1 // Copyright 2009 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.
5 // HTTP server. See RFC 7230 through 7235.
33 "golang.org/x/net/http/httpguts"
36 // Errors used by the HTTP server.
38 // ErrBodyNotAllowed is returned by ResponseWriter.Write calls
39 // when the HTTP method or response code does not permit a
41 ErrBodyNotAllowed
= errors
.New("http: request method or response status code does not allow body")
43 // ErrHijacked is returned by ResponseWriter.Write calls when
44 // the underlying connection has been hijacked using the
45 // Hijacker interface. A zero-byte write on a hijacked
46 // connection will return ErrHijacked without any other side
48 ErrHijacked
= errors
.New("http: connection has been hijacked")
50 // ErrContentLength is returned by ResponseWriter.Write calls
51 // when a Handler set a Content-Length response header with a
52 // declared size and then attempted to write more bytes than
54 ErrContentLength
= errors
.New("http: wrote more than the declared Content-Length")
56 // Deprecated: ErrWriteAfterFlush is no longer returned by
57 // anything in the net/http package. Callers should not
58 // compare errors against this variable.
59 ErrWriteAfterFlush
= errors
.New("unused")
62 // A Handler responds to an HTTP request.
64 // ServeHTTP should write reply headers and data to the ResponseWriter
65 // and then return. Returning signals that the request is finished; it
66 // is not valid to use the ResponseWriter or read from the
67 // Request.Body after or concurrently with the completion of the
70 // Depending on the HTTP client software, HTTP protocol version, and
71 // any intermediaries between the client and the Go server, it may not
72 // be possible to read from the Request.Body after writing to the
73 // ResponseWriter. Cautious handlers should read the Request.Body
74 // first, and then reply.
76 // Except for reading the body, handlers should not modify the
79 // If ServeHTTP panics, the server (the caller of ServeHTTP) assumes
80 // that the effect of the panic was isolated to the active request.
81 // It recovers the panic, logs a stack trace to the server error log,
82 // and either closes the network connection or sends an HTTP/2
83 // RST_STREAM, depending on the HTTP protocol. To abort a handler so
84 // the client sees an interrupted response but the server doesn't log
85 // an error, panic with the value ErrAbortHandler.
86 type Handler
interface {
87 ServeHTTP(ResponseWriter
, *Request
)
90 // A ResponseWriter interface is used by an HTTP handler to
91 // construct an HTTP response.
93 // A ResponseWriter may not be used after the Handler.ServeHTTP method
95 type ResponseWriter
interface {
96 // Header returns the header map that will be sent by
97 // WriteHeader. The Header map also is the mechanism with which
98 // Handlers can set HTTP trailers.
100 // Changing the header map after a call to WriteHeader (or
101 // Write) has no effect unless the modified headers are
104 // There are two ways to set Trailers. The preferred way is to
105 // predeclare in the headers which trailers you will later
106 // send by setting the "Trailer" header to the names of the
107 // trailer keys which will come later. In this case, those
108 // keys of the Header map are treated as if they were
109 // trailers. See the example. The second way, for trailer
110 // keys not known to the Handler until after the first Write,
111 // is to prefix the Header map keys with the TrailerPrefix
112 // constant value. See TrailerPrefix.
114 // To suppress automatic response headers (such as "Date"), set
115 // their value to nil.
118 // Write writes the data to the connection as part of an HTTP reply.
120 // If WriteHeader has not yet been called, Write calls
121 // WriteHeader(http.StatusOK) before writing the data. If the Header
122 // does not contain a Content-Type line, Write adds a Content-Type set
123 // to the result of passing the initial 512 bytes of written data to
124 // DetectContentType. Additionally, if the total size of all written
125 // data is under a few KB and there are no Flush calls, the
126 // Content-Length header is added automatically.
128 // Depending on the HTTP protocol version and the client, calling
129 // Write or WriteHeader may prevent future reads on the
130 // Request.Body. For HTTP/1.x requests, handlers should read any
131 // needed request body data before writing the response. Once the
132 // headers have been flushed (due to either an explicit Flusher.Flush
133 // call or writing enough data to trigger a flush), the request body
134 // may be unavailable. For HTTP/2 requests, the Go HTTP server permits
135 // handlers to continue to read the request body while concurrently
136 // writing the response. However, such behavior may not be supported
137 // by all HTTP/2 clients. Handlers should read before writing if
138 // possible to maximize compatibility.
139 Write([]byte) (int, error
)
141 // WriteHeader sends an HTTP response header with the provided
144 // If WriteHeader is not called explicitly, the first call to Write
145 // will trigger an implicit WriteHeader(http.StatusOK).
146 // Thus explicit calls to WriteHeader are mainly used to
149 // The provided code must be a valid HTTP 1xx-5xx status code.
150 // Only one header may be written. Go does not currently
151 // support sending user-defined 1xx informational headers,
152 // with the exception of 100-continue response header that the
153 // Server sends automatically when the Request.Body is read.
154 WriteHeader(statusCode
int)
157 // The Flusher interface is implemented by ResponseWriters that allow
158 // an HTTP handler to flush buffered data to the client.
160 // The default HTTP/1.x and HTTP/2 ResponseWriter implementations
161 // support Flusher, but ResponseWriter wrappers may not. Handlers
162 // should always test for this ability at runtime.
164 // Note that even for ResponseWriters that support Flush,
165 // if the client is connected through an HTTP proxy,
166 // the buffered data may not reach the client until the response
168 type Flusher
interface {
169 // Flush sends any buffered data to the client.
173 // The Hijacker interface is implemented by ResponseWriters that allow
174 // an HTTP handler to take over the connection.
176 // The default ResponseWriter for HTTP/1.x connections supports
177 // Hijacker, but HTTP/2 connections intentionally do not.
178 // ResponseWriter wrappers may also not support Hijacker. Handlers
179 // should always test for this ability at runtime.
180 type Hijacker
interface {
181 // Hijack lets the caller take over the connection.
182 // After a call to Hijack the HTTP server library
183 // will not do anything else with the connection.
185 // It becomes the caller's responsibility to manage
186 // and close the connection.
188 // The returned net.Conn may have read or write deadlines
189 // already set, depending on the configuration of the
190 // Server. It is the caller's responsibility to set
191 // or clear those deadlines as needed.
193 // The returned bufio.Reader may contain unprocessed buffered
194 // data from the client.
196 // After a call to Hijack, the original Request.Body must not
197 // be used. The original Request's Context remains valid and
198 // is not canceled until the Request's ServeHTTP method
200 Hijack() (net
.Conn
, *bufio
.ReadWriter
, error
)
203 // The CloseNotifier interface is implemented by ResponseWriters which
204 // allow detecting when the underlying connection has gone away.
206 // This mechanism can be used to cancel long operations on the server
207 // if the client has disconnected before the response is ready.
209 // Deprecated: the CloseNotifier interface predates Go's context package.
210 // New code should use Request.Context instead.
211 type CloseNotifier
interface {
212 // CloseNotify returns a channel that receives at most a
213 // single value (true) when the client connection has gone
216 // CloseNotify may wait to notify until Request.Body has been
219 // After the Handler has returned, there is no guarantee
220 // that the channel receives a value.
222 // If the protocol is HTTP/1.1 and CloseNotify is called while
223 // processing an idempotent request (such a GET) while
224 // HTTP/1.1 pipelining is in use, the arrival of a subsequent
225 // pipelined request may cause a value to be sent on the
226 // returned channel. In practice HTTP/1.1 pipelining is not
227 // enabled in browsers and not seen often in the wild. If this
228 // is a problem, use HTTP/2 or only use CloseNotify on methods
230 CloseNotify() <-chan bool
234 // ServerContextKey is a context key. It can be used in HTTP
235 // handlers with Context.Value to access the server that
236 // started the handler. The associated value will be of
238 ServerContextKey
= &contextKey
{"http-server"}
240 // LocalAddrContextKey is a context key. It can be used in
241 // HTTP handlers with Context.Value to access the local
242 // address the connection arrived on.
243 // The associated value will be of type net.Addr.
244 LocalAddrContextKey
= &contextKey
{"local-addr"}
247 // A conn represents the server side of an HTTP connection.
249 // server is the server on which the connection arrived.
250 // Immutable; never nil.
253 // cancelCtx cancels the connection-level context.
254 cancelCtx context
.CancelFunc
256 // rwc is the underlying network connection.
257 // This is never wrapped by other types and is the value given out
258 // to CloseNotifier callers. It is usually of type *net.TCPConn or
262 // remoteAddr is rwc.RemoteAddr().String(). It is not populated synchronously
263 // inside the Listener's Accept goroutine, as some implementations block.
264 // It is populated immediately inside the (*conn).serve goroutine.
265 // This is the value of a Handler's (*Request).RemoteAddr.
268 // tlsState is the TLS connection state when using TLS.
269 // nil means not TLS.
270 tlsState
*tls
.ConnectionState
272 // werr is set to the first write error to rwc.
273 // It is set via checkConnErrorWriter{w}, where bufw writes.
276 // r is bufr's read source. It's a wrapper around rwc that provides
277 // io.LimitedReader-style limiting (while reading request headers)
278 // and functionality to support CloseNotifier. See *connReader docs.
281 // bufr reads from r.
284 // bufw writes to checkConnErrorWriter{c}, which populates werr on error.
287 // lastMethod is the method of the most recent request
288 // on this connection, if any.
291 curReq atomic
.Value
// of *response (which has a Request in it)
293 curState
struct{ atomic
uint64 } // packed (unixtime<<8|uint8(ConnState))
295 // mu guards hijackedv
298 // hijackedv is whether this connection has been hijacked
299 // by a Handler with the Hijacker interface.
300 // It is guarded by mu.
304 func (c
*conn
) hijacked() bool {
310 // c.mu must be held.
311 func (c
*conn
) hijackLocked() (rwc net
.Conn
, buf
*bufio
.ReadWriter
, err error
) {
313 return nil, nil, ErrHijacked
315 c
.r
.abortPendingRead()
319 rwc
.SetDeadline(time
.Time
{})
321 buf
= bufio
.NewReadWriter(c
.bufr
, bufio
.NewWriter(rwc
))
323 if _
, err
:= c
.bufr
.Peek(c
.bufr
.Buffered() + 1); err
!= nil {
324 return nil, nil, fmt
.Errorf("unexpected Peek failure reading buffered byte: %v", err
)
327 c
.setState(rwc
, StateHijacked
, runHooks
)
331 // This should be >= 512 bytes for DetectContentType,
332 // but otherwise it's somewhat arbitrary.
333 const bufferBeforeChunkingSize
= 2048
335 // chunkWriter writes to a response's conn buffer, and is the writer
336 // wrapped by the response.w buffered writer.
338 // chunkWriter also is responsible for finalizing the Header, including
339 // conditionally setting the Content-Type and setting a Content-Length
340 // in cases where the handler's final output is smaller than the buffer
341 // size. It also conditionally adds chunk headers, when in chunking mode.
343 // See the comment above (*response).Write for the entire write flow.
344 type chunkWriter
struct {
347 // header is either nil or a deep clone of res.handlerHeader
348 // at the time of res.writeHeader, if res.writeHeader is
349 // called and extra buffering is being done to calculate
350 // Content-Type and/or Content-Length.
353 // wroteHeader tells whether the header's been written to "the
354 // wire" (or rather: w.conn.buf). this is unlike
355 // (*response).wroteHeader, which tells only whether it was
356 // logically written.
359 // set by the writeHeader method:
360 chunking
bool // using chunked transfer encoding for reply body
364 crlf
= []byte("\r\n")
365 colonSpace
= []byte(": ")
368 func (cw
*chunkWriter
) Write(p
[]byte) (n
int, err error
) {
372 if cw
.res
.req
.Method
== "HEAD" {
377 _
, err
= fmt
.Fprintf(cw
.res
.conn
.bufw
, "%x\r\n", len(p
))
379 cw
.res
.conn
.rwc
.Close()
383 n
, err
= cw
.res
.conn
.bufw
.Write(p
)
384 if cw
.chunking
&& err
== nil {
385 _
, err
= cw
.res
.conn
.bufw
.Write(crlf
)
388 cw
.res
.conn
.rwc
.Close()
393 func (cw
*chunkWriter
) flush() {
397 cw
.res
.conn
.bufw
.Flush()
400 func (cw
*chunkWriter
) close() {
405 bw
:= cw
.res
.conn
.bufw
// conn's bufio writer
406 // zero chunk to mark EOF
407 bw
.WriteString("0\r\n")
408 if trailers
:= cw
.res
.finalTrailers(); trailers
!= nil {
409 trailers
.Write(bw
) // the writer handles noting errors
411 // final blank line after the trailers (whether
413 bw
.WriteString("\r\n")
417 // A response represents the server side of an HTTP response.
418 type response
struct {
420 req
*Request
// request for this response
421 reqBody io
.ReadCloser
422 cancelCtx context
.CancelFunc
// when ServeHTTP exits
423 wroteHeader
bool // reply header has been (logically) written
424 wroteContinue
bool // 100 Continue response was written
425 wants10KeepAlive
bool // HTTP/1.0 w/ Connection "keep-alive"
426 wantsClose
bool // HTTP request has Connection "close"
428 // canWriteContinue is a boolean value accessed as an atomic int32
429 // that says whether or not a 100 Continue header can be written
430 // to the connection.
431 // writeContinueMu must be held while writing the header.
432 // These two fields together synchronize the body reader
433 // (the expectContinueReader, which wants to write 100 Continue)
434 // against the main writer.
435 canWriteContinue atomicBool
436 writeContinueMu sync
.Mutex
438 w
*bufio
.Writer
// buffers output in chunks to chunkWriter
441 // handlerHeader is the Header that Handlers get access to,
442 // which may be retained and mutated even after WriteHeader.
443 // handlerHeader is copied into cw.header at WriteHeader
444 // time, and privately mutated thereafter.
446 calledHeader
bool // handler accessed handlerHeader via Header
448 written
int64 // number of bytes written in body
449 contentLength
int64 // explicitly-declared Content-Length; or -1
450 status
int // status code passed to WriteHeader
452 // close connection after this reply. set on request and
453 // updated after response from handler if there's a
454 // "Connection: keep-alive" response header and a
458 // requestBodyLimitHit is set by requestTooLarge when
459 // maxBytesReader hits its max size. It is checked in
460 // WriteHeader, to make sure we don't consume the
461 // remaining request body to try to advance to the next HTTP
462 // request. Instead, when this is set, we stop reading
463 // subsequent requests on this connection and stop reading
465 requestBodyLimitHit
bool
467 // trailers are the headers to be sent after the handler
468 // finishes writing the body. This field is initialized from
469 // the Trailer response header when the response header is
473 handlerDone atomicBool
// set true when the handler exits
475 // Buffers for Date, Content-Length, and status code
476 dateBuf
[len(TimeFormat
)]byte
480 // closeNotifyCh is the channel returned by CloseNotify.
481 // TODO(bradfitz): this is currently (for Go 1.8) always
482 // non-nil. Make this lazily-created again as it used to be?
