aboutsummaryrefslogtreecommitdiff
path: root/vendor/golang.org/x/net/http2/http2.go
blob: 5571ccfd26132f87f7d1686c4cf3596588496f5e (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
// 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"
	"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))
}

// 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 {
	_  incomparable
	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 {
	_       incomparable
	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 == "*"
}

// incomparable is a zero-width, non-comparable type. Adding it to a struct
// makes that struct also non-comparable, and generally doesn't add
// any size (as long as it's first).
type incomparable [0]func()