Imported Upstream version 1.4upstream/1.4

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)
+}