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Diffstat (limited to 'src/net/http/server.go')
| -rw-r--r-- | src/net/http/server.go | 3529 |
1 files changed, 3529 insertions, 0 deletions
diff --git a/src/net/http/server.go b/src/net/http/server.go new file mode 100644 index 0000000..198102f --- /dev/null +++ b/src/net/http/server.go @@ -0,0 +1,3529 @@ +// Copyright 2009 The Go Authors. All rights reserved. +// Use of this source code is governed by a BSD-style +// license that can be found in the LICENSE file. + +// HTTP server. See RFC 7230 through 7235. + +package http + +import ( + "bufio" + "bytes" + "context" + "crypto/tls" + "errors" + "fmt" + "io" + "log" + "math/rand" + "net" + "net/textproto" + "net/url" + urlpkg "net/url" + "os" + "path" + "runtime" + "sort" + "strconv" + "strings" + "sync" + "sync/atomic" + "time" + + "golang.org/x/net/http/httpguts" +) + +// Errors used by the HTTP server. +var ( + // ErrBodyNotAllowed is returned by ResponseWriter.Write calls + // when the HTTP method or response code does not permit a + // body. + ErrBodyNotAllowed = errors.New("http: request method or response status code does not allow body") + + // ErrHijacked is returned by ResponseWriter.Write calls when + // the underlying connection has been hijacked using the + // Hijacker interface. A zero-byte write on a hijacked + // connection will return ErrHijacked without any other side + // effects. + ErrHijacked = errors.New("http: connection has been hijacked") + + // ErrContentLength is returned by ResponseWriter.Write calls + // when a Handler set a Content-Length response header with a + // declared size and then attempted to write more bytes than + // declared. + ErrContentLength = errors.New("http: wrote more than the declared Content-Length") + + // Deprecated: ErrWriteAfterFlush is no longer returned by + // anything in the net/http package. Callers should not + // compare errors against this variable. + ErrWriteAfterFlush = errors.New("unused") +) + +// A Handler responds to an HTTP request. +// +// ServeHTTP should write reply headers and data to the ResponseWriter +// and then return. Returning signals that the request is finished; it +// is not valid to use the ResponseWriter or read from the +// Request.Body after or concurrently with the completion of the +// ServeHTTP call. +// +// Depending on the HTTP client software, HTTP protocol version, and +// any intermediaries between the client and the Go server, it may not +// be possible to read from the Request.Body after writing to the +// ResponseWriter. Cautious handlers should read the Request.Body +// first, and then reply. +// +// Except for reading the body, handlers should not modify the +// provided Request. +// +// If ServeHTTP panics, the server (the caller of ServeHTTP) assumes +// that the effect of the panic was isolated to the active request. +// It recovers the panic, logs a stack trace to the server error log, +// and either closes the network connection or sends an HTTP/2 +// RST_STREAM, depending on the HTTP protocol. To abort a handler so +// the client sees an interrupted response but the server doesn't log +// an error, panic with the value ErrAbortHandler. +type Handler interface { + ServeHTTP(ResponseWriter, *Request) +} + +// A ResponseWriter interface is used by an HTTP handler to +// construct an HTTP response. +// +// A ResponseWriter may not be used after the Handler.ServeHTTP method +// has returned. +type ResponseWriter interface { + // Header returns the header map that will be sent by + // WriteHeader. The Header map also is the mechanism with which + // Handlers can set HTTP trailers. + // + // Changing the header map after a call to WriteHeader (or + // Write) has no effect unless the modified headers are + // trailers. + // + // There are two ways to set Trailers. The preferred way is to + // predeclare in the headers which trailers you will later + // send by setting the "Trailer" header to the names of the + // trailer keys which will come later. In this case, those + // keys of the Header map are treated as if they were + // trailers. See the example. The second way, for trailer + // keys not known to the Handler until after the first Write, + // is to prefix the Header map keys with the TrailerPrefix + // constant value. See TrailerPrefix. + // + // To suppress automatic response headers (such as "Date"), set + // their value to nil. + Header() Header + + // Write writes the data to the connection as part of an HTTP reply. + // + // If WriteHeader has not yet been called, Write calls + // WriteHeader(http.StatusOK) before writing the data. If the Header + // does not contain a Content-Type line, Write adds a Content-Type set + // to the result of passing the initial 512 bytes of written data to + // DetectContentType. Additionally, if the total size of all written + // data is under a few KB and there are no Flush calls, the + // Content-Length header is added automatically. + // + // Depending on the HTTP protocol version and the client, calling + // Write or WriteHeader may prevent future reads on the + // Request.Body. For HTTP/1.x requests, handlers should read any + // needed request body data before writing the response. Once the + // headers have been flushed (due to either an explicit Flusher.Flush + // call or writing enough data to trigger a flush), the request body + // may be unavailable. For HTTP/2 requests, the Go HTTP server permits + // handlers to continue to read the request body while concurrently + // writing the response. However, such behavior may not be supported + // by all HTTP/2 clients. Handlers should read before writing if + // possible to maximize compatibility. + Write([]byte) (int, error) + + // WriteHeader sends an HTTP response header with the provided + // status code. + // + // If WriteHeader is not called explicitly, the first call to Write + // will trigger an implicit WriteHeader(http.StatusOK). + // Thus explicit calls to WriteHeader are mainly used to + // send error codes. + // + // The provided code must be a valid HTTP 1xx-5xx status code. + // Only one header may be written. Go does not currently + // support sending user-defined 1xx informational headers, + // with the exception of 100-continue response header that the + // Server sends automatically when the Request.Body is read. + WriteHeader(statusCode int) +} + +// The Flusher interface is implemented by ResponseWriters that allow +// an HTTP handler to flush buffered data to the client. +// +// The default HTTP/1.x and HTTP/2 ResponseWriter implementations +// support Flusher, but ResponseWriter wrappers may not. Handlers +// should always test for this ability at runtime. +// +// Note that even for ResponseWriters that support Flush, +// if the client is connected through an HTTP proxy, +// the buffered data may not reach the client until the response +// completes. +type Flusher interface { + // Flush sends any buffered data to the client. + Flush() +} + +// The Hijacker interface is implemented by ResponseWriters that allow +// an HTTP handler to take over the connection. +// +// The default ResponseWriter for HTTP/1.x connections supports +// Hijacker, but HTTP/2 connections intentionally do not. +// ResponseWriter wrappers may also not support Hijacker. Handlers +// should always test for this ability at runtime. +type Hijacker interface { + // Hijack lets the caller take over the connection. + // After a call to Hijack the HTTP server library + // will not do anything else with the connection. + // + // It becomes the caller's responsibility to manage + // and close the connection. + // + // The returned net.Conn may have read or write deadlines + // already set, depending on the configuration of the + // Server. It is the caller's responsibility to set + // or clear those deadlines as needed. + // + // The returned bufio.Reader may contain unprocessed buffered + // data from the client. + // + // After a call to Hijack, the original Request.Body must not + // be used. The original Request's Context remains valid and + // is not canceled until the Request's ServeHTTP method + // returns. + Hijack() (net.Conn, *bufio.ReadWriter, error) +} + +// The CloseNotifier interface is implemented by ResponseWriters which +// allow detecting when the underlying connection has gone away. +// +// This mechanism can be used to cancel long operations on the server +// if the client has disconnected before the response is ready. +// +// Deprecated: the CloseNotifier interface predates Go's context package. +// New code should use Request.Context instead. +type CloseNotifier interface { + // CloseNotify returns a channel that receives at most a + // single value (true) when the client connection has gone + // away. + // + // CloseNotify may wait to notify until Request.Body has been + // fully read. + // + // After the Handler has returned, there is no guarantee + // that the channel receives a value. + // + // If the protocol is HTTP/1.1 and CloseNotify is called while + // processing an idempotent request (such a GET) while + // HTTP/1.1 pipelining is in use, the arrival of a subsequent + // pipelined request may cause a value to be sent on the + // returned channel. In practice HTTP/1.1 pipelining is not + // enabled in browsers and not seen often in the wild. If this + // is a problem, use HTTP/2 or only use CloseNotify on methods + // such as POST. + CloseNotify() <-chan bool +} + +var ( + // ServerContextKey is a context key. It can be used in HTTP + // handlers with Context.Value to access the server that + // started the handler. The associated value will be of + // type *Server. + ServerContextKey = &contextKey{"http-server"} + + // LocalAddrContextKey is a context key. It can be used in + // HTTP handlers with Context.Value to access the local + // address the connection arrived on. + // The associated value will be of type net.Addr. + LocalAddrContextKey = &contextKey{"local-addr"} +) + +// A conn represents the server side of an HTTP connection. +type conn struct { + // server is the server on which the connection arrived. + // Immutable; never nil. + server *Server + + // cancelCtx cancels the connection-level context. + cancelCtx context.CancelFunc + + // rwc is the underlying network connection. + // This is never wrapped by other types and is the value given out + // to CloseNotifier callers. It is usually of type *net.TCPConn or + // *tls.Conn. + rwc net.Conn + + // remoteAddr is rwc.RemoteAddr().String(). It is not populated synchronously + // inside the Listener's Accept goroutine, as some implementations block. + // It is populated immediately inside the (*conn).serve goroutine. + // This is the value of a Handler's (*Request).RemoteAddr. + remoteAddr string + + // tlsState is the TLS connection state when using TLS. + // nil means not TLS. + tlsState *tls.ConnectionState + + // werr is set to the first write error to rwc. + // It is set via checkConnErrorWriter{w}, where bufw writes. + werr error + + // r is bufr's read source. It's a wrapper around rwc that provides + // io.LimitedReader-style limiting (while reading request headers) + // and functionality to support CloseNotifier. See *connReader docs. + r *connReader + + // bufr reads from r. + bufr *bufio.Reader + + // bufw writes to checkConnErrorWriter{c}, which populates werr on error. + bufw *bufio.Writer + + // lastMethod is the method of the most recent request + // on this connection, if any. + lastMethod string + + curReq atomic.Value // of *response (which has a Request in it) + + curState struct{ atomic uint64 } // packed (unixtime<<8|uint8(ConnState)) + + // mu guards hijackedv + mu sync.Mutex + + // hijackedv is whether this connection has been hijacked + // by a Handler with the Hijacker interface. + // It is guarded by mu. + hijackedv bool +} + +func (c *conn) hijacked() bool { + c.mu.Lock() + defer c.mu.Unlock() + return c.hijackedv +} + +// c.mu must be held. +func (c *conn) hijackLocked() (rwc net.Conn, buf *bufio.ReadWriter, err error) { + if c.hijackedv { + return nil, nil, ErrHijacked + } + c.r.abortPendingRead() + + c.hijackedv = true + rwc = c.rwc + rwc.SetDeadline(time.Time{}) + + buf = bufio.NewReadWriter(c.bufr, bufio.NewWriter(rwc)) + if c.r.hasByte { + if _, err := c.bufr.Peek(c.bufr.Buffered() + 1); err != nil { + return nil, nil, fmt.Errorf("unexpected Peek failure reading buffered byte: %v", err) + } + } + c.setState(rwc, StateHijacked, runHooks) + return +} + +// This should be >= 512 bytes for DetectContentType, +// but otherwise it's somewhat arbitrary. +const bufferBeforeChunkingSize = 2048 + +// chunkWriter writes to a response's conn buffer, and is the writer +// wrapped by the response.bufw buffered writer. +// +// chunkWriter also is responsible for finalizing the Header, including +// conditionally setting the Content-Type and setting a Content-Length +// in cases where the handler's final output is smaller than the buffer +// size. It also conditionally adds chunk headers, when in chunking mode. +// +// See the comment above (*response).Write for the entire write flow. +type chunkWriter struct { + res *response + + // header is either nil or a deep clone of res.handlerHeader + // at the time of res.writeHeader, if res.writeHeader is + // called and extra buffering is being done to calculate + // Content-Type and/or Content-Length. + header Header + + // wroteHeader tells whether the header's been written to "the + // wire" (or rather: w.conn.buf). this is unlike + // (*response).wroteHeader, which tells only whether it was + // logically written. + wroteHeader bool + + // set by the writeHeader method: + chunking bool // using chunked transfer encoding for reply body +} + +var ( + crlf = []byte("\r\n") + colonSpace = []byte(": ") +) + +func (cw *chunkWriter) Write(p []byte) (n int, err error) { + if !cw.wroteHeader { + cw.writeHeader(p) + } + if cw.res.req.Method == "HEAD" { + // Eat writes. + return len(p), nil + } + if