Source file src/pkg/net/http/httputil/persist.go

     1	// Copyright 2009 The Go Authors. All rights reserved.
     2	// Use of this source code is governed by a BSD-style
     3	// license that can be found in the LICENSE file.
     4	
     5	package httputil
     6	
     7	import (
     8		"bufio"
     9		"errors"
    10		"io"
    11		"net"
    12		"net/http"
    13		"net/textproto"
    14		"sync"
    15	)
    16	
    17	var (
    18		// Deprecated: No longer used.
    19		ErrPersistEOF = &http.ProtocolError{ErrorString: "persistent connection closed"}
    20	
    21		// Deprecated: No longer used.
    22		ErrClosed = &http.ProtocolError{ErrorString: "connection closed by user"}
    23	
    24		// Deprecated: No longer used.
    25		ErrPipeline = &http.ProtocolError{ErrorString: "pipeline error"}
    26	)
    27	
    28	// This is an API usage error - the local side is closed.
    29	// ErrPersistEOF (above) reports that the remote side is closed.
    30	var errClosed = errors.New("i/o operation on closed connection")
    31	
    32	// ServerConn is an artifact of Go's early HTTP implementation.
    33	// It is low-level, old, and unused by Go's current HTTP stack.
    34	// We should have deleted it before Go 1.
    35	//
    36	// Deprecated: Use the Server in package net/http instead.
    37	type ServerConn struct {
    38		mu              sync.Mutex // read-write protects the following fields
    39		c               net.Conn
    40		r               *bufio.Reader
    41		re, we          error // read/write errors
    42		lastbody        io.ReadCloser
    43		nread, nwritten int
    44		pipereq         map[*http.Request]uint
    45	
    46		pipe textproto.Pipeline
    47	}
    48	
    49	// NewServerConn is an artifact of Go's early HTTP implementation.
    50	// It is low-level, old, and unused by Go's current HTTP stack.
    51	// We should have deleted it before Go 1.
    52	//
    53	// Deprecated: Use the Server in package net/http instead.
    54	func NewServerConn(c net.Conn, r *bufio.Reader) *ServerConn {
    55		if r == nil {
    56			r = bufio.NewReader(c)
    57		}
    58		return &ServerConn{c: c, r: r, pipereq: make(map[*http.Request]uint)}
    59	}
    60	
    61	// Hijack detaches the ServerConn and returns the underlying connection as well
    62	// as the read-side bufio which may have some left over data. Hijack may be
    63	// called before Read has signaled the end of the keep-alive logic. The user
    64	// should not call Hijack while Read or Write is in progress.
    65	func (sc *ServerConn) Hijack() (net.Conn, *bufio.Reader) {
    66		sc.mu.Lock()
    67		defer sc.mu.Unlock()
    68		c := sc.c
    69		r := sc.r
    70		sc.c = nil
    71		sc.r = nil
    72		return c, r
    73	}
    74	
    75	// Close calls Hijack and then also closes the underlying connection.
    76	func (sc *ServerConn) Close() error {
    77		c, _ := sc.Hijack()
    78		if c != nil {
    79			return c.Close()
    80		}
    81		return nil
    82	}
    83	
    84	// Read returns the next request on the wire. An ErrPersistEOF is returned if
    85	// it is gracefully determined that there are no more requests (e.g. after the
    86	// first request on an HTTP/1.0 connection, or after a Connection:close on a
    87	// HTTP/1.1 connection).
    88	func (sc *ServerConn) Read() (*http.Request, error) {
    89		var req *http.Request
    90		var err error
    91	
    92		// Ensure ordered execution of Reads and Writes
    93		id := sc.pipe.Next()
    94		sc.pipe.StartRequest(id)
    95		defer func() {
    96			sc.pipe.EndRequest(id)
    97			if req == nil {
    98				sc.pipe.StartResponse(id)
    99				sc.pipe.EndResponse(id)
   100			} else {
   101				// Remember the pipeline id of this request
   102				sc.mu.Lock()
   103				sc.pipereq[req] = id
   104				sc.mu.Unlock()
   105			}
   106		}()
   107	
   108		sc.mu.Lock()
   109		if sc.we != nil { // no point receiving if write-side broken or closed
   110			defer sc.mu.Unlock()
   111			return nil, sc.we
   112		}
   113		if sc.re != nil {
   114			defer sc.mu.Unlock()
   115			return nil, sc.re
   116		}
   117		if sc.r == nil { // connection closed by user in the meantime
   118			defer sc.mu.Unlock()
   119			return nil, errClosed
   120		}
   121		r := sc.r
   122		lastbody := sc.lastbody
   123		sc.lastbody = nil
   124		sc.mu.Unlock()
   125	
   126		// Make sure body is fully consumed, even if user does not call body.Close
   127		if lastbody != nil {
   128			// body.Close is assumed to be idempotent and multiple calls to
   129			// it should return the error that its first invocation
   130			// returned.
