diff options
Diffstat (limited to 'src/net/http/httputil/persist.go')
| -rw-r--r-- | src/net/http/httputil/persist.go | 429 |
1 files changed, 429 insertions, 0 deletions
diff --git a/src/net/http/httputil/persist.go b/src/net/http/httputil/persist.go new file mode 100644 index 000000000..987bcc96b --- /dev/null +++ b/src/net/http/httputil/persist.go @@ -0,0 +1,429 @@ +// 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. + +package httputil + +import ( + "bufio" + "errors" + "io" + "net" + "net/http" + "net/textproto" + "sync" +) + +var ( + ErrPersistEOF = &http.ProtocolError{ErrorString: "persistent connection closed"} + ErrClosed = &http.ProtocolError{ErrorString: "connection closed by user"} + ErrPipeline = &http.ProtocolError{ErrorString: "pipeline error"} +) + +// This is an API usage error - the local side is closed. +// ErrPersistEOF (above) reports that the remote side is closed. +var errClosed = errors.New("i/o operation on closed connection") + +// A ServerConn reads requests and sends responses over an underlying +// connection, until the HTTP keepalive logic commands an end. ServerConn +// also allows hijacking the underlying connection by calling Hijack +// to regain control over the connection. ServerConn supports pipe-lining, +// i.e. requests can be read out of sync (but in the same order) while the +// respective responses are sent. +// +// ServerConn is low-level and old. Applications should instead use Server +// in the net/http package. +type ServerConn struct { + lk sync.Mutex // read-write protects the following fields + c net.Conn + r *bufio.Reader + re, we error // read/write errors + lastbody io.ReadCloser + nread, nwritten int + pipereq map[*http.Request]uint + + pipe textproto.Pipeline +} + +// NewServerConn returns a new ServerConn reading and writing c. If r is not +// nil, it is the buffer to use when reading c. +// +// ServerConn is low-level and old. Applications should instead use Server +// in the net/http package. +func NewServerConn(c net.Conn, r *bufio.Reader) *ServerConn { + if r == nil { + r = bufio.NewReader(c) + } + return &ServerConn{c: c, r: r, pipereq: make(map[*http.Request]uint)} +} + +// Hijack detaches the ServerConn and returns the underlying connection as well +// as the read-side bufio which may have some left over data. Hijack may be +// called before Read has signaled the end of the keep-alive logic. The user +// should not call Hijack while Read or Write is in progress. +func (sc *ServerConn) Hijack() (c net.Conn, r *bufio.Reader) { + sc.lk.Lock() + defer sc.lk.Unlock() + c = sc.c + r = sc.r + sc.c = nil + sc.r = nil + return +} + +// Close calls Hijack and then also closes the underlying connection +func (sc *ServerConn) Close() error { + c, _ := sc.Hijack() + if c != nil { + return c.Close() + } + return nil +} + +// Read returns the next request on the wire. An ErrPersistEOF is returned if +// it is gracefully determined that there are no more requests (e.g. after the +// first request on an HTTP/1.0 connection, or after a Connection:close on a +// HTTP/1.1 connection). +func (sc *ServerConn) Read() (req *http.Request, err error) { + + // Ensure ordered execution of Reads and Writes + id := sc.pipe.Next() + sc.pipe.StartRequest(id) + defer func() { + sc.pipe.EndRequest(id) + if req == nil { + sc.pipe.StartResponse(id) + sc.pipe.EndResponse(id) + } else { + // Remember the pipeline id of this request + sc.lk.Lock() + sc.pipereq[req] = id + sc.lk.Unlock() + } + }() + + sc.lk.Lock() + if sc.we != nil { // no point receiving if write-side broken or closed + defer sc.lk.Unlock() + return nil, sc.we + } + if sc.re != nil { + defer sc.lk.Unlock() + return nil, sc.re + } + if sc.r == nil { // connection closed by user in the meantime + defer sc.lk.Unlock() + return nil, errClosed + } + r := sc.r + lastbody := sc.lastbody + sc.lastbody = nil + sc.lk.Unlock() + + // Make sure body is fully consumed, even if user does not call body.Close + if lastbody != nil { + // body.Close is assumed to be idempotent and multiple calls to + // it should return the error that its first invocation + // returned. + err = lastbody.Close() + if err != nil { + sc.lk.Lock() + defer sc.lk.Unlock() + sc.re = err + return nil, err + } + } + + req, err = http.ReadRequest(r) + sc.lk.Lock() + defer sc.lk.Unlock() + if err != nil { + if err == io.ErrUnexpectedEOF { + // A close from the opposing client is treated as a + // graceful close, even if there was some unparse-able + // data before the close. + sc.re = ErrPersistEOF + return nil, sc.re + } else { + sc.re = err + return req, err + } + } + sc.lastbody = req.Body + sc.nread++ + if req.Close { + sc.re = ErrPersistEOF + return req, sc.re + } + return req, err +} + +// Pending returns the number of unanswered requests +// that have been received on the connection. +func (sc *ServerConn) Pending() int { + sc.lk.Lock() + defer sc.lk.Unlock() + return sc.nread - sc.nwritten +} + +// Write writes resp in response to req. To close the connection gracefully, set the +// Response.Close field to true. Write should be considered operational until +// it returns an error, regardless of any errors returned on the Read side. +func (sc *ServerConn) Write(req *http.Request, resp *http.Response) error { + + // Retrieve the pipeline ID of this request/response pair + sc.lk.Lock() + id, ok := sc.pipereq[req] + delete(sc.pipereq, req) + if !ok { + sc.lk.Unlock() + return ErrPipeline + } + sc.lk.Unlock() + + // Ensure pipeline order + sc.pipe.StartResponse(id) + defer sc.pipe.EndResponse(id) + + sc.lk.Lock() + if sc.we != nil { + defer sc.lk.Unlock() + return sc.we + } + if sc.c == nil { // connection closed by user in the meantime + defer sc.lk.Unlock() + return ErrClosed + } + c := sc.c + if sc.nread <= sc.nwritten { + defer sc.lk.Unlock() + return errors.New("persist server pipe count") + } + if resp.Close { + // After signaling a keep-alive close, any pipelined unread + // requests will be lost. It is up to the user to drain them + // before signaling. + sc.re = ErrPersistEOF + } + sc.lk.Unlock() + + err := resp.Write(c) + sc.lk.Lock() + defer sc.lk.Unlock() + if err != nil { + sc.we = err + return err + } + sc.nwritten++ + + return nil +} + +// A ClientConn sends request and receives headers over an underlying +// connection, while respecting the HTTP keepalive logic. ClientConn +// supports hijacking the connection calling Hijack to +// regain control of the underlying net.Conn and deal with it as desired. +// +// ClientConn is low-level and old. Applications should instead use +// Client or Transport in the net/http package. +type ClientConn struct { + lk sync.Mutex // read-write protects the following fields + c net.Conn + r *bufio.Reader + re, we error // read/write errors + lastbody io.ReadCloser + nread, nwritten int + pipereq map[*http.Request]uint + + pipe textproto.Pipeline + writeReq func(*http.Request, io.Writer) error +} + +// NewClientConn returns a new ClientConn reading and writing c. If r is not +// nil, it is the buffer to use when reading c. +// +// ClientConn is low-level and old. Applications should use Client or +// Transport in the net/http package. +func NewClientConn(c net.Conn, r *bufio.Reader) *ClientConn { + if r == nil { + r = bufio.NewReader(c) + } + return &ClientConn{ + c: c, + r: r, + pipereq: make(map[*http.Request]uint), + writeReq: (*http.Request).Write, + } +} + +// NewProxyClientConn works like NewClientConn but writes Requests +// using Request's WriteProxy method. +// +// New code should not use NewProxyClientConn. See Client or +// Transport in the net/http package instead. +func NewProxyClientConn(c net.Conn, r *bufio.Reader) *ClientConn { + cc := NewClientConn(c, r) + cc.writeReq = (*http.Request).WriteProxy + return cc +} + +// Hijack detaches the ClientConn and returns the underlying connection as well +// as the read-side bufio which may have some left over data. Hijack