483 closeNotifyCh
chan bool
484 didCloseNotify
int32 // atomic (only 0->1 winner should send)
487 // TrailerPrefix is a magic prefix for ResponseWriter.Header map keys
488 // that, if present, signals that the map entry is actually for
489 // the response trailers, and not the response headers. The prefix
490 // is stripped after the ServeHTTP call finishes and the values are
491 // sent in the trailers.
493 // This mechanism is intended only for trailers that are not known
494 // prior to the headers being written. If the set of trailers is fixed
495 // or known before the header is written, the normal Go trailers mechanism
497 // https://pkg.go.dev/net/http#ResponseWriter
498 // https://pkg.go.dev/net/http#example-ResponseWriter-Trailers
499 const TrailerPrefix
= "Trailer:"
501 // finalTrailers is called after the Handler exits and returns a non-nil
502 // value if the Handler set any trailers.
503 func (w
*response
) finalTrailers() Header
{
505 for k
, vv
:= range w
.handlerHeader
{
506 if strings
.HasPrefix(k
, TrailerPrefix
) {
510 t
[strings
.TrimPrefix(k
, TrailerPrefix
)] = vv
513 for _
, k
:= range w
.trailers
{
517 for _
, v
:= range w
.handlerHeader
[k
] {
524 type atomicBool
int32
526 func (b
*atomicBool
) isSet() bool { return atomic
.LoadInt32((*int32)(b
)) != 0 }
527 func (b
*atomicBool
) setTrue() { atomic
.StoreInt32((*int32)(b
), 1) }
528 func (b
*atomicBool
) setFalse() { atomic
.StoreInt32((*int32)(b
), 0) }
530 // declareTrailer is called for each Trailer header when the
531 // response header is written. It notes that a header will need to be
532 // written in the trailers at the end of the response.
533 func (w
*response
) declareTrailer(k
string) {
534 k
= CanonicalHeaderKey(k
)
535 if !httpguts
.ValidTrailerHeader(k
) {
536 // Forbidden by RFC 7230, section 4.1.2
539 w
.trailers
= append(w
.trailers
, k
)
542 // requestTooLarge is called by maxBytesReader when too much input has
543 // been read from the client.
544 func (w
*response
) requestTooLarge() {
545 w
.closeAfterReply
= true
546 w
.requestBodyLimitHit
= true
548 w
.Header().Set("Connection", "close")
552 // needsSniff reports whether a Content-Type still needs to be sniffed.
553 func (w
*response
) needsSniff() bool {
554 _
, haveType
:= w
.handlerHeader
["Content-Type"]
555 return !w
.cw
.wroteHeader
&& !haveType
&& w
.written
< sniffLen
558 // writerOnly hides an io.Writer value's optional ReadFrom method
560 type writerOnly
struct {
564 // ReadFrom is here to optimize copying from an *os.File regular file
565 // to a *net.TCPConn with sendfile, or from a supported src type such
566 // as a *net.TCPConn on Linux with splice.
567 func (w
*response
) ReadFrom(src io
.Reader
) (n
int64, err error
) {
568 bufp
:= copyBufPool
.Get().(*[]byte)
570 defer copyBufPool
.Put(bufp
)
572 // Our underlying w.conn.rwc is usually a *TCPConn (with its
573 // own ReadFrom method). If not, just fall back to the normal
575 rf
, ok
:= w
.conn
.rwc
.(io
.ReaderFrom
)
577 return io
.CopyBuffer(writerOnly
{w
}, src
, buf
)
580 // Copy the first sniffLen bytes before switching to ReadFrom.
581 // This ensures we don't start writing the response before the
582 // source is available (see golang.org/issue/5660) and provides
583 // enough bytes to perform Content-Type sniffing when required.
584 if !w
.cw
.wroteHeader
{
585 n0
, err
:= io
.CopyBuffer(writerOnly
{w
}, io
.LimitReader(src
, sniffLen
), buf
)
587 if err
!= nil || n0
< sniffLen
{
592 w
.w
.Flush() // get rid of any previous writes
593 w
.cw
.flush() // make sure Header is written; flush data to rwc
595 // Now that cw has been flushed, its chunking field is guaranteed initialized.
596 if !w
.cw
.chunking
&& w
.bodyAllowed() {
597 n0
, err
:= rf
.ReadFrom(src
)
603 n0
, err
:= io
.CopyBuffer(writerOnly
{w
}, src
, buf
)
608 // debugServerConnections controls whether all server connections are wrapped
609 // with a verbose logging wrapper.
610 const debugServerConnections
= false
612 // Create new connection from rwc.
613 func (srv
*Server
) newConn(rwc net
.Conn
) *conn
{
618 if debugServerConnections
{
619 c
.rwc
= newLoggingConn("server", c
.rwc
)
624 type readResult
struct {
628 b
byte // byte read, if n == 1
631 // connReader is the io.Reader wrapper used by *conn. It combines a
632 // selectively-activated io.LimitedReader (to bound request header
633 // read sizes) with support for selectively keeping an io.Reader.Read
634 // call blocked in a background goroutine to wait for activity and
635 // trigger a CloseNotifier channel.
636 type connReader
struct {
639 mu sync
.Mutex
// guards following
644 aborted
bool // set true before conn.rwc deadline is set to past
645 remain
int64 // bytes remaining
648 func (cr
*connReader
) lock() {
651 cr
.cond
= sync
.NewCond(&cr
.mu
)
655 func (cr
*connReader
) unlock() { cr
.mu
.Unlock() }
657 func (cr
*connReader
) startBackgroundRead() {
661 panic("invalid concurrent Body.Read call")
667 cr
.conn
.rwc
.SetReadDeadline(time
.Time
{})
668 go cr
.backgroundRead()
671 func (cr
*connReader
) backgroundRead() {
672 n
, err
:= cr
.conn
.rwc
.Read(cr
.byteBuf
[:])
676 // We were past the end of the previous request's body already
677 // (since we wouldn't be in a background read otherwise), so
678 // this is a pipelined HTTP request. Prior to Go 1.11 we used to
679 // send on the CloseNotify channel and cancel the context here,
680 // but the behavior was documented as only "may", and we only
681 // did that because that's how CloseNotify accidentally behaved
682 // in very early Go releases prior to context support. Once we
683 // added context support, people used a Handler's
684 // Request.Context() and passed it along. Having that context
685 // cancel on pipelined HTTP requests caused problems.
686 // Fortunately, almost nothing uses HTTP/1.x pipelining.
687 // Unfortunately, apt-get does, or sometimes does.
688 // New Go 1.11 behavior: don't fire CloseNotify or cancel
689 // contexts on pipelined requests. Shouldn't affect people, but
690 // fixes cases like Issue 23921. This does mean that a client
691 // closing their TCP connection after sending a pipelined
692 // request won't cancel the context, but we'll catch that on any
693 // write failure (in checkConnErrorWriter.Write).
694 // If the server never writes, yes, there are still contrived
695 // server & client behaviors where this fails to ever cancel the
696 // context, but that's kinda why HTTP/1.x pipelining died
699 if ne
, ok
:= err
.(net
.Error
); ok
&& cr
.aborted
&& ne
.Timeout() {
700 // Ignore this error. It's the expected error from
701 // another goroutine calling abortPendingRead.
702 } else if err
!= nil {
703 cr
.handleReadError(err
)
711 func (cr
*connReader
) abortPendingRead() {
718 cr
.conn
.rwc
.SetReadDeadline(aLongTimeAgo
)
722 cr
.conn
.rwc
.SetReadDeadline(time
.Time
{})
725 func (cr
*connReader
) setReadLimit(remain
int64) { cr
.remain
= remain
}
726 func (cr
*connReader
) setInfiniteReadLimit() { cr
.remain
= maxInt64
}
727 func (cr
*connReader
) hitReadLimit() bool { return cr
.remain
<= 0 }
729 // handleReadError is called whenever a Read from the client returns a
732 // The provided non-nil err is almost always io.EOF or a "use of
733 // closed network connection". In any case, the error is not
734 // particularly interesting, except perhaps for debugging during
735 // development. Any error means the connection is dead and we should
738 // It may be called from multiple goroutines.
739 func (cr
*connReader
) handleReadError(_ error
) {
744 // may be called from multiple goroutines.
745 func (cr
*connReader
) closeNotify() {
746 res
, _
:= cr
.conn
.curReq
.Load().(*response
)
747 if res
!= nil && atomic
.CompareAndSwapInt32(&res
.didCloseNotify
, 0, 1) {
748 res
.closeNotifyCh
<- true
752 func (cr
*connReader
) Read(p
[]byte) (n
int, err error
) {
756 if cr
.conn
.hijacked() {
757 panic("invalid Body.Read call. After hijacked, the original Request must not be used")
759 panic("invalid concurrent Body.Read call")
761 if cr
.hitReadLimit() {
769 if int64(len(p
)) > cr
.remain
{
780 n
, err
= cr
.conn
.rwc
.Read(p
)
785 cr
.handleReadError(err
)
787 cr
.remain
-= int64(n
)
795 bufioReaderPool sync
.Pool
796 bufioWriter2kPool sync
.Pool
797 bufioWriter4kPool sync
.Pool
800 var copyBufPool
= sync
.Pool
{
802 b
:= make([]byte, 32*1024)
807 func bufioWriterPool(size
int) *sync
.Pool
{
810 return &bufioWriter2kPool
812 return &bufioWriter4kPool
817 func newBufioReader(r io
.Reader
) *bufio
.Reader
{
818 if v
:= bufioReaderPool
.Get(); v
!= nil {
819 br
:= v
.(*bufio
.Reader
)
823 // Note: if this reader size is ever changed, update
824 // TestHandlerBodyClose's assumptions.
825 return bufio
.NewReader(r
)
828 func putBufioReader(br
*bufio
.Reader
) {
830 bufioReaderPool
.Put(br
)
833 func newBufioWriterSize(w io
.Writer
, size
int) *bufio
.Writer
{
834 pool
:= bufioWriterPool(size
)
836 if v
:= pool
.Get(); v
!= nil {
837 bw
:= v
.(*bufio
.Writer
)
842 return bufio
.NewWriterSize(w
, size
)
845 func putBufioWriter(bw
*bufio
.Writer
) {
847 if pool
:= bufioWriterPool(bw
.Available()); pool
!= nil {
852 // DefaultMaxHeaderBytes is the maximum permitted size of the headers
853 // in an HTTP request.
854 // This can be overridden by setting Server.MaxHeaderBytes.
855 const DefaultMaxHeaderBytes
= 1 << 20 // 1 MB
857 func (srv
*Server
) maxHeaderBytes() int {
858 if srv
.MaxHeaderBytes
> 0 {
859 return srv
.MaxHeaderBytes
861 return DefaultMaxHeaderBytes
864 func (srv
*Server
) initialReadLimitSize() int64 {
865 return int64(srv
.maxHeaderBytes()) + 4096 // bufio slop
868 // tlsHandshakeTimeout returns the time limit permitted for the TLS
869 // handshake, or zero for unlimited.
871 // It returns the minimum of any positive ReadHeaderTimeout,
872 // ReadTimeout, or WriteTimeout.
873 func (srv
*Server
) tlsHandshakeTimeout() time
.Duration
{
874 var ret time
.Duration
875 for _
, v
:= range [...]time
.Duration
{
876 srv
.ReadHeaderTimeout
,
883 if ret
== 0 || v
< ret
{
890 // wrapper around io.ReadCloser which on first read, sends an
891 // HTTP/1.1 100 Continue header
892 type expectContinueReader
struct {
894 readCloser io
.ReadCloser
899 func (ecr
*expectContinueReader
) Read(p
[]byte) (n
int, err error
) {
900 if ecr
.closed.isSet() {
901 return 0, ErrBodyReadAfterClose
904 if !w
.wroteContinue
&& w
.canWriteContinue
.isSet() && !w
.conn
.hijacked() {
905 w
.wroteContinue
= true
906 w
.writeContinueMu
.Lock()
907 if w
.canWriteContinue
.isSet() {
908 w
.conn
.bufw
.WriteString("HTTP/1.1 100 Continue\r\n\r\n")
910 w
.canWriteContinue
.setFalse()
912 w
.writeContinueMu
.Unlock()
914 n
, err
= ecr
.readCloser
.Read(p
)
921 func (ecr
*expectContinueReader
) Close() error
{
923 return ecr
.readCloser
.Close()
926 // TimeFormat is the time format to use when generating times in HTTP
927 // headers. It is like time.RFC1123 but hard-codes GMT as the time
928 // zone. The time being formatted must be in UTC for Format to
929 // generate the correct format.
931 // For parsing this time format, see ParseTime.
932 const TimeFormat
= "Mon, 02 Jan 2006 15:04:05 GMT"
934 // appendTime is a non-allocating version of []byte(t.UTC().Format(TimeFormat))
935 func appendTime(b
[]byte, t time
.Time
) []byte {
936 const days
= "SunMonTueWedThuFriSat"
937 const months
= "JanFebMarAprMayJunJulAugSepOctNovDec"
940 yy
, mm
, dd
:= t
.Date()
941 hh
, mn
, ss
:= t
.Clock()
942 day
:= days
[3*t
.Weekday():]
943 mon
:= months
[3*(mm
-1):]
946 day
[0], day
[1], day
[2], ',', ' ',
947 byte('0'+dd
/10), byte('0'+dd%10
), ' ',
948 mon
[0], mon
[1], mon
[2], ' ',
949 byte('0'+yy
/1000), byte('0'+(yy
/100)%10
), byte('0'+(yy
/10)%10
), byte('0'+yy%10
), ' ',
950 byte('0'+hh
/10), byte('0'+hh%10
), ':',
951 byte('0'+mn
/10), byte('0'+mn%10
), ':',
952 byte('0'+ss
/10), byte('0'+ss%10
), ' ',
956 var errTooLarge
= errors
.New("http: request too large")
958 // Read next request from connection.
959 func (c
*conn
) readRequest(ctx context
.Context
) (w
*response
, err error
) {
961 return nil, ErrHijacked
965 wholeReqDeadline time
.Time
// or zero if none
966 hdrDeadline time
.Time
// or zero if none
969 if d
:= c
.server
.readHeaderTimeout(); d
> 0 {
970 hdrDeadline
= t0
.Add(d
)
972 if d
:= c
.server
.ReadTimeout
; d
> 0 {
973 wholeReqDeadline
= t0
.Add(d
)
975 c
.rwc
.SetReadDeadline(hdrDeadline
)
976 if d
:= c
.server
.WriteTimeout
; d
> 0 {
978 c
.rwc
.SetWriteDeadline(time
.Now().Add(d
))
982 c
.r
.setReadLimit(c
.server
.initialReadLimitSize())
983 if c
.lastMethod
== "POST" {
984 // RFC 7230 section 3 tolerance for old buggy clients.
