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// 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 (
"fmt"
)
// headerFieldTable implements a list of HeaderFields.
// This is used to implement the static and dynamic tables.
type headerFieldTable struct {
// For static tables, entries are never evicted.
//
// For dynamic tables, entries are evicted from ents[0] and added to the end.
// Each entry has a unique id that starts at one and increments for each
// entry that is added. This unique id is stable across evictions, meaning
// it can be used as a pointer to a specific entry. As in hpack, unique ids
// are 1-based. The unique id for ents[k] is k + evictCount + 1.
//
// Zero is not a valid unique id.
//
// evictCount should not overflow in any remotely practical situation. In
// practice, we will have one dynamic table per HTTP/2 connection. If we
// assume a very powerful server that handles 1M QPS per connection and each
// request adds (then evicts) 100 entries from the table, it would still take
// 2M years for evictCount to overflow.
ents []HeaderField
evictCount uint64
// byName maps a HeaderField name to the unique id of the newest entry with
// the same name. See above for a definition of "unique id".
byName map[string]uint64
// byNameValue maps a HeaderField name/value pair to the unique id of the newest
// entry with the same name and value. See above for a definition of "unique id".
byNameValue map[pairNameValue]uint64
}
type pairNameValue struct {
name, value string
}
func (t *headerFieldTable) init() {
t.byName = make(map[string]uint64)
t.byNameValue = make(map[pairNameValue]uint64)
}
// len reports the number of entries in the table.
func (t *headerFieldTable) len() int {
return len(t.ents)
}
// addEntry adds a new entry.
func (t *headerFieldTable) addEntry(f HeaderField) {
id := uint64(t.len()) + t.evictCount + 1
t.byName[f.Name] = id
t.byNameValue[pairNameValue{f.Name, f.Value}] = id
t.ents = append(t.ents, f)
}
// evictOldest evicts the n oldest entries in the table.
func (t *headerFieldTable) evictOldest(n int) {
if n > t.len() {
panic(fmt.Sprintf("evictOldest(%v) on table with %v entries", n, t.len()))
}
for k := 0; k < n; k++ {
f := t.ents[k]
id := t.evictCount + uint64(k) + 1
if t.byName[f.Name] == id {
delete(t.byName, f.Name)
}
if p := (pairNameValue{f.Name, f.Value}); t.byNameValue[p] == id {
delete(t.byNameValue, p)
}
}
copy(t.ents, t.ents[n:])
for k := t.len() - n; k < t.len(); k++ {
t.ents[k] = HeaderField{} // so strings can be garbage collected
}
t.ents = t.ents[:t.len()-n]
if t.evictCount+uint64(n) < t.evictCount {
panic("evictCount overflow")
}
t.evictCount += uint64(n)
}
// search finds f in the table. 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.
//
// The returned index is a 1-based HPACK index. For dynamic tables, HPACK says
// that index 1 should be the newest entry, but t.ents[0] is the oldest entry,
// meaning t.ents is reversed for dynamic tables. Hence, when t is a dynamic
// table, the return value i actually refers to the entry t.ents[t.len()-i].
//
// All tables are assumed to be a dynamic tables except for the global
// staticTable pointer.
//
// See Section 2.3.3.
func (t *headerFieldTable) search(f HeaderField) (i uint64, nameValueMatch bool) {
if !f.Sensitive {
if id := t.byNameValue[pairNameValue{f.Name, f.Value}]; id != 0 {
return t.idToIndex(id), true
}
}
if id := t.byName[f.Name]; id != 0 {
return t.idToIndex(id), false
}
return 0, false
}
// idToIndex converts a unique id to an HPACK index.
// See Section 2.3.3.