may be +// called before the user or Read have signaled the end of the keep-alive +// logic. The user should not call Hijack while Read or Write is in progress. +func (cc *ClientConn) Hijack() (c net.Conn, r *bufio.Reader) { + cc.lk.Lock() + defer cc.lk.Unlock() + c = cc.c + r = cc.r + cc.c = nil + cc.r = nil + return +} + +// Close calls Hijack and then also closes the underlying connection +func (cc *ClientConn) Close() error { + c, _ := cc.Hijack() + if c != nil { + return c.Close() + } + return nil +} + +// Write writes a request. An ErrPersistEOF error is returned if the connection +// has been closed in an HTTP keepalive sense. If req.Close equals true, the +// keepalive connection is logically closed after this request and the opposing +// server is informed. An ErrUnexpectedEOF indicates the remote closed the +// underlying TCP connection, which is usually considered as graceful close. +func (cc *ClientConn) Write(req *http.Request) (err error) { + + // Ensure ordered execution of Writes + id := cc.pipe.Next() + cc.pipe.StartRequest(id) + defer func() { + cc.pipe.EndRequest(id) + if err != nil { + cc.pipe.StartResponse(id) + cc.pipe.EndResponse(id) + } else { + // Remember the pipeline id of this request + cc.lk.Lock() + cc.pipereq[req] = id + cc.lk.Unlock() + } + }() + + cc.lk.Lock() + if cc.re != nil { // no point sending if read-side closed or broken + defer cc.lk.Unlock() + return cc.re + } + if cc.we != nil { + defer cc.lk.Unlock() + return cc.we + } + if cc.c == nil { // connection closed by user in the meantime + defer cc.lk.Unlock() + return errClosed + } + c := cc.c + if req.Close { + // We write the EOF to the write-side error, because there + // still might be some pipelined reads + cc.we = ErrPersistEOF + } + cc.lk.Unlock() + + err = cc.writeReq(req, c) + cc.lk.Lock() + defer cc.lk.Unlock() + if err != nil { + cc.we = err + return err + } + cc.nwritten++ + + return nil +} + +// Pending returns the number of unanswered requests +// that have been sent on the connection. +func (cc *ClientConn) Pending() int { + cc.lk.Lock() + defer cc.lk.Unlock() + return cc.nwritten - cc.nread +} + +// Read reads the next response from the wire. A valid response might be +// returned together with an ErrPersistEOF, which means that the remote +// requested that this be the last request serviced. Read can be called +// concurrently with Write, but not with another Read. +func (cc *ClientConn) Read(req *http.Request) (resp *http.Response, err error) { + // Retrieve the pipeline ID of this request/response pair + cc.lk.Lock() + id, ok := cc.pipereq[req] + delete(cc.pipereq, req) + if !ok { + cc.lk.Unlock() + return nil, ErrPipeline + } + cc.lk.Unlock() + + // Ensure pipeline order + cc.pipe.StartResponse(id) + defer cc.pipe.EndResponse(id) + + cc.lk.Lock() + if cc.re != nil { + defer cc.lk.Unlock() + return nil, cc.re + } + if cc.r == nil { // connection closed by user in the meantime + defer cc.lk.Unlock() + return nil, errClosed + } + r := cc.r + lastbody := cc.lastbody + cc.lastbody = nil + cc.lk.Unlock() + + // Make sure body is fully consumed, even if user does not call body.Close + if lastbody != nil { + // body.Close is assumed to be idempotent and multiple calls to + // it should return the error that its first invocation + // returned. + err = lastbody.Close() + if err != nil { + cc.lk.Lock() + defer cc.lk.Unlock() + cc.re = err + return nil, err + } + } + + resp, err = http.ReadResponse(r, req) + cc.lk.Lock() + defer cc.lk.Unlock() + if err != nil { + cc.re = err + return resp, err + } + cc.lastbody = resp.Body + + cc.nread++ + + if resp.Close { + cc.re = ErrPersistEOF // don't send any more requests + return resp, cc.re + } + return resp, err +} + +// Do is convenience method that writes a request and reads a response. +func (cc *ClientConn) Do(req *http.Request) (resp *http.Response, err error) { + err = cc.Write(req) + if err != nil { + return + } + return cc.Read(req) +} |