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Holger Hildebrandtfa074992020-03-27 15:42:06 +00001// Copyright 2014 The Go Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style
3// license that can be found in the LICENSE file.
4
5// Package http2 implements the HTTP/2 protocol.
6//
7// This package is low-level and intended to be used directly by very
8// few people. Most users will use it indirectly through the automatic
9// use by the net/http package (from Go 1.6 and later).
10// For use in earlier Go versions see ConfigureServer. (Transport support
11// requires Go 1.6 or later)
12//
13// See https://http2.github.io/ for more information on HTTP/2.
14//
15// See https://http2.golang.org/ for a test server running this code.
16//
17package http2 // import "golang.org/x/net/http2"
18
19import (
20 "bufio"
21 "crypto/tls"
22 "fmt"
23 "io"
24 "net/http"
25 "os"
26 "sort"
27 "strconv"
28 "strings"
29 "sync"
30
31 "golang.org/x/net/http/httpguts"
32)
33
34var (
35 VerboseLogs bool
36 logFrameWrites bool
37 logFrameReads bool
38 inTests bool
39)
40
41func init() {
42 e := os.Getenv("GODEBUG")
43 if strings.Contains(e, "http2debug=1") {
44 VerboseLogs = true
45 }
46 if strings.Contains(e, "http2debug=2") {
47 VerboseLogs = true
48 logFrameWrites = true
49 logFrameReads = true
50 }
51}
52
53const (
54 // ClientPreface is the string that must be sent by new
55 // connections from clients.
56 ClientPreface = "PRI * HTTP/2.0\r\n\r\nSM\r\n\r\n"
57
58 // SETTINGS_MAX_FRAME_SIZE default
59 // http://http2.github.io/http2-spec/#rfc.section.6.5.2
60 initialMaxFrameSize = 16384
61
62 // NextProtoTLS is the NPN/ALPN protocol negotiated during
63 // HTTP/2's TLS setup.
64 NextProtoTLS = "h2"
65
66 // http://http2.github.io/http2-spec/#SettingValues
67 initialHeaderTableSize = 4096
68
69 initialWindowSize = 65535 // 6.9.2 Initial Flow Control Window Size
70
71 defaultMaxReadFrameSize = 1 << 20
72)
73
74var (
75 clientPreface = []byte(ClientPreface)
76)
77
78type streamState int
79
80// HTTP/2 stream states.
81//
82// See http://tools.ietf.org/html/rfc7540#section-5.1.
83//
84// For simplicity, the server code merges "reserved (local)" into
85// "half-closed (remote)". This is one less state transition to track.
86// The only downside is that we send PUSH_PROMISEs slightly less
87// liberally than allowable. More discussion here:
88// https://lists.w3.org/Archives/Public/ietf-http-wg/2016JulSep/0599.html
89//
90// "reserved (remote)" is omitted since the client code does not
91// support server push.
92const (
93 stateIdle streamState = iota
94 stateOpen
95 stateHalfClosedLocal
96 stateHalfClosedRemote
97 stateClosed
98)
99
100var stateName = [...]string{
101 stateIdle: "Idle",
102 stateOpen: "Open",
103 stateHalfClosedLocal: "HalfClosedLocal",
104 stateHalfClosedRemote: "HalfClosedRemote",
105 stateClosed: "Closed",
106}
107
108func (st streamState) String() string {
109 return stateName[st]
110}
111
112// Setting is a setting parameter: which setting it is, and its value.
113type Setting struct {
114 // ID is which setting is being set.
115 // See http://http2.github.io/http2-spec/#SettingValues
116 ID SettingID
117
118 // Val is the value.
119 Val uint32
120}
121
122func (s Setting) String() string {
123 return fmt.Sprintf("[%v = %d]", s.ID, s.Val)
124}
125
126// Valid reports whether the setting is valid.
