From a18a13fb09eac00cdacf1f74080524182b7243de Mon Sep 17 00:00:00 2001 From: Niall Sheridan Date: Mon, 6 Jun 2016 00:55:30 +0100 Subject: update vendor --- vendor/golang.org/x/net/http2/hpack/hpack.go | 542 +++++++++++++++++++++++++++ 1 file changed, 542 insertions(+) create mode 100644 vendor/golang.org/x/net/http2/hpack/hpack.go (limited to 'vendor/golang.org/x/net/http2/hpack/hpack.go') diff --git a/vendor/golang.org/x/net/http2/hpack/hpack.go b/vendor/golang.org/x/net/http2/hpack/hpack.go new file mode 100644 index 0000000..8aa197a --- /dev/null +++ b/vendor/golang.org/x/net/http2/hpack/hpack.go @@ -0,0 +1,542 @@ +// 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 implements HPACK, a compression format for +// efficiently representing HTTP header fields in the context of HTTP/2. +// +// See http://tools.ietf.org/html/draft-ietf-httpbis-header-compression-09 +package hpack + +import ( + "bytes" + "errors" + "fmt" +) + +// A DecodingError is something the spec defines as a decoding error. +type DecodingError struct { + Err error +} + +func (de DecodingError) Error() string { + return fmt.Sprintf("decoding error: %v", de.Err) +} + +// An InvalidIndexError is returned when an encoder references a table +// entry before the static table or after the end of the dynamic table. +type InvalidIndexError int + +func (e InvalidIndexError) Error() string { + return fmt.Sprintf("invalid indexed representation index %d", int(e)) +} + +// A HeaderField is a name-value pair. Both the name and value are +// treated as opaque sequences of octets. +type HeaderField struct { + Name, Value string + + // Sensitive means that this header field should never be + // indexed. + Sensitive 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 (hf HeaderField) IsPseudo() bool { + return len(hf.Name) != 0 && hf.Name[0] == ':' +} + +func (hf HeaderField) String() string { + var suffix string + if hf.Sensitive { + suffix = " (sensitive)" + } + return fmt.Sprintf("header field %q = %q%s", hf.Name, hf.Value, suffix) +} + +// Size returns the size of an entry per RFC 7540 section 5.2. +func (hf HeaderField) Size() uint32 { + // http://http2.github.io/http2-spec/compression.html#rfc.section.4.1 + // "The size of the dynamic table is the sum of the size of + // its entries. The size of an entry is the sum of its name's + // length in octets (as defined in Section 5.2), its value's + // length in octets (see Section 5.2), plus 32. The size of + // an entry is calculated using the length of the name and + // value without any Huffman encoding applied." + + // This can overflow if somebody makes a large HeaderField + // Name and/or Value by hand, but we don't care, because that + // won't happen on the wire because the encoding doesn't allow + // it. + return uint32(len(hf.Name) + len(hf.Value) + 32) +} + +// A Decoder is the decoding context for incremental processing of +// header blocks. +type Decoder struct { + dynTab dynamicTable + emit func(f HeaderField) + + emitEnabled bool // whether calls to emit are enabled + maxStrLen int // 0 means unlimited + + // buf is the unparsed buffer. It's only written to + // saveBuf if it was truncated in the middle of a header + // block. Because it's usually not owned, we can only + // process it under Write. + buf []byte // not owned; only valid during Write + + // saveBuf is previous data passed to Write which we weren't able + // to fully parse before. Unlike buf, we own this data. + saveBuf bytes.Buffer +} + +// 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 NewDecoder(maxDynamicTableSize uint32, emitFunc func(f HeaderField)) *Decoder { + d := &Decoder{ + emit: emitFunc, + emitEnabled: true, + } + d.dynTab.allowedMaxSize = maxDynamicTableSize + d.dynTab.setMaxSize(maxDynamicTableSize) + return d +} + +// ErrStringLength