985 peek
, _
:= c
.bufr
.Peek(4) // ReadRequest will get err below
986 c
.bufr
.Discard(numLeadingCRorLF(peek
))
988 req
, err
:= readRequest(c
.bufr
)
990 if c
.r
.hitReadLimit() {
991 return nil, errTooLarge
996 if !http1ServerSupportsRequest(req
) {
997 return nil, statusError
{StatusHTTPVersionNotSupported
, "unsupported protocol version"}
1000 c
.lastMethod
= req
.Method
1001 c
.r
.setInfiniteReadLimit()
1003 hosts
, haveHost
:= req
.Header
["Host"]
1004 isH2Upgrade
:= req
.isH2Upgrade()
1005 if req
.ProtoAtLeast(1, 1) && (!haveHost ||
len(hosts
) == 0) && !isH2Upgrade
&& req
.Method
!= "CONNECT" {
1006 return nil, badRequestError("missing required Host header")
1008 if len(hosts
) == 1 && !httpguts
.ValidHostHeader(hosts
[0]) {
1009 return nil, badRequestError("malformed Host header")
1011 for k
, vv
:= range req
.Header
{
1012 if !httpguts
.ValidHeaderFieldName(k
) {
1013 return nil, badRequestError("invalid header name")
1015 for _
, v
:= range vv
{
1016 if !httpguts
.ValidHeaderFieldValue(v
) {
1017 return nil, badRequestError("invalid header value")
1021 delete(req
.Header
, "Host")
1023 ctx
, cancelCtx
:= context
.WithCancel(ctx
)
1025 req
.RemoteAddr
= c
.remoteAddr
1026 req
.TLS
= c
.tlsState
1027 if body
, ok
:= req
.Body
.(*body
); ok
{
1028 body
.doEarlyClose
= true
1031 // Adjust the read deadline if necessary.
1032 if !hdrDeadline
.Equal(wholeReqDeadline
) {
1033 c
.rwc
.SetReadDeadline(wholeReqDeadline
)
1038 cancelCtx
: cancelCtx
,
1041 handlerHeader
: make(Header
),
1043 closeNotifyCh
: make(chan bool, 1),
1045 // We populate these ahead of time so we're not
1046 // reading from req.Header after their Handler starts
1047 // and maybe mutates it (Issue 14940)
1048 wants10KeepAlive
: req
.wantsHttp10KeepAlive(),
1049 wantsClose
: req
.wantsClose(),
1052 w
.closeAfterReply
= true
1055 w
.w
= newBufioWriterSize(&w
.cw
, bufferBeforeChunkingSize
)
1059 // http1ServerSupportsRequest reports whether Go's HTTP/1.x server
1060 // supports the given request.
1061 func http1ServerSupportsRequest(req
*Request
) bool {
1062 if req
.ProtoMajor
== 1 {
1065 // Accept "PRI * HTTP/2.0" upgrade requests, so Handlers can
1066 // wire up their own HTTP/2 upgrades.
1067 if req
.ProtoMajor
== 2 && req
.ProtoMinor
== 0 &&
1068 req
.Method
== "PRI" && req
.RequestURI
== "*" {
1071 // Reject HTTP/0.x, and all other HTTP/2+ requests (which
1072 // aren't encoded in ASCII anyway).
1076 func (w
*response
) Header() Header
{
1077 if w
.cw
.header
== nil && w
.wroteHeader
&& !w
.cw
.wroteHeader
{
1078 // Accessing the header between logically writing it
1079 // and physically writing it means we need to allocate
1080 // a clone to snapshot the logically written state.
1081 w
.cw
.header
= w
.handlerHeader
.Clone()
1083 w
.calledHeader
= true
1084 return w
.handlerHeader
1087 // maxPostHandlerReadBytes is the max number of Request.Body bytes not
1088 // consumed by a handler that the server will read from the client
1089 // in order to keep a connection alive. If there are more bytes than
1090 // this then the server to be paranoid instead sends a "Connection:
1093 // This number is approximately what a typical machine's TCP buffer
1094 // size is anyway. (if we have the bytes on the machine, we might as
1096 const maxPostHandlerReadBytes
= 256 << 10
1098 func checkWriteHeaderCode(code
int) {
1099 // Issue 22880: require valid WriteHeader status codes.
1100 // For now we only enforce that it's three digits.
1101 // In the future we might block things over 599 (600 and above aren't defined
1102 // at https://httpwg.org/specs/rfc7231.html#status.codes)
1103 // and we might block under 200 (once we have more mature 1xx support).
1104 // But for now any three digits.
1106 // We used to send "HTTP/1.1 000 0" on the wire in responses but there's
1107 // no equivalent bogus thing we can realistically send in HTTP/2,
1108 // so we'll consistently panic instead and help people find their bugs
1109 // early. (We can't return an error from WriteHeader even if we wanted to.)
1110 if code
< 100 || code
> 999 {
1111 panic(fmt
.Sprintf("invalid WriteHeader code %v", code
))
1115 // relevantCaller searches the call stack for the first function outside of net/http.
1116 // The purpose of this function is to provide more helpful error messages.
1117 func relevantCaller() runtime
.Frame
{
1118 pc
:= make([]uintptr, 16)
1119 n
:= runtime
.Callers(1, pc
)
1120 frames
:= runtime
.CallersFrames(pc
[:n
])
1121 prefix1
:= "net/http."
1122 prefix2
:= "net/http."
1123 if runtime
.Compiler
== "gccgo" {
1126 var frame runtime
.Frame
1128 frame
, more
:= frames
.Next()
1129 if !strings
.HasPrefix(frame
.Function
, prefix1
) && !strings
.HasPrefix(frame
.Function
, prefix2
) {
1139 func (w
*response
) WriteHeader(code
int) {
1140 if w
.conn
.hijacked() {
1141 caller
:= relevantCaller()
1142 w
.conn
.server
.logf("http: response.WriteHeader on hijacked connection from %s (%s:%d)", caller
.Function
, path
.Base(caller
.File
), caller
.Line
)
1146 caller
:= relevantCaller()
1147 w
.conn
.server
.logf("http: superfluous response.WriteHeader call from %s (%s:%d)", caller
.Function
, path
.Base(caller
.File
), caller
.Line
)
1150 checkWriteHeaderCode(code
)
1151 w
.wroteHeader
= true
1154 if w
.calledHeader
&& w
.cw
.header
== nil {
1155 w
.cw
.header
= w
.handlerHeader
.Clone()
1158 if cl
:= w
.handlerHeader
.get("Content-Length"); cl
!= "" {
1159 v
, err
:= strconv
.ParseInt(cl
, 10, 64)
1160 if err
== nil && v
>= 0 {
1163 w
.conn
.server
.logf("http: invalid Content-Length of %q", cl
)
1164 w
.handlerHeader
.Del("Content-Length")
1169 // extraHeader is the set of headers sometimes added by chunkWriter.writeHeader.
1170 // This type is used to avoid extra allocations from cloning and/or populating
1171 // the response Header map and all its 1-element slices.
1172 type extraHeader
struct {
1175 transferEncoding
string
1176 date
[]byte // written if not nil
1177 contentLength
[]byte // written if not nil
1180 // Sorted the same as extraHeader.Write's loop.
1181 var extraHeaderKeys
= [][]byte{
1182 []byte("Content-Type"),
1183 []byte("Connection"),
1184 []byte("Transfer-Encoding"),
1188 headerContentLength
= []byte("Content-Length: ")
1189 headerDate
= []byte("Date: ")
1192 // Write writes the headers described in h to w.
1194 // This method has a value receiver, despite the somewhat large size
1195 // of h, because it prevents an allocation. The escape analysis isn't
1196 // smart enough to realize this function doesn't mutate h.
1197 func (h extraHeader
) Write(w
*bufio
.Writer
) {
1203 if h
.contentLength
!= nil {
1204 w
.Write(headerContentLength
)
1205 w
.Write(h
.contentLength
)
1208 for i
, v
:= range []string{h
.contentType
, h
.connection
, h
.transferEncoding
} {
1210 w
.Write(extraHeaderKeys
[i
])
1218 // writeHeader finalizes the header sent to the client and writes it
1219 // to cw.res.conn.bufw.
1221 // p is not written by writeHeader, but is the first chunk of the body
1222 // that will be written. It is sniffed for a Content-Type if none is
1223 // set explicitly. It's also used to set the Content-Length, if the
1224 // total body size was small and the handler has already finished
1226 func (cw
*chunkWriter
) writeHeader(p
[]byte) {
1230 cw
.wroteHeader
= true
1233 keepAlivesEnabled
:= w
.conn
.server
.doKeepAlives()
1234 isHEAD
:= w
.req
.Method
== "HEAD"
1236 // header is written out to w.conn.buf below. Depending on the
1237 // state of the handler, we either own the map or not. If we
1238 // don't own it, the exclude map is created lazily for
1239 // WriteSubset to remove headers. The setHeader struct holds
1240 // headers we need to add.
1242 owned
:= header
!= nil
1244 header
= w
.handlerHeader
1246 var excludeHeader
map[string]bool
1247 delHeader
:= func(key
string) {
1252 if _
, ok
:= header
[key
]; !ok
{
1255 if excludeHeader
== nil {
1256 excludeHeader
= make(map[string]bool)
1258 excludeHeader
[key
] = true
1260 var setHeader extraHeader
1262 // Don't write out the fake "Trailer:foo" keys. See TrailerPrefix.
1264 for k
:= range cw
.header
{
1265 if strings
.HasPrefix(k
, TrailerPrefix
) {
1266 if excludeHeader
== nil {
1267 excludeHeader
= make(map[string]bool)
1269 excludeHeader
[k
] = true
1273 for _
, v
:= range cw
.header
["Trailer"] {
1275 foreachHeaderElement(v
, cw
.res
.declareTrailer
)
1278 te
:= header
.get("Transfer-Encoding")
1281 // If the handler is done but never sent a Content-Length
1282 // response header and this is our first (and last) write, set
1283 // it, even to zero. This helps HTTP/1.0 clients keep their
1284 // "keep-alive" connections alive.
1285 // Exceptions: 304/204/1xx responses never get Content-Length, and if
1286 // it was a HEAD request, we don't know the difference between
1287 // 0 actual bytes and 0 bytes because the handler noticed it
1288 // was a HEAD request and chose not to write anything. So for
1289 // HEAD, the handler should either write the Content-Length or
1290 // write non-zero bytes. If it's actually 0 bytes and the
1291 // handler never looked at the Request.Method, we just don't
1292 // send a Content-Length header.
1293 // Further, we don't send an automatic Content-Length if they
1294 // set a Transfer-Encoding, because they're generally incompatible.
1295 if w
.handlerDone
.isSet() && !trailers
&& !hasTE
&& bodyAllowedForStatus(w
.status
) && header
.get("Content-Length") == "" && (!isHEAD ||
len(p
) > 0) {
1296 w
.contentLength
= int64(len(p
))
1297 setHeader
.contentLength
= strconv
.AppendInt(cw
.res
.clenBuf
[:0], int64(len(p
)), 10)
1300 // If this was an HTTP/1.0 request with keep-alive and we sent a
1301 // Content-Length back, we can make this a keep-alive response ...
1302 if w
.wants10KeepAlive
&& keepAlivesEnabled
{
1303 sentLength
:= header
.get("Content-Length") != ""
1304 if sentLength
&& header
.get("Connection") == "keep-alive" {
1305 w
.closeAfterReply
= false
1309 // Check for an explicit (and valid) Content-Length header.
1310 hasCL
:= w
.contentLength
!= -1
1312 if w
.wants10KeepAlive
&& (isHEAD || hasCL ||
!bodyAllowedForStatus(w
.status
)) {
1313 _
, connectionHeaderSet
:= header
["Connection"]
1314 if !connectionHeaderSet
{
1315 setHeader
.connection
= "keep-alive"
1317 } else if !w
.req
.ProtoAtLeast(1, 1) || w
.wantsClose
{
1318 w
.closeAfterReply
= true
1321 if header
.get("Connection") == "close" ||
!keepAlivesEnabled
{
1322 w
.closeAfterReply
= true
1325 // If the client wanted a 100-continue but we never sent it to
1326 // them (or, more strictly: we never finished reading their
1327 // request body), don't reuse this connection because it's now
1328 // in an unknown state: we might be sending this response at
1329 // the same time the client is now sending its request body
1330 // after a timeout. (Some HTTP clients send Expect:
1331 // 100-continue but knowing that some servers don't support
1332 // it, the clients set a timer and send the body later anyway)
1333 // If we haven't seen EOF, we can't skip over the unread body
1334 // because we don't know if the next bytes on the wire will be
1335 // the body-following-the-timer or the subsequent request.
1337 if ecr
, ok
:= w
.req
.Body
.(*expectContinueReader
); ok
&& !ecr
.sawEOF
.isSet() {
1338 w
.closeAfterReply
= true
1341 // Per RFC 2616, we should consume the request body before
1342 // replying, if the handler hasn't already done so. But we
1343 // don't want to do an unbounded amount of reading here for
1344 // DoS reasons, so we only try up to a threshold.
1345 // TODO(bradfitz): where does RFC 2616 say that? See Issue 15527
1346 // about HTTP/1.x Handlers concurrently reading and writing, like
1347 // HTTP/2 handlers can do. Maybe this code should be relaxed?
1348 if w
.req
.ContentLength
!= 0 && !w
.closeAfterReply
{
1349 var discard
, tooBig
bool
1351 switch bdy
:= w
.req
.Body
.(type) {
1352 case *expectContinueReader
:
1353 if bdy
.resp
.wroteContinue
{
1361 // Body was closed in handler with non-EOF error.
1362 w
.closeAfterReply
= true
1364 case bdy
.unreadDataSizeLocked() >= maxPostHandlerReadBytes
:
1375 _
, err
:= io
.CopyN(io
.Discard
, w
.reqBody
, maxPostHandlerReadBytes
+1)
1378 // There must be even more data left over.
1380 case ErrBodyReadAfterClose
:
1381 // Body was already consumed and closed.
1383 // The remaining body was just consumed, close it.
1384 err
= w
.reqBody
.Close()
1386 w
.closeAfterReply
= true
1389 // Some other kind of error occurred, like a read timeout, or
1390 // corrupt chunked encoding. In any case, whatever remains
1391 // on the wire must not be parsed as another HTTP request.
1392 w
.closeAfterReply
= true
1398 delHeader("Connection")
1399 setHeader
.connection
= "close"
1404 if bodyAllowedForStatus(code
) {
1405 // If no content type, apply sniffing algorithm to body.
1406 _
, haveType
:= header
["Content-Type"]
1408 // If the Content-Encoding was set and is non-blank,
1409 // we shouldn't sniff the body. See Issue 31753.
1410 ce
:= header
.Get("Content-Encoding")
1411 hasCE
:= len(ce
) > 0
1412 if !hasCE
&& !haveType
&& !hasTE
&& len(p
) > 0 {
1413 setHeader
.contentType
= DetectContentType(p
)
1416 for _
, k
:= range suppressedHeaders(code
) {
1421 if !header
.has("Date") {
1422 setHeader
.date
= appendTime(cw
.res
.dateBuf
[:0], time
.Now())
1425 if hasCL
&& hasTE
&& te
!= "identity" {
1426 // TODO: return an error if WriteHeader gets a return parameter
1427 // For now just ignore the Content-Length.
