e.dynTab.search(f) + if nameValueMatch || (i == 0 && j != 0) { + i = j + uint64(len(staticTable)) + } + return +} + +// SetMaxDynamicTableSize changes the dynamic header table size to v. +// The actual size is bounded by the value passed to +// SetMaxDynamicTableSizeLimit. +func (e *Encoder) SetMaxDynamicTableSize(v uint32) { + if v > e.maxSizeLimit { + v = e.maxSizeLimit + } + if v < e.minSize { + e.minSize = v + } + e.tableSizeUpdate = true + e.dynTab.setMaxSize(v) +} + +// 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 (e *Encoder) SetMaxDynamicTableSizeLimit(v uint32) { + e.maxSizeLimit = v + if e.dynTab.maxSize > v { + e.tableSizeUpdate = true + e.dynTab.setMaxSize(v) + } +} + +// shouldIndex reports whether f should be indexed. +func (e *Encoder) shouldIndex(f HeaderField) bool { + return !f.Sensitive && f.Size() <= e.dynTab.maxSize +} + +// appendIndexed appends index i, as encoded in "Indexed Header Field" +// representation, to dst and returns the extended buffer. +func appendIndexed(dst []byte, i uint64) []byte { + first := len(dst) + dst = appendVarInt(dst, 7, i) + dst[first] |= 0x80 + return dst +} + +// appendNewName appends f, as encoded in one of "Literal Header field +// - New Name" representation variants, to dst and returns the +// extended buffer. +// +// If f.Sensitive is true, "Never Indexed" representation is used. If +// f.Sensitive is false and indexing is true, "Inremental Indexing" +// representation is used. +func appendNewName(dst []byte, f HeaderField, indexing bool) []byte { + dst = append(dst, encodeTypeByte(indexing, f.Sensitive)) + dst = appendHpackString(dst, f.Name) + return appendHpackString(dst, f.Value) +} + +// appendIndexedName appends f and index i referring indexed name +// entry, as encoded in one of "Literal Header field - Indexed Name" +// representation variants, to dst and returns the extended buffer. +// +// If f.Sensitive is true, "Never Indexed" representation is used. If +// f.Sensitive is false and indexing is true, "Incremental Indexing" +// representation is used. +func appendIndexedName(dst []byte, f HeaderField, i uint64, indexing bool) []byte { + first := len(dst) + var n byte + if indexing { + n = 6 + } else { + n = 4 + } + dst = appendVarInt(dst, n, i) + dst[first] |= encodeTypeByte(indexing, f.Sensitive) + return appendHpackString(dst, f.Value) +} + +// appendTableSize appends v, as encoded in "Header Table Size Update" +// representation, to dst and returns the extended buffer. +func appendTableSize(dst []byte, v uint32) []byte { + first := len(dst) + dst = appendVarInt(dst, 5, uint64(v)) + dst[first] |= 0x20 + return dst +} + +// appendVarInt appends i, as encoded in variable integer form using n +// bit prefix, to dst and returns the extended buffer. +// +// See +// http://http2.github.io/http2-spec/compression.html#integer.representation +func appendVarInt(dst []byte, n byte, i uint64) []byte { + k := uint64((1 << n) - 1) + if i < k { + return append(dst, byte(i)) + } + dst = append(dst, byte(k)) + i -= k + for ; i >= 128; i >>= 7 { + dst = append(dst, byte(0x80|(i&0x7f))) + } + return append(dst, byte(i)) +} + +// appendHpackString appends s, as encoded in "String Literal" +// representation, to dst and returns the the extended buffer. +// +// s will be encoded in Huffman codes only when it produces strictly +// shorter byte string. +func appendHpackString(dst []byte, s string) []byte { + huffmanLength := HuffmanEncodeLength(s) + if huffmanLength < uint64(len(s)) { + first := len(dst) + dst = appendVarInt(dst, 7, huffmanLength) + dst = AppendHuffmanString(dst, s) + dst[first] |= 0x80 + } else { + dst = appendVarInt(dst, 7, uint64(len(s))) + dst = append(dst, s...) + } + return dst +} + +// encodeTypeByte returns type byte. If sensitive is true, type byte +// for "Never Indexed" representation is returned. If sensitive is +// false and indexing is true, type byte for "Incremental Indexing" +// representation is returned. Otherwise, type byte for "Without +// Indexing" is returned. +func encodeTypeByte(indexing, sensitive bool) byte { + if sensitive { + return 0x10 + } + if indexing { + return 0x40 + } + return 0 +} |