cw.chunking { + _, err = fmt.Fprintf(cw.res.conn.bufw, "%x\r\n", len(p)) + if err != nil { + cw.res.conn.rwc.Close() + return + } + } + n, err = cw.res.conn.bufw.Write(p) + if cw.chunking && err == nil { + _, err = cw.res.conn.bufw.Write(crlf) + } + if err != nil { + cw.res.conn.rwc.Close() + } + return +} + +func (cw *chunkWriter) flush() { + if !cw.wroteHeader { + cw.writeHeader(nil) + } + cw.res.conn.bufw.Flush() +} + +func (cw *chunkWriter) close() { + if !cw.wroteHeader { + cw.writeHeader(nil) + } + if cw.chunking { + bw := cw.res.conn.bufw // conn's bufio writer + // zero chunk to mark EOF + bw.WriteString("0\r\n") + if trailers := cw.res.finalTrailers(); trailers != nil { + trailers.Write(bw) // the writer handles noting errors + } + // final blank line after the trailers (whether + // present or not) + bw.WriteString("\r\n") + } +} + +// A response represents the server side of an HTTP response. +type response struct { + conn *conn + req *Request // request for this response + reqBody io.ReadCloser + cancelCtx context.CancelFunc // when ServeHTTP exits + wroteHeader bool // reply header has been (logically) written + wroteContinue bool // 100 Continue response was written + wants10KeepAlive bool // HTTP/1.0 w/ Connection "keep-alive" + wantsClose bool // HTTP request has Connection "close" + + // canWriteContinue is a boolean value accessed as an atomic int32 + // that says whether or not a 100 Continue header can be written + // to the connection. + // writeContinueMu must be held while writing the header. + // These two fields together synchronize the body reader + // (the expectContinueReader, which wants to write 100 Continue) + // against the main writer. + canWriteContinue atomicBool + writeContinueMu sync.Mutex + + w *bufio.Writer // buffers output in chunks to chunkWriter + cw chunkWriter + + // handlerHeader is the Header that Handlers get access to, + // which may be retained and mutated even after WriteHeader. + // handlerHeader is copied into cw.header at WriteHeader + // time, and privately mutated thereafter. + handlerHeader Header + calledHeader bool // handler accessed handlerHeader via Header + + written int64 // number of bytes written in body + contentLength int64 // explicitly-declared Content-Length; or -1 + status int // status code passed to WriteHeader + + // close connection after this reply. set on request and + // updated after response from handler if there's a + // "Connection: keep-alive" response header and a + // Content-Length. + closeAfterReply bool + + // requestBodyLimitHit is set by requestTooLarge when + // maxBytesReader hits its max size. It is checked in + // WriteHeader, to make sure we don't consume the + // remaining request body to try to advance to the next HTTP + // request. Instead, when this is set, we stop reading + // subsequent requests on this connection and stop reading + // input from it. + requestBodyLimitHit bool + + // trailers are the headers to be sent after the handler + // finishes writing the body. This field is initialized from + // the Trailer response header when the response header is + // written. + trailers []string + + handlerDone atomicBool // set true when the handler exits + + // Buffers for Date, Content-Length, and status code + dateBuf [len(TimeFormat)]byte + clenBuf [10]byte + statusBuf [3]byte + + // closeNotifyCh is the channel returned by CloseNotify. + // TODO(bradfitz): this is currently (for Go 1.8) always + // non-nil. Make this lazily-created again as it used to be? + closeNotifyCh chan bool + didCloseNotify int32 // atomic (only 0->1 winner should send) +} + +// TrailerPrefix is a magic prefix for ResponseWriter.Header map keys +// that, if present, signals that the map entry is actually for +// the response trailers, and not the response headers. The prefix +// is stripped after the ServeHTTP call finishes and the values are +// sent in the trailers. +// +// This mechanism is intended only for trailers that are not known +// prior to the headers being written. If the set of trailers is fixed +// or known before the header is written, the normal Go trailers mechanism +// is preferred: +// https://golang.org/pkg/net/http/#ResponseWriter +// https://golang.org/pkg/net/http/#example_ResponseWriter_trailers +const TrailerPrefix = "Trailer:" + +// finalTrailers is called after the Handler exits and returns a non-nil +// value if the Handler set any trailers. +func (w *response) finalTrailers() Header { + var t Header + for k, vv := range w.handlerHeader { + if strings.HasPrefix(k, TrailerPrefix) { + if t == nil { + t = make(Header) + } + t[strings.TrimPrefix(k, TrailerPrefix)] = vv + } + } + for _, k := range w.trailers { + if t == nil { + t = make(Header) + } + for _, v := range w.handlerHeader[k] { + t.Add(k, v) + } + } + return t +} + +type atomicBool int32 + +func (b *atomicBool) isSet() bool { return atomic.LoadInt32((*int32)(b)) != 0 } +func (b *atomicBool) setTrue() { atomic.StoreInt32((*int32)(b), 1) } +func (b *atomicBool) setFalse() { atomic.StoreInt32((*int32)(b), 0) } + +// declareTrailer is called for each Trailer header when the +// response header is written. It notes that a header will need to be +// written in the trailers at the end of the response. +func (w *response) declareTrailer(k string) { + k = CanonicalHeaderKey(k) + if !httpguts.ValidTrailerHeader(k) { + // Forbidden by RFC 7230, section 4.1.2 + return + } + w.trailers = append(w.trailers, k) +} + +// requestTooLarge is called by maxBytesReader when too much input has +// been read from the client. +func (w *response) requestTooLarge() { + w.closeAfterReply = true + w.requestBodyLimitHit = true + if !w.wroteHeader { + w.Header().Set("Connection", "close") + } +} + +// needsSniff reports whether a Content-Type still needs to be sniffed. +func (w *response) needsSniff() bool { + _, haveType := w.handlerHeader["Content-Type"] + return !w.cw.wroteHeader && !haveType && w.written < sniffLen +} + +// writerOnly hides an io.Writer value's optional ReadFrom method +// from io.Copy. +type writerOnly struct { + io.Writer +} + +// ReadFrom is here to optimize copying from an *os.File regular file +// to a *net.TCPConn with sendfile, or from a supported src type such +// as a *net.TCPConn on Linux with splice. +func (w *response) ReadFrom(src io.Reader) (n int64, err error) { + bufp := copyBufPool.Get().(*[]byte) + buf := *bufp + defer copyBufPool.Put(bufp) + + // Our underlying w.conn.rwc is usually a *TCPConn (with its + // own ReadFrom method). If not, just fall back to the normal + // copy method. + rf, ok := w.conn.rwc.(io.ReaderFrom) + if !ok { + return io.CopyBuffer(writerOnly{w}, src, buf) + } + + // Copy the first sniffLen bytes before switching to ReadFrom. + // This ensures we don't start writing the response before the + // source is available (see golang.org/issue/5660) and provides + // enough bytes to perform Content-Type sniffing when required. + if !w.cw.wroteHeader { + n0, err := io.CopyBuffer(writerOnly{w}, io.LimitReader(src, sniffLen), buf) + n += n0 + if err != nil || n0 < sniffLen { + return n, err + } + } + + w.w.Flush() // get rid of any previous writes + w.cw.flush() // make sure Header is written; flush data to rwc + + // Now that cw has been flushed, its chunking field is guaranteed initialized. + if !w.cw.chunking && w.bodyAllowed() { + n0, err := rf.ReadFrom(src) + n += n0 + w.written += n0 + return n, err + } + + n0, err := io.CopyBuffer(writerOnly{w}, src, buf) + n += n0 + return n, err +} + +// debugServerConnections controls whether all server connections are wrapped +// with a verbose logging wrapper. +const debugServerConnections = false + +// Create new connection from rwc. +func (srv *Server) newConn(rwc net.Conn) *conn { + c := &conn{ + server: srv, + rwc: rwc, + } + if debugServerConnections { + c.rwc = newLoggingConn("server", c.rwc) + } + return c +} + +type readResult struct { + _ incomparable + n int + err error + b byte // byte read, if n == 1 +} + +// connReader is the io.Reader wrapper used by *conn. It combines a +// selectively-activated io.LimitedReader (to bound request header +// read sizes) with support for selectively keeping an io.Reader.Read +// call blocked in a background goroutine to wait for activity and +// trigger a CloseNotifier channel. +type connReader struct { + conn *conn + + mu sync.Mutex // guards following + hasByte bool + byteBuf [1]byte + cond *sync.Cond + inRead bool + aborted bool // set true before conn.rwc deadline is set to past + remain int64 // bytes remaining +} + +func (cr *connReader) lock() { + cr.mu.Lock() + if cr.cond == nil { + cr.cond = sync.NewCond(&cr.mu) + } +} + +func (cr *connReader) unlock() { cr.mu.Unlock() } + +func (cr *connReader) startBackgroundRead() { + cr.lock() + defer cr.unlock() + if cr.inRead { + panic("invalid concurrent Body.Read call") + } + if cr.hasByte { + return + } + cr.inRead = true + cr.conn.rwc.SetReadDeadline(time.Time{}) + go cr.backgroundRead() +} + +func (cr *connReader) backgroundRead() { + n, err := cr.conn.rwc.Read(cr.byteBuf[:]) + cr.lock() + if n == 1 { + cr.hasByte = true + // We were past the end of the previous request's body already + // (since we wouldn't be in a background read otherwise), so + // this is a pipelined HTTP request. Prior to Go 1.11 we used to + // send on the CloseNotify channel and cancel the context here, + // but the behavior was documented as only "may", and we only + // did that because that's how CloseNotify accidentally behaved + // in very early Go releases prior to context support. Once we + // added context support, people used a Handler's + // Request.Context() and passed it along. Having that context + // cancel on pipelined HTTP requests caused problems. + // Fortunately, almost nothing uses HTTP/1.x pipelining. + // Unfortunately, apt-get does, or sometimes does. + // New Go 1.11 behavior: don't fire CloseNotify or cancel + // contexts on pipelined requests. Shouldn't affect people, but + // fixes cases like Issue 23921. This does mean that a client + // closing their TCP connection after sending a pipelined + // request won't cancel the context, but we'll catch that on any + // write failure (in checkConnErrorWriter.Write). + // If the server never writes, yes, there are still contrived + // server & client behaviors where this fails to ever cancel the + // context, but that's kinda why HTTP/1.x pipelining died + // anyway. + } + if ne, ok := err.(net.Error); ok && cr.aborted && ne.Timeout() { + // Ignore this error. It's the expected error from + // another goroutine calling abortPendingRead. + } else if err != nil { + cr.handleReadError(err) + } + cr.aborted = false + cr.inRead = false + cr.unlock() + cr.cond.Broadcast() +} + +func (cr *connReader) abortPendingRead() { + cr.lock() + defer cr.unlock() + if !cr.inRead { + return + } + cr.aborted = true + cr.conn.rwc.SetReadDeadline(aLongTimeAgo) + for cr.inRead { + cr.cond.Wait() + } + cr.conn.rwc.SetReadDeadline(time.Time{}) +} + +func (cr *connReader) setReadLimit(remain int64) { cr.remain = remain } +func (cr *connReader) setInfiniteReadLimit() { cr.remain = maxInt64 } +func (cr *connReader) hitReadLimit() bool { return cr.remain <= 0 } + +// handleReadError is called whenever a Read from the client returns a +// non-nil error. +// +// The provided non-nil err is almost always io.EOF or a "use of +// closed network connection". In any case, the error is not +// particularly interesting, except perhaps for debugging during +// development. Any error means the connection is dead and we should +// down its context. +// +// It may be called from multiple goroutines. +func (cr *connReader) handleReadError(_ error) { + cr.conn.cancelCtx() + cr.closeNotify() +} + +// may be called from multiple goroutines. +func (cr *connReader) closeNotify() { + res, _ := cr.conn.curReq.Load().(*response) + if res != nil && atomic.CompareAndSwapInt32(&res.didCloseNotify, 0, 1) { + res.closeNotifyCh <- true + } +} + +func (cr *connReader) Read(p []byte) (n int, err error) { + cr.lock() + if cr.inRead { + cr.unlock() + if cr.conn.hijacked() { + panic("invalid Body.Read call. After hijacked, the original Request must not be used") + } + panic("invalid concurrent Body.Read call") + } + if cr.hitReadLimit() { + cr.unlock() + return 0, io.EOF + } + if len(p) == 0 { + cr.unlock() + return 0, nil + } + if int64(len(p)) > cr.remain { + p = p[:cr.remain] + } + if cr.hasByte { + p[0] = cr.byteBuf[0] + cr.hasByte = false + cr.unlock() + return 1, nil + } + cr.inRead = true + cr.unlock() + n, err = cr.conn.rwc.Read(p) + + cr.lock() + cr.inRead = false + if err != nil { + cr.handleReadError(err) + } + cr.remain -= int64(n) + cr.unlock() + + cr.cond.Broadcast() + return n, err +} + +var ( + bufioReaderPool sync.Pool + bufioWriter2kPool sync.Pool + bufioWriter4kPool sync.Pool +) + +var copyBufPool = sync.Pool{ + New: func() interface{} { + b := make([]byte, 32*1024) + return &b + }, +} + +func bufioWriterPool(size int) *sync.Pool { + switch size { + case 2 << 10: + return &bufioWriter2kPool + case 4 << 10: + return &bufioWriter4kPool + } + return nil +} + +func newBufioReader(r io.Reader) *bufio.Reader { + if v := bufioReaderPool.Get(); v != nil { + br := v.(*bufio.Reader) + br.Reset(r) + return br + } + // Note: if this reader size is ever changed, update + // TestHandlerBodyClose's assumptions. + return bufio.NewReader(r) +} + +func putBufioReader(br *bufio.Reader) { + br.Reset(nil) + bufioReaderPool.Put(br) +} + +func newBufioWriterSize(w io.Writer, size int) *bufio.Writer { + pool := bufioWriterPool(size) + if pool != nil { + if v := pool.Get(); v != nil { + bw := v.