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// 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 http
import (
"bufio"
"io"
"net"
"net/textproto"
"os"
"sync"
)
var (
ErrPersistEOF = &ProtocolError{"persistent connection closed"}
ErrPipeline = &ProtocolError{"pipeline error"}
)
// 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 should not be needed by most applications.
// See Server.
type ServerConn struct {
lk sync.Mutex // read-write protects the following fields
c net.Conn
r *bufio.Reader
re, we os.Error // read/write errors
lastbody io.ReadCloser
nread, nwritten int
pipereq map[*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.
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[*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() os.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 *Request, err os.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, os.EBADF
}
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 = 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 *Request, resp *Response) os.Error {
// Retrieve the pipeline ID of this request/response pair
sc.lk.Lock()
id, ok := sc.pipereq[req]
sc.pipereq[req] = 0, false
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 os.EBADF
}
c := sc.c
if sc.nread <= sc.nwritten {
defer sc.lk.Unlock()
return os.NewError("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 should not be needed by most applications.
// See Client.
type ClientConn struct {
lk sync.Mutex // read-write protects the following fields
c net.Conn
r *bufio.Reader
re, we os.Error // read/write errors
lastbody io.ReadCloser
nread, nwritten int
pipereq map[*Request]uint
pipe textproto.Pipeline
writeReq func(*Request, io.Writer) os.Error
}
// NewClientConn returns a new ClientConn reading and writing c. If r is not
// nil, it is the buffer to use when reading c.
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[*Request]uint),
writeReq: (*Request).Write,
}
}
// NewProxyClientConn works like NewClientConn but writes Requests
// using Request's WriteProxy method.
func NewProxyClientConn(c net.Conn, r *bufio.Reader) *ClientConn {
cc := NewClientConn(c, r)
cc.writeReq = (*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() os.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 *Request) (err os.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 os.EBADF
}
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 *Request) (*Response, os.Error) {
return cc.readUsing(req, ReadResponse)
}
// readUsing is the implementation of Read with a replaceable
// ReadResponse-like function, used by the Transport.
func (cc *ClientConn) readUsing(req *Request, readRes func(*bufio.Reader, *Request) (*Response, os.Error)) (resp *Response, err os.Error) {
// Retrieve the pipeline ID of this request/response pair
cc.lk.Lock()
id, ok := cc.pipereq[req]
cc.pipereq[req] = 0, false
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, os.EBADF
}
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 invokation
// returned.
err = lastbody.Close()
if err != nil {
cc.lk.Lock()
defer cc.lk.Unlock()
cc.re = err
return nil, err
}
}
resp, err = readRes(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 *Request) (resp *Response, err os.Error) {
err = cc.Write(req)
if err != nil {
return
}
return cc.Read(req)
}