func (t *headerFieldTable) idToIndex(id uint64) uint64 {
if id <= t.evictCount {
panic(fmt.Sprintf("id (%v) <= evictCount (%v)", id, t.evictCount))
}
k := id - t.evictCount - 1 // convert id to an index t.ents[k]
if t != staticTable {
return uint64(t.len()) - k // dynamic table
}
return k + 1
}
// http://tools.ietf.org/html/draft-ietf-httpbis-header-compression-07#appendix-B
var staticTable = newStaticTable()
var staticTableEntries = [...]HeaderField{
HeaderField{Name: ":authority"},
HeaderField{Name: ":method", Value: "GET"},
HeaderField{Name: ":method", Value: "POST"},
HeaderField{Name: ":path", Value: "/"},
HeaderField{Name: ":path", Value: "/index.html"},
HeaderField{Name: ":scheme", Value: "http"},
HeaderField{Name: ":scheme", Value: "https"},
HeaderField{Name: ":status", Value: "200"},
HeaderField{Name: ":status", Value: "204"},
HeaderField{Name: ":status", Value: "206"},
HeaderField{Name: ":status", Value: "304"},
HeaderField{Name: ":status", Value: "400"},
HeaderField{Name: ":status", Value: "404"},
HeaderField{Name: ":status", Value: "500"},
HeaderField{Name: "accept-charset"},
HeaderField{Name: "accept-encoding", Value: "gzip, deflate"},
HeaderField{Name: "accept-language"},
HeaderField{Name: "accept-ranges"},
HeaderField{Name: "accept"},
HeaderField{Name: "access-control-allow-origin"},
HeaderField{Name: "age"},
HeaderField{Name: "allow"},
HeaderField{Name: "authorization"},
HeaderField{Name: "cache-control"},
HeaderField{Name: "content-disposition"},
HeaderField{Name: "content-encoding"},
HeaderField{Name: "content-language"},
HeaderField{Name: "content-length"},
HeaderField{Name: "content-location"},
HeaderField{Name: "content-range"},
HeaderField{Name: "content-type"},
HeaderField{Name: "cookie"},
HeaderField{Name: "date"},
HeaderField{Name: "etag"},
HeaderField{Name: "expect"},
HeaderField{Name: "expires"},
HeaderField{Name: "from"},
HeaderField{Name: "host"},
HeaderField{Name: "if-match"},
HeaderField{Name: "if-modified-since"},
HeaderField{Name: "if-none-match"},
HeaderField{Name: "if-range"},
HeaderField{Name: "if-unmodified-since"},
HeaderField{Name: "last-modified"},
HeaderField{Name: "link"},
HeaderField{Name: "location"},
HeaderField{Name: "max-forwards"},
HeaderField{Name: "proxy-authenticate"},
HeaderField{Name: "proxy-authorization"},
HeaderField{Name: "range"},
HeaderField{Name: "referer"},
HeaderField{Name: "refresh"},
HeaderField{Name: "retry-after"},
HeaderField{Name: "server"},
HeaderField{Name: "set-cookie"},
HeaderField{Name: "strict-transport-security"},
HeaderField{Name: "transfer-encoding"},
HeaderField{Name: "user-agent"},
HeaderField{Name: "vary"},
HeaderField{Name: "via"},
HeaderField{Name: "www-authenticate"},
}
func newStaticTable() *headerFieldTable {
t := &headerFieldTable{}
t.init()
for _, e := range staticTableEntries[:] {
t.addEntry(e)
}
return t
}
var huffmanCodes = [256]uint32{
0x1ff8,
0x7fffd8,
0xfffffe2,
0xfffffe3,
0xfffffe4,
0xfffffe5,
0xfffffe6,
0xfffffe7,
0xfffffe8,
0xffffea,
0x3ffffffc,
0xfffffe9,
0xfffffea,
0x3ffffffd,
0xfffffeb,
0xfffffec,
0xfffffed,
0xfffffee,