(*bufio.Writer) + bw.Reset(w) + return bw + } + } + return bufio.NewWriterSize(w, size) +} + +func putBufioWriter(bw *bufio.Writer) { + bw.Reset(nil) + if pool := bufioWriterPool(bw.Available()); pool != nil { + pool.Put(bw) + } +} + +// DefaultMaxHeaderBytes is the maximum permitted size of the headers +// in an HTTP request. +// This can be overridden by setting Server.MaxHeaderBytes. +const DefaultMaxHeaderBytes = 1 << 20 // 1 MB + +func (srv *Server) maxHeaderBytes() int { + if srv.MaxHeaderBytes > 0 { + return srv.MaxHeaderBytes + } + return DefaultMaxHeaderBytes +} + +func (srv *Server) initialReadLimitSize() int64 { + return int64(srv.maxHeaderBytes()) + 4096 // bufio slop +} + +// wrapper around io.ReadCloser which on first read, sends an +// HTTP/1.1 100 Continue header +type expectContinueReader struct { + resp *response + readCloser io.ReadCloser + closed atomicBool + sawEOF atomicBool +} + +func (ecr *expectContinueReader) Read(p []byte) (n int, err error) { + if ecr.closed.isSet() { + return 0, ErrBodyReadAfterClose + } + w := ecr.resp + if !w.wroteContinue && w.canWriteContinue.isSet() && !w.conn.hijacked() { + w.wroteContinue = true + w.writeContinueMu.Lock() + if w.canWriteContinue.isSet() { + w.conn.bufw.WriteString("HTTP/1.1 100 Continue\r\n\r\n") + w.conn.bufw.Flush() + w.canWriteContinue.setFalse() + } + w.writeContinueMu.Unlock() + } + n, err = ecr.readCloser.Read(p) + if err == io.EOF { + ecr.sawEOF.setTrue() + } + return +} + +func (ecr *expectContinueReader) Close() error { + ecr.closed.setTrue() + return ecr.readCloser.Close() +} + +// TimeFormat is the time format to use when generating times in HTTP +// headers. It is like time.RFC1123 but hard-codes GMT as the time +// zone. The time being formatted must be in UTC for Format to +// generate the correct format. +// +// For parsing this time format, see ParseTime. +const TimeFormat = "Mon, 02 Jan 2006 15:04:05 GMT" + +// appendTime is a non-allocating version of []byte(t.UTC().Format(TimeFormat)) +func appendTime(b []byte, t time.Time) []byte { + const days = "SunMonTueWedThuFriSat" + const months = "JanFebMarAprMayJunJulAugSepOctNovDec" + + t = t.UTC() + yy, mm, dd := t.Date() + hh, mn, ss := t.Clock() + day := days[3*t.Weekday():] + mon := months[3*(mm-1):] + + return append(b, + day[0], day[1], day[2], ',', ' ', + byte('0'+dd/10), byte('0'+dd%10), ' ', + mon[0], mon[1], mon[2], ' ', + byte('0'+yy/1000), byte('0'+(yy/100)%10), byte('0'+(yy/10)%10), byte('0'+yy%10), ' ', + byte('0'+hh/10), byte('0'+hh%10), ':', + byte('0'+mn/10), byte('0'+mn%10), ':', + byte('0'+ss/10), byte('0'+ss%10), ' ', + 'G', 'M', 'T') +} + +var errTooLarge = errors.New("http: request too large") + +// Read next request from connection. +func (c *conn) readRequest(ctx context.Context) (w *response, err error) { + if c.hijacked() { + return nil, ErrHijacked + } + + var ( + wholeReqDeadline time.Time // or zero if none + hdrDeadline time.Time // or zero if none + ) + t0 := time.Now() + if d := c.server.readHeaderTimeout(); d != 0 { + hdrDeadline = t0.Add(d) + } + if d := c.server.ReadTimeout; d != 0 { + wholeReqDeadline = t0.Add(d) + } + c.rwc.SetReadDeadline(hdrDeadline) + if d := c.server.WriteTimeout; d != 0 { + defer func() { + c.rwc.SetWriteDeadline(time.Now().Add(d)) + }() + } + + c.r.setReadLimit(c.server.initialReadLimitSize()) + if c.lastMethod == "POST" { + // RFC 7230 section 3 tolerance for old buggy clients. + peek, _ := c.bufr.Peek(4) // ReadRequest will get err below + c.bufr.Discard(numLeadingCRorLF(peek)) + } + req, err := readRequest(c.bufr, keepHostHeader) + if err != nil { + if c.r.hitReadLimit() { + return nil, errTooLarge + } + return nil, err + } + + if !http1ServerSupportsRequest(req) { + return nil, statusError{StatusHTTPVersionNotSupported, "unsupported protocol version"} + } + + c.lastMethod = req.Method + c.r.setInfiniteReadLimit() + + hosts, haveHost := req.Header["Host"] + isH2Upgrade := req.isH2Upgrade() + if req.ProtoAtLeast(1, 1) && (!haveHost || len(hosts) == 0) && !isH2Upgrade && req.Method != "CONNECT" { + return nil, badRequestError("missing required Host header") + } + if len(hosts) > 1 { + return nil, badRequestError("too many Host headers") + } + if len(hosts) == 1 && !httpguts.ValidHostHeader(hosts[0]) { + return nil, badRequestError("malformed Host header") + } + for k, vv := range req.Header { + if !httpguts.ValidHeaderFieldName(k) { + return nil, badRequestError("invalid header name") + } + for _, v := range vv { + if !httpguts.ValidHeaderFieldValue(v) { + return nil, badRequestError("invalid header value") + } + } + } + delete(req.Header, "Host") + + ctx, cancelCtx := context.WithCancel(ctx) + req.ctx = ctx + req.RemoteAddr = c.remoteAddr + req.TLS = c.tlsState + if body, ok := req.Body.(*body); ok { + body.doEarlyClose = true + } + + // Adjust the read deadline if necessary. + if !hdrDeadline.Equal(wholeReqDeadline) { + c.rwc.SetReadDeadline(wholeReqDeadline) + } + + w = &response{ + conn: c, + cancelCtx: cancelCtx, + req: req, + reqBody: req.Body, + handlerHeader: make(Header), + contentLength: -1, + closeNotifyCh: make(chan bool, 1), + + // We populate these ahead of time so we're not + // reading from req.Header after their Handler starts + // and maybe mutates it (Issue 14940) + wants10KeepAlive: req.wantsHttp10KeepAlive(), + wantsClose: req.wantsClose(), + } + if isH2Upgrade { + w.closeAfterReply = true + } + w.cw.res = w + w.w = newBufioWriterSize(&w.cw, bufferBeforeChunkingSize) + return w, nil +} + +// http1ServerSupportsRequest reports whether Go's HTTP/1.x server +// supports the given request. +func http1ServerSupportsRequest(req *Request) bool { + if req.ProtoMajor == 1 { + return true + } + // Accept "PRI * HTTP/2.0" upgrade requests, so Handlers can + // wire up their own HTTP/2 upgrades. + if req.ProtoMajor == 2 && req.ProtoMinor == 0 && + req.Method == "PRI" && req.RequestURI == "*" { + return true + } + // Reject HTTP/0.x, and all other HTTP/2+ requests (which + // aren't encoded in ASCII anyway). + return false +} + +func (w *response) Header() Header { + if w.cw.header == nil && w.wroteHeader && !w.cw.wroteHeader { + // Accessing the header between logically writing it + // and physically writing it means we need to allocate + // a clone to snapshot the logically written state. + w.cw.header = w.handlerHeader.Clone() + } + w.calledHeader = true + return w.handlerHeader +} + +// maxPostHandlerReadBytes is the max number of Request.Body bytes not +// consumed by a handler that the server will read from the client +// in order to keep a connection alive. If there are more bytes than +// this then the server to be paranoid instead sends a "Connection: +// close" response. +// +// This number is approximately what a typical machine's TCP buffer +// size is anyway. (if we have the bytes on the machine, we might as +// well read them) +const maxPostHandlerReadBytes = 256 << 10 + +func checkWriteHeaderCode(code int) { + // Issue 22880: require valid WriteHeader status codes. + // For now we only enforce that it's three digits. + // In the future we might block things over 599 (600 and above aren't defined + // at https://httpwg.org/specs/rfc7231.html#status.codes) + // and we might block under 200 (once we have more mature 1xx support). + // But for now any three digits. + // + // We used to send "HTTP/1.1 000 0" on the wire in responses but there's + // no equivalent bogus thing we can realistically send in HTTP/2, + // so we'll consistently panic instead and help people find their bugs + // early. (We can't return an error from WriteHeader even if we wanted to.) + if code < 100 || code > 999 { + panic(fmt.Sprintf("invalid WriteHeader code %v", code)) + } +} + +// relevantCaller searches the call stack for the first function outside of net/http. +// The purpose of this function is to provide more helpful error messages. +func relevantCaller() runtime.Frame { + pc := make([]uintptr, 16) + n := runtime.Callers(1, pc) + frames := runtime.CallersFrames(pc[:n]) + var frame runtime.Frame + for { + frame, more := frames.Next() + if !strings.HasPrefix(frame.Function, "net/http.") { + return frame + } + if !more { + break + } + } + return frame +} + +func (w *response) WriteHeader(code int) { + if w.conn.hijacked() { + caller := relevantCaller() + w.conn.server.logf("http: response.WriteHeader on hijacked connection from %s (%s:%d)", caller.Function, path.Base(caller.File), caller.Line) + return + } + if w.wroteHeader { + caller := relevantCaller() + w.conn.server.logf("http: superfluous response.WriteHeader call from %s (%s:%d)", caller.Function, path.Base(caller.File), caller.Line) + return + } + checkWriteHeaderCode(code) + w.wroteHeader = true + w.status = code + + if w.calledHeader && w.cw.header == nil { + w.cw.header = w.handlerHeader.Clone() + } + + if cl := w.handlerHeader.get("Content-Length"); cl != "" { + v, err := strconv.ParseInt(cl, 10, 64) + if err == nil && v >= 0 { + w.contentLength = v + } else { + w.conn.server.logf("http: invalid Content-Length of %q", cl) + w.handlerHeader.Del("Content-Length") + } + } +} + +// extraHeader is the set of headers sometimes added by chunkWriter.writeHeader. +// This type is used to avoid extra allocations from cloning and/or populating +// the response Header map and all its 1-element slices. +type extraHeader struct { + contentType string + connection string + transferEncoding string + date []byte // written if not nil + contentLength []byte // written if not nil +} + +// Sorted the same as extraHeader.Write's loop. +var extraHeaderKeys = [][]byte{ + []byte("Content-Type"), + []byte("Connection"), + []byte("Transfer-Encoding"), +} + +var ( + headerContentLength = []byte("Content-Length: ") + headerDate = []byte("Date: ") +) + +// Write writes the headers described in h to w. +// +// This method has a value receiver, despite the somewhat large size +// of h, because it prevents an allocation. The escape analysis isn't +// smart enough to realize this function doesn't mutate h. +func (h extraHeader) Write(w *bufio.Writer) { + if h.date != nil { + w.Write(headerDate) + w.Write(h.date) + w.Write(crlf) + } + if h.contentLength != nil { + w.Write(headerContentLength) + w.Write(h.contentLength) + w.Write(crlf) + } + for i, v := range []string{h.contentType, h.connection, h.transferEncoding} { + if v != "" { + w.Write(extraHeaderKeys[i]) + w.Write(colonSpace) + w.WriteString(v) + w.Write(crlf) + } + } +} + +// writeHeader finalizes the header sent to the client and writes it +// to cw.res.conn.bufw. +// +// p is not written by writeHeader, but is the first chunk of the body +// that will be written. It is sniffed for a Content-Type if none is +// set explicitly. It's also used to set the Content-Length, if the +// total body size was small and the handler has already finished +// running. +func (cw *chunkWriter) writeHeader(p []byte) { + if cw.wroteHeader { + return + } + cw.wroteHeader = true + + w := cw.res + keepAlivesEnabled := w.conn.server.doKeepAlives() + isHEAD := w.req.Method == "HEAD" + + // header is written out to w.conn.buf below. Depending on the + // state of the handler, we either own the map or not. If we + // don't own it, the exclude map is created lazily for + // WriteSubset to remove headers. The setHeader struct holds + // headers we need to add. + header := cw.header + owned := header != nil + if !owned { + header = w.handlerHeader + } + var excludeHeader map[string]bool + delHeader := func(key string) { + if owned { + header.Del(key) + return + } + if _, ok := header[key]; !ok { + return + } + if excludeHeader == nil { + excludeHeader = make(map[string]bool) + } + excludeHeader[key] = true + } + var setHeader extraHeader + + // Don't write out the fake "Trailer:foo" keys. See TrailerPrefix. + trailers := false + for k := range cw.header { + if strings.HasPrefix(k, TrailerPrefix) { + if excludeHeader == nil { + excludeHeader = make(map[string]bool) + } + excludeHeader[k] = true + trailers = true + } + } + for _, v := range cw.header["Trailer"] { + trailers = true + foreachHeaderElement(v, cw.res.declareTrailer) + } + + te := header.get("Transfer-Encoding") + hasTE := te != "" + + // If the handler is done but never sent a Content-Length + // response header and this is our first (and last) write, set + // it, even to zero. This helps HTTP/1.0 clients keep their + // "keep-alive" connections alive. + // Exceptions: 304/204/1xx responses never get Content-Length, and if + // it was a HEAD request, we don't know the difference between + // 0 actual bytes and 0 bytes because the handler noticed it + // was a HEAD request and chose not to write anything. So for + // HEAD, the handler should either write the Content-Length or + // write non-zero bytes. If it's actually 0 bytes and the + // handler never looked at the Request.Method, we just don't + // send a Content-Length header. + // Further, we don't send an automatic Content-Length if they + // set a Transfer-Encoding, because they're generally incompatible. + if w.handlerDone.isSet() && !trailers && !hasTE && bodyAllowedForStatus(w.status) && header.get("Content-Length") == "" && (!isHEAD || len(p) > 0) { + w.contentLength = int64(len(p)) + setHeader.contentLength = strconv.AppendInt(cw.res.clenBuf[:0], int64(len(p)), 10) + } + + // If this was an HTTP/1.0 request with keep-alive and we sent a + // Content-Length back, we can make this a keep-alive response ... + if w.wants10KeepAlive && keepAlivesEnabled { + sentLength := header.get("Content-Length") != "" + if sentLength && header.get("Connection") == "keep-alive" { + w.closeAfterReply = false + } + } + + // Check for an explicit (and valid) Content-Length header. + hasCL := w.contentLength != -1 + + if w.wants10KeepAlive && (isHEAD || hasCL || !bodyAllowedForStatus(w.status)) { + _, connectionHeaderSet := header["Connection"] + if !connectionHeaderSet { + setHeader.connection = "keep-alive" + } + } else if !w.req.ProtoAtLeast(1, 1) || w.wantsClose { + w.closeAfterReply = true + } + + if header.get("Connection") == "close" || !keepAlivesEnabled { + w.closeAfterReply = true + } + + // If the client wanted a 100-continue but we never sent it to + // them (or, more strictly: we never finished reading their + // request body), don't reuse this connection because it's now + // in an unknown state: we might be sending this response at + // the same time the client is now sending its request body + // after a timeout. (Some HTTP clients send Expect: + // 100-continue but knowing that some servers don't support + // it, the clients set a timer and send the body later anyway) + // If we haven't seen EOF, we can't skip over the unread body + // because we don't know if the next bytes on the wire will be + // the body-following-the-timer or the subsequent request. + // See Issue 11549. + if ecr, ok := w.req.Body.