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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 http2 implements the HTTP/2 protocol.
//
// This package is low-level and intended to be used directly by very
// few people. Most users will use it indirectly through the automatic
// use by the net/http package (from Go 1.6 and later).
// For use in earlier Go versions see ConfigureServer. (Transport support
// requires Go 1.6 or later)
//
// See https://http2.github.io/ for more information on HTTP/2.
//
// See https://http2.golang.org/ for a test server running this code.
//
package http2 // import "golang.org/x/net/http2"
import (
"bufio"
"crypto/tls"
"errors"
"fmt"
"io"
"net/http"
"os"
"sort"
"strconv"
"strings"
"sync"
"golang.org/x/net/http/httpguts"
)
var (
VerboseLogs bool
logFrameWrites bool
logFrameReads bool
inTests bool
)
func init() {
e := os.Getenv("GODEBUG")
if strings.Contains(e, "http2debug=1") {
VerboseLogs = true
}
if strings.Contains(e, "http2debug=2") {
VerboseLogs = true
logFrameWrites = true
logFrameReads = true
}
}
const (
// ClientPreface is the string that must be sent by new
// connections from clients.
ClientPreface = "PRI * HTTP/2.0\r\n\r\nSM\r\n\r\n"
// SETTINGS_MAX_FRAME_SIZE default
// http://http2.github.io/http2-spec/#rfc.section.6.5.2
initialMaxFrameSize = 16384
// NextProtoTLS is the NPN/ALPN protocol negotiated during
// HTTP/2's TLS setup.
NextProtoTLS = "h2"
// http://http2.github.io/http2-spec/#SettingValues
initialHeaderTableSize = 4096
initialWindowSize = 65535 // 6.9.2 Initial Flow Control Window Size
defaultMaxReadFrameSize = 1 << 20
)
var (
clientPreface = []byte(ClientPreface)
)
type streamState int
// HTTP/2 stream states.
//
// See http://tools.ietf.org/html/rfc7540#section-5.1.
//
// For simplicity, the server code merges "reserved (local)" into
// "half-closed (remote)". This is one less state transition to track.
// The only downside is that we send PUSH_PROMISEs slightly less
// liberally than allowable. More discussion here:
// https://lists.w3.org/Archives/Public/ietf-http-wg/2016JulSep/0599.html
//
// "reserved (remote)" is omitted since the client code does not
// support server push.
const (
stateIdle streamState = iota
stateOpen
stateHalfClosedLocal
stateHalfClosedRemote
stateClosed
)
var stateName = [...]string{
stateIdle: "Idle",
stateOpen: "Open",
stateHalfClosedLocal: "HalfClosedLocal",
stateHalfClosedRemote: "HalfClosedRemote",
stateClosed: "Closed",
}
func (st streamState) String() string {
return stateName[st]
}
// Setting is a setting parameter: which setting it is, and its value.
type Setting struct {
// ID is which setting is being set.
// See http://http2.github.io/http2-spec/#SettingValues
ID SettingID
// Val is the value.
Val uint32
}
func (s Setting) String() string {
return fmt.Sprintf("[%v = %d]", s.ID, s.Val)
}
// Valid reports whether the setting is valid.
func (s Setting) Valid() error {
// Limits and error codes from 6.5.2 Defined SETTINGS Parameters
switch s.ID {
case SettingEnablePush:
if s.Val != 1 && s.Val != 0 {
return ConnectionError(ErrCodeProtocol)
}
case SettingInitialWindowSize:
if s.Val > 1<<31-1 {
return ConnectionError(ErrCodeFlowControl)
}
case SettingMaxFrameSize:
if s.Val < 16384 || s.Val > 1<<24-1 {
return ConnectionError(ErrCodeProtocol)
}
}
return nil
}
// A SettingID is an HTTP/2 setting as defined in
// http://http2.github.io/http2-spec/#iana-settings
type SettingID uint16
const (
SettingHeaderTableSize SettingID = 0x1
SettingEnablePush SettingID = 0x2
SettingMaxConcurrentStreams SettingID = 0x3
SettingInitialWindowSize SettingID = 0x4
SettingMaxFrameSize SettingID = 0x5
SettingMaxHeaderListSize SettingID = 0x6
)
var settingName = map[SettingID]string{
SettingHeaderTableSize: "HEADER_TABLE_SIZE",
SettingEnablePush: "ENABLE_PUSH",
SettingMaxConcurrentStreams: "MAX_CONCURRENT_STREAMS",
SettingInitialWindowSize: "INITIAL_WINDOW_SIZE",
SettingMaxFrameSize: "MAX_FRAME_SIZE",
SettingMaxHeaderListSize: "MAX_HEADER_LIST_SIZE",
}
func (s SettingID) String() string {
if v, ok := settingName[s]; ok {
return v
}
return fmt.Sprintf("UNKNOWN_SETTING_%d", uint16(s))
}
var (
errInvalidHeaderFieldName = errors.New("http2: invalid header field name")
errInvalidHeaderFieldValue = errors.New("http2: invalid header field value")
)
// validWireHeaderFieldName reports whether v is a valid header field
// name (key). See httpguts.ValidHeaderName for the base rules.