127func (s Setting) Valid() error {
128 // Limits and error codes from 6.5.2 Defined SETTINGS Parameters
129 switch s.ID {
130 case SettingEnablePush:
131 if s.Val != 1 && s.Val != 0 {
132 return ConnectionError(ErrCodeProtocol)
133 }
134 case SettingInitialWindowSize:
135 if s.Val > 1<<31-1 {
136 return ConnectionError(ErrCodeFlowControl)
137 }
138 case SettingMaxFrameSize:
139 if s.Val < 16384 || s.Val > 1<<24-1 {
140 return ConnectionError(ErrCodeProtocol)
141 }
142 }
143 return nil
144}
145
146// A SettingID is an HTTP/2 setting as defined in
147// http://http2.github.io/http2-spec/#iana-settings
148type SettingID uint16
149
150const (
151 SettingHeaderTableSize SettingID = 0x1
152 SettingEnablePush SettingID = 0x2
153 SettingMaxConcurrentStreams SettingID = 0x3
154 SettingInitialWindowSize SettingID = 0x4
155 SettingMaxFrameSize SettingID = 0x5
156 SettingMaxHeaderListSize SettingID = 0x6
157)
158
159var settingName = map[SettingID]string{
160 SettingHeaderTableSize: "HEADER_TABLE_SIZE",
161 SettingEnablePush: "ENABLE_PUSH",
162 SettingMaxConcurrentStreams: "MAX_CONCURRENT_STREAMS",
163 SettingInitialWindowSize: "INITIAL_WINDOW_SIZE",
164 SettingMaxFrameSize: "MAX_FRAME_SIZE",
165 SettingMaxHeaderListSize: "MAX_HEADER_LIST_SIZE",
166}
167
168func (s SettingID) String() string {
169 if v, ok := settingName[s]; ok {
170 return v
171 }
172 return fmt.Sprintf("UNKNOWN_SETTING_%d", uint16(s))
173}
174
175// validWireHeaderFieldName reports whether v is a valid header field
176// name (key). See httpguts.ValidHeaderName for the base rules.
177//
178// Further, http2 says:
179// "Just as in HTTP/1.x, header field names are strings of ASCII
180// characters that are compared in a case-insensitive
181// fashion. However, header field names MUST be converted to
182// lowercase prior to their encoding in HTTP/2. "
183func validWireHeaderFieldName(v string) bool {
184 if len(v) == 0 {
185 return false
186 }
187 for _, r := range v {
188 if !httpguts.IsTokenRune(r) {
189 return false
190 }
191 if 'A' <= r && r <= 'Z' {
192 return false
193 }
194 }
195 return true
196}
197
198func httpCodeString(code int) string {
199 switch code {
200 case 200:
201 return "200"
202 case 404:
203 return "404"
204 }
205 return strconv.Itoa(code)
206}
207
208// from pkg io
209type stringWriter interface {
210 WriteString(s string) (n int, err error)
211}
212
213// A gate lets two goroutines coordinate their activities.
214type gate chan struct{}
215
216func (g gate) Done() { g <- struct{}{} }
217func (g gate) Wait() { <-g }
218
219// A closeWaiter is like a sync.WaitGroup but only goes 1 to 0 (open to closed).
220type closeWaiter chan struct{}
221
222// Init makes a closeWaiter usable.
223// It exists because so a closeWaiter value can be placed inside a
224// larger struct and have the Mutex and Cond's memory in the same
225// allocation.
226func (cw *closeWaiter) Init() {
227 *cw = make(chan struct{})
228}
229
230// Close marks the closeWaiter as closed and unblocks any waiters.
231func (cw closeWaiter) Close() {
232 close(cw)
233}
234
235// Wait waits for the closeWaiter to become closed.
236func (cw closeWaiter) Wait() {
237 <-cw
238}
239
240// bufferedWriter is a buffered writer that writes to w.
241// Its buffered writer is lazily allocated as needed, to minimize
242// idle memory usage with many connections.
243type bufferedWriter struct {
244 w io.Writer // immutable
245 bw *bufio.Writer // non-nil when data is buffered
246}
247
248func newBufferedWriter(w io.Writer) *bufferedWriter {
249 return &bufferedWriter{w: w}
250}
251
252// bufWriterPoolBufferSize is the size of bufio.Writer's
253// buffers created using bufWriterPool.