(*expectContinueReader); ok && !ecr.sawEOF.isSet() { + w.closeAfterReply = true + } + + // Per RFC 2616, we should consume the request body before + // replying, if the handler hasn't already done so. But we + // don't want to do an unbounded amount of reading here for + // DoS reasons, so we only try up to a threshold. + // TODO(bradfitz): where does RFC 2616 say that? See Issue 15527 + // about HTTP/1.x Handlers concurrently reading and writing, like + // HTTP/2 handlers can do. Maybe this code should be relaxed? + if w.req.ContentLength != 0 && !w.closeAfterReply { + var discard, tooBig bool + + switch bdy := w.req.Body.(type) { + case *expectContinueReader: + if bdy.resp.wroteContinue { + discard = true + } + case *body: + bdy.mu.Lock() + switch { + case bdy.closed: + if !bdy.sawEOF { + // Body was closed in handler with non-EOF error. + w.closeAfterReply = true + } + case bdy.unreadDataSizeLocked() >= maxPostHandlerReadBytes: + tooBig = true + default: + discard = true + } + bdy.mu.Unlock() + default: + discard = true + } + + if discard { + _, err := io.CopyN(io.Discard, w.reqBody, maxPostHandlerReadBytes+1) + switch err { + case nil: + // There must be even more data left over. + tooBig = true + case ErrBodyReadAfterClose: + // Body was already consumed and closed. + case io.EOF: + // The remaining body was just consumed, close it. + err = w.reqBody.Close() + if err != nil { + w.closeAfterReply = true + } + default: + // Some other kind of error occurred, like a read timeout, or + // corrupt chunked encoding. In any case, whatever remains + // on the wire must not be parsed as another HTTP request. + w.closeAfterReply = true + } + } + + if tooBig { + w.requestTooLarge() + delHeader("Connection") + setHeader.connection = "close" + } + } + + code := w.status + if bodyAllowedForStatus(code) { + // If no content type, apply sniffing algorithm to body. + _, haveType := header["Content-Type"] + + // If the Content-Encoding was set and is non-blank, + // we shouldn't sniff the body. See Issue 31753. + ce := header.Get("Content-Encoding") + hasCE := len(ce) > 0 + if !hasCE && !haveType && !hasTE && len(p) > 0 { + setHeader.contentType = DetectContentType(p) + } + } else { + for _, k := range suppressedHeaders(code) { + delHeader(k) + } + } + + if !header.has("Date") { + setHeader.date = appendTime(cw.res.dateBuf[:0], time.Now()) + } + + if hasCL && hasTE && te != "identity" { + // TODO: return an error if WriteHeader gets a return parameter + // For now just ignore the Content-Length. + w.conn.server.logf("http: WriteHeader called with both Transfer-Encoding of %q and a Content-Length of %d", + te, w.contentLength) + delHeader("Content-Length") + hasCL = false + } + + if w.req.Method == "HEAD" || !bodyAllowedForStatus(code) { + // do nothing + } else if code == StatusNoContent { + delHeader("Transfer-Encoding") + } else if hasCL { + delHeader("Transfer-Encoding") + } else if w.req.ProtoAtLeast(1, 1) { + // HTTP/1.1 or greater: Transfer-Encoding has been set to identity, and no + // content-length has been provided. The connection must be closed after the + // reply is written, and no chunking is to be done. This is the setup + // recommended in the Server-Sent Events candidate recommendation 11, + // section 8. + if hasTE && te == "identity" { + cw.chunking = false + w.closeAfterReply = true + } else { + // HTTP/1.1 or greater: use chunked transfer encoding + // to avoid closing the connection at EOF. + cw.chunking = true + setHeader.transferEncoding = "chunked" + if hasTE && te == "chunked" { + // We will send the chunked Transfer-Encoding header later. + delHeader("Transfer-Encoding") + } + } + } else { + // HTTP version < 1.1: cannot do chunked transfer + // encoding and we don't know the Content-Length so + // signal EOF by closing connection. + w.closeAfterReply = true + delHeader("Transfer-Encoding") // in case already set + } + + // Cannot use Content-Length with non-identity Transfer-Encoding. + if cw.chunking { + delHeader("Content-Length") + } + if !w.req.ProtoAtLeast(1, 0) { + return + } + + // Only override the Connection header if it is not a successful + // protocol switch response and if KeepAlives are not enabled. + // See https://golang.org/issue/36381. + delConnectionHeader := w.closeAfterReply && + (!keepAlivesEnabled || !hasToken(cw.header.get("Connection"), "close")) && + !isProtocolSwitchResponse(w.status, header) + if delConnectionHeader { + delHeader("Connection") + if w.req.ProtoAtLeast(1, 1) { + setHeader.connection = "close" + } + } + + writeStatusLine(w.conn.bufw, w.req.ProtoAtLeast(1, 1), code, w.statusBuf[:]) + cw.header.WriteSubset(w.conn.bufw, excludeHeader) + setHeader.Write(w.conn.bufw) + w.conn.bufw.Write(crlf) +} + +// foreachHeaderElement splits v according to the "#rule" construction +// in RFC 7230 section 7 and calls fn for each non-empty element. +func foreachHeaderElement(v string, fn func(string)) { + v = textproto.TrimString(v) + if v == "" { + return + } + if !strings.Contains(v, ",") { + fn(v) + return + } + for _, f := range strings.Split(v, ",") { + if f = textproto.TrimString(f); f != "" { + fn(f) + } + } +} + +// writeStatusLine writes an HTTP/1.x Status-Line (RFC 7230 Section 3.1.2) +// to bw. is11 is whether the HTTP request is HTTP/1.1. false means HTTP/1.0. +// code is the response status code. +// scratch is an optional scratch buffer. If it has at least capacity 3, it's used. +func writeStatusLine(bw *bufio.Writer, is11 bool, code int, scratch []byte) { + if is11 { + bw.WriteString("HTTP/1.1 ") + } else { + bw.WriteString("HTTP/1.0 ") + } + if text, ok := statusText[code]; ok { + bw.Write(strconv.AppendInt(scratch[:0], int64(code), 10)) + bw.WriteByte(' ') + bw.WriteString(text) + bw.WriteString("\r\n") + } else { + // don't worry about performance + fmt.Fprintf(bw, "%03d status code %d\r\n", code, code) + } +} + +// bodyAllowed reports whether a Write is allowed for this response type. +// It's illegal to call this before the header has been flushed. +func (w *response) bodyAllowed() bool { + if !w.wroteHeader { + panic("") + } + return bodyAllowedForStatus(w.status) +} + +// The Life Of A Write is like this: +// +// Handler starts. No header has been sent. The handler can either +// write a header, or just start writing. Writing before sending a header +// sends an implicitly empty 200 OK header. +// +// If the handler didn't declare a Content-Length up front, we either +// go into chunking mode or, if the handler finishes running before +// the chunking buffer size, we compute a Content-Length and send that +// in the header instead. +// +// Likewise, if the handler didn't set a Content-Type, we sniff that +// from the initial chunk of output. +// +// The Writers are wired together like: +// +// 1. *response (the ResponseWriter) -> +// 2. (*response).w, a *bufio.Writer of bufferBeforeChunkingSize bytes +// 3. chunkWriter.Writer (whose writeHeader finalizes Content-Length/Type) +// and which writes the chunk headers, if needed. +// 4. conn.buf, a bufio.Writer of default (4kB) bytes, writing to -> +// 5. checkConnErrorWriter{c}, which notes any non-nil error on Write +// and populates c.werr with it if so. but otherwise writes to: +// 6. the rwc, the net.Conn. +// +// TODO(bradfitz): short-circuit some of the buffering when the +// initial header contains both a Content-Type and Content-Length. +// Also short-circuit in (1) when the header's been sent and not in +// chunking mode, writing directly to (4) instead, if (2) has no +// buffered data. More generally, we could short-circuit from (1) to +// (3) even in chunking mode if the write size from (1) is over some +// threshold and nothing is in (2). The answer might be mostly making +// bufferBeforeChunkingSize smaller and having bufio's fast-paths deal +// with this instead. +func (w *response) Write(data []byte) (n int, err error) { + return w.write(len(data), data, "") +} + +func (w *response) WriteString(data string) (n int, err error) { + return w.write(len(data), nil, data) +} + +// either dataB or dataS is non-zero. +func (w *response) write(lenData int, dataB []byte, dataS string) (n int, err error) { + if w.conn.hijacked() { + if lenData > 0 { + caller := relevantCaller() + w.conn.server.logf("http: response.Write on hijacked connection from %s (%s:%d)", caller.Function, path.Base(caller.File), caller.Line) + } + return 0, ErrHijacked + } + + if w.canWriteContinue.isSet() { + // Body reader wants to write 100 Continue but hasn't yet. + // Tell it not to. The store must be done while holding the lock + // because the lock makes sure that there is not an active write + // this very moment. + w.writeContinueMu.Lock() + w.canWriteContinue.setFalse() + w.writeContinueMu.Unlock() + } + + if !w.wroteHeader { + w.WriteHeader(StatusOK) + } + if lenData == 0 { + return 0, nil + } + if !w.bodyAllowed() { + return 0, ErrBodyNotAllowed + } + + w.written += int64(lenData) // ignoring errors, for errorKludge + if w.contentLength != -1 && w.written > w.contentLength { + return 0, ErrContentLength + } + if dataB != nil { + return w.w.Write(dataB) + } else { + return w.w.WriteString(dataS) + } +} + +func (w *response) finishRequest() { + w.handlerDone.setTrue() + + if !w.wroteHeader { + w.WriteHeader(StatusOK) + } + + w.w.Flush() + putBufioWriter(w.w) + w.cw.close() + w.conn.bufw.Flush() + + w.conn.r.abortPendingRead() + + // Close the body (regardless of w.closeAfterReply) so we can + // re-use its bufio.Reader later safely. + w.reqBody.Close() + + if w.req.MultipartForm != nil { + w.req.MultipartForm.RemoveAll() + } +} + +// shouldReuseConnection reports whether the underlying TCP connection can be reused. +// It must only be called after the handler is done executing. +func (w *response) shouldReuseConnection() bool { + if w.closeAfterReply { + // The request or something set while executing the + // handler indicated we shouldn't reuse this + // connection. + return false + } + + if w.req.Method != "HEAD" && w.contentLength != -1 && w.bodyAllowed() && w.contentLength != w.written { + // Did not write enough. Avoid getting out of sync. + return false + } + + // There was some error writing to the underlying connection + // during the request, so don't re-use this conn. + if w.conn.werr != nil { + return false + } + + if w.closedRequestBodyEarly() { + return false + } + + return true +} + +func (w *response) closedRequestBodyEarly() bool { + body, ok := w.req.Body.(*body) + return ok && body.didEarlyClose() +} + +func (w *response) Flush() { + if !w.wroteHeader { + w.WriteHeader(StatusOK) + } + w.w.Flush() + w.cw.flush() +} + +func (c *conn) finalFlush() { + if c.bufr != nil { + // Steal the bufio.Reader (~4KB worth of memory) and its associated + // reader for a future connection. + putBufioReader(c.bufr) + c.bufr = nil + } + + if c.bufw != nil { + c.bufw.Flush() + // Steal the bufio.Writer (~4KB worth of memory) and its associated + // writer for a future connection. + putBufioWriter(c.bufw) + c.bufw = nil + } +} + +// Close the connection. +func (c *conn) close() { + c.finalFlush() + c.rwc.Close() +} + +// rstAvoidanceDelay is the amount of time we sleep after closing the +// write side of a TCP connection before closing the entire socket. +// By sleeping, we increase the chances that the client sees our FIN +// and processes its final data before they process the subsequent RST +// from closing a connection with known unread data. +// This RST seems to occur mostly on BSD systems. (And Windows?) +// This timeout is somewhat arbitrary (~latency around the planet). +const rstAvoidanceDelay = 500 * time.Millisecond + +type closeWriter interface { + CloseWrite() error +} + +var _ closeWriter = (*net.TCPConn)(nil) + +// closeWrite flushes any outstanding data and sends a FIN packet (if +// client is connected via TCP), signalling that we're done. We then +// pause for a bit, hoping the client processes it before any +// subsequent RST. +// +// See https://golang.org/issue/3595 +func (c *conn) closeWriteAndWait() { + c.finalFlush() + if tcp, ok := c.rwc.(closeWriter); ok { + tcp.CloseWrite() + } + time.Sleep(rstAvoidanceDelay) +} + +// validNextProto reports whether the proto is a valid ALPN protocol name. +// Everything is valid except the empty string and built-in protocol types, +// so that those can't be overridden with alternate implementations. +func validNextProto(proto string) bool { + switch proto { + case "", "http/1.1", "http/1.0": + return false + } + return true +} + +const ( + runHooks = true + skipHooks = false +) + +func (c *conn) setState(nc net.Conn, state ConnState, runHook bool) { + srv := c.server + switch state { + case StateNew: + srv.trackConn(c, true) + case StateHijacked, StateClosed: + srv.trackConn(c, false) + } + if state > 0xff || state < 0 { + panic("internal error") + } + packedState := uint64(time.Now().Unix()<<8) | uint64(state) + atomic.StoreUint64(&c.curState.atomic, packedState) + if !runHook { + return + } + if hook := srv.ConnState; hook != nil { + hook(nc, state) + } +} + +func (c *conn) getState() (state ConnState, unixSec int64) { + packedState := atomic.LoadUint64(&c.curState.atomic) + return ConnState(packedState & 0xff), int64(packedState >> 8) +} + +// badRequestError is a literal string (used by in the server in HTML, +// unescaped) to tell the user why their request was bad. It should +// be plain text without user info or other embedded errors. +func badRequestError(e string) error { return statusError{StatusBadRequest, e} } + +// statusError is an error used to respond to a request with an HTTP status. +// The text should be plain text without user info or other embedded errors. +type statusError struct { + code int + text string +} + +func (e statusError) Error() string { return StatusText(e.code) + ": " + e.text } + +// ErrAbortHandler is a sentinel panic value to abort a handler. +// While any panic from ServeHTTP aborts the response to the client, +// panicking with ErrAbortHandler also suppresses logging of a stack +// trace to the server's error log. +var ErrAbortHandler = errors.New("net/http: abort Handler") + +// isCommonNetReadError reports whether err is a common error +// encountered during reading a request off the network when the +// client has gone away or had its read fail somehow. This is used to +// determine which logs are interesting enough to log about. +func isCommonNetReadError(err error) bool { + if err == io.EOF { + return true + } + if neterr, ok := err.