//
// Further, http2 says:
// "Just as in HTTP/1.x, header field names are strings of ASCII
// characters that are compared in a case-insensitive
// fashion. However, header field names MUST be converted to
// lowercase prior to their encoding in HTTP/2. "
func validWireHeaderFieldName(v string) bool {
if len(v) == 0 {
return false
}
for _, r := range v {
if !httpguts.IsTokenRune(r) {
return false
}
if 'A' <= r && r <= 'Z' {
return false
}
}
return true
}
func httpCodeString(code int) string {
switch code {
case 200:
return "200"
case 404:
return "404"
}
return strconv.Itoa(code)
}
// from pkg io
type stringWriter interface {
WriteString(s string) (n int, err error)
}
// A gate lets two goroutines coordinate their activities.
type gate chan struct{}
func (g gate) Done() { g <- struct{}{} }
func (g gate) Wait() { <-g }
// A closeWaiter is like a sync.WaitGroup but only goes 1 to 0 (open to closed).
type closeWaiter chan struct{}
// Init makes a closeWaiter usable.
// It exists because so a closeWaiter value can be placed inside a
// larger struct and have the Mutex and Cond's memory in the same
// allocation.
func (cw *closeWaiter) Init() {
*cw = make(chan struct{})
}
// Close marks the closeWaiter as closed and unblocks any waiters.
func (cw closeWaiter) Close() {
close(cw)
}
// Wait waits for the closeWaiter to become closed.
func (cw closeWaiter) Wait() {
<-cw
}
// bufferedWriter is a buffered writer that writes to w.
// Its buffered writer is lazily allocated as needed, to minimize
// idle memory usage with many connections.
type bufferedWriter struct {
w io.Writer // immutable
bw *bufio.Writer // non-nil when data is buffered
}
func newBufferedWriter(w io.Writer) *bufferedWriter {
return &bufferedWriter{w: w}
}
// bufWriterPoolBufferSize is the size of bufio.Writer's
// buffers created using bufWriterPool.
//
// TODO: pick a less arbitrary value? this is a bit under
// (3 x typical 1500 byte MTU) at least. Other than that,
// not much thought went into it.
const bufWriterPoolBufferSize = 4 << 10
var bufWriterPool = sync.Pool{
New: func() interface{} {
return bufio.NewWriterSize(nil, bufWriterPoolBufferSize)
},
}
func (w *bufferedWriter) Available() int {
if w.bw == nil {
return bufWriterPoolBufferSize
}
return w.bw.Available()
}
func (w *bufferedWriter) Write(p []byte) (n int, err error) {
if w.bw == nil {
bw := bufWriterPool.Get().(*bufio.Writer)
bw.Reset(w.w)
w.bw = bw
}
return w.bw.Write(p)
}
func (w *bufferedWriter) Flush() error {
bw := w.bw
if bw == nil {
return nil
}
err := bw.Flush()
bw.Reset(nil)
bufWriterPool.Put(bw)
w.bw = nil
return err
}
func mustUint31(v int32) uint32 {
if v < 0 || v > 2147483647 {
panic("out of range")
}
return uint32(v)
}
// bodyAllowedForStatus reports whether a given response status code
// permits a body. See RFC 7230, section 3.3.
func bodyAllowedForStatus(status int) bool {
switch {
case status >= 100 && status <= 199:
return false
case status == 204:
return false
case status == 304:
return false
}
return true
}
type httpError struct {
msg string
timeout bool
}
func (e *httpError) Error() string { return e.msg }
func (e *httpError) Timeout() bool { return e.timeout }
func (e *httpError) Temporary() bool { return true }
var errTimeout error = &httpError{msg: "http2: timeout awaiting response headers", timeout: true}
type connectionStater interface {
ConnectionState() tls.ConnectionState
}
var sorterPool = sync.Pool{New: func() interface{} { return new(sorter) }}
type sorter struct {
v []string // owned by sorter
}
func (s *sorter) Len() int { return len(s.v) }
func (s *sorter) Swap(i, j int) { s.v[i], s.v[j] = s.v[j], s.v[i] }
func (s *sorter) Less(i, j int) bool { return s.v[i] < s.v[j] }
// Keys returns the sorted keys of h.
//
// The returned slice is only valid until s used again or returned to
// its pool.
func (s *sorter) Keys(h http.Header) []string {
keys := s.v[:0]
for k := range h {
keys = append(keys, k)
}
s.v = keys
sort.Sort(s)
return keys
}
func (s *sorter) SortStrings(ss []string) {
// Our sorter works on s.v, which sorter owns, so
// stash it away while we sort the user's buffer.
save := s.v
s.v = ss
sort.Sort(s)
s.v = save
}
// validPseudoPath reports whether v is a valid :path pseudo-header
// value. It must be either:
//
// *) a non-empty string starting with '/'
// *) the string '*', for OPTIONS requests.
//
// For now this is only used a quick check for deciding when to clean
// up Opaque URLs before sending requests from the Transport.
// See golang.org/issue/16847
//
// We used to enforce that the path also didn't start with "//", but
// Google's GFE accepts such paths and Chrome sends them, so ignore
// that part of the spec. See golang.org/issue/19103.
func validPseudoPath(v string) bool {
return (len(v) > 0 && v[0] == '/') || v == "*"
}
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