254//
255// TODO: pick a less arbitrary value? this is a bit under
256// (3 x typical 1500 byte MTU) at least. Other than that,
257// not much thought went into it.
258const bufWriterPoolBufferSize = 4 << 10
259
260var bufWriterPool = sync.Pool{
261 New: func() interface{} {
262 return bufio.NewWriterSize(nil, bufWriterPoolBufferSize)
263 },
264}
265
266func (w *bufferedWriter) Available() int {
267 if w.bw == nil {
268 return bufWriterPoolBufferSize
269 }
270 return w.bw.Available()
271}
272
273func (w *bufferedWriter) Write(p []byte) (n int, err error) {
274 if w.bw == nil {
275 bw := bufWriterPool.Get().(*bufio.Writer)
276 bw.Reset(w.w)
277 w.bw = bw
278 }
279 return w.bw.Write(p)
280}
281
282func (w *bufferedWriter) Flush() error {
283 bw := w.bw
284 if bw == nil {
285 return nil
286 }
287 err := bw.Flush()
288 bw.Reset(nil)
289 bufWriterPool.Put(bw)
290 w.bw = nil
291 return err
292}
293
294func mustUint31(v int32) uint32 {
295 if v < 0 || v > 2147483647 {
296 panic("out of range")
297 }
298 return uint32(v)
299}
300
301// bodyAllowedForStatus reports whether a given response status code
302// permits a body. See RFC 7230, section 3.3.
303func bodyAllowedForStatus(status int) bool {
304 switch {
305 case status >= 100 && status <= 199:
306 return false
307 case status == 204:
308 return false
309 case status == 304:
310 return false
311 }
312 return true
313}
314
315type httpError struct {
316 msg string
317 timeout bool
318}
319
320func (e *httpError) Error() string { return e.msg }
321func (e *httpError) Timeout() bool { return e.timeout }
322func (e *httpError) Temporary() bool { return true }
323
324var errTimeout error = &httpError{msg: "http2: timeout awaiting response headers", timeout: true}
325
326type connectionStater interface {
327 ConnectionState() tls.ConnectionState
328}
329
330var sorterPool = sync.Pool{New: func() interface{} { return new(sorter) }}
331
332type sorter struct {
333 v []string // owned by sorter
334}
335
336func (s *sorter) Len() int { return len(s.v) }
337func (s *sorter) Swap(i, j int) { s.v[i], s.v[j] = s.v[j], s.v[i] }
338func (s *sorter) Less(i, j int) bool { return s.v[i] < s.v[j] }
339
340// Keys returns the sorted keys of h.
341//
342// The returned slice is only valid until s used again or returned to
343// its pool.
344func (s *sorter) Keys(h http.Header) []string {
345 keys := s.v[:0]
346 for k := range h {
347 keys = append(keys, k)
348 }
349 s.v = keys
350 sort.Sort(s)
351 return keys
352}
353
354func (s *sorter) SortStrings(ss []string) {
355 // Our sorter works on s.v, which sorter owns, so
356 // stash it away while we sort the user's buffer.
357 save := s.v
358 s.v = ss
359 sort.Sort(s)
360 s.v = save
361}
362
363// validPseudoPath reports whether v is a valid :path pseudo-header
364// value. It must be either:
365//
366// *) a non-empty string starting with '/'
367// *) the string '*', for OPTIONS requests.
368//
369// For now this is only used a quick check for deciding when to clean
370// up Opaque URLs before sending requests from the Transport.
371// See golang.org/issue/16847
372//
373// We used to enforce that the path also didn't start with "//", but
374// Google's GFE accepts such paths and Chrome sends them, so ignore
375// that part of the spec. See golang.org/issue/19103.
376func validPseudoPath(v string) bool {
377 return (len(v) > 0 && v[0] == '/') || v == "*"
378}