(net.Error); ok && neterr.Timeout() { + return true + } + if oe, ok := err.(*net.OpError); ok && oe.Op == "read" { + return true + } + return false +} + +// Serve a new connection. +func (c *conn) serve(ctx context.Context) { + c.remoteAddr = c.rwc.RemoteAddr().String() + ctx = context.WithValue(ctx, LocalAddrContextKey, c.rwc.LocalAddr()) + defer func() { + if err := recover(); err != nil && err != ErrAbortHandler { + const size = 64 << 10 + buf := make([]byte, size) + buf = buf[:runtime.Stack(buf, false)] + c.server.logf("http: panic serving %v: %v\n%s", c.remoteAddr, err, buf) + } + if !c.hijacked() { + c.close() + c.setState(c.rwc, StateClosed, runHooks) + } + }() + + if tlsConn, ok := c.rwc.(*tls.Conn); ok { + if d := c.server.ReadTimeout; d != 0 { + c.rwc.SetReadDeadline(time.Now().Add(d)) + } + if d := c.server.WriteTimeout; d != 0 { + c.rwc.SetWriteDeadline(time.Now().Add(d)) + } + if err := tlsConn.Handshake(); err != nil { + // If the handshake failed due to the client not speaking + // TLS, assume they're speaking plaintext HTTP and write a + // 400 response on the TLS conn's underlying net.Conn. + if re, ok := err.(tls.RecordHeaderError); ok && re.Conn != nil && tlsRecordHeaderLooksLikeHTTP(re.RecordHeader) { + io.WriteString(re.Conn, "HTTP/1.0 400 Bad Request\r\n\r\nClient sent an HTTP request to an HTTPS server.\n") + re.Conn.Close() + return + } + c.server.logf("http: TLS handshake error from %s: %v", c.rwc.RemoteAddr(), err) + return + } + c.tlsState = new(tls.ConnectionState) + *c.tlsState = tlsConn.ConnectionState() + if proto := c.tlsState.NegotiatedProtocol; validNextProto(proto) { + if fn := c.server.TLSNextProto[proto]; fn != nil { + h := initALPNRequest{ctx, tlsConn, serverHandler{c.server}} + // Mark freshly created HTTP/2 as active and prevent any server state hooks + // from being run on these connections. This prevents closeIdleConns from + // closing such connections. See issue https://golang.org/issue/39776. + c.setState(c.rwc, StateActive, skipHooks) + fn(c.server, tlsConn, h) + } + return + } + } + + // HTTP/1.x from here on. + + ctx, cancelCtx := context.WithCancel(ctx) + c.cancelCtx = cancelCtx + defer cancelCtx() + + c.r = &connReader{conn: c} + c.bufr = newBufioReader(c.r) + c.bufw = newBufioWriterSize(checkConnErrorWriter{c}, 4<<10) + + for { + w, err := c.readRequest(ctx) + if c.r.remain != c.server.initialReadLimitSize() { + // If we read any bytes off the wire, we're active. + c.setState(c.rwc, StateActive, runHooks) + } + if err != nil { + const errorHeaders = "\r\nContent-Type: text/plain; charset=utf-8\r\nConnection: close\r\n\r\n" + + switch { + case err == errTooLarge: + // Their HTTP client may or may not be + // able to read this if we're + // responding to them and hanging up + // while they're still writing their + // request. Undefined behavior. + const publicErr = "431 Request Header Fields Too Large" + fmt.Fprintf(c.rwc, "HTTP/1.1 "+publicErr+errorHeaders+publicErr) + c.closeWriteAndWait() + return + + case isUnsupportedTEError(err): + // Respond as per RFC 7230 Section 3.3.1 which says, + // A server that receives a request message with a + // transfer coding it does not understand SHOULD + // respond with 501 (Unimplemented). + code := StatusNotImplemented + + // We purposefully aren't echoing back the transfer-encoding's value, + // so as to mitigate the risk of cross side scripting by an attacker. + fmt.Fprintf(c.rwc, "HTTP/1.1 %d %s%sUnsupported transfer encoding", code, StatusText(code), errorHeaders) + return + + case isCommonNetReadError(err): + return // don't reply + + default: + if v, ok := err.(statusError); ok { + 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) + return + } + publicErr := "400 Bad Request" + fmt.Fprintf(c.rwc, "HTTP/1.1 "+publicErr+errorHeaders+publicErr) + return + } + } + + // Expect 100 Continue support + req := w.req + if req.expectsContinue() { + if req.ProtoAtLeast(1, 1) && req.ContentLength != 0 { + // Wrap the Body reader with one that replies on the connection + req.Body = &expectContinueReader{readCloser: req.Body, resp: w} + w.canWriteContinue.setTrue() + } + } else if req.Header.get("Expect") != "" { + w.sendExpectationFailed() + return + } + + c.curReq.Store(w) + + if requestBodyRemains(req.Body) { + registerOnHitEOF(req.Body, w.conn.r.startBackgroundRead) + } else { + w.conn.r.startBackgroundRead() + } + + // HTTP cannot have multiple simultaneous active requests.[*] + // Until the server replies to this request, it can't read another, + // so we might as well run the handler in this goroutine. + // [*] Not strictly true: HTTP pipelining. We could let them all process + // in parallel even if their responses need to be serialized. + // But we're not going to implement HTTP pipelining because it + // was never deployed in the wild and the answer is HTTP/2. + serverHandler{c.server}.ServeHTTP(w, w.req) + w.cancelCtx() + if c.hijacked() { + return + } + w.finishRequest() + if !w.shouldReuseConnection() { + if w.requestBodyLimitHit || w.closedRequestBodyEarly() { + c.closeWriteAndWait() + } + return + } + c.setState(c.rwc, StateIdle, runHooks) + c.curReq.Store((*response)(nil)) + + if !w.conn.server.doKeepAlives() { + // We're in shutdown mode. We might've replied + // to the user without "Connection: close" and + // they might think they can send another + // request, but such is life with HTTP/1.1. + return + } + + if d := c.server.idleTimeout(); d != 0 { + c.rwc.SetReadDeadline(time.Now().Add(d)) + if _, err := c.bufr.Peek(4); err != nil { + return + } + } + c.rwc.SetReadDeadline(time.Time{}) + } +} + +func (w *response) sendExpectationFailed() { + // TODO(bradfitz): let ServeHTTP handlers handle + // requests with non-standard expectation[s]? Seems + // theoretical at best, and doesn't fit into the + // current ServeHTTP model anyway. We'd need to + // make the ResponseWriter an optional + // "ExpectReplier" interface or something. + // + // For now we'll just obey RFC 7231 5.1.1 which says + // "A server that receives an Expect field-value other + // than 100-continue MAY respond with a 417 (Expectation + // Failed) status code to indicate that the unexpected + // expectation cannot be met." + w.Header().Set("Connection", "close") + w.WriteHeader(StatusExpectationFailed) + w.finishRequest() +} + +// Hijack implements the Hijacker.Hijack method. Our response is both a ResponseWriter +// and a Hijacker. +func (w *response) Hijack() (rwc net.Conn, buf *bufio.ReadWriter, err error) { + if w.handlerDone.isSet() { + panic("net/http: Hijack called after ServeHTTP finished") + } + if w.wroteHeader { + w.cw.flush() + } + + c := w.conn + c.mu.Lock() + defer c.mu.Unlock() + + // Release the bufioWriter that writes to the chunk writer, it is not + // used after a connection has been hijacked. + rwc, buf, err = c.hijackLocked() + if err == nil { + putBufioWriter(w.w) + w.w = nil + } + return rwc, buf, err +} + +func (w *response) CloseNotify() <-chan bool { + if w.handlerDone.isSet() { + panic("net/http: CloseNotify called after ServeHTTP finished") + } + return w.closeNotifyCh +} + +func registerOnHitEOF(rc io.ReadCloser, fn func()) { + switch v := rc.(type) { + case *expectContinueReader: + registerOnHitEOF(v.readCloser, fn) + case *body: + v.registerOnHitEOF(fn) + default: + panic("unexpected type " + fmt.Sprintf("%T", rc)) + } +} + +// requestBodyRemains reports whether future calls to Read +// on rc might yield more data. +func requestBodyRemains(rc io.ReadCloser) bool { + if rc == NoBody { + return false + } + switch v := rc.(type) { + case *expectContinueReader: + return requestBodyRemains(v.readCloser) + case *body: + return v.bodyRemains() + default: + panic("unexpected type " + fmt.Sprintf("%T", rc)) + } +} + +// The HandlerFunc type is an adapter to allow the use of +// ordinary functions as HTTP handlers. If f is a function +// with the appropriate signature, HandlerFunc(f) is a +// Handler that calls f. +type HandlerFunc func(ResponseWriter, *Request) + +// ServeHTTP calls f(w, r). +func (f HandlerFunc) ServeHTTP(w ResponseWriter, r *Request) { + f(w, r) +} + +// Helper handlers + +// Error replies to the request with the specified error message and HTTP code. +// It does not otherwise end the request; the caller should ensure no further +// writes are done to w. +// The error message should be plain text. +func Error(w ResponseWriter, error string, code int) { + w.Header().Set("Content-Type", "text/plain; charset=utf-8") + w.Header().Set("X-Content-Type-Options", "nosniff") + w.WriteHeader(code) + fmt.Fprintln(w, error) +} + +// NotFound replies to the request with an HTTP 404 not found error. +func NotFound(w ResponseWriter, r *Request) { Error(w, "404 page not found", StatusNotFound) } + +// NotFoundHandler returns a simple request handler +// that replies to each request with a ``404 page not found'' reply. +func NotFoundHandler() Handler { return HandlerFunc(NotFound) } + +// StripPrefix returns a handler that serves HTTP requests by removing the +// given prefix from the request URL's Path (and RawPath if set) and invoking +// the handler h. StripPrefix handles a request for a path that doesn't begin +// with prefix by replying with an HTTP 404 not found error. The prefix must +// match exactly: if the prefix in the request contains escaped characters +// the reply is also an HTTP 404 not found error. +func StripPrefix(prefix string, h Handler) Handler { + if prefix == "" { + return h + } + return HandlerFunc(func(w ResponseWriter, r *Request) { + p := strings.TrimPrefix(r.URL.Path, prefix) + rp := strings.TrimPrefix(r.URL.RawPath, prefix) + if len(p) < len(r.URL.Path) && (r.URL.RawPath == "" || len(rp) < len(r.URL.RawPath)) { + r2 := new(Request) + *r2 = *r + r2.URL = new(url.URL) + *r2.URL = *r.URL + r2.URL.Path = p + r2.URL.RawPath = rp + h.ServeHTTP(w, r2) + } else { + NotFound(w, r) + } + }) +} + +// Redirect replies to the request with a redirect to url, +// which may be a path relative to the request path. +// +// The provided code should be in the 3xx range and is usually +// StatusMovedPermanently, StatusFound or StatusSeeOther. +// +// If the Content-Type header has not been set, Redirect sets it +// to "text/html; charset=utf-8" and writes a small HTML body. +// Setting the Content-Type header to any value, including nil, +// disables that behavior. +func Redirect(w ResponseWriter, r *Request, url string, code int) { + if u, err := urlpkg.Parse(url); err == nil { + // If url was relative, make its path absolute by + // combining with request path. + // The client would probably do this for us, + // but doing it ourselves is more reliable. + // See RFC 7231, section 7.1.2 + if u.Scheme == "" && u.Host == "" { + oldpath := r.URL.Path + if oldpath == "" { // should not happen, but avoid a crash if it does + oldpath = "/" + } + + // no leading http://server + if url == "" || url[0] != '/' { + // make relative path absolute + olddir, _ := path.Split(oldpath) + url = olddir + url + } + + var query string + if i := strings.Index(url, "?"); i != -1 { + url, query = url[:i], url[i:] + } + + // clean up but preserve trailing slash + trailing := strings.HasSuffix(url, "/") + url = path.Clean(url) + if trailing && !strings.HasSuffix(url, "/") { + url += "/" + } + url += query + } + } + + h := w.Header() + + // RFC 7231 notes that a short HTML body is usually included in + // the response because older user agents may not understand 301/307. + // Do it only if the request didn't already have a Content-Type header. + _, hadCT := h["Content-Type"] + + h.Set("Location", hexEscapeNonASCII(url)) + if !hadCT && (r.Method == "GET" || r.Method == "HEAD") { + h.Set("Content-Type", "text/html; charset=utf-8") + } + w.WriteHeader(code) + + // Shouldn't send the body for POST or HEAD; that leaves GET. + if !hadCT && r.Method == "GET" { + body := "<a href=\"" + htmlEscape(url) + "\">" + statusText[code] + "</a>.