1428 w
.conn
.server
.logf("http: WriteHeader called with both Transfer-Encoding of %q and a Content-Length of %d",
1429 te
, w
.contentLength
)
1430 delHeader("Content-Length")
1434 if w
.req
.Method
== "HEAD" ||
!bodyAllowedForStatus(code
) || code
== StatusNoContent
{
1435 // Response has no body.
1436 delHeader("Transfer-Encoding")
1438 // Content-Length has been provided, so no chunking is to be done.
1439 delHeader("Transfer-Encoding")
1440 } else if w
.req
.ProtoAtLeast(1, 1) {
1441 // HTTP/1.1 or greater: Transfer-Encoding has been set to identity, and no
1442 // content-length has been provided. The connection must be closed after the
1443 // reply is written, and no chunking is to be done. This is the setup
1444 // recommended in the Server-Sent Events candidate recommendation 11,
1446 if hasTE
&& te
== "identity" {
1448 w
.closeAfterReply
= true
1449 delHeader("Transfer-Encoding")
1451 // HTTP/1.1 or greater: use chunked transfer encoding
1452 // to avoid closing the connection at EOF.
1454 setHeader
.transferEncoding
= "chunked"
1455 if hasTE
&& te
== "chunked" {
1456 // We will send the chunked Transfer-Encoding header later.
1457 delHeader("Transfer-Encoding")
1461 // HTTP version < 1.1: cannot do chunked transfer
1462 // encoding and we don't know the Content-Length so
1463 // signal EOF by closing connection.
1464 w
.closeAfterReply
= true
1465 delHeader("Transfer-Encoding") // in case already set
1468 // Cannot use Content-Length with non-identity Transfer-Encoding.
1470 delHeader("Content-Length")
1472 if !w
.req
.ProtoAtLeast(1, 0) {
1476 // Only override the Connection header if it is not a successful
1477 // protocol switch response and if KeepAlives are not enabled.
1478 // See https://golang.org/issue/36381.
1479 delConnectionHeader
:= w
.closeAfterReply
&&
1480 (!keepAlivesEnabled ||
!hasToken(cw
.header
.get("Connection"), "close")) &&
1481 !isProtocolSwitchResponse(w
.status
, header
)
1482 if delConnectionHeader
{
1483 delHeader("Connection")
1484 if w
.req
.ProtoAtLeast(1, 1) {
1485 setHeader
.connection
= "close"
1489 writeStatusLine(w
.conn
.bufw
, w
.req
.ProtoAtLeast(1, 1), code
, w
.statusBuf
[:])
1490 cw
.header
.WriteSubset(w
.conn
.bufw
, excludeHeader
)
1491 setHeader
.Write(w
.conn
.bufw
)
1492 w
.conn
.bufw
.Write(crlf
)
1495 // foreachHeaderElement splits v according to the "#rule" construction
1496 // in RFC 7230 section 7 and calls fn for each non-empty element.
1497 func foreachHeaderElement(v
string, fn
func(string)) {
1498 v
= textproto
.TrimString(v
)
1502 if !strings
.Contains(v
, ",") {
1506 for _
, f
:= range strings
.Split(v
, ",") {
1507 if f
= textproto
.TrimString(f
); f
!= "" {
1513 // writeStatusLine writes an HTTP/1.x Status-Line (RFC 7230 Section 3.1.2)
1514 // to bw. is11 is whether the HTTP request is HTTP/1.1. false means HTTP/1.0.
1515 // code is the response status code.
1516 // scratch is an optional scratch buffer. If it has at least capacity 3, it's used.
1517 func writeStatusLine(bw
*bufio
.Writer
, is11
bool, code
int, scratch
[]byte) {
1519 bw
.WriteString("HTTP/1.1 ")
1521 bw
.WriteString("HTTP/1.0 ")
1523 if text
, ok
:= statusText
[code
]; ok
{
1524 bw
.Write(strconv
.AppendInt(scratch
[:0], int64(code
), 10))
1526 bw
.WriteString(text
)
1527 bw
.WriteString("\r\n")
1529 // don't worry about performance
1530 fmt
.Fprintf(bw
, "%03d status code %d\r\n", code
, code
)
1534 // bodyAllowed reports whether a Write is allowed for this response type.
1535 // It's illegal to call this before the header has been flushed.
1536 func (w
*response
) bodyAllowed() bool {
1540 return bodyAllowedForStatus(w
.status
)
1543 // The Life Of A Write is like this:
1545 // Handler starts. No header has been sent. The handler can either
1546 // write a header, or just start writing. Writing before sending a header
1547 // sends an implicitly empty 200 OK header.
1549 // If the handler didn't declare a Content-Length up front, we either
1550 // go into chunking mode or, if the handler finishes running before
1551 // the chunking buffer size, we compute a Content-Length and send that
1552 // in the header instead.
1554 // Likewise, if the handler didn't set a Content-Type, we sniff that
1555 // from the initial chunk of output.
1557 // The Writers are wired together like:
1559 // 1. *response (the ResponseWriter) ->
1560 // 2. (*response).w, a *bufio.Writer of bufferBeforeChunkingSize bytes ->
1561 // 3. chunkWriter.Writer (whose writeHeader finalizes Content-Length/Type)
1562 // and which writes the chunk headers, if needed ->
1563 // 4. conn.bufw, a *bufio.Writer of default (4kB) bytes, writing to ->
1564 // 5. checkConnErrorWriter{c}, which notes any non-nil error on Write
1565 // and populates c.werr with it if so, but otherwise writes to ->
1566 // 6. the rwc, the net.Conn.
1568 // TODO(bradfitz): short-circuit some of the buffering when the
1569 // initial header contains both a Content-Type and Content-Length.
1570 // Also short-circuit in (1) when the header's been sent and not in
1571 // chunking mode, writing directly to (4) instead, if (2) has no
1572 // buffered data. More generally, we could short-circuit from (1) to
1573 // (3) even in chunking mode if the write size from (1) is over some
1574 // threshold and nothing is in (2). The answer might be mostly making
1575 // bufferBeforeChunkingSize smaller and having bufio's fast-paths deal
1576 // with this instead.
1577 func (w
*response
) Write(data
[]byte) (n
int, err error
) {
1578 return w
.write(len(data
), data
, "")
1581 func (w
*response
) WriteString(data
string) (n
int, err error
) {
1582 return w
.write(len(data
), nil, data
)
1585 // either dataB or dataS is non-zero.
1586 func (w
*response
) write(lenData
int, dataB
[]byte, dataS
string) (n
int, err error
) {
1587 if w
.conn
.hijacked() {
1589 caller
:= relevantCaller()
1590 w
.conn
.server
.logf("http: response.Write on hijacked connection from %s (%s:%d)", caller
.Function
, path
.Base(caller
.File
), caller
.Line
)
1592 return 0, ErrHijacked
1595 if w
.canWriteContinue
.isSet() {
1596 // Body reader wants to write 100 Continue but hasn't yet.
1597 // Tell it not to. The store must be done while holding the lock
1598 // because the lock makes sure that there is not an active write
1599 // this very moment.
1600 w
.writeContinueMu
.Lock()
1601 w
.canWriteContinue
.setFalse()
1602 w
.writeContinueMu
.Unlock()
1606 w
.WriteHeader(StatusOK
)
1611 if !w
.bodyAllowed() {
1612 return 0, ErrBodyNotAllowed
1615 w
.written
+= int64(lenData
) // ignoring errors, for errorKludge
1616 if w
.contentLength
!= -1 && w
.written
> w
.contentLength
{
1617 return 0, ErrContentLength
1620 return w
.w
.Write(dataB
)
1622 return w
.w
.WriteString(dataS
)
1626 func (w
*response
) finishRequest() {
1627 w
.handlerDone
.setTrue()
1630 w
.WriteHeader(StatusOK
)
1638 w
.conn
.r
.abortPendingRead()
1640 // Close the body (regardless of w.closeAfterReply) so we can
1641 // re-use its bufio.Reader later safely.
1644 if w
.req
.MultipartForm
!= nil {
1645 w
.req
.MultipartForm
.RemoveAll()
1649 // shouldReuseConnection reports whether the underlying TCP connection can be reused.
1650 // It must only be called after the handler is done executing.
1651 func (w
*response
) shouldReuseConnection() bool {
1652 if w
.closeAfterReply
{
1653 // The request or something set while executing the
1654 // handler indicated we shouldn't reuse this
1659 if w
.req
.Method
!= "HEAD" && w
.contentLength
!= -1 && w
.bodyAllowed() && w
.contentLength
!= w
.written
{
1660 // Did not write enough. Avoid getting out of sync.
1664 // There was some error writing to the underlying connection
1665 // during the request, so don't re-use this conn.
1666 if w
.conn
.werr
!= nil {
1670 if w
.closedRequestBodyEarly() {
1677 func (w
*response
) closedRequestBodyEarly() bool {
1678 body
, ok
:= w
.req
.Body
.(*body
)
1679 return ok
&& body
.didEarlyClose()
1682 func (w
*response
) Flush() {
1684 w
.WriteHeader(StatusOK
)
1690 func (c
*conn
) finalFlush() {
1692 // Steal the bufio.Reader (~4KB worth of memory) and its associated
1693 // reader for a future connection.
1694 putBufioReader(c
.bufr
)
1700 // Steal the bufio.Writer (~4KB worth of memory) and its associated
1701 // writer for a future connection.
1702 putBufioWriter(c
.bufw
)
1707 // Close the connection.
1708 func (c
*conn
) close() {
1713 // rstAvoidanceDelay is the amount of time we sleep after closing the
1714 // write side of a TCP connection before closing the entire socket.
1715 // By sleeping, we increase the chances that the client sees our FIN
1716 // and processes its final data before they process the subsequent RST
1717 // from closing a connection with known unread data.
1718 // This RST seems to occur mostly on BSD systems. (And Windows?)
1719 // This timeout is somewhat arbitrary (~latency around the planet).
1720 const rstAvoidanceDelay
= 500 * time
.Millisecond
1722 type closeWriter
interface {
1726 var _ closeWriter
= (*net
.TCPConn
)(nil)
1728 // closeWrite flushes any outstanding data and sends a FIN packet (if
1729 // client is connected via TCP), signalling that we're done. We then
1730 // pause for a bit, hoping the client processes it before any
1733 // See https://golang.org/issue/3595
1734 func (c
*conn
) closeWriteAndWait() {
1736 if tcp
, ok
:= c
.rwc
.(closeWriter
); ok
{
1739 time
.Sleep(rstAvoidanceDelay
)
1742 // validNextProto reports whether the proto is a valid ALPN protocol name.
1743 // Everything is valid except the empty string and built-in protocol types,
1744 // so that those can't be overridden with alternate implementations.
1745 func validNextProto(proto
string) bool {
1747 case "", "http/1.1", "http/1.0":
1758 func (c
*conn
) setState(nc net
.Conn
, state ConnState
, runHook
bool) {
1762 srv
.trackConn(c
, true)
1763 case StateHijacked
, StateClosed
:
1764 srv
.trackConn(c
, false)
1766 if state
> 0xff || state
< 0 {
1767 panic("internal error")
1769 packedState
:= uint64(time
.Now().Unix()<<8) |
uint64(state
)
1770 atomic
.StoreUint64(&c
.curState
.atomic
, packedState
)
1774 if hook
:= srv
.ConnState
; hook
!= nil {
1779 func (c
*conn
) getState() (state ConnState
, unixSec
int64) {
1780 packedState
:= atomic
.LoadUint64(&c
.curState
.atomic
)
1781 return ConnState(packedState
& 0xff), int64(packedState
>> 8)
1784 // badRequestError is a literal string (used by in the server in HTML,
1785 // unescaped) to tell the user why their request was bad. It should
1786 // be plain text without user info or other embedded errors.
1787 func badRequestError(e
string) error
{ return statusError
{StatusBadRequest
, e
} }
1789 // statusError is an error used to respond to a request with an HTTP status.
1790 // The text should be plain text without user info or other embedded errors.
1791 type statusError
struct {
1796 func (e statusError
) Error() string { return StatusText(e
.code
) + ": " + e
.text
}
1798 // ErrAbortHandler is a sentinel panic value to abort a handler.
1799 // While any panic from ServeHTTP aborts the response to the client,
1800 // panicking with ErrAbortHandler also suppresses logging of a stack
1801 // trace to the server's error log.
1802 var ErrAbortHandler
= errors
.New("net/http: abort Handler")
1804 // isCommonNetReadError reports whether err is a common error
1805 // encountered during reading a request off the network when the
1806 // client has gone away or had its read fail somehow. This is used to
1807 // determine which logs are interesting enough to log about.
1808 func isCommonNetReadError(err error
) bool {
1812 if neterr
, ok
:= err
.(net
.Error
); ok
&& neterr
.Timeout() {
1815 if oe
, ok
:= err
.(*net
.OpError
); ok
&& oe
.Op
== "read" {
1821 // Serve a new connection.
1822 func (c
*conn
) serve(ctx context
.Context
) {
1823 c
.remoteAddr
= c
.rwc
.RemoteAddr().String()
1824 ctx
= context
.WithValue(ctx
, LocalAddrContextKey
, c
.rwc
.LocalAddr())
1825 var inFlightResponse
*response
1827 if err
:= recover(); err
!= nil && err
!= ErrAbortHandler
{
1828 const size
= 64 << 10
1829 buf
:= make([]byte, size
)
1830 buf
= buf
[:runtime
.Stack(buf
, false)]
1831 c
.server
.logf("http: panic serving %v: %v\n%s", c
.remoteAddr
, err
, buf
)
1833 if inFlightResponse
!= nil {
1834 inFlightResponse
.cancelCtx()
1837 if inFlightResponse
!= nil {
1838 inFlightResponse
.conn
.r
.abortPendingRead()
1839 inFlightResponse
.reqBody
.Close()
1842 c
.setState(c
.rwc
, StateClosed
, runHooks
)
1846 if tlsConn
, ok
:= c
.rwc
.(*tls
.Conn
); ok
{
1847 tlsTO
:= c
.server
.tlsHandshakeTimeout()
1849 dl
:= time
.Now().Add(tlsTO
)
1850 c
.rwc
.SetReadDeadline(dl
)
1851 c
.rwc
.SetWriteDeadline(dl
)
1853 if err
:= tlsConn
.HandshakeContext(ctx
); err
!= nil {
1854 // If the handshake failed due to the client not speaking
1855 // TLS, assume they're speaking plaintext HTTP and write a
1856 // 400 response on the TLS conn's underlying net.Conn.
1857 if re
, ok
:= err
.(tls
.RecordHeaderError
); ok
&& re
.Conn
!= nil && tlsRecordHeaderLooksLikeHTTP(re
.RecordHeader
) {
1858 io
.WriteString(re
.Conn
, "HTTP/1.0 400 Bad Request\r\n\r\nClient sent an HTTP request to an HTTPS server.\n")
1862 c
.server
.logf("http: TLS handshake error from %s: %v", c
.rwc
.RemoteAddr(), err
)
1865 // Restore Conn-level deadlines.