is returned by Decoder.Write when the max string length +// (as configured by Decoder.SetMaxStringLength) would be violated. +var ErrStringLength = errors.New("hpack: string too long") + +// 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 (d *Decoder) SetMaxStringLength(n int) { + d.maxStrLen = n +} + +// SetEmitFunc changes the callback used when new header fields +// are decoded. +// It must be non-nil. It does not affect EmitEnabled. +func (d *Decoder) SetEmitFunc(emitFunc func(f HeaderField)) { + d.emit = emitFunc +} + +// 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 (d *Decoder) SetEmitEnabled(v bool) { d.emitEnabled = v } + +// EmitEnabled reports whether calls to the emitFunc provided to NewDecoder +// are currently enabled. The default is true. +func (d *Decoder) EmitEnabled() bool { return d.emitEnabled } + +// TODO: add method *Decoder.Reset(maxSize, emitFunc) to let callers re-use Decoders and their +// underlying buffers for garbage reasons. + +func (d *Decoder) SetMaxDynamicTableSize(v uint32) { + d.dynTab.setMaxSize(v) +} + +// SetAllowedMaxDynamicTableSize sets the upper bound that the encoded +// stream (via dynamic table size updates) may set the maximum size +// to. +func (d *Decoder) SetAllowedMaxDynamicTableSize(v uint32) { + d.dynTab.allowedMaxSize = v +} + +type dynamicTable struct { + // ents is the FIFO described at + // http://http2.github.io/http2-spec/compression.html#rfc.section.2.3.2 + // The newest (low index) is append at the end, and items are + // evicted from the front. + ents []HeaderField + size uint32 + maxSize uint32 // current maxSize + allowedMaxSize uint32 // maxSize may go up to this, inclusive +} + +func (dt *dynamicTable) setMaxSize(v uint32) { + dt.maxSize = v + dt.evict() +} + +// TODO: change dynamicTable to be a struct with a slice and a size int field, +// per http://http2.github.io/http2-spec/compression.html#rfc.section.4.1: +// +// +// Then make add increment the size. maybe the max size should move from Decoder to +// dynamicTable and add should return an ok bool if there was enough space. +// +// Later we'll need a remove operation on dynamicTable. + +func (dt *dynamicTable) add(f HeaderField) { + dt.ents = append(dt.ents, f) + dt.size += f.Size() + dt.evict() +} + +// If we're too big, evict old stuff (front of the slice) +func (dt *dynamicTable) evict() { + base := dt.ents // keep base pointer of slice + for dt.size > dt.maxSize { + dt.size -= dt.ents[0].Size() + dt.ents = dt.ents[1:] + } + + // Shift slice contents down if we evicted things. + if len(dt.ents) != len(base) { + copy(base, dt.ents) + dt.ents = base[:len(dt.ents)] + } +} + +// constantTimeStringCompare compares string a and b in a constant +// time manner. +func constantTimeStringCompare(a, b string) bool { + if len(a) != len(b) { + return false + } + + c := byte(0) + + for i := 0; i < len(a); i++ { + c |= a[i] ^ b[i] + } + + return c == 0 +} + +// Search searches f in the table. The return value i is 0 if there is +// no name match. If there is name match or name/value match, i is the +// index of that entry (1-based). If both name and value match, +// nameValueMatch becomes true. +func (dt *dynamicTable) search(f HeaderField) (i uint64, nameValueMatch bool) { + l := len(dt.ents) + for j := l - 1; j >= 0; j-- { + ent := dt.ents[j] + if !constantTimeStringCompare(ent.Name, f.Name) { + continue + } + if i == 0 { + i = uint64(l - j) + } + if f.Sensitive { + continue + } + if !constantTimeStringCompare(ent.Value, f.Value) { + continue + } + i = uint64(l - j) + nameValueMatch = true + return + } + return +} + +func (d *Decoder) maxTableIndex() int { + return len(d.dynTab.ents) + len(staticTable) +} + +func (d *Decoder) at(i uint64) (hf HeaderField, ok bool) { + if i < 1 { + return + } + if i > uint64(d.maxTableIndex()) { + return + } + if i <= uint64(len(staticTable)) { + return staticTable[i-1], true + } + dents := d.dynTab.ents + return dents[len(dents)-(int(i)-len(staticTable))], true +} + +// Decode decodes an entire block. +// +// TODO: remove this method and make it incremental later? This is +// easier for debugging now. +func (d *Decoder) DecodeFull(p []byte) ([]HeaderField, error) { + var hf []HeaderField + saveFunc := d.emit + defer func() { d.emit = saveFunc }() + d.emit = func(f HeaderField) { hf = append(hf, f) } + if _, err := d.Write(p); err != nil { + return nil, err + } + if err := d.Close(); err != nil { + return nil, err + } + return hf, nil +} + +func (d *Decoder) Close() error { + if d.saveBuf.Len() > 0 { + d.saveBuf.Reset() + return DecodingError{errors.New("truncated headers")} + } + return nil +} + +func (d *Decoder) Write(p []byte) (n int, err error) { + if len(p) == 0 { + // Prevent state machine CPU attacks (making us redo + // work up to the point of finding out we don't have + // enough data) + return + } + // Only copy the data if we have to. Optimistically assume + // that p will contain a complete header block. + if d.saveBuf.Len() == 0 { + d.buf = p + } else { + d.saveBuf.Write(p) + d.buf = d.saveBuf.Bytes() + d.saveBuf.Reset() + } + + for len(d.buf) > 0 { + err = d.parseHeaderFieldRepr() + if err == errNeedMore { + // Extra paranoia, making sure saveBuf won't + // get too large. All the varint and string + // reading code earlier should already catch + // overlong things and return ErrStringLength, + // but keep this as a last resort. + const varIntOverhead = 8 // conservative + if d.maxStrLen != 0 && int64(len(d.buf)) > 2*(int64(d.maxStrLen)+varIntOverhead) { + return 0, ErrStringLength + } + d.saveBuf.Write(d.buf) + return len(p), nil + } + if err != nil { + break + } + } + return len(p), err +} + +// errNeedMore is an internal sentinel error value that means the +// buffer is truncated and we need to read more data before we can +// continue parsing. +var errNeedMore = errors.New("need more data") + +type indexType int + +const ( + indexedTrue indexType = iota + indexedFalse + indexedNever +) + +func (v indexType) indexed() bool { return v == indexedTrue } +func (v indexType) sensitive() bool { return v == indexedNever } + +// returns errNeedMore if there isn't enough data available. +// any other error is fatal. +// consumes d.buf iff it returns nil. +// precondition: must be called with len(d.buf) > 0 +func (d *Decoder) parseHeaderFieldRepr() error { + b := d.buf[0] + switch { + case b&128 != 0: + // Indexed representation. + // High bit set? + // http://http2.github.io/http2-spec/compression.html#rfc.section.6.1 + return d.parseFieldIndexed() + case b&192 == 64: + // 6.2.1 Literal Header Field with Incremental Indexing + // 0b10xxxxxx: top two bits are 10 + // http://http2.github.io/http2-spec/compression.html#rfc.section.6.2.1 + return d.parseFieldLiteral(6, indexedTrue) + case b&240 == 0: + // 6.2.2 Literal Header Field without Indexing + // 0b0000xxxx: top four bits are 0000 + // http://http2.github.io/http2-spec/compression.html#rfc.section.6.2.2 + return d.parseFieldLiteral(4, indexedFalse) + case b&240 == 16: + // 6.2.3 Literal Header Field never Indexed + // 0b0001xxxx: top four bits are 0001 + // http://http2.github.io/http2-spec/compression.html#rfc.section.6.2.3 + return d.parseFieldLiteral(4, indexedNever) + case b&224 == 32: + // 6.3 Dynamic Table Size Update + // Top three bits are '001'. + // http://http2.github.io/http2-spec/compression.html#rfc.section.6.3 + return d.parseDynamicTableSizeUpdate() + } + + return DecodingError{errors.New("invalid encoding")} +} + +// (same invariants and behavior as parseHeaderFieldRepr) +func (d *Decoder) parseFieldIndexed() error { + buf := d.buf + idx, buf, err := readVarInt(7, buf) + if err != nil { + return err + } + hf, ok := d.at(idx) + if !ok { + return DecodingError{InvalidIndexError(idx)} + } + d.buf = buf + return d.callEmit(HeaderField{Name: hf.Name, Value: hf.Value}) +} + +// (same invariants and behavior as parseHeaderFieldRepr) +func (d *Decoder) parseFieldLiteral(n uint8, it indexType) error { + buf := d.buf + nameIdx, buf, err := readVarInt(n, buf) + if err != nil { + return err + } + + var hf HeaderField + wantStr := d.emitEnabled || it.indexed() + if nameIdx > 0 { + ihf, ok := d.at(nameIdx) + if !ok { + return DecodingError{InvalidIndexError(nameIdx)} + } + hf.Name = ihf.Name + } else { + hf.Name, buf, err = d.readString(buf, wantStr) + if err != nil { + return err + } + } + hf.Value, buf, err = d.readString(buf, wantStr) + if err != nil { + return err + } + d.buf = buf + if it.indexed() { + d.dynTab.add(hf) + } + hf.Sensitive = it.sensitive() + return d.callEmit(hf) +} + +func (d *Decoder) callEmit(hf HeaderField) error { + if d.maxStrLen != 0 { + if len(hf.Name) > d.maxStrLen || len(hf.Value) > d.maxStrLen { + return ErrStringLength + } + } + if d.emitEnabled { + d.emit(hf) + } + return nil +} + +// (same invariants and behavior as parseHeaderFieldRepr) +func (d *Decoder) parseDynamicTableSizeUpdate() error { + buf := d.buf + size, buf, err := readVarInt(5, buf) + if err != nil { + return err + } + if size > uint64(d.dynTab.allowedMaxSize) { + return DecodingError{errors.New("dynamic table size update too large")} + } + d.dynTab.setMaxSize(uint32(size)) + d.buf = buf + return nil +} + +var errVarintOverflow = DecodingError{errors.New("varint integer overflow")} + +// readVarInt reads an unsigned variable length integer off the +// beginning of p. n is the parameter as described in +// http://http2.github.io/http2-spec/compression.html#rfc.section.5.1. +// +// n must always be between 1 and 8. +// +// The returned remain buffer is either a smaller suffix of p, or err != nil. +// The error is errNeedMore if p doesn't contain a complete integer. +func readVarInt(n byte, p []byte) (i uint64, remain []byte, err error) { + if n < 1 || n > 8 { + panic("bad n") + } + if len(p) == 0 { + return 0, p, errNeedMore + } + i = uint64(p[0]) + if n < 8 { + i &= (1 << uint64(n)) - 1 + } + if i < (1< 0 { + b := p[0] + p = p[1:] + i += uint64(b&127) << m + if b&128 == 0 { + return i, p, nil + } + m += 7 + if m >= 63 { // TODO: proper overflow check. making this up. + return 0, origP, errVarintOverflow + } + } + return 0, origP, errNeedMore +} + +// readString decodes an hpack string from p. +// +// wantStr is whether s will be used. If false, decompression and +// []byte->string garbage are skipped if s will be ignored +// anyway. This does mean that huffman decoding errors for non-indexed +// strings past the MAX_HEADER_LIST_SIZE are ignored, but the server +// is returning an error anyway, and because they're not indexed, the error +// won't affect the decoding state. +func (d *Decoder) readString(p []byte, wantStr bool) (s string, remain []byte, err error) { + if len(p) == 0 { + return "", p, errNeedMore + } + isHuff := p[0]&128 != 0 + strLen, p, err := readVarInt(7, p) + if err != nil { + return "", p, err + } + if d.maxStrLen != 0 && strLen > uint64(d.maxStrLen) { + return "", nil, ErrStringLength + } + if uint64(len(p)) < strLen { + return "", p, errNeedMore + } + if !isHuff { + if wantStr { + s = string(p[:strLen]) + } + return s, p[strLen:], nil + } + + if wantStr { + buf := bufPool.Get().(*bytes.Buffer) + buf.Reset() // don't trust others + defer bufPool.Put(buf) + if err := huffmanDecode(buf, d.maxStrLen, p[:strLen]); err != nil { + buf.Reset() + return "", nil, err + } + s = buf.String() + buf.Reset() // be nice to GC + } + return s, p[strLen:], nil +} -- cgit v1.2.3