   131			err = lastbody.Close()
   132			if err != nil {
   133				sc.mu.Lock()
   134				defer sc.mu.Unlock()
   135				sc.re = err
   136				return nil, err
   137			}
   138		}
   139	
   140		req, err = http.ReadRequest(r)
   141		sc.mu.Lock()
   142		defer sc.mu.Unlock()
   143		if err != nil {
   144			if err == io.ErrUnexpectedEOF {
   145				// A close from the opposing client is treated as a
   146				// graceful close, even if there was some unparse-able
   147				// data before the close.
   148				sc.re = ErrPersistEOF
   149				return nil, sc.re
   150			} else {
   151				sc.re = err
   152				return req, err
   153			}
   154		}
   155		sc.lastbody = req.Body
   156		sc.nread++
   157		if req.Close {
   158			sc.re = ErrPersistEOF
   159			return req, sc.re
   160		}
   161		return req, err
   162	}
   163	
   164	// Pending returns the number of unanswered requests
   165	// that have been received on the connection.
   166	func (sc *ServerConn) Pending() int {
   167		sc.mu.Lock()
   168		defer sc.mu.Unlock()
   169		return sc.nread - sc.nwritten
   170	}
   171	
   172	// Write writes resp in response to req. To close the connection gracefully, set the
   173	// Response.Close field to true. Write should be considered operational until
   174	// it returns an error, regardless of any errors returned on the Read side.
   175	func (sc *ServerConn) Write(req *http.Request, resp *http.Response) error {
   176	
   177		// Retrieve the pipeline ID of this request/response pair
   178		sc.mu.Lock()
   179		id, ok := sc.pipereq[req]
   180		delete(sc.pipereq, req)
   181		if !ok {
   182			sc.mu.Unlock()
   183			return ErrPipeline
   184		}
   185		sc.mu.Unlock()
   186	
   187		// Ensure pipeline order
   188		sc.pipe.StartResponse(id)
   189		defer sc.pipe.EndResponse(id)
   190	
   191		sc.mu.Lock()
   192		if sc.we != nil {
   193			defer sc.mu.Unlock()
   194			return sc.we
   195		}
   196		if sc.c == nil { // connection closed by user in the meantime
   197			defer sc.mu.Unlock()
   198			return ErrClosed
   199		}
   200		c := sc.c
   201		if sc.nread <= sc.nwritten {
   202			defer sc.mu.Unlock()
   203			return errors.New("persist server pipe count")
   204		}
   205		if resp.Close {
   206			// After signaling a keep-alive close, any pipelined unread
   207			// requests will be lost. It is up to the user to drain them
   208			// before signaling.
   209			sc.re = ErrPersistEOF
   210		}
   211		sc.mu.Unlock()
   212	
   213		err := resp.Write(c)
   214		sc.mu.Lock()
   215		defer sc.mu.Unlock()
   216		if err != nil {
   217			sc.we = err
   218			return err
   219		}
   220		sc.nwritten++
   221	
   222		return nil
   223	}
   224	
   225	// ClientConn is an artifact of Go's early HTTP implementation.
   226	// It is low-level, old, and unused by Go's current HTTP stack.
   227	// We should have deleted it before Go 1.
   228	//
   229	// Deprecated: Use Client or Transport in package net/http instead.
   230	type ClientConn struct {
   231		mu              sync.Mutex // read-write protects the following fields
   232		c               net.Conn
   233		r               *bufio.Reader
   234		re, we          error // read/write errors
   235		lastbody        io.ReadCloser
   236		nread, nwritten int
   237		pipereq         map[*http.Request]uint
   238	
   239		pipe     textproto.Pipeline
   240		writeReq func(*http.Request, io.Writer) error
   241	}
   242	
   243	// NewClientConn is an artifact of Go's early HTTP implementation.
   244	// It is low-level, old, and unused by Go's current HTTP stack.
   245	// We should have deleted it before Go 1.
   246	//
   247	// Deprecated: Use the Client or Transport in package net/http instead.
   248	func NewClientConn(c net.Conn, r *bufio.Reader) *ClientConn {
   249		if r == nil {
   250			r = bufio.NewReader(c)
   251		}
   252		return &ClientConn{
   253			c:        c,
   254			r:        r,
   255			pipereq:  make(map[*http.Request]uint),
   256			writeReq: (*http.Request).Write,
   257		}
   258	}
   259	
   260	// NewProxyClientConn is an artifact of Go's early HTTP implementation.
   261	// It is low-level, old, and unused by Go's current HTTP stack.
   262	// We should have deleted it before Go 1.
   263	//
   264	// Deprecated: Use the Client or Transport in package net/http instead.
   265	func NewProxyClientConn(c net.Conn, r *bufio.Reader) *ClientConn {
   266		cc := NewClientConn(c, r)
   267		cc.writeReq = (*http.Request).WriteProxy
   268		return cc
   269	}
   270	
   271	// Hijack detaches the ClientConn and returns the underlying connection as well
   272	// as the read-side bufio which may have some left over data. Hijack may be
   273	// called before the user or Read have signaled the end of the keep-alive
   274	// logic. The user should not call Hijack while Read or Write is in progress.