1867 c
.rwc
.SetReadDeadline(time
.Time
{})
1868 c
.rwc
.SetWriteDeadline(time
.Time
{})
1870 c
.tlsState
= new(tls
.ConnectionState
)
1871 *c
.tlsState
= tlsConn
.ConnectionState()
1872 if proto
:= c
.tlsState
.NegotiatedProtocol
; validNextProto(proto
) {
1873 if fn
:= c
.server
.TLSNextProto
[proto
]; fn
!= nil {
1874 h
:= initALPNRequest
{ctx
, tlsConn
, serverHandler
{c
.server
}}
1875 // Mark freshly created HTTP/2 as active and prevent any server state hooks
1876 // from being run on these connections. This prevents closeIdleConns from
1877 // closing such connections. See issue https://golang.org/issue/39776.
1878 c
.setState(c
.rwc
, StateActive
, skipHooks
)
1879 fn(c
.server
, tlsConn
, h
)
1885 // HTTP/1.x from here on.
1887 ctx
, cancelCtx
:= context
.WithCancel(ctx
)
1888 c
.cancelCtx
= cancelCtx
1891 c
.r
= &connReader
{conn
: c
}
1892 c
.bufr
= newBufioReader(c
.r
)
1893 c
.bufw
= newBufioWriterSize(checkConnErrorWriter
{c
}, 4<<10)
1896 w
, err
:= c
.readRequest(ctx
)
1897 if c
.r
.remain
!= c
.server
.initialReadLimitSize() {
1898 // If we read any bytes off the wire, we're active.
1899 c
.setState(c
.rwc
, StateActive
, runHooks
)
1902 const errorHeaders
= "\r\nContent-Type: text/plain; charset=utf-8\r\nConnection: close\r\n\r\n"
1905 case err
== errTooLarge
:
1906 // Their HTTP client may or may not be
1907 // able to read this if we're
1908 // responding to them and hanging up
1909 // while they're still writing their
1910 // request. Undefined behavior.
1911 const publicErr
= "431 Request Header Fields Too Large"
1912 fmt
.Fprintf(c
.rwc
, "HTTP/1.1 "+publicErr
+errorHeaders
+publicErr
)
1913 c
.closeWriteAndWait()
1916 case isUnsupportedTEError(err
):
1917 // Respond as per RFC 7230 Section 3.3.1 which says,
1918 // A server that receives a request message with a
1919 // transfer coding it does not understand SHOULD
1920 // respond with 501 (Unimplemented).
1921 code
:= StatusNotImplemented
1923 // We purposefully aren't echoing back the transfer-encoding's value,
1924 // so as to mitigate the risk of cross side scripting by an attacker.
1925 fmt
.Fprintf(c
.rwc
, "HTTP/1.1 %d %s%sUnsupported transfer encoding", code
, StatusText(code
), errorHeaders
)
1928 case isCommonNetReadError(err
):
1929 return // don't reply
1932 if v
, ok
:= err
.(statusError
); ok
{
1933 fmt
.Fprintf(c
.rwc
, "HTTP/1.1 %d %s: %s%s%d %s: %s", v
.code
, StatusText(v
.code
), v
.text
, errorHeaders
, v
.code
, StatusText(v
.code
), v
.text
)
1936 publicErr
:= "400 Bad Request"
1937 fmt
.Fprintf(c
.rwc
, "HTTP/1.1 "+publicErr
+errorHeaders
+publicErr
)
1942 // Expect 100 Continue support
1944 if req
.expectsContinue() {
1945 if req
.ProtoAtLeast(1, 1) && req
.ContentLength
!= 0 {
1946 // Wrap the Body reader with one that replies on the connection
1947 req
.Body
= &expectContinueReader
{readCloser
: req
.Body
, resp
: w
}
1948 w
.canWriteContinue
.setTrue()
1950 } else if req
.Header
.get("Expect") != "" {
1951 w
.sendExpectationFailed()
1957 if requestBodyRemains(req
.Body
) {
1958 registerOnHitEOF(req
.Body
, w
.conn
.r
.startBackgroundRead
)
1960 w
.conn
.r
.startBackgroundRead()
1963 // HTTP cannot have multiple simultaneous active requests.[*]
1964 // Until the server replies to this request, it can't read another,
1965 // so we might as well run the handler in this goroutine.
1966 // [*] Not strictly true: HTTP pipelining. We could let them all process
1967 // in parallel even if their responses need to be serialized.
1968 // But we're not going to implement HTTP pipelining because it
1969 // was never deployed in the wild and the answer is HTTP/2.
1970 inFlightResponse
= w
1971 serverHandler
{c
.server
}.ServeHTTP(w
, w
.req
)
1972 inFlightResponse
= nil
1978 if !w
.shouldReuseConnection() {
1979 if w
.requestBodyLimitHit || w
.closedRequestBodyEarly() {
1980 c
.closeWriteAndWait()
1984 c
.setState(c
.rwc
, StateIdle
, runHooks
)
1985 c
.curReq
.Store((*response
)(nil))
1987 if !w
.conn
.server
.doKeepAlives() {
1988 // We're in shutdown mode. We might've replied
1989 // to the user without "Connection: close" and
1990 // they might think they can send another
1991 // request, but such is life with HTTP/1.1.
1995 if d
:= c
.server
.idleTimeout(); d
!= 0 {
1996 c
.rwc
.SetReadDeadline(time
.Now().Add(d
))
1997 if _
, err
:= c
.bufr
.Peek(4); err
!= nil {
2001 c
.rwc
.SetReadDeadline(time
.Time
{})
2005 func (w
*response
) sendExpectationFailed() {
2006 // TODO(bradfitz): let ServeHTTP handlers handle
2007 // requests with non-standard expectation[s]? Seems
2008 // theoretical at best, and doesn't fit into the
2009 // current ServeHTTP model anyway. We'd need to
2010 // make the ResponseWriter an optional
2011 // "ExpectReplier" interface or something.
2013 // For now we'll just obey RFC 7231 5.1.1 which says
2014 // "A server that receives an Expect field-value other
2015 // than 100-continue MAY respond with a 417 (Expectation
2016 // Failed) status code to indicate that the unexpected
2017 // expectation cannot be met."
2018 w
.Header().Set("Connection", "close")
2019 w
.WriteHeader(StatusExpectationFailed
)
2023 // Hijack implements the Hijacker.Hijack method. Our response is both a ResponseWriter
2025 func (w
*response
) Hijack() (rwc net
.Conn
, buf
*bufio
.ReadWriter
, err error
) {
2026 if w
.handlerDone
.isSet() {
2027 panic("net/http: Hijack called after ServeHTTP finished")
2037 // Release the bufioWriter that writes to the chunk writer, it is not
2038 // used after a connection has been hijacked.
2039 rwc
, buf
, err
= c
.hijackLocked()
2044 return rwc
, buf
, err
2047 func (w
*response
) CloseNotify() <-chan bool {
2048 if w
.handlerDone
.isSet() {
2049 panic("net/http: CloseNotify called after ServeHTTP finished")
2051 return w
.closeNotifyCh
2054 func registerOnHitEOF(rc io
.ReadCloser
, fn
func()) {
2055 switch v
:= rc
.(type) {
2056 case *expectContinueReader
:
2057 registerOnHitEOF(v
.readCloser
, fn
)
2059 v
.registerOnHitEOF(fn
)
2061 panic("unexpected type " + fmt
.Sprintf("%T", rc
))
2065 // requestBodyRemains reports whether future calls to Read
2066 // on rc might yield more data.
2067 func requestBodyRemains(rc io
.ReadCloser
) bool {
2071 switch v
:= rc
.(type) {
2072 case *expectContinueReader
:
2073 return requestBodyRemains(v
.readCloser
)
2075 return v
.bodyRemains()
2077 panic("unexpected type " + fmt
.Sprintf("%T", rc
))
2081 // The HandlerFunc type is an adapter to allow the use of
2082 // ordinary functions as HTTP handlers. If f is a function
2083 // with the appropriate signature, HandlerFunc(f) is a
2084 // Handler that calls f.
2085 type HandlerFunc
func(ResponseWriter
, *Request
)
2087 // ServeHTTP calls f(w, r).
2088 func (f HandlerFunc
) ServeHTTP(w ResponseWriter
, r
*Request
) {
2094 // Error replies to the request with the specified error message and HTTP code.
2095 // It does not otherwise end the request; the caller should ensure no further
2096 // writes are done to w.
2097 // The error message should be plain text.
2098 func Error(w ResponseWriter
, error
string, code
int) {
2099 w
.Header().Set("Content-Type", "text/plain; charset=utf-8")
2100 w
.Header().Set("X-Content-Type-Options", "nosniff")
2102 fmt
.Fprintln(w
, error
)
2105 // NotFound replies to the request with an HTTP 404 not found error.
2106 func NotFound(w ResponseWriter
, r
*Request
) { Error(w
, "404 page not found", StatusNotFound
) }
2108 // NotFoundHandler returns a simple request handler
2109 // that replies to each request with a ``404 page not found'' reply.
2110 func NotFoundHandler() Handler
{ return HandlerFunc(NotFound
) }
2112 // StripPrefix returns a handler that serves HTTP requests by removing the
2113 // given prefix from the request URL's Path (and RawPath if set) and invoking
2114 // the handler h. StripPrefix handles a request for a path that doesn't begin
2115 // with prefix by replying with an HTTP 404 not found error. The prefix must
2116 // match exactly: if the prefix in the request contains escaped characters
2117 // the reply is also an HTTP 404 not found error.
2118 func StripPrefix(prefix
string, h Handler
) Handler
{
2122 return HandlerFunc(func(w ResponseWriter
, r
*Request
) {
2123 p
:= strings
.TrimPrefix(r
.URL
.Path
, prefix
)
2124 rp
:= strings
.TrimPrefix(r
.URL
.RawPath
, prefix
)
2125 if len(p
) < len(r
.URL
.Path
) && (r
.URL
.RawPath
== "" ||
len(rp
) < len(r
.URL
.RawPath
)) {
2128 r2
.URL
= new(url
.URL
)
2139 // Redirect replies to the request with a redirect to url,
2140 // which may be a path relative to the request path.
2142 // The provided code should be in the 3xx range and is usually
2143 // StatusMovedPermanently, StatusFound or StatusSeeOther.
2145 // If the Content-Type header has not been set, Redirect sets it
2146 // to "text/html; charset=utf-8" and writes a small HTML body.
2147 // Setting the Content-Type header to any value, including nil,
2148 // disables that behavior.
2149 func Redirect(w ResponseWriter
, r
*Request
, url
string, code
int) {
2150 if u
, err
:= urlpkg
.Parse(url
); err
== nil {
2151 // If url was relative, make its path absolute by
2152 // combining with request path.
2153 // The client would probably do this for us,
2154 // but doing it ourselves is more reliable.
2155 // See RFC 7231, section 7.1.2
2156 if u
.Scheme
== "" && u
.Host
== "" {
2157 oldpath
:= r
.URL
.Path
2158 if oldpath
== "" { // should not happen, but avoid a crash if it does
2162 // no leading http://server
2163 if url
== "" || url
[0] != '/' {
2164 // make relative path absolute
2165 olddir
, _
:= path
.Split(oldpath
)
2170 if i
:= strings
.Index(url
, "?"); i
!= -1 {
2171 url
, query
= url
[:i
], url
[i
:]
2174 // clean up but preserve trailing slash
2175 trailing
:= strings
.HasSuffix(url
, "/")
2176 url
= path
.Clean(url
)
2177 if trailing
&& !strings
.HasSuffix(url
, "/") {
2186 // RFC 7231 notes that a short HTML body is usually included in
2187 // the response because older user agents may not understand 301/307.
2188 // Do it only if the request didn't already have a Content-Type header.
2189 _
, hadCT
:= h
["Content-Type"]
2191 h
.Set("Location", hexEscapeNonASCII(url
))
2192 if !hadCT
&& (r
.Method
== "GET" || r
.Method
== "HEAD") {
2193 h
.Set("Content-Type", "text/html; charset=utf-8")
2197 // Shouldn't send the body for POST or HEAD; that leaves GET.
2198 if !hadCT
&& r
.Method
== "GET" {
2199 body
:= "<a href=\"" + htmlEscape(url
) + "\">" + statusText
[code
] + "</a>.\n"
2200 fmt
.Fprintln(w
, body
)
2204 var htmlReplacer
= strings
.NewReplacer(
2208 // """ is shorter than """.
2210 // "'" is shorter than "'" and apos was not in HTML until HTML5.
2214 func htmlEscape(s
string) string {
2215 return htmlReplacer
.Replace(s
)
2218 // Redirect to a fixed URL
2219 type redirectHandler
struct {
2224 func (rh
*redirectHandler
) ServeHTTP(w ResponseWriter
, r
*Request
) {
2225 Redirect(w
, r
, rh
.url
, rh
.code
)
2228 // RedirectHandler returns a request handler that redirects
2229 // each request it receives to the given url using the given
2232 // The provided code should be in the 3xx range and is usually
2233 // StatusMovedPermanently, StatusFound or StatusSeeOther.
2234 func RedirectHandler(url
string, code
int) Handler
{
2235 return &redirectHandler
{url
, code
}
2238 // ServeMux is an HTTP request multiplexer.
2239 // It matches the URL of each incoming request against a list of registered
2240 // patterns and calls the handler for the pattern that
2241 // most closely matches the URL.
2243 // Patterns name fixed, rooted paths, like "/favicon.ico",
2244 // or rooted subtrees, like "/images/" (note the trailing slash).
2245 // Longer patterns take precedence over shorter ones, so that
2246 // if there are handlers registered for both "/images/"
2247 // and "/images/thumbnails/", the latter handler will be
2248 // called for paths beginning "/images/thumbnails/" and the
2249 // former will receive requests for any other paths in the
2250 // "/images/" subtree.
2252 // Note that since a pattern ending in a slash names a rooted subtree,
2253 // the pattern "/" matches all paths not matched by other registered
2254 // patterns, not just the URL with Path == "/".
2256 // If a subtree has been registered and a request is received naming the
2257 // subtree root without its trailing slash, ServeMux redirects that
2258 // request to the subtree root (adding the trailing slash). This behavior can
2259 // be overridden with a separate registration for the path without
2260 // the trailing slash. For example, registering "/images/" causes ServeMux
2261 // to redirect a request for "/images" to "/images/", unless "/images" has
2262 // been registered separately.
2264 // Patterns may optionally begin with a host name, restricting matches to
2265 // URLs on that host only. Host-specific patterns take precedence over
2266 // general patterns, so that a handler might register for the two patterns
2267 // "/codesearch" and "codesearch.google.com/" without also taking over
2268 // requests for "http://www.google.com/".
2270 // ServeMux also takes care of sanitizing the URL request path and the Host
2271 // header, stripping the port number and redirecting any request containing . or
2272 // .. elements or repeated slashes to an equivalent, cleaner URL.