0xfffffef,
0xffffff0,
0xffffff1,
0xffffff2,
0x3ffffffe,
0xffffff3,
0xffffff4,
0xffffff5,
0xffffff6,
0xffffff7,
0xffffff8,
0xffffff9,
0xffffffa,
0xffffffb,
0x14,
0x3f8,
0x3f9,
0xffa,
0x1ff9,
0x15,
0xf8,
0x7fa,
0x3fa,
0x3fb,
0xf9,
0x7fb,
0xfa,
0x16,
0x17,
0x18,
0x0,
0x1,
0x2,
0x19,
0x1a,
0x1b,
0x1c,
0x1d,
0x1e,
0x1f,
0x5c,
0xfb,
0x7ffc,
0x20,
0xffb,
0x3fc,
0x1ffa,
0x21,
0x5d,
0x5e,
0x5f,
0x60,
0x61,
0x62,
0x63,
0x64,
0x65,
0x66,
0x67,
0x68,
0x69,
0x6a,
0x6b,
0x6c,
0x6d,
0x6e,
0x6f,
0x70,
0x71,
0x72,
0xfc,
0x73,
0xfd,
0x1ffb,
0x7fff0,
0x1ffc,
0x3ffc,
0x22,
0x7ffd,
0x3,
0x23,
0x4,
0x24,
0x5,
0x25,
0x26,
0x27,
0x6,
0x74,
0x75,
0x28,
0x29,
0x2a,
0x7,
0x2b,
0x76,
0x2c,
0x8,
0x9,
0x2d,
0x77,
0x78,
0x79,
0x7a,
0x7b,
0x7ffe,
0x7fc,
0x3ffd,
0x1ffd,
0xffffffc,
0xfffe6,
0x3fffd2,
0xfffe7,
0xfffe8,
0x3fffd3,
0x3fffd4,
0x3fffd5,
0x7fffd9,
0x3fffd6,
0x7fffda,
0x7fffdb,
0x7fffdc,
0x7fffdd,
0x7fffde,
0xffffeb,
0x7fffdf,
0xffffec,
0xffffed,
0x3fffd7,
0x7fffe0,
0xffffee,
0x7fffe1,
0x7fffe2,
0x7fffe3,
0x7fffe4,
0x1fffdc,
0x3fffd8,
0x7fffe5,
0x3fffd9,
0x7fffe6,
0x7fffe7,
0xffffef,
0x3fffda,
0x1fffdd,
0xfffe9,
0x3fffdb,
0x3fffdc,
0x7fffe8,
0x7fffe9,
0x1fffde,
0x7fffea,
0x3fffdd,
0x3fffde,
0xfffff0,
0x1fffdf,
0x3fffdf,
0x7fffeb,
0x7fffec,
0x1fffe0,
0x1fffe1,
0x3fffe0,
0x1fffe2,
0x7fffed,
0x3fffe1,
0x7fffee,
0x7fffef,
0xfffea,
0x3fffe2,
0x3fffe3,
0x3fffe4,
0x7ffff0,
0x3fffe5,
0x3fffe6,
0x7ffff1,
0x3ffffe0,
0x3ffffe1,
0xfffeb,
0x7fff1,
0x3fffe7,
0x7ffff2,
0x3fffe8,
0x1ffffec,
0x3ffffe2,
0x3ffffe3,
0x3ffffe4,
0x7ffffde,
0x7ffffdf,
0x3ffffe5,
0xfffff1,
0x1ffffed,
0x7fff2,
0x1fffe3,
0x3ffffe6,
0x7ffffe0,
0x7ffffe1,
0x3ffffe7,
0x7ffffe2,
0xfffff2,
0x1fffe4,
0x1fffe5,
0x3ffffe8,
0x3ffffe9,
0xffffffd,
0x7ffffe3,
0x7ffffe4,
0x7ffffe5,
0xfffec,
0xfffff3,
0xfffed,
0x1fffe6,
0x3fffe9,
0x1fffe7,
0x1fffe8,
0x7ffff3,
0x3fffea,
0x3fffeb,
0x1ffffee,
0x1ffffef,
0xfffff4,
0xfffff5,
0x3ffffea,
0x7ffff4,
0x3ffffeb,
0x7ffffe6,
0x3ffffec,
0x3ffffed,
0x7ffffe7,
0x7ffffe8,
0x7ffffe9,
0x7ffffea,
0x7ffffeb,
0xffffffe,
0x7ffffec,
0x7ffffed,
0x7ffffee,
0x7ffffef,
0x7fffff0,
0x3ffffee,
}
var huffmanCodeLen = [256]uint8{
13, 23, 28, 28, 28, 28, 28, 28, 28, 24, 30, 28, 28, 30, 28, 28,
28, 28, 28, 28, 28, 28, 30, 28, 28, 28, 28, 28, 28, 28, 28, 28,
6, 10, 10, 12, 13, 6, 8, 11, 10, 10, 8, 11, 8, 6, 6, 6,
5, 5, 5, 6, 6, 6, 6, 6, 6, 6, 7, 8, 15, 6, 12, 10,
13, 6, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
7, 7, 7, 7, 7, 7, 7, 7, 8, 7, 8, 13, 19, 13, 14, 6,
15, 5, 6, 5, 6, 5, 6, 6, 6, 5, 7, 7, 6, 6, 6, 5,
6, 7, 6, 5, 5, 6, 7, 7, 7, 7, 7, 15, 11, 14, 13, 28,
20, 22, 20, 20, 22, 22, 22, 23, 22, 23, 23, 23, 23, 23, 24, 23,
24, 24, 22, 23, 24, 23, 23, 23, 23, 21, 22, 23, 22, 23, 23, 24,
22, 21, 20, 22, 22, 23, 23, 21, 23, 22, 22, 24, 21, 22, 23, 23,
21, 21, 22, 21, 23, 22, 23, 23, 20, 22, 22, 22, 23, 22, 22, 23,
26, 26, 20, 19, 22, 23, 22, 25, 26, 26, 26, 27, 27, 26, 24, 25,
19, 21, 26, 27, 27, 26, 27, 24, 21, 21, 26, 26, 28, 27, 27, 27,
20, 24, 20, 21, 22, 21, 21, 23, 22, 22, 25, 25, 24, 24, 26, 23,
26, 27, 26, 26, 27, 27, 27, 27, 27, 28, 27, 27, 27, 27, 27, 26,
}