   275	func (cc *ClientConn) Hijack() (c net.Conn, r *bufio.Reader) {
   276		cc.mu.Lock()
   277		defer cc.mu.Unlock()
   278		c = cc.c
   279		r = cc.r
   280		cc.c = nil
   281		cc.r = nil
   282		return
   283	}
   284	
   285	// Close calls Hijack and then also closes the underlying connection.
   286	func (cc *ClientConn) Close() error {
   287		c, _ := cc.Hijack()
   288		if c != nil {
   289			return c.Close()
   290		}
   291		return nil
   292	}
   293	
   294	// Write writes a request. An ErrPersistEOF error is returned if the connection
   295	// has been closed in an HTTP keep-alive sense. If req.Close equals true, the
   296	// keep-alive connection is logically closed after this request and the opposing
   297	// server is informed. An ErrUnexpectedEOF indicates the remote closed the
   298	// underlying TCP connection, which is usually considered as graceful close.
   299	func (cc *ClientConn) Write(req *http.Request) error {
   300		var err error
   301	
   302		// Ensure ordered execution of Writes
   303		id := cc.pipe.Next()
   304		cc.pipe.StartRequest(id)
   305		defer func() {
   306			cc.pipe.EndRequest(id)
   307			if err != nil {
   308				cc.pipe.StartResponse(id)
   309				cc.pipe.EndResponse(id)
   310			} else {
   311				// Remember the pipeline id of this request
   312				cc.mu.Lock()
   313				cc.pipereq[req] = id
   314				cc.mu.Unlock()
   315			}
   316		}()
   317	
   318		cc.mu.Lock()
   319		if cc.re != nil { // no point sending if read-side closed or broken
   320			defer cc.mu.Unlock()
   321			return cc.re
   322		}
   323		if cc.we != nil {
   324			defer cc.mu.Unlock()
   325			return cc.we
   326		}
   327		if cc.c == nil { // connection closed by user in the meantime
   328			defer cc.mu.Unlock()
   329			return errClosed
   330		}
   331		c := cc.c
   332		if req.Close {
   333			// We write the EOF to the write-side error, because there
   334			// still might be some pipelined reads
   335			cc.we = ErrPersistEOF
   336		}
   337		cc.mu.Unlock()
   338	
   339		err = cc.writeReq(req, c)
   340		cc.mu.Lock()
   341		defer cc.mu.Unlock()
   342		if err != nil {
   343			cc.we = err
   344			return err
   345		}
   346		cc.nwritten++
   347	
   348		return nil
   349	}
   350	
   351	// Pending returns the number of unanswered requests
   352	// that have been sent on the connection.
   353	func (cc *ClientConn) Pending() int {
   354		cc.mu.Lock()
   355		defer cc.mu.Unlock()
   356		return cc.nwritten - cc.nread
   357	}
   358	
   359	// Read reads the next response from the wire. A valid response might be
   360	// returned together with an ErrPersistEOF, which means that the remote
   361	// requested that this be the last request serviced. Read can be called
   362	// concurrently with Write, but not with another Read.
   363	func (cc *ClientConn) Read(req *http.Request) (resp *http.Response, err error) {
   364		// Retrieve the pipeline ID of this request/response pair
   365		cc.mu.Lock()
   366		id, ok := cc.pipereq[req]
   367		delete(cc.pipereq, req)
   368		if !ok {
   369			cc.mu.Unlock()
   370			return nil, ErrPipeline
   371		}
   372		cc.mu.Unlock()
   373	
   374		// Ensure pipeline order
   375		cc.pipe.StartResponse(id)
   376		defer cc.pipe.EndResponse(id)
   377	
   378		cc.mu.Lock()
   379		if cc.re != nil {
   380			defer cc.mu.Unlock()
   381			return nil, cc.re
   382		}
   383		if cc.r == nil { // connection closed by user in the meantime
   384			defer cc.mu.Unlock()
   385			return nil, errClosed
   386		}
   387		r := cc.r
   388		lastbody := cc.lastbody
   389		cc.lastbody = nil
   390		cc.mu.Unlock()
   391	
   392		// Make sure body is fully consumed, even if user does not call body.Close
   393		if lastbody != nil {
   394			// body.Close is assumed to be idempotent and multiple calls to
   395			// it should return the error that its first invocation
   396			// returned.
   397			err = lastbody.Close()
   398			if err != nil {
   399				cc.mu.Lock()
   400				defer cc.mu.Unlock()
   401				cc.re = err
   402				return nil, err
   403			}
   404		}
   405	
   406		resp, err = http.ReadResponse(r, req)
   407		cc.mu.Lock()
   408		defer cc.mu.Unlock()
   409		if err != nil {
   410			cc.re = err
   411			return resp, err
   412		}
   413		cc.lastbody = resp.Body
   414	
   415		cc.nread++
   416	
   417		if resp.Close {
   418			cc.re = ErrPersistEOF // don't send any more requests
   419			return resp, cc.re
   420		}
   421		return resp, err
   422	}
   423	
   424	// Do is convenience method that writes a request and reads a response.
   425	func (cc *ClientConn) Do(req *http.Request) (*http.Response, error) {
   426		err := cc.Write(req)
   427		if err != nil {
   428			return nil, err
   429		}
   430		return cc.Read(req)
   431	}
   432	

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