2273 type ServeMux
struct {
2275 m
map[string]muxEntry
2276 es
[]muxEntry
// slice of entries sorted from longest to shortest.
2277 hosts
bool // whether any patterns contain hostnames
2280 type muxEntry
struct {
2285 // NewServeMux allocates and returns a new ServeMux.
2286 func NewServeMux() *ServeMux
{ return new(ServeMux
) }
2288 // DefaultServeMux is the default ServeMux used by Serve.
2289 var DefaultServeMux
= &defaultServeMux
2291 var defaultServeMux ServeMux
2293 // cleanPath returns the canonical path for p, eliminating . and .. elements.
2294 func cleanPath(p
string) string {
2302 // path.Clean removes trailing slash except for root;
2303 // put the trailing slash back if necessary.
2304 if p
[len(p
)-1] == '/' && np
!= "/" {
2305 // Fast path for common case of p being the string we want:
2306 if len(p
) == len(np
)+1 && strings
.HasPrefix(p
, np
) {
2315 // stripHostPort returns h without any trailing ":<port>".
2316 func stripHostPort(h
string) string {
2317 // If no port on host, return unchanged
2318 if !strings
.Contains(h
, ":") {
2321 host
, _
, err
:= net
.SplitHostPort(h
)
2323 return h
// on error, return unchanged
2328 // Find a handler on a handler map given a path string.
2329 // Most-specific (longest) pattern wins.
2330 func (mux
*ServeMux
) match(path
string) (h Handler
, pattern
string) {
2331 // Check for exact match first.
2332 v
, ok
:= mux
.m
[path
]
2334 return v
.h
, v
.pattern
2337 // Check for longest valid match. mux.es contains all patterns
2338 // that end in / sorted from longest to shortest.
2339 for _
, e
:= range mux
.es
{
2340 if strings
.HasPrefix(path
, e
.pattern
) {
2341 return e
.h
, e
.pattern
2347 // redirectToPathSlash determines if the given path needs appending "/" to it.
2348 // This occurs when a handler for path + "/" was already registered, but
2349 // not for path itself. If the path needs appending to, it creates a new
2350 // URL, setting the path to u.Path + "/" and returning true to indicate so.
2351 func (mux
*ServeMux
) redirectToPathSlash(host
, path
string, u
*url
.URL
) (*url
.URL
, bool) {
2353 shouldRedirect
:= mux
.shouldRedirectRLocked(host
, path
)
2355 if !shouldRedirect
{
2359 u
= &url
.URL
{Path
: path
, RawQuery
: u
.RawQuery
}
2363 // shouldRedirectRLocked reports whether the given path and host should be redirected to
2364 // path+"/". This should happen if a handler is registered for path+"/" but
2365 // not path -- see comments at ServeMux.
2366 func (mux
*ServeMux
) shouldRedirectRLocked(host
, path
string) bool {
2367 p
:= []string{path
, host
+ path
}
2369 for _
, c
:= range p
{
2370 if _
, exist
:= mux
.m
[c
]; exist
{
2379 for _
, c
:= range p
{
2380 if _
, exist
:= mux
.m
[c
+"/"]; exist
{
2381 return path
[n
-1] != '/'
2388 // Handler returns the handler to use for the given request,
2389 // consulting r.Method, r.Host, and r.URL.Path. It always returns
2390 // a non-nil handler. If the path is not in its canonical form, the
2391 // handler will be an internally-generated handler that redirects
2392 // to the canonical path. If the host contains a port, it is ignored
2393 // when matching handlers.
2395 // The path and host are used unchanged for CONNECT requests.
2397 // Handler also returns the registered pattern that matches the
2398 // request or, in the case of internally-generated redirects,
2399 // the pattern that will match after following the redirect.
2401 // If there is no registered handler that applies to the request,
2402 // Handler returns a ``page not found'' handler and an empty pattern.
2403 func (mux
*ServeMux
) Handler(r
*Request
) (h Handler
, pattern
string) {
2405 // CONNECT requests are not canonicalized.
2406 if r
.Method
== "CONNECT" {
2407 // If r.URL.Path is /tree and its handler is not registered,
2408 // the /tree -> /tree/ redirect applies to CONNECT requests
2409 // but the path canonicalization does not.
2410 if u
, ok
:= mux
.redirectToPathSlash(r
.URL
.Host
, r
.URL
.Path
, r
.URL
); ok
{
2411 return RedirectHandler(u
.String(), StatusMovedPermanently
), u
.Path
2414 return mux
.handler(r
.Host
, r
.URL
.Path
)
2417 // All other requests have any port stripped and path cleaned
2418 // before passing to mux.handler.
2419 host
:= stripHostPort(r
.Host
)
2420 path
:= cleanPath(r
.URL
.Path
)
2422 // If the given path is /tree and its handler is not registered,
2423 // redirect for /tree/.
2424 if u
, ok
:= mux
.redirectToPathSlash(host
, path
, r
.URL
); ok
{
2425 return RedirectHandler(u
.String(), StatusMovedPermanently
), u
.Path
2428 if path
!= r
.URL
.Path
{
2429 _
, pattern
= mux
.handler(host
, path
)
2430 u
:= &url
.URL
{Path
: path
, RawQuery
: r
.URL
.RawQuery
}
2431 return RedirectHandler(u
.String(), StatusMovedPermanently
), pattern
2434 return mux
.handler(host
, r
.URL
.Path
)
2437 // handler is the main implementation of Handler.
2438 // The path is known to be in canonical form, except for CONNECT methods.
2439 func (mux
*ServeMux
) handler(host
, path
string) (h Handler
, pattern
string) {
2441 defer mux
.mu
.RUnlock()
2443 // Host-specific pattern takes precedence over generic ones
2445 h
, pattern
= mux
.match(host
+ path
)
2448 h
, pattern
= mux
.match(path
)
2451 h
, pattern
= NotFoundHandler(), ""
2456 // ServeHTTP dispatches the request to the handler whose
2457 // pattern most closely matches the request URL.
2458 func (mux
*ServeMux
) ServeHTTP(w ResponseWriter
, r
*Request
) {
2459 if r
.RequestURI
== "*" {
2460 if r
.ProtoAtLeast(1, 1) {
2461 w
.Header().Set("Connection", "close")
2463 w
.WriteHeader(StatusBadRequest
)
2466 h
, _
:= mux
.Handler(r
)
2470 // Handle registers the handler for the given pattern.
2471 // If a handler already exists for pattern, Handle panics.
2472 func (mux
*ServeMux
) Handle(pattern
string, handler Handler
) {
2474 defer mux
.mu
.Unlock()
2477 panic("http: invalid pattern")
2480 panic("http: nil handler")
2482 if _
, exist
:= mux
.m
[pattern
]; exist
{
2483 panic("http: multiple registrations for " + pattern
)
2487 mux
.m
= make(map[string]muxEntry
)
2489 e
:= muxEntry
{h
: handler
, pattern
: pattern
}
2491 if pattern
[len(pattern
)-1] == '/' {
2492 mux
.es
= appendSorted(mux
.es
, e
)
2495 if pattern
[0] != '/' {
2500 func appendSorted(es
[]muxEntry
, e muxEntry
) []muxEntry
{
2502 i
:= sort
.Search(n
, func(i
int) bool {
2503 return len(es
[i
].pattern
) < len(e
.pattern
)
2506 return append(es
, e
)
2508 // we now know that i points at where we want to insert
2509 es
= append(es
, muxEntry
{}) // try to grow the slice in place, any entry works.
2510 copy(es
[i
+1:], es
[i
:]) // Move shorter entries down
2515 // HandleFunc registers the handler function for the given pattern.
2516 func (mux
*ServeMux
) HandleFunc(pattern
string, handler
func(ResponseWriter
, *Request
)) {
2518 panic("http: nil handler")
2520 mux
.Handle(pattern
, HandlerFunc(handler
))
2523 // Handle registers the handler for the given pattern
2524 // in the DefaultServeMux.
2525 // The documentation for ServeMux explains how patterns are matched.
2526 func Handle(pattern
string, handler Handler
) { DefaultServeMux
.Handle(pattern
, handler
) }
2528 // HandleFunc registers the handler function for the given pattern
2529 // in the DefaultServeMux.
2530 // The documentation for ServeMux explains how patterns are matched.
2531 func HandleFunc(pattern
string, handler
func(ResponseWriter
, *Request
)) {
2532 DefaultServeMux
.HandleFunc(pattern
, handler
)
2535 // Serve accepts incoming HTTP connections on the listener l,
2536 // creating a new service goroutine for each. The service goroutines
2537 // read requests and then call handler to reply to them.
2539 // The handler is typically nil, in which case the DefaultServeMux is used.
2541 // HTTP/2 support is only enabled if the Listener returns *tls.Conn
2542 // connections and they were configured with "h2" in the TLS
2543 // Config.NextProtos.
2545 // Serve always returns a non-nil error.
2546 func Serve(l net
.Listener
, handler Handler
) error
{
2547 srv
:= &Server
{Handler
: handler
}
2551 // ServeTLS accepts incoming HTTPS connections on the listener l,
2552 // creating a new service goroutine for each. The service goroutines
2553 // read requests and then call handler to reply to them.
2555 // The handler is typically nil, in which case the DefaultServeMux is used.
2557 // Additionally, files containing a certificate and matching private key
2558 // for the server must be provided. If the certificate is signed by a
2559 // certificate authority, the certFile should be the concatenation
2560 // of the server's certificate, any intermediates, and the CA's certificate.
2562 // ServeTLS always returns a non-nil error.
2563 func ServeTLS(l net
.Listener
, handler Handler
, certFile
, keyFile
string) error
{
2564 srv
:= &Server
{Handler
: handler
}
2565 return srv
.ServeTLS(l
, certFile
, keyFile
)
2568 // A Server defines parameters for running an HTTP server.
2569 // The zero value for Server is a valid configuration.
2570 type Server
struct {
2571 // Addr optionally specifies the TCP address for the server to listen on,
2572 // in the form "host:port". If empty, ":http" (port 80) is used.
2573 // The service names are defined in RFC 6335 and assigned by IANA.
2574 // See net.Dial for details of the address format.
2577 Handler Handler
// handler to invoke, http.DefaultServeMux if nil
2579 // TLSConfig optionally provides a TLS configuration for use
2580 // by ServeTLS and ListenAndServeTLS. Note that this value is
2581 // cloned by ServeTLS and ListenAndServeTLS, so it's not
2582 // possible to modify the configuration with methods like
2583 // tls.Config.SetSessionTicketKeys. To use
2584 // SetSessionTicketKeys, use Server.Serve with a TLS Listener
2586 TLSConfig
*tls
.Config
2588 // ReadTimeout is the maximum duration for reading the entire
2589 // request, including the body. A zero or negative value means
2590 // there will be no timeout.
2592 // Because ReadTimeout does not let Handlers make per-request
2593 // decisions on each request body's acceptable deadline or
2594 // upload rate, most users will prefer to use
2595 // ReadHeaderTimeout. It is valid to use them both.
2596 ReadTimeout time
.Duration
2598 // ReadHeaderTimeout is the amount of time allowed to read
2599 // request headers. The connection's read deadline is reset
2600 // after reading the headers and the Handler can decide what
2601 // is considered too slow for the body. If ReadHeaderTimeout
2602 // is zero, the value of ReadTimeout is used. If both are
2603 // zero, there is no timeout.
2604 ReadHeaderTimeout time
.Duration
2606 // WriteTimeout is the maximum duration before timing out
2607 // writes of the response. It is reset whenever a new
2608 // request's header is read. Like ReadTimeout, it does not
2609 // let Handlers make decisions on a per-request basis.
2610 // A zero or negative value means there will be no timeout.
2611 WriteTimeout time
.Duration
2613 // IdleTimeout is the maximum amount of time to wait for the
2614 // next request when keep-alives are enabled. If IdleTimeout
2615 // is zero, the value of ReadTimeout is used. If both are
2616 // zero, there is no timeout.
2617 IdleTimeout time
.Duration
2619 // MaxHeaderBytes controls the maximum number of bytes the
2620 // server will read parsing the request header's keys and
2621 // values, including the request line. It does not limit the
2622 // size of the request body.
2623 // If zero, DefaultMaxHeaderBytes is used.
2626 // TLSNextProto optionally specifies a function to take over
2627 // ownership of the provided TLS connection when an ALPN
2628 // protocol upgrade has occurred. The map key is the protocol
2629 // name negotiated. The Handler argument should be used to
2630 // handle HTTP requests and will initialize the Request's TLS
2631 // and RemoteAddr if not already set. The connection is
2632 // automatically closed when the function returns.
2633 // If TLSNextProto is not nil, HTTP/2 support is not enabled
2635 TLSNextProto
map[string]func(*Server
, *tls
.Conn
, Handler
)
2637 // ConnState specifies an optional callback function that is
2638 // called when a client connection changes state. See the
2639 // ConnState type and associated constants for details.
2640 ConnState
func(net
.Conn
, ConnState
)
2642 // ErrorLog specifies an optional logger for errors accepting
2643 // connections, unexpected behavior from handlers, and
2644 // underlying FileSystem errors.
2645 // If nil, logging is done via the log package's standard logger.
2646 ErrorLog
*log
.Logger
2648 // BaseContext optionally specifies a function that returns
2649 // the base context for incoming requests on this server.
2650 // The provided Listener is the specific Listener that's
2651 // about to start accepting requests.
2652 // If BaseContext is nil, the default is context.Background().
2653 // If non-nil, it must return a non-nil context.
2654 BaseContext
func(net
.Listener
) context
.Context
2656 // ConnContext optionally specifies a function that modifies
2657 // the context used for a new connection c. The provided ctx
2658 // is derived from the base context and has a ServerContextKey
2660 ConnContext
func(ctx context
.Context
, c net
.Conn
) context
.Context
2662 inShutdown atomicBool
// true when server is in shutdown
2664 disableKeepAlives
int32 // accessed atomically.
2665 nextProtoOnce sync
.Once
// guards setupHTTP2_* init
2666 nextProtoErr error
// result of http2.ConfigureServer if used
2669 listeners
map[*net
.Listener
]struct{}
2670 activeConn
map[*conn
]struct{}
2671 doneChan
chan struct{}
2675 func (s
*Server
) getDoneChan() <-chan struct{} {
2678 return s
.getDoneChanLocked()
2681 func (s
*Server
) getDoneChanLocked() chan struct{} {
2682 if s
.doneChan
== nil {
2683 s
.doneChan
= make(chan struct{})
2688 func (s
*Server
) closeDoneChanLocked() {
2689 ch
:= s
.getDoneChanLocked()
2692 // Already closed. Don't close again.
2694 // Safe to close here. We're the only closer, guarded
2700 // Close immediately closes all active net.Listeners and any
2701 // connections in state StateNew, StateActive, or StateIdle. For a
2702 // graceful shutdown, use Shutdown.
2704 // Close does not attempt to close (and does not even know about)
2705 // any hijacked connections, such as WebSockets.