\n" + fmt.Fprintln(w, body) + } +} + +var htmlReplacer = strings.NewReplacer( + "&", "&", + "<", "<", + ">", ">", + // """ is shorter than """. + `"`, """, + // "'" is shorter than "'" and apos was not in HTML until HTML5. + "'", "'", +) + +func htmlEscape(s string) string { + return htmlReplacer.Replace(s) +} + +// Redirect to a fixed URL +type redirectHandler struct { + url string + code int +} + +func (rh *redirectHandler) ServeHTTP(w ResponseWriter, r *Request) { + Redirect(w, r, rh.url, rh.code) +} + +// RedirectHandler returns a request handler that redirects +// each request it receives to the given url using the given +// status code. +// +// The provided code should be in the 3xx range and is usually +// StatusMovedPermanently, StatusFound or StatusSeeOther. +func RedirectHandler(url string, code int) Handler { + return &redirectHandler{url, code} +} + +// ServeMux is an HTTP request multiplexer. +// It matches the URL of each incoming request against a list of registered +// patterns and calls the handler for the pattern that +// most closely matches the URL. +// +// Patterns name fixed, rooted paths, like "/favicon.ico", +// or rooted subtrees, like "/images/" (note the trailing slash). +// Longer patterns take precedence over shorter ones, so that +// if there are handlers registered for both "/images/" +// and "/images/thumbnails/", the latter handler will be +// called for paths beginning "/images/thumbnails/" and the +// former will receive requests for any other paths in the +// "/images/" subtree. +// +// Note that since a pattern ending in a slash names a rooted subtree, +// the pattern "/" matches all paths not matched by other registered +// patterns, not just the URL with Path == "/". +// +// If a subtree has been registered and a request is received naming the +// subtree root without its trailing slash, ServeMux redirects that +// request to the subtree root (adding the trailing slash). This behavior can +// be overridden with a separate registration for the path without +// the trailing slash. For example, registering "/images/" causes ServeMux +// to redirect a request for "/images" to "/images/", unless "/images" has +// been registered separately. +// +// Patterns may optionally begin with a host name, restricting matches to +// URLs on that host only. Host-specific patterns take precedence over +// general patterns, so that a handler might register for the two patterns +// "/codesearch" and "codesearch.google.com/" without also taking over +// requests for "http://www.google.com/". +// +// ServeMux also takes care of sanitizing the URL request path and the Host +// header, stripping the port number and redirecting any request containing . or +// .. elements or repeated slashes to an equivalent, cleaner URL. +type ServeMux struct { + mu sync.RWMutex + m map[string]muxEntry + es []muxEntry // slice of entries sorted from longest to shortest. + hosts bool // whether any patterns contain hostnames +} + +type muxEntry struct { + h Handler + pattern string +} + +// NewServeMux allocates and returns a new ServeMux. +func NewServeMux() *ServeMux { return new(ServeMux) } + +// DefaultServeMux is the default ServeMux used by Serve. +var DefaultServeMux = &defaultServeMux + +var defaultServeMux ServeMux + +// cleanPath returns the canonical path for p, eliminating . and .. elements. +func cleanPath(p string) string { + if p == "" { + return "/" + } + if p[0] != '/' { + p = "/" + p + } + np := path.Clean(p) + // path.Clean removes trailing slash except for root; + // put the trailing slash back if necessary. + if p[len(p)-1] == '/' && np != "/" { + // Fast path for common case of p being the string we want: + if len(p) == len(np)+1 && strings.HasPrefix(p, np) { + np = p + } else { + np += "/" + } + } + return np +} + +// stripHostPort returns h without any trailing ":<port>". +func stripHostPort(h string) string { + // If no port on host, return unchanged + if strings.IndexByte(h, ':') == -1 { + return h + } + host, _, err := net.SplitHostPort(h) + if err != nil { + return h // on error, return unchanged + } + return host +} + +// Find a handler on a handler map given a path string. +// Most-specific (longest) pattern wins. +func (mux *ServeMux) match(path string) (h Handler, pattern string) { + // Check for exact match first. + v, ok := mux.m[path] + if ok { + return v.h, v.pattern + } + + // Check for longest valid match. mux.es contains all patterns + // that end in / sorted from longest to shortest. + for _, e := range mux.es { + if strings.HasPrefix(path, e.pattern) { + return e.h, e.pattern + } + } + return nil, "" +} + +// redirectToPathSlash determines if the given path needs appending "/" to it. +// This occurs when a handler for path + "/" was already registered, but +// not for path itself. If the path needs appending to, it creates a new +// URL, setting the path to u.Path + "/" and returning true to indicate so. +func (mux *ServeMux) redirectToPathSlash(host, path string, u *url.URL) (*url.URL, bool) { + mux.mu.RLock() + shouldRedirect := mux.shouldRedirectRLocked(host, path) + mux.mu.RUnlock() + if !shouldRedirect { + return u, false + } + path = path + "/" + u = &url.URL{Path: path, RawQuery: u.RawQuery} + return u, true +} + +// shouldRedirectRLocked reports whether the given path and host should be redirected to +// path+"/". This should happen if a handler is registered for path+"/" but +// not path -- see comments at ServeMux. +func (mux *ServeMux) shouldRedirectRLocked(host, path string) bool { + p := []string{path, host + path} + + for _, c := range p { + if _, exist := mux.m[c]; exist { + return false + } + } + + n := len(path) + if n == 0 { + return false + } + for _, c := range p { + if _, exist := mux.m[c+"/"]; exist { + return path[n-1] != '/' + } + } + + return false +} + +// Handler returns the handler to use for the given request, +// consulting r.Method, r.Host, and r.URL.Path. It always returns +// a non-nil handler. If the path is not in its canonical form, the +// handler will be an internally-generated handler that redirects +// to the canonical path. If the host contains a port, it is ignored +// when matching handlers. +// +// The path and host are used unchanged for CONNECT requests. +// +// Handler also returns the registered pattern that matches the +// request or, in the case of internally-generated redirects, +// the pattern that will match after following the redirect. +// +// If there is no registered handler that applies to the request, +// Handler returns a ``page not found'' handler and an empty pattern. +func (mux *ServeMux) Handler(r *Request) (h Handler, pattern string) { + + // CONNECT requests are not canonicalized. + if r.Method == "CONNECT" { + // If r.URL.Path is /tree and its handler is not registered, + // the /tree -> /tree/ redirect applies to CONNECT requests + // but the path canonicalization does not. + if u, ok := mux.redirectToPathSlash(r.URL.Host, r.URL.Path, r.URL); ok { + return RedirectHandler(u.String(), StatusMovedPermanently), u.Path + } + + return mux.handler(r.Host, r.URL.Path) + } + + // All other requests have any port stripped and path cleaned + // before passing to mux.handler. + host := stripHostPort(r.Host) + path := cleanPath(r.URL.Path) + + // If the given path is /tree and its handler is not registered, + // redirect for /tree/. + if u, ok := mux.redirectToPathSlash(host, path, r.URL); ok { + return RedirectHandler(u.String(), StatusMovedPermanently), u.Path + } + + if path != r.URL.Path { + _, pattern = mux.handler(host, path) + url := *r.URL + url.Path = path + return RedirectHandler(url.String(), StatusMovedPermanently), pattern + } + + return mux.handler(host, r.URL.Path) +} + +// handler is the main implementation of Handler. +// The path is known to be in canonical form, except for CONNECT methods. +func (mux *ServeMux) handler(host, path string) (h Handler, pattern string) { + mux.mu.RLock() + defer mux.mu.RUnlock() + + // Host-specific pattern takes precedence over generic ones + if mux.hosts { + h, pattern = mux.match(host + path) + } + if h == nil { + h, pattern = mux.match(path) + } + if h == nil { + h, pattern = NotFoundHandler(), "" + } + return +} + +// ServeHTTP dispatches the request to the handler whose +// pattern most closely matches the request URL. +func (mux *ServeMux) ServeHTTP(w ResponseWriter, r *Request) { + if r.RequestURI == "*" { + if r.ProtoAtLeast(1, 1) { + w.Header().Set("Connection", "close") + } + w.WriteHeader(StatusBadRequest) + return + } + h, _ := mux.Handler(r) + h.ServeHTTP(w, r) +} + +// Handle registers the handler for the given pattern. +// If a handler already exists for pattern, Handle panics. +func (mux *ServeMux) Handle(pattern string, handler Handler) { + mux.mu.Lock() + defer mux.mu.Unlock() + + if pattern == "" { + panic("http: invalid pattern") + } + if handler == nil { + panic("http: nil handler") + } + if _, exist := mux.m[pattern]; exist { + panic("http: multiple registrations for " + pattern) + } + + if mux.m == nil { + mux.m = make(map[string]muxEntry) + } + e := muxEntry{h: handler, pattern: pattern} + mux.m[pattern] = e + if pattern[len(pattern)-1] == '/' { + mux.es = appendSorted(mux.es, e) + } + + if pattern[0] != '/' { + mux.hosts = true + } +} + +func appendSorted(es []muxEntry, e muxEntry) []muxEntry { + n := len(es) + i := sort.Search(n, func(i int) bool { + return len(es[i].pattern) < len(e.pattern) + }) + if i == n { + return append(es, e) + } + // we now know that i points at where we want to insert + es = append(es, muxEntry{}) // try to grow the slice in place, any entry works. + copy(es[i+1:], es[i:]) // Move shorter entries down + es[i] = e + return es +} + +// HandleFunc registers the handler function for the given pattern. +func (mux *ServeMux) HandleFunc(pattern string, handler func(ResponseWriter, *Request)) { + if handler == nil { + panic("http: nil handler") + } + mux.Handle(pattern, HandlerFunc(handler)) +} + +// Handle registers the handler for the given pattern +// in the DefaultServeMux. +// The documentation for ServeMux explains how patterns are matched. +func Handle(pattern string, handler Handler) { DefaultServeMux.Handle(pattern, handler) } + +// HandleFunc registers the handler function for the given pattern +// in the DefaultServeMux. +// The documentation for ServeMux explains how patterns are matched. +func HandleFunc(pattern string, handler func(ResponseWriter, *Request)) { + DefaultServeMux.HandleFunc(pattern, handler) +} + +// Serve accepts incoming HTTP connections on the listener l, +// creating a new service goroutine for each. The service goroutines +// read requests and then call handler to reply to them. +// +// The handler is typically nil, in which case the DefaultServeMux is used. +// +// HTTP/2 support is only enabled if the Listener returns *tls.Conn +// connections and they were configured with "h2" in the TLS +// Config.NextProtos. +// +// Serve always returns a non-nil error. +func Serve(l net.Listener, handler Handler) error { + srv := &Server{Handler: handler} + return srv.Serve(l) +} + +// ServeTLS accepts incoming HTTPS connections on the listener l, +// creating a new service goroutine for each. The service goroutines +// read requests and then call handler to reply to them. +// +// The handler is typically nil, in which case the DefaultServeMux is used. +// +// Additionally, files containing a certificate and matching private key +// for the server must be provided. If the certificate is signed by a +// certificate authority, the certFile should be the concatenation +// of the server's certificate, any intermediates, and the CA's certificate. +// +// ServeTLS always returns a non-nil error. +func ServeTLS(l net.Listener, handler Handler, certFile, keyFile string) error { + srv := &Server{Handler: handler} + return srv.ServeTLS(l, certFile, keyFile) +} + +// A Server defines parameters for running an HTTP server. +// The zero value for Server is a valid configuration. +type Server struct { + // Addr optionally specifies the TCP address for the server to listen on, + // in the form "host:port". If empty, ":http" (port 80) is used. + // The service names are defined in RFC 6335 and assigned by IANA. + // See net.Dial for details of the address format. + Addr string + + Handler Handler // handler to invoke, http.DefaultServeMux if nil + + // TLSConfig optionally provides a TLS configuration for use + // by ServeTLS and ListenAndServeTLS. Note that this value is + // cloned by ServeTLS and ListenAndServeTLS, so it's not + // possible to modify the configuration with methods like + // tls.Config.SetSessionTicketKeys. To use + // SetSessionTicketKeys, use Server.Serve with a TLS Listener + // instead. + TLSConfig *tls.Config + + // ReadTimeout is the maximum duration for reading the entire + // request, including the body. + // + // Because ReadTimeout does not let Handlers make per-request + // decisions on each request body's acceptable deadline or + // upload rate, most users will prefer to use + // ReadHeaderTimeout. It is valid to use them both. + ReadTimeout time.Duration + + // ReadHeaderTimeout is the amount of time allowed to read + // request headers. The connection's read deadline is reset + // after reading the headers and the Handler can decide what + // is considered too slow for the body. If ReadHeaderTimeout + // is zero, the value of ReadTimeout is used. If both are + // zero, there is no timeout. + ReadHeaderTimeout time.Duration + + // WriteTimeout is the maximum duration before timing out + // writes of the response. It is reset whenever a new + // request's header is read. Like ReadTimeout, it does not + // let Handlers make decisions on a per-request basis. + WriteTimeout time.Duration + + // IdleTimeout is the maximum amount of time to wait for the + // next request when keep-alives are enabled. If IdleTimeout + // is zero, the value of ReadTimeout is used. If both are + // zero, there is no timeout. + IdleTimeout time.Duration + + // MaxHeaderBytes controls the maximum number of bytes the + // server will read parsing the request header's keys and + // values, including the request line. It does not limit the + // size of the request body. + // If zero, DefaultMaxHeaderBytes is used. + MaxHeaderBytes int + + // TLSNextProto optionally specifies a function to take over + // ownership of the provided TLS connection when an ALPN + // protocol upgrade has occurred. The map key is the protocol + // name negotiated. The Handler argument should be used to + // handle HTTP requests and will initialize the Request's TLS + // and RemoteAddr if not already set. The connection is + // automatically closed when the function returns. + // If TLSNextProto is not nil, HTTP/2 support is not enabled + // automatically. + TLSNextProto map[string]func(*Server, *tls.Conn, Handler) + + // ConnState specifies an optional callback function that is + // called when a client connection changes state. See the + // ConnState type and associated constants for