2707 // Close returns any error returned from closing the Server's
2708 // underlying Listener(s).
2709 func (srv
*Server
) Close() error
{
2710 srv
.inShutdown
.setTrue()
2712 defer srv
.mu
.Unlock()
2713 srv
.closeDoneChanLocked()
2714 err
:= srv
.closeListenersLocked()
2715 for c
:= range srv
.activeConn
{
2717 delete(srv
.activeConn
, c
)
2722 // shutdownPollIntervalMax is the max polling interval when checking
2723 // quiescence during Server.Shutdown. Polling starts with a small
2724 // interval and backs off to the max.
2725 // Ideally we could find a solution that doesn't involve polling,
2726 // but which also doesn't have a high runtime cost (and doesn't
2727 // involve any contentious mutexes), but that is left as an
2728 // exercise for the reader.
2729 const shutdownPollIntervalMax
= 500 * time
.Millisecond
2731 // Shutdown gracefully shuts down the server without interrupting any
2732 // active connections. Shutdown works by first closing all open
2733 // listeners, then closing all idle connections, and then waiting
2734 // indefinitely for connections to return to idle and then shut down.
2735 // If the provided context expires before the shutdown is complete,
2736 // Shutdown returns the context's error, otherwise it returns any
2737 // error returned from closing the Server's underlying Listener(s).
2739 // When Shutdown is called, Serve, ListenAndServe, and
2740 // ListenAndServeTLS immediately return ErrServerClosed. Make sure the
2741 // program doesn't exit and waits instead for Shutdown to return.
2743 // Shutdown does not attempt to close nor wait for hijacked
2744 // connections such as WebSockets. The caller of Shutdown should
2745 // separately notify such long-lived connections of shutdown and wait
2746 // for them to close, if desired. See RegisterOnShutdown for a way to
2747 // register shutdown notification functions.
2749 // Once Shutdown has been called on a server, it may not be reused;
2750 // future calls to methods such as Serve will return ErrServerClosed.
2751 func (srv
*Server
) Shutdown(ctx context
.Context
) error
{
2752 srv
.inShutdown
.setTrue()
2755 lnerr
:= srv
.closeListenersLocked()
2756 srv
.closeDoneChanLocked()
2757 for _
, f
:= range srv
.onShutdown
{
2762 pollIntervalBase
:= time
.Millisecond
2763 nextPollInterval
:= func() time
.Duration
{
2765 interval
:= pollIntervalBase
+ time
.Duration(rand
.Intn(int(pollIntervalBase
/10)))
2766 // Double and clamp for next time.
2767 pollIntervalBase
*= 2
2768 if pollIntervalBase
> shutdownPollIntervalMax
{
2769 pollIntervalBase
= shutdownPollIntervalMax
2774 timer
:= time
.NewTimer(nextPollInterval())
2777 if srv
.closeIdleConns() && srv
.numListeners() == 0 {
2784 timer
.Reset(nextPollInterval())
2789 // RegisterOnShutdown registers a function to call on Shutdown.
2790 // This can be used to gracefully shutdown connections that have
2791 // undergone ALPN protocol upgrade or that have been hijacked.
2792 // This function should start protocol-specific graceful shutdown,
2793 // but should not wait for shutdown to complete.
2794 func (srv
*Server
) RegisterOnShutdown(f
func()) {
2796 srv
.onShutdown
= append(srv
.onShutdown
, f
)
2800 func (s
*Server
) numListeners() int {
2803 return len(s
.listeners
)
2806 // closeIdleConns closes all idle connections and reports whether the
2807 // server is quiescent.
2808 func (s
*Server
) closeIdleConns() bool {
2812 for c
:= range s
.activeConn
{
2813 st
, unixSec
:= c
.getState()
2814 // Issue 22682: treat StateNew connections as if
2815 // they're idle if we haven't read the first request's
2816 // header in over 5 seconds.
2817 if st
== StateNew
&& unixSec
< time
.Now().Unix()-5 {
2820 if st
!= StateIdle || unixSec
== 0 {
2821 // Assume unixSec == 0 means it's a very new
2822 // connection, without state set yet.
2827 delete(s
.activeConn
, c
)
2832 func (s
*Server
) closeListenersLocked() error
{
2834 for ln
:= range s
.listeners
{
2835 if cerr
:= (*ln
).Close(); cerr
!= nil && err
== nil {
2842 // A ConnState represents the state of a client connection to a server.
2843 // It's used by the optional Server.ConnState hook.
2847 // StateNew represents a new connection that is expected to
2848 // send a request immediately. Connections begin at this
2849 // state and then transition to either StateActive or
2851 StateNew ConnState
= iota
2853 // StateActive represents a connection that has read 1 or more
2854 // bytes of a request. The Server.ConnState hook for
2855 // StateActive fires before the request has entered a handler
2856 // and doesn't fire again until the request has been
2857 // handled. After the request is handled, the state
2858 // transitions to StateClosed, StateHijacked, or StateIdle.
2859 // For HTTP/2, StateActive fires on the transition from zero
2860 // to one active request, and only transitions away once all
2861 // active requests are complete. That means that ConnState
2862 // cannot be used to do per-request work; ConnState only notes
2863 // the overall state of the connection.
2866 // StateIdle represents a connection that has finished
2867 // handling a request and is in the keep-alive state, waiting
2868 // for a new request. Connections transition from StateIdle
2869 // to either StateActive or StateClosed.
2872 // StateHijacked represents a hijacked connection.
2873 // This is a terminal state. It does not transition to StateClosed.
2876 // StateClosed represents a closed connection.
2877 // This is a terminal state. Hijacked connections do not
2878 // transition to StateClosed.
2882 var stateName
= map[ConnState
]string{
2884 StateActive
: "active",
2886 StateHijacked
: "hijacked",
2887 StateClosed
: "closed",
2890 func (c ConnState
) String() string {
2894 // serverHandler delegates to either the server's Handler or
2895 // DefaultServeMux and also handles "OPTIONS *" requests.
2896 type serverHandler
struct {
2900 func (sh serverHandler
) ServeHTTP(rw ResponseWriter
, req
*Request
) {
2901 handler
:= sh
.srv
.Handler
2903 handler
= DefaultServeMux
2905 if req
.RequestURI
== "*" && req
.Method
== "OPTIONS" {
2906 handler
= globalOptionsHandler
{}
2909 if req
.URL
!= nil && strings
.Contains(req
.URL
.RawQuery
, ";") {
2910 var allowQuerySemicolonsInUse
int32
2911 req
= req
.WithContext(context
.WithValue(req
.Context(), silenceSemWarnContextKey
, func() {
2912 atomic
.StoreInt32(&allowQuerySemicolonsInUse
, 1)
2915 if atomic
.LoadInt32(&allowQuerySemicolonsInUse
) == 0 {
2916 sh
.srv
.logf("http: URL query contains semicolon, which is no longer a supported separator; parts of the query may be stripped when parsed; see golang.org/issue/25192")
2921 handler
.ServeHTTP(rw
, req
)
2924 var silenceSemWarnContextKey
= &contextKey
{"silence-semicolons"}
2926 // AllowQuerySemicolons returns a handler that serves requests by converting any
2927 // unescaped semicolons in the URL query to ampersands, and invoking the handler h.
2929 // This restores the pre-Go 1.17 behavior of splitting query parameters on both
2930 // semicolons and ampersands. (See golang.org/issue/25192). Note that this
2931 // behavior doesn't match that of many proxies, and the mismatch can lead to
2934 // AllowQuerySemicolons should be invoked before Request.ParseForm is called.
2935 func AllowQuerySemicolons(h Handler
) Handler
{
2936 return HandlerFunc(func(w ResponseWriter
, r
*Request
) {
2937 if silenceSemicolonsWarning
, ok
:= r
.Context().Value(silenceSemWarnContextKey
).(func()); ok
{
2938 silenceSemicolonsWarning()
2940 if strings
.Contains(r
.URL
.RawQuery
, ";") {
2943 r2
.URL
= new(url
.URL
)
2945 r2
.URL
.RawQuery
= strings
.ReplaceAll(r
.URL
.RawQuery
, ";", "&")
2953 // ListenAndServe listens on the TCP network address srv.Addr and then
2954 // calls Serve to handle requests on incoming connections.
2955 // Accepted connections are configured to enable TCP keep-alives.
2957 // If srv.Addr is blank, ":http" is used.
2959 // ListenAndServe always returns a non-nil error. After Shutdown or Close,
2960 // the returned error is ErrServerClosed.
2961 func (srv
*Server
) ListenAndServe() error
{
2962 if srv
.shuttingDown() {
2963 return ErrServerClosed
2969 ln
, err
:= net
.Listen("tcp", addr
)
2973 return srv
.Serve(ln
)
2976 var testHookServerServe
func(*Server
, net
.Listener
) // used if non-nil
2978 // shouldDoServeHTTP2 reports whether Server.Serve should configure
2979 // automatic HTTP/2. (which sets up the srv.TLSNextProto map)
2980 func (srv
*Server
) shouldConfigureHTTP2ForServe() bool {
2981 if srv
.TLSConfig
== nil {
2982 // Compatibility with Go 1.6:
2983 // If there's no TLSConfig, it's possible that the user just
2984 // didn't set it on the http.Server, but did pass it to
2985 // tls.NewListener and passed that listener to Serve.
2986 // So we should configure HTTP/2 (to set up srv.TLSNextProto)
2987 // in case the listener returns an "h2" *tls.Conn.
2990 // The user specified a TLSConfig on their http.Server.
2991 // In this, case, only configure HTTP/2 if their tls.Config
2992 // explicitly mentions "h2". Otherwise http2.ConfigureServer
2993 // would modify the tls.Config to add it, but they probably already
2994 // passed this tls.Config to tls.NewListener. And if they did,
2995 // it's too late anyway to fix it. It would only be potentially racy.
2997 return strSliceContains(srv
.TLSConfig
.NextProtos
, http2NextProtoTLS
)
3000 // ErrServerClosed is returned by the Server's Serve, ServeTLS, ListenAndServe,
3001 // and ListenAndServeTLS methods after a call to Shutdown or Close.
3002 var ErrServerClosed
= errors
.New("http: Server closed")
3004 // Serve accepts incoming connections on the Listener l, creating a
3005 // new service goroutine for each. The service goroutines read requests and
3006 // then call srv.Handler to reply to them.
3008 // HTTP/2 support is only enabled if the Listener returns *tls.Conn
3009 // connections and they were configured with "h2" in the TLS
3010 // Config.NextProtos.
3012 // Serve always returns a non-nil error and closes l.
3013 // After Shutdown or Close, the returned error is ErrServerClosed.
3014 func (srv
*Server
) Serve(l net
.Listener
) error
{
3015 if fn
:= testHookServerServe
; fn
!= nil {
3016 fn(srv
, l
) // call hook with unwrapped listener
3020 l
= &onceCloseListener
{Listener
: l
}
3023 if err
:= srv
.setupHTTP2_Serve(); err
!= nil {
3027 if !srv
.trackListener(&l
, true) {
3028 return ErrServerClosed
3030 defer srv
.trackListener(&l
, false)
3032 baseCtx
:= context
.Background()
3033 if srv
.BaseContext
!= nil {
3034 baseCtx
= srv
.BaseContext(origListener
)
3036 panic("BaseContext returned a nil context")
3040 var tempDelay time
.Duration
// how long to sleep on accept failure
3042 ctx
:= context
.WithValue(baseCtx
, ServerContextKey
, srv
)
3044 rw
, err
:= l
.Accept()
3047 case <-srv
.getDoneChan():
3048 return ErrServerClosed
3051 if ne
, ok
:= err
.(net
.Error
); ok
&& ne
.Temporary() {
3053 tempDelay
= 5 * time
.Millisecond
3057 if max
:= 1 * time
.Second
; tempDelay
> max
{
3060 srv
.logf("http: Accept error: %v; retrying in %v", err
, tempDelay
)
3061 time
.Sleep(tempDelay
)
3067 if cc
:= srv
.ConnContext
; cc
!= nil {
3068 connCtx
= cc(connCtx
, rw
)
3070 panic("ConnContext returned nil")
3074 c
:= srv
.newConn(rw
)
3075 c
.setState(c
.rwc
, StateNew
, runHooks
) // before Serve can return
3080 // ServeTLS accepts incoming connections on the Listener l, creating a
3081 // new service goroutine for each. The service goroutines perform TLS
3082 // setup and then read requests, calling srv.Handler to reply to them.
3084 // Files containing a certificate and matching private key for the
3085 // server must be provided if neither the Server's
3086 // TLSConfig.Certificates nor TLSConfig.GetCertificate are populated.
3087 // If the certificate is signed by a certificate authority, the
3088 // certFile should be the concatenation of the server's certificate,
3089 // any intermediates, and the CA's certificate.
3091 // ServeTLS always returns a non-nil error. After Shutdown or Close, the
3092 // returned error is ErrServerClosed.
3093 func (srv
*Server
) ServeTLS(l net
.Listener
, certFile
, keyFile
string) error
{
3094 // Setup HTTP/2 before srv.Serve, to initialize srv.TLSConfig
3095 // before we clone it and create the TLS Listener.
3096 if err
:= srv
.setupHTTP2_ServeTLS(); err
!= nil {
3100 config
:= cloneTLSConfig(srv
.TLSConfig
)
3101 if !strSliceContains(config
.NextProtos
, "http/1.1") {
3102 config
.NextProtos
= append(config
.NextProtos
, "http/1.1")
3105 configHasCert
:= len(config
.Certificates
) > 0 || config
.GetCertificate
!= nil
3106 if !configHasCert || certFile
!= "" || keyFile
!= "" {
3108 config
.Certificates
= make([]tls
.Certificate
, 1)
3109 config
.Certificates
[0], err
= tls
.LoadX509KeyPair(certFile
, keyFile
)
3115 tlsListener
:= tls
.NewListener(l
, config
)
3116 return srv
.Serve(tlsListener
)
3119 // trackListener adds or removes a net.Listener to the set of tracked
3122 // We store a pointer to interface in the map set, in case the
3123 // net.Listener is not comparable. This is safe because we only call
3124 // trackListener via Serve and can track+defer untrack the same
3125 // pointer to local variable there. We never need to compare a
3126 // Listener from another caller.
3128 // It reports whether the server is still up (not Shutdown or Closed).
3129 func (s
*Server
) trackListener(ln
*net
.Listener
, add
bool) bool {
3132 if s
.listeners
== nil {
3133 s
.listeners
= make(map[*net
.Listener
]struct{})
3136 if s
.shuttingDown() {
3139 s
.listeners
[ln
] = struct{}{}
3141 delete(s
.listeners
, ln
)
3146 func (s
*Server
) trackConn(c
*conn
, add
bool) {
3149 if s
.activeConn
== nil {
3150 s
.activeConn
= make(map[*conn
]struct{})
3153 s
.activeConn
[c
] = struct{}{}
3155 delete(s
.activeConn
, c
)
3159 func (s
*Server
) idleTimeout() time
.Duration
{
3160 if s
.IdleTimeout
!= 0 {
3161 return s
.IdleTimeout
3163 return s
.ReadTimeout
3166 func (s
*Server
) readHeaderTimeout() time
.Duration
{
3167 if s
.ReadHeaderTimeout
!= 0 {
3168 return s
.ReadHeaderTimeout
3170 return s
.ReadTimeout
3173 func (s
*Server
) doKeepAlives() bool {
3174 return atomic
.LoadInt32(&s
.disableKeepAlives
) == 0 && !s
.shuttingDown()
3177 func (s
*Server
) shuttingDown() bool {
3178 return s
.inShutdown
.isSet()
3181 // SetKeepAlivesEnabled controls whether HTTP keep-alives are enabled.