details. + ConnState func(net.Conn, ConnState) + + // ErrorLog specifies an optional logger for errors accepting + // connections, unexpected behavior from handlers, and + // underlying FileSystem errors. + // If nil, logging is done via the log package's standard logger. + ErrorLog *log.Logger + + // BaseContext optionally specifies a function that returns + // the base context for incoming requests on this server. + // The provided Listener is the specific Listener that's + // about to start accepting requests. + // If BaseContext is nil, the default is context.Background(). + // If non-nil, it must return a non-nil context. + BaseContext func(net.Listener) context.Context + + // ConnContext optionally specifies a function that modifies + // the context used for a new connection c. The provided ctx + // is derived from the base context and has a ServerContextKey + // value. + ConnContext func(ctx context.Context, c net.Conn) context.Context + + inShutdown atomicBool // true when when server is in shutdown + + disableKeepAlives int32 // accessed atomically. + nextProtoOnce sync.Once // guards setupHTTP2_* init + nextProtoErr error // result of http2.ConfigureServer if used + + mu sync.Mutex + listeners map[*net.Listener]struct{} + activeConn map[*conn]struct{} + doneChan chan struct{} + onShutdown []func() +} + +func (s *Server) getDoneChan() <-chan struct{} { + s.mu.Lock() + defer s.mu.Unlock() + return s.getDoneChanLocked() +} + +func (s *Server) getDoneChanLocked() chan struct{} { + if s.doneChan == nil { + s.doneChan = make(chan struct{}) + } + return s.doneChan +} + +func (s *Server) closeDoneChanLocked() { + ch := s.getDoneChanLocked() + select { + case <-ch: + // Already closed. Don't close again. + default: + // Safe to close here. We're the only closer, guarded + // by s.mu. + close(ch) + } +} + +// Close immediately closes all active net.Listeners and any +// connections in state StateNew, StateActive, or StateIdle. For a +// graceful shutdown, use Shutdown. +// +// Close does not attempt to close (and does not even know about) +// any hijacked connections, such as WebSockets. +// +// Close returns any error returned from closing the Server's +// underlying Listener(s). +func (srv *Server) Close() error { + srv.inShutdown.setTrue() + srv.mu.Lock() + defer srv.mu.Unlock() + srv.closeDoneChanLocked() + err := srv.closeListenersLocked() + for c := range srv.activeConn { + c.rwc.Close() + delete(srv.activeConn, c) + } + return err +} + +// shutdownPollIntervalMax is the max polling interval when checking +// quiescence during Server.Shutdown. Polling starts with a small +// interval and backs off to the max. +// Ideally we could find a solution that doesn't involve polling, +// but which also doesn't have a high runtime cost (and doesn't +// involve any contentious mutexes), but that is left as an +// exercise for the reader. +const shutdownPollIntervalMax = 500 * time.Millisecond + +// Shutdown gracefully shuts down the server without interrupting any +// active connections. Shutdown works by first closing all open +// listeners, then closing all idle connections, and then waiting +// indefinitely for connections to return to idle and then shut down. +// If the provided context expires before the shutdown is complete, +// Shutdown returns the context's error, otherwise it returns any +// error returned from closing the Server's underlying Listener(s). +// +// When Shutdown is called, Serve, ListenAndServe, and +// ListenAndServeTLS immediately return ErrServerClosed. Make sure the +// program doesn't exit and waits instead for Shutdown to return. +// +// Shutdown does not attempt to close nor wait for hijacked +// connections such as WebSockets. The caller of Shutdown should +// separately notify such long-lived connections of shutdown and wait +// for them to close, if desired. See RegisterOnShutdown for a way to +// register shutdown notification functions. +// +// Once Shutdown has been called on a server, it may not be reused; +// future calls to methods such as Serve will return ErrServerClosed. +func (srv *Server) Shutdown(ctx context.Context) error { + srv.inShutdown.setTrue() + + srv.mu.Lock() + lnerr := srv.closeListenersLocked() + srv.closeDoneChanLocked() + for _, f := range srv.onShutdown { + go f() + } + srv.mu.Unlock() + + pollIntervalBase := time.Millisecond + nextPollInterval := func() time.Duration { + // Add 10% jitter. + interval := pollIntervalBase + time.Duration(rand.Intn(int(pollIntervalBase/10))) + // Double and clamp for next time. + pollIntervalBase *= 2 + if pollIntervalBase > shutdownPollIntervalMax { + pollIntervalBase = shutdownPollIntervalMax + } + return interval + } + + timer := time.NewTimer(nextPollInterval()) + defer timer.Stop() + for { + if srv.closeIdleConns() && srv.numListeners() == 0 { + return lnerr + } + select { + case <-ctx.Done(): + return ctx.Err() + case <-timer.C: + timer.Reset(nextPollInterval()) + } + } +} + +// RegisterOnShutdown registers a function to call on Shutdown. +// This can be used to gracefully shutdown connections that have +// undergone ALPN protocol upgrade or that have been hijacked. +// This function should start protocol-specific graceful shutdown, +// but should not wait for shutdown to complete. +func (srv *Server) RegisterOnShutdown(f func()) { + srv.mu.Lock() + srv.onShutdown = append(srv.onShutdown, f) + srv.mu.Unlock() +} + +func (s *Server) numListeners() int { + s.mu.Lock() + defer s.mu.Unlock() + return len(s.listeners) +} + +// closeIdleConns closes all idle connections and reports whether the +// server is quiescent. +func (s *Server) closeIdleConns() bool { + s.mu.Lock() + defer s.mu.Unlock() + quiescent := true + for c := range s.activeConn { + st, unixSec := c.getState() + // Issue 22682: treat StateNew connections as if + // they're idle if we haven't read the first request's + // header in over 5 seconds. + if st == StateNew && unixSec < time.Now().Unix()-5 { + st = StateIdle + } + if st != StateIdle || unixSec == 0 { + // Assume unixSec == 0 means it's a very new + // connection, without state set yet. + quiescent = false + continue + } + c.rwc.Close() + delete(s.activeConn, c) + } + return quiescent +} + +func (s *Server) closeListenersLocked() error { + var err error + for ln := range s.listeners { + if cerr := (*ln).Close(); cerr != nil && err == nil { + err = cerr + } + } + return err +} + +// A ConnState represents the state of a client connection to a server. +// It's used by the optional Server.ConnState hook. +type ConnState int + +const ( + // StateNew represents a new connection that is expected to + // send a request immediately. Connections begin at this + // state and then transition to either StateActive or + // StateClosed. + StateNew ConnState = iota + + // StateActive represents a connection that has read 1 or more + // bytes of a request. The Server.ConnState hook for + // StateActive fires before the request has entered a handler + // and doesn't fire again until the request has been + // handled. After the request is handled, the state + // transitions to StateClosed, StateHijacked, or StateIdle. + // For HTTP/2, StateActive fires on the transition from zero + // to one active request, and only transitions away once all + // active requests are complete. That means that ConnState + // cannot be used to do per-request work; ConnState only notes + // the overall state of the connection. + StateActive + + // StateIdle represents a connection that has finished + // handling a request and is in the keep-alive state, waiting + // for a new request. Connections transition from StateIdle + // to either StateActive or StateClosed. + StateIdle + + // StateHijacked represents a hijacked connection. + // This is a terminal state. It does not transition to StateClosed. + StateHijacked + + // StateClosed represents a closed connection. + // This is a terminal state. Hijacked connections do not + // transition to StateClosed. + StateClosed +) + +var stateName = map[ConnState]string{ + StateNew: "new", + StateActive: "active", + StateIdle: "idle", + StateHijacked: "hijacked", + StateClosed: "closed", +} + +func (c ConnState) String() string { + return stateName[c] +} + +// serverHandler delegates to either the server's Handler or +// DefaultServeMux and also handles "OPTIONS *" requests. +type serverHandler struct { + srv *Server +} + +func (sh serverHandler) ServeHTTP(rw ResponseWriter, req *Request) { + handler := sh.srv.Handler + if handler == nil { + handler = DefaultServeMux + } + if req.RequestURI == "*" && req.Method == "OPTIONS" { + handler = globalOptionsHandler{} + } + handler.ServeHTTP(rw, req) +} + +// ListenAndServe listens on the TCP network address srv.Addr and then +// calls Serve to handle requests on incoming connections. +// Accepted connections are configured to enable TCP keep-alives. +// +// If srv.Addr is blank, ":http" is used. +// +// ListenAndServe always returns a non-nil error. After Shutdown or Close, +// the returned error is ErrServerClosed. +func (srv *Server) ListenAndServe() error { + if srv.shuttingDown() { + return ErrServerClosed + } + addr := srv.Addr + if addr == "" { + addr = ":http" + } + ln, err := net.Listen("tcp", addr) + if err != nil { + return err + } + return srv.Serve(ln) +} + +var testHookServerServe func(*Server, net.Listener) // used if non-nil + +// shouldDoServeHTTP2 reports whether Server.Serve should configure +// automatic HTTP/2. (which sets up the srv.TLSNextProto map) +func (srv *Server) shouldConfigureHTTP2ForServe() bool { + if srv.TLSConfig == nil { + // Compatibility with Go 1.6: + // If there's no TLSConfig, it's possible that the user just + // didn't set it on the http.Server, but did pass it to + // tls.NewListener and passed that listener to Serve. + // So we should configure HTTP/2 (to set up srv.TLSNextProto) + // in case the listener returns an "h2" *tls.Conn. + return true + } + // The user specified a TLSConfig on their http.Server. + // In this, case, only configure HTTP/2 if their tls.Config + // explicitly mentions "h2". Otherwise http2.ConfigureServer + // would modify the tls.Config to add it, but they probably already + // passed this tls.Config to tls.NewListener. And if they did, + // it's too late anyway to fix it. It would only be potentially racy. + // See Issue 15908. + return strSliceContains(srv.TLSConfig.NextProtos, http2NextProtoTLS) +} + +// ErrServerClosed is returned by the Server's Serve, ServeTLS, ListenAndServe, +// and ListenAndServeTLS methods after a call to Shutdown or Close. +var ErrServerClosed = errors.New("http: Server closed") + +// Serve accepts incoming connections on the Listener l, creating a +// new service goroutine for each. The service goroutines read requests and +// then call srv.Handler to reply to them. +// +// HTTP/2 support is only enabled if the Listener returns *tls.Conn +// connections and they were configured with "h2" in the TLS +// Config.NextProtos. +// +// Serve always returns a non-nil error and closes l. +// After Shutdown or Close, the returned error is ErrServerClosed. +func (srv *Server) Serve(l net.Listener) error { + if fn := testHookServerServe; fn != nil { + fn(srv, l) // call hook with unwrapped listener + } + + origListener := l + l = &onceCloseListener{Listener: l} + defer l.Close() + + if err := srv.setupHTTP2_Serve(); err != nil { + return err + } + + if !srv.trackListener(&l, true) { + return ErrServerClosed + } + defer srv.trackListener(&l, false) + + baseCtx := context.Background() + if srv.BaseContext != nil { + baseCtx = srv.BaseContext(origListener) + if baseCtx == nil { + panic("BaseContext returned a nil context") + } + } + + var tempDelay time.Duration // how long to sleep on accept failure + + ctx := context.WithValue(baseCtx, ServerContextKey, srv) + for { + rw, err := l.Accept() + if err != nil { + select { + case <-srv.getDoneChan(): + return ErrServerClosed + default: + } + if ne, ok := err.(net.Error); ok && ne.Temporary() { + if tempDelay == 0 { + tempDelay = 5 * time.Millisecond + } else { + tempDelay *= 2 + } + if max := 1 * time.Second; tempDelay > max { + tempDelay = max + } + srv.logf("http: Accept error: %v; retrying in %v", err, tempDelay) + time.Sleep(tempDelay) + continue + } + return err + } + connCtx := ctx + if cc := srv.ConnContext; cc != nil { + connCtx = cc(connCtx, rw) + if connCtx == nil { + panic("ConnContext returned nil") + } + } + tempDelay = 0 + c := srv.newConn(rw) + c.setState(c.rwc, StateNew, runHooks) // before Serve can return + go c.serve(connCtx) + } +} + +// ServeTLS accepts incoming connections on the Listener l, creating a +// new service goroutine for each. The service goroutines perform TLS +// setup and then read requests, calling srv.Handler to reply to them. +// +// Files containing a certificate and matching private key for the +// server must be provided if neither the Server's +// TLSConfig.Certificates nor TLSConfig.GetCertificate are populated. +// If the certificate is signed by a certificate authority, the +// certFile should be the concatenation of the server's certificate, +// any intermediates, and the CA's certificate. +// +// ServeTLS always returns a non-nil error. After Shutdown or Close, the +// returned error is ErrServerClosed. +func (srv *Server) ServeTLS(l net.Listener, certFile, keyFile string) error { + // Setup HTTP/2 before srv.Serve, to initialize srv.TLSConfig + // before we clone it and create the TLS Listener. + if err := srv.setupHTTP2_ServeTLS(); err != nil { + return err + } + + config := cloneTLSConfig(srv.TLSConfig) + if !strSliceContains(config.NextProtos, "http/1.1") { + config.NextProtos = append(config.NextProtos, "http/1.1") + } + + configHasCert := len(config.Certificates) > 0 || config.GetCertificate != nil + if !configHasCert || certFile != "" || keyFile != "" { + var err error + config.Certificates = make([]tls.Certificate, 1) + config.Certificates[0], err = tls.LoadX509KeyPair(certFile, keyFile) + if err != nil { + return err + } + } + + tlsListener := tls.NewListener(l, config) + return srv.Serve(tlsListener) +} + +// trackListener adds or removes a net.Listener to the set of tracked +// listeners. +// +// We store a pointer to interface in the map set, in case the +// net.Listener is not comparable. This is safe because we only call +// trackListener via Serve and can track+defer untrack the same +// pointer to local variable there. We never need to compare a +// Listener from another caller. +// +// It reports whether the server is still up (not Shutdown or Closed). +func (s *Server) trackListener(ln *net.Listener, add bool) bool { + s.mu.Lock() + defer s.mu.Unlock() + if s.listeners == nil { + s.listeners = make(map[*net.Listener]struct{}) + } + if add { + if s.shuttingDown() { + return false + } + s.listeners[ln] = struct{}{} + } else { + delete(s.listeners, ln) + } + return true +} + +func (s *Server) trackConn(c *conn, add bool) { + s.mu.Lock() + defer s.mu.Unlock() + if s.activeConn == nil { + s.activeConn = make(map[*conn]struct{}) + } + if add { + s.activeConn[c] = struct{}{} + } else { + delete(s.activeConn, c) + } +} + +func (s *Server) idleTimeout() time.Duration { + if s.IdleTimeout != 0 { + return s.IdleTimeout + } + return s.ReadTimeout +} + +func (s *Server) readHeaderTimeout() time.Duration { + if s.ReadHeaderTimeout != 0 { + return s.ReadHeaderTimeout + } + return s.ReadTimeout +} + +func (s *Server) doKeepAlives() bool { + return atomic.LoadInt32(&s.disableKeepAlives) == 0 && !s.shuttingDown() +} + +func (s *Server) shuttingDown() bool { + return s.inShutdown.isSet() +} + +// SetKeepAlivesEnabled controls whether HTTP keep-alives are enabled. +// By default, keep-alives are always enabled. Only very +// resource-constrained environments or servers in the process of +// shutting down should disable them. +func (srv *Server) SetKeepAlivesEnabled(v bool) { + if v { + atomic.StoreInt32(&srv.disableKeepAlives, 0) + return + } + atomic.StoreInt32(&srv.disableKeepAlives, 1) + + // Close idle HTTP/1 conns: + srv.closeIdleConns() + + // TODO: Issue 26303: close HTTP/2 conns as soon as they become idle. +} + +func (s *Server) logf(format string, args ...interface{}) { + if s.ErrorLog != nil { + s.ErrorLog.Printf(format, args...) + } else { + log.Printf(format, args...) + } +} + +// logf prints to the ErrorLog of the *Server associated with request r +// via ServerContextKey. If there's no associated server, or if ErrorLog +// is nil, logging is done via the log package's standard logger. +func logf(r *Request, format string, args ...interface{}) { + s, _ := r.Context().Value(ServerContextKey).(*Server) + if s != nil && s.ErrorLog != nil { + s.ErrorLog.Printf(format, args...) + } else { + log.Printf(format, args...) + } +} + +// ListenAndServe listens on the TCP network address addr and then calls +// Serve with handler to handle requests on incoming connections. +// Accepted connections are configured to enable TCP keep-alives. +// +// The handler is typically nil, in which case the DefaultServeMux is used. +// +// ListenAndServe always returns a non-nil error. +func ListenAndServe(addr string, handler Handler) error { + server := &Server{Addr: addr, Handler: handler} + return server.ListenAndServe() +} + +// ListenAndServeTLS acts identically to ListenAndServe, except that it +// expects HTTPS connections. Additionally, files containing a certificate and +// matching private key for the server must be provided. If the certificate +// is signed by a certificate authority, the certFile should be the concatenation +// of the server's certificate, any intermediates, and the CA's certificate. +func ListenAndServeTLS(addr, certFile, keyFile string, handler Handler) error { + server := &Server{Addr: addr, Handler: handler} + return server.ListenAndServeTLS(certFile, keyFile) +} + +// ListenAndServeTLS listens on the TCP network address srv.Addr and +// then calls ServeTLS to handle requests on incoming TLS connections. +// Accepted connections are configured to enable TCP keep-alives. +// +// Filenames containing a certificate and matching private key for the +// server must be provided if neither the Server's TLSConfig.Certificates +// nor TLSConfig.GetCertificate are populated. If the certificate is +// signed by a certificate authority, the certFile should be the +// concatenation of the server's certificate, any intermediates, and +// the CA's certificate. +// +// If srv.Addr is blank, ":https" is used. +// +// ListenAndServeTLS always returns a non-nil error. After Shutdown or +// Close, the returned error is ErrServerClosed. +func (srv *Server) ListenAndServeTLS(certFile, keyFile string) error { + if srv.shuttingDown() { + return ErrServerClosed + } + addr := srv.Addr + if addr == "" { + addr = ":https" + } + + ln, err := net.Listen("tcp", addr) + if err != nil { + return err + } + + defer ln.Close() + + return srv.ServeTLS(ln, certFile, keyFile) +} + +// setupHTTP2_ServeTLS conditionally configures HTTP/2 on +// srv and reports whether there was an error setting it up. If it is +// not configured for policy reasons, nil is returned. +func (srv *Server) setupHTTP2_ServeTLS() error { + srv.nextProtoOnce.Do(srv.onceSetNextProtoDefaults) + return srv.nextProtoErr +} + +// setupHTTP2_Serve is called from (*Server).Serve and conditionally +// configures HTTP/2 on srv using a more conservative policy than +// setupHTTP2_ServeTLS because Serve is called after tls.Listen, +// and may be called concurrently. See shouldConfigureHTTP2ForServe. +// +// The tests named TestTransportAutomaticHTTP2* and +// TestConcurrentServerServe in server_test.go demonstrate some +// of the supported use cases and motivations. +func (srv *Server) setupHTTP2_Serve() error { + srv.nextProtoOnce.Do(srv.onceSetNextProtoDefaults_Serve) + return srv.nextProtoErr +} + +func (srv *Server) onceSetNextProtoDefaults_Serve() { + if srv.shouldConfigureHTTP2ForServe() { + srv.onceSetNextProtoDefaults() + } +} + +// onceSetNextProtoDefaults configures HTTP/2, if the user hasn't +// configured otherwise. (by setting srv.TLSNextProto non-nil) +// It must only be called via srv.nextProtoOnce (use srv.setupHTTP2_*). +func (srv *Server) onceSetNextProtoDefaults() { + if omitBundledHTTP2 || strings.Contains(os.Getenv("GODEBUG"), "http2server=0") { + return + } + // Enable HTTP/2 by default if the user hasn't otherwise + // configured their TLSNextProto map. + if srv.TLSNextProto == nil { + conf := &http2Server{ + NewWriteScheduler: func() http2WriteScheduler { return http2NewPriorityWriteScheduler(nil) }, + } + srv.nextProtoErr = http2ConfigureServer(srv, conf) + } +} + +// TimeoutHandler returns a Handler that runs h with the given time limit. +// +// The new Handler calls h.ServeHTTP to handle each request, but if a +// call runs for longer than its time limit, the handler responds with +// a 503 Service Unavailable error and the given message in its body. +// (If msg is empty, a suitable default message will be sent.) +// After such a timeout, writes by h to its ResponseWriter will return +// ErrHandlerTimeout. +// +// TimeoutHandler supports the Pusher interface but does not support +// the Hijacker or Flusher interfaces. +func TimeoutHandler(h Handler, dt time.Duration, msg string) Handler { + return &timeoutHandler{ + handler: h, + body: msg, + dt: dt, + } +} + +// ErrHandlerTimeout is returned on ResponseWriter Write calls +// in handlers which have timed out. +var ErrHandlerTimeout = errors.New("http: Handler timeout") + +type timeoutHandler struct { + handler Handler + body string + dt time.Duration + + // When set, no context will be created and this context will + // be used instead. + testContext context.Context +} + +func (h *timeoutHandler) errorBody() string { + if h.body != "" { + return h.body + } + return "<html><head><title>Timeout</title></head><body><h1>Timeout</h1></body></html>" +} + +func (h *timeoutHandler) ServeHTTP(w ResponseWriter, r *Request) { + ctx := h.testContext + if ctx == nil { + var cancelCtx context.CancelFunc + ctx, cancelCtx = context.WithTimeout(r.Context(), h.dt) + defer cancelCtx() + } + r = r.WithContext(ctx) + done := make(chan struct{}) + tw := &timeoutWriter{ + w: w, + h: make(Header), + req: r, + } + panicChan := make(chan interface{}, 1) + go func() { + defer func() { + if p := recover(); p != nil { + panicChan <- p + } + }() + h.handler.ServeHTTP(tw, r) + close(done) + }() + select { + case p := <-panicChan: + panic(p) + case <-done: + tw.mu.Lock() + defer tw.mu.Unlock() + dst := w.Header() + for k, vv := range tw.h { + dst[k] = vv + } + if !tw.wroteHeader { + tw.code = StatusOK + } + w.WriteHeader(tw.code) + w.Write(tw.wbuf.Bytes()) + case <-ctx.Done(): + tw.mu.Lock() + defer tw.mu.Unlock() + w.WriteHeader(StatusServiceUnavailable) + io.WriteString(w, h.errorBody()) + tw.timedOut = true + } +} + +type timeoutWriter struct { + w ResponseWriter + h Header + wbuf bytes.Buffer + req *Request + + mu sync.Mutex + timedOut bool + wroteHeader bool + code int +} + +var _ Pusher = (*timeoutWriter)(nil) + +// Push implements the Pusher interface. +func (tw *timeoutWriter) Push(target string, opts *PushOptions) error { + if pusher, ok := tw.w.(Pusher); ok { + return pusher.Push(target, opts) + } + return ErrNotSupported +} + +func (tw *timeoutWriter) Header() Header { return tw.h } + +func (tw *timeoutWriter) Write(p []byte) (int, error) { + tw.mu.Lock() + defer tw.mu.Unlock() + if tw.timedOut { + return 0, ErrHandlerTimeout + } + if !tw.wroteHeader { + tw.writeHeaderLocked(StatusOK) + } + return tw.wbuf.Write(p) +} + +func (tw *timeoutWriter) writeHeaderLocked(code int) { + checkWriteHeaderCode(code) + + switch { + case tw.timedOut: + return + case tw.wroteHeader: + if tw.req != nil { + caller := relevantCaller() + logf(tw.req, "http: superfluous response.WriteHeader call from %s (%s:%d)", caller.Function, path.Base(caller.File), caller.Line) + } + default: + tw.wroteHeader = true + tw.code = code + } +} + +func (tw *timeoutWriter) WriteHeader(code int) { + tw.mu.Lock() + defer tw.mu.Unlock() + tw.writeHeaderLocked(code) +} + +// onceCloseListener wraps a net.Listener, protecting it from +// multiple Close calls. +type onceCloseListener struct { + net.Listener + once sync.Once + closeErr error +} + +func (oc *onceCloseListener) Close() error { + oc.once.Do(oc.close) + return oc.closeErr +} + +func (oc *onceCloseListener) close() { oc.closeErr = oc.Listener.Close() } + +// globalOptionsHandler responds to "OPTIONS *" requests. +type globalOptionsHandler struct{} + +func (globalOptionsHandler) ServeHTTP(w ResponseWriter, r *Request) { + w.Header().Set("Content-Length", "0") + if r.ContentLength != 0 { + // Read up to 4KB of OPTIONS body (as mentioned in the + // spec as being reserved for future use), but anything + // over that is considered a waste of server resources + // (or an attack) and we abort and close the connection, + // courtesy of MaxBytesReader's EOF behavior. + mb := MaxBytesReader(w, r.Body, 4<<10) + io.Copy(io.Discard, mb) + } +} + +// initALPNRequest is an HTTP handler that initializes certain +// uninitialized fields in its *Request. Such partially-initialized +// Requests come from ALPN protocol handlers. +type initALPNRequest struct { + ctx context.Context + c *tls.Conn + h serverHandler +} + +// BaseContext is an exported but unadvertised http.Handler method +// recognized by x/net/http2 to pass down a context; the TLSNextProto +// API predates context support so we shoehorn through the only +// interface we have available. +func (h initALPNRequest) BaseContext() context.Context { return h.ctx } + +func (h initALPNRequest) ServeHTTP(rw ResponseWriter, req *Request) { + if req.TLS == nil { + req.TLS = &tls.ConnectionState{} + *req.TLS = h.c.ConnectionState() + } + if req.Body == nil { + req.Body = NoBody + } + if req.RemoteAddr == "" { + req.RemoteAddr = h.c.RemoteAddr().String() + } + h.h.ServeHTTP(rw, req) +} + +// loggingConn is used for debugging. +type loggingConn struct { + name string + net.Conn +} + +var ( + uniqNameMu sync.Mutex + uniqNameNext = make(map[string]int) +) + +func newLoggingConn(baseName string, c net.Conn) net.Conn { + uniqNameMu.Lock() + defer uniqNameMu.Unlock() + uniqNameNext[baseName]++ + return &loggingConn{ + name: fmt.Sprintf("%s-%d", baseName, uniqNameNext[baseName]), + Conn: c, + } +} + +func (c *loggingConn) Write(p []byte) (n int, err error) { + log.Printf("%s.Write(%d) = ....", c.name, len(p)) + n, err = c.Conn.Write(p) + log.Printf("%s.Write(%d) = %d, %v", c.name, len(p), n, err) + return +} + +func (c *loggingConn) Read(p []byte) (n int, err error) { + log.Printf("%s.Read(%d) = ....", c.name, len(p)) + n, err = c.Conn.Read(p) + log.Printf("%s.Read(%d) = %d, %v", c.name, len(p), n, err) + return +} + +func (c *loggingConn) Close() (err error) { + log.Printf("%s.Close() = ...", c.name) + err = c.Conn.Close() + log.Printf("%s.Close() = %v", c.name, err) + return +} + +// checkConnErrorWriter writes to c.rwc and records any write errors to c.werr. +// It only contains one field (and a pointer field at that), so it +// fits in an interface value without an extra allocation. +type checkConnErrorWriter struct { + c *conn +} + +func (w checkConnErrorWriter) Write(p []byte) (n int, err error) { + n, err = w.c.rwc.Write(p) + if err != nil && w.c.werr == nil { + w.c.werr = err + w.c.cancelCtx() + } + return +} + +func numLeadingCRorLF(v []byte) (n int) { + for _, b := range v { + if b == '\r' || b == '\n' { + n++ + continue + } + break + } + return + +} + +func strSliceContains(ss []string, s string) bool { + for _, v := range ss { + if v == s { + return true + } + } + return false +} + +// tlsRecordHeaderLooksLikeHTTP reports whether a TLS record header +// looks like it might've been a misdirected plaintext HTTP request. +func tlsRecordHeaderLooksLikeHTTP(hdr [5]byte) bool { + switch string(hdr[:]) { + case "GET /", "HEAD ", "POST ", "PUT /", "OPTIO": + return true + } + return false +} |