3182 // By default, keep-alives are always enabled. Only very
3183 // resource-constrained environments or servers in the process of
3184 // shutting down should disable them.
3185 func (srv
*Server
) SetKeepAlivesEnabled(v
bool) {
3187 atomic
.StoreInt32(&srv
.disableKeepAlives
, 0)
3190 atomic
.StoreInt32(&srv
.disableKeepAlives
, 1)
3192 // Close idle HTTP/1 conns:
3193 srv
.closeIdleConns()
3195 // TODO: Issue 26303: close HTTP/2 conns as soon as they become idle.
3198 func (s
*Server
) logf(format
string, args
...any
) {
3199 if s
.ErrorLog
!= nil {
3200 s
.ErrorLog
.Printf(format
, args
...)
3202 log
.Printf(format
, args
...)
3206 // logf prints to the ErrorLog of the *Server associated with request r
3207 // via ServerContextKey. If there's no associated server, or if ErrorLog
3208 // is nil, logging is done via the log package's standard logger.
3209 func logf(r
*Request
, format
string, args
...any
) {
3210 s
, _
:= r
.Context().Value(ServerContextKey
).(*Server
)
3211 if s
!= nil && s
.ErrorLog
!= nil {
3212 s
.ErrorLog
.Printf(format
, args
...)
3214 log
.Printf(format
, args
...)
3218 // ListenAndServe listens on the TCP network address addr and then calls
3219 // Serve with handler to handle requests on incoming connections.
3220 // Accepted connections are configured to enable TCP keep-alives.
3222 // The handler is typically nil, in which case the DefaultServeMux is used.
3224 // ListenAndServe always returns a non-nil error.
3225 func ListenAndServe(addr
string, handler Handler
) error
{
3226 server
:= &Server
{Addr
: addr
, Handler
: handler
}
3227 return server
.ListenAndServe()
3230 // ListenAndServeTLS acts identically to ListenAndServe, except that it
3231 // expects HTTPS connections. Additionally, files containing a certificate and
3232 // matching private key for the server must be provided. If the certificate
3233 // is signed by a certificate authority, the certFile should be the concatenation
3234 // of the server's certificate, any intermediates, and the CA's certificate.
3235 func ListenAndServeTLS(addr
, certFile
, keyFile
string, handler Handler
) error
{
3236 server
:= &Server
{Addr
: addr
, Handler
: handler
}
3237 return server
.ListenAndServeTLS(certFile
, keyFile
)
3240 // ListenAndServeTLS listens on the TCP network address srv.Addr and
3241 // then calls ServeTLS to handle requests on incoming TLS connections.
3242 // Accepted connections are configured to enable TCP keep-alives.
3244 // Filenames containing a certificate and matching private key for the
3245 // server must be provided if neither the Server's TLSConfig.Certificates
3246 // nor TLSConfig.GetCertificate are populated. If the certificate is
3247 // signed by a certificate authority, the certFile should be the
3248 // concatenation of the server's certificate, any intermediates, and
3249 // the CA's certificate.
3251 // If srv.Addr is blank, ":https" is used.
3253 // ListenAndServeTLS always returns a non-nil error. After Shutdown or
3254 // Close, the returned error is ErrServerClosed.
3255 func (srv
*Server
) ListenAndServeTLS(certFile
, keyFile
string) error
{
3256 if srv
.shuttingDown() {
3257 return ErrServerClosed
3264 ln
, err
:= net
.Listen("tcp", addr
)
3271 return srv
.ServeTLS(ln
, certFile
, keyFile
)
3274 // setupHTTP2_ServeTLS conditionally configures HTTP/2 on
3275 // srv and reports whether there was an error setting it up. If it is
3276 // not configured for policy reasons, nil is returned.
3277 func (srv
*Server
) setupHTTP2_ServeTLS() error
{
3278 srv
.nextProtoOnce
.Do(srv
.onceSetNextProtoDefaults
)
3279 return srv
.nextProtoErr
3282 // setupHTTP2_Serve is called from (*Server).Serve and conditionally
3283 // configures HTTP/2 on srv using a more conservative policy than
3284 // setupHTTP2_ServeTLS because Serve is called after tls.Listen,
3285 // and may be called concurrently. See shouldConfigureHTTP2ForServe.
3287 // The tests named TestTransportAutomaticHTTP2* and
3288 // TestConcurrentServerServe in server_test.go demonstrate some
3289 // of the supported use cases and motivations.
3290 func (srv
*Server
) setupHTTP2_Serve() error
{
3291 srv
.nextProtoOnce
.Do(srv
.onceSetNextProtoDefaults_Serve
)
3292 return srv
.nextProtoErr
3295 func (srv
*Server
) onceSetNextProtoDefaults_Serve() {
3296 if srv
.shouldConfigureHTTP2ForServe() {
3297 srv
.onceSetNextProtoDefaults()
3301 // onceSetNextProtoDefaults configures HTTP/2, if the user hasn't
3302 // configured otherwise. (by setting srv.TLSNextProto non-nil)
3303 // It must only be called via srv.nextProtoOnce (use srv.setupHTTP2_*).
3304 func (srv
*Server
) onceSetNextProtoDefaults() {
3305 if omitBundledHTTP2 || godebug
.Get("http2server") == "0" {
3308 // Enable HTTP/2 by default if the user hasn't otherwise
3309 // configured their TLSNextProto map.
3310 if srv
.TLSNextProto
== nil {
3311 conf
:= &http2Server
{
3312 NewWriteScheduler
: func() http2WriteScheduler
{ return http2NewPriorityWriteScheduler(nil) },
3314 srv
.nextProtoErr
= http2ConfigureServer(srv
, conf
)
3318 // TimeoutHandler returns a Handler that runs h with the given time limit.
3320 // The new Handler calls h.ServeHTTP to handle each request, but if a
3321 // call runs for longer than its time limit, the handler responds with
3322 // a 503 Service Unavailable error and the given message in its body.
3323 // (If msg is empty, a suitable default message will be sent.)
3324 // After such a timeout, writes by h to its ResponseWriter will return
3325 // ErrHandlerTimeout.
3327 // TimeoutHandler supports the Pusher interface but does not support
3328 // the Hijacker or Flusher interfaces.
3329 func TimeoutHandler(h Handler
, dt time
.Duration
, msg
string) Handler
{
3330 return &timeoutHandler
{
3337 // ErrHandlerTimeout is returned on ResponseWriter Write calls
3338 // in handlers which have timed out.
3339 var ErrHandlerTimeout
= errors
.New("http: Handler timeout")
3341 type timeoutHandler
struct {
3346 // When set, no context will be created and this context will
3348 testContext context
.Context
3351 func (h
*timeoutHandler
) errorBody() string {
3355 return "<html><head><title>Timeout</title></head><body><h1>Timeout</h1></body></html>"
3358 func (h
*timeoutHandler
) ServeHTTP(w ResponseWriter
, r
*Request
) {
3359 ctx
:= h
.testContext
3361 var cancelCtx context
.CancelFunc
3362 ctx
, cancelCtx
= context
.WithTimeout(r
.Context(), h
.dt
)
3365 r
= r
.WithContext(ctx
)
3366 done
:= make(chan struct{})
3367 tw
:= &timeoutWriter
{
3372 panicChan
:= make(chan any
, 1)
3375 if p
:= recover(); p
!= nil {
3379 h
.handler
.ServeHTTP(tw
, r
)
3383 case p
:= <-panicChan
:
3387 defer tw
.mu
.Unlock()
3389 for k
, vv
:= range tw
.h
{
3392 if !tw
.wroteHeader
{
3395 w
.WriteHeader(tw
.code
)
3396 w
.Write(tw
.wbuf
.Bytes())
3399 defer tw
.mu
.Unlock()
3400 switch err
:= ctx
.Err(); err
{
3401 case context
.DeadlineExceeded
:
3402 w
.WriteHeader(StatusServiceUnavailable
)
3403 io
.WriteString(w
, h
.errorBody())
3404 tw
.err
= ErrHandlerTimeout
3406 w
.WriteHeader(StatusServiceUnavailable
)
3412 type timeoutWriter
struct {
3424 var _ Pusher
= (*timeoutWriter
)(nil)
3426 // Push implements the Pusher interface.
3427 func (tw
*timeoutWriter
) Push(target
string, opts
*PushOptions
) error
{
3428 if pusher
, ok
:= tw
.w
.(Pusher
); ok
{
3429 return pusher
.Push(target
, opts
)
3431 return ErrNotSupported
3434 func (tw
*timeoutWriter
) Header() Header
{ return tw
.h
}
3436 func (tw
*timeoutWriter
) Write(p
[]byte) (int, error
) {
3438 defer tw
.mu
.Unlock()
3442 if !tw
.wroteHeader
{
3443 tw
.writeHeaderLocked(StatusOK
)
3445 return tw
.wbuf
.Write(p
)
3448 func (tw
*timeoutWriter
) writeHeaderLocked(code
int) {
3449 checkWriteHeaderCode(code
)
3454 case tw
.wroteHeader
:
3456 caller
:= relevantCaller()
3457 logf(tw
.req
, "http: superfluous response.WriteHeader call from %s (%s:%d)", caller
.Function
, path
.Base(caller
.File
), caller
.Line
)
3460 tw
.wroteHeader
= true
3465 func (tw
*timeoutWriter
) WriteHeader(code
int) {
3467 defer tw
.mu
.Unlock()
3468 tw
.writeHeaderLocked(code
)
3471 // onceCloseListener wraps a net.Listener, protecting it from
3472 // multiple Close calls.
3473 type onceCloseListener
struct {
3479 func (oc
*onceCloseListener
) Close() error
{
3480 oc
.once
.Do(oc
.close)
3484 func (oc
*onceCloseListener
) close() { oc
.closeErr
= oc
.Listener
.Close() }
3486 // globalOptionsHandler responds to "OPTIONS *" requests.
3487 type globalOptionsHandler
struct{}
3489 func (globalOptionsHandler
) ServeHTTP(w ResponseWriter
, r
*Request
) {
3490 w
.Header().Set("Content-Length", "0")
3491 if r
.ContentLength
!= 0 {
3492 // Read up to 4KB of OPTIONS body (as mentioned in the
3493 // spec as being reserved for future use), but anything
3494 // over that is considered a waste of server resources
3495 // (or an attack) and we abort and close the connection,
3496 // courtesy of MaxBytesReader's EOF behavior.
3497 mb
:= MaxBytesReader(w
, r
.Body
, 4<<10)
3498 io
.Copy(io
.Discard
, mb
)
3502 // initALPNRequest is an HTTP handler that initializes certain
3503 // uninitialized fields in its *Request. Such partially-initialized
3504 // Requests come from ALPN protocol handlers.
3505 type initALPNRequest
struct {
3511 // BaseContext is an exported but unadvertised http.Handler method
3512 // recognized by x/net/http2 to pass down a context; the TLSNextProto
3513 // API predates context support so we shoehorn through the only
3514 // interface we have available.
3515 func (h initALPNRequest
) BaseContext() context
.Context
{ return h
.ctx
}
3517 func (h initALPNRequest
) ServeHTTP(rw ResponseWriter
, req
*Request
) {
3519 req
.TLS
= &tls
.ConnectionState
{}
3520 *req
.TLS
= h
.c
.ConnectionState()
3522 if req
.Body
== nil {
3525 if req
.RemoteAddr
== "" {
3526 req
.RemoteAddr
= h
.c
.RemoteAddr().String()
3528 h
.h
.ServeHTTP(rw
, req
)
3531 // loggingConn is used for debugging.
3532 type loggingConn
struct {
3538 uniqNameMu sync
.Mutex
3539 uniqNameNext
= make(map[string]int)
3542 func newLoggingConn(baseName
string, c net
.Conn
) net
.Conn
{
3544 defer uniqNameMu
.Unlock()
3545 uniqNameNext
[baseName
]++
3546 return &loggingConn
{
3547 name
: fmt
.Sprintf("%s-%d", baseName
, uniqNameNext
[baseName
]),
3552 func (c
*loggingConn
) Write(p
[]byte) (n
int, err error
) {
3553 log
.Printf("%s.Write(%d) = ....", c
.name
, len(p
))
3554 n
, err
= c
.Conn
.Write(p
)
3555 log
.Printf("%s.Write(%d) = %d, %v", c
.name
, len(p
), n
, err
)
3559 func (c
*loggingConn
) Read(p
[]byte) (n
int, err error
) {
3560 log
.Printf("%s.Read(%d) = ....", c
.name
, len(p
))
3561 n
, err
= c
.Conn
.Read(p
)
3562 log
.Printf("%s.Read(%d) = %d, %v", c
.name
, len(p
), n
, err
)
3566 func (c
*loggingConn
) Close() (err error
) {
3567 log
.Printf("%s.Close() = ...", c
.name
)
3568 err
= c
.Conn
.Close()
3569 log
.Printf("%s.Close() = %v", c
.name
, err
)
3573 // checkConnErrorWriter writes to c.rwc and records any write errors to c.werr.
3574 // It only contains one field (and a pointer field at that), so it
3575 // fits in an interface value without an extra allocation.
3576 type checkConnErrorWriter
struct {
3580 func (w checkConnErrorWriter
) Write(p
[]byte) (n
int, err error
) {
3581 n
, err
= w
.c
.rwc
.Write(p
)
3582 if err
!= nil && w
.c
.werr
== nil {
3589 func numLeadingCRorLF(v
[]byte) (n
int) {
3590 for _
, b
:= range v
{
3591 if b
== '\r' || b
== '\n' {
3601 func strSliceContains(ss
[]string, s
string) bool {
3602 for _
, v
:= range ss
{
3610 // tlsRecordHeaderLooksLikeHTTP reports whether a TLS record header
3611 // looks like it might've been a misdirected plaintext HTTP request.
3612 func tlsRecordHeaderLooksLikeHTTP(hdr
[5]byte) bool {
3613 switch string(hdr
[:]) {
3614 case "GET /", "HEAD ", "POST ", "PUT /", "OPTIO":
3620 // MaxBytesHandler returns a Handler that runs h with its ResponseWriter and Request.Body wrapped by a MaxBytesReader.
3621 func MaxBytesHandler(h Handler
, n
int64) Handler
{
3622 return HandlerFunc(func(w ResponseWriter
, r
*Request
) {
3624 r2
.Body
= MaxBytesReader(w
, r
.Body
, n
)