summaryrefslogtreecommitdiff
path: root/libgo/go/net/http/transport.go
blob: dc70be43f2d7bb48c1bb0a4eeccd14edd1fd2a24 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
// Copyright 2011 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 client implementation. See RFC 2616.
// 
// This is the low-level Transport implementation of RoundTripper.
// The high-level interface is in client.go.

package http

import (
	"bufio"
	"compress/gzip"
	"crypto/tls"
	"encoding/base64"
	"errors"
	"fmt"
	"io"
	"io/ioutil"
	"log"
	"net"
	"net/url"
	"os"
	"strings"
	"sync"
)

// DefaultTransport is the default implementation of Transport and is
// used by DefaultClient.  It establishes a new network connection for
// each call to Do and uses HTTP proxies as directed by the
// $HTTP_PROXY and $NO_PROXY (or $http_proxy and $no_proxy)
// environment variables.
var DefaultTransport RoundTripper = &Transport{Proxy: ProxyFromEnvironment}

// DefaultMaxIdleConnsPerHost is the default value of Transport's
// MaxIdleConnsPerHost.
const DefaultMaxIdleConnsPerHost = 2

// Transport is an implementation of RoundTripper that supports http,
// https, and http proxies (for either http or https with CONNECT).
// Transport can also cache connections for future re-use.
type Transport struct {
	lk       sync.Mutex
	idleConn map[string][]*persistConn
	altProto map[string]RoundTripper // nil or map of URI scheme => RoundTripper

	// TODO: tunable on global max cached connections
	// TODO: tunable on timeout on cached connections
	// TODO: optional pipelining

	// Proxy specifies a function to return a proxy for a given
	// Request. If the function returns a non-nil error, the
	// request is aborted with the provided error.
	// If Proxy is nil or returns a nil *URL, no proxy is used.
	Proxy func(*Request) (*url.URL, error)

	// Dial specifies the dial function for creating TCP
	// connections.
	// If Dial is nil, net.Dial is used.
	Dial func(net, addr string) (c net.Conn, err error)

	// TLSClientConfig specifies the TLS configuration to use with
	// tls.Client. If nil, the default configuration is used.
	TLSClientConfig *tls.Config

	DisableKeepAlives  bool
	DisableCompression bool

	// MaxIdleConnsPerHost, if non-zero, controls the maximum idle
	// (keep-alive) to keep to keep per-host.  If zero,
	// DefaultMaxIdleConnsPerHost is used.
	MaxIdleConnsPerHost int
}

// ProxyFromEnvironment returns the URL of the proxy to use for a
// given request, as indicated by the environment variables
// $HTTP_PROXY and $NO_PROXY (or $http_proxy and $no_proxy).
// Either URL or an error is returned.
func ProxyFromEnvironment(req *Request) (*url.URL, error) {
	proxy := getenvEitherCase("HTTP_PROXY")
	if proxy == "" {
		return nil, nil
	}
	if !useProxy(canonicalAddr(req.URL)) {
		return nil, nil
	}
	proxyURL, err := url.ParseRequest(proxy)
	if err != nil {
		return nil, errors.New("invalid proxy address")
	}
	if proxyURL.Host == "" {
		proxyURL, err = url.ParseRequest("http://" + proxy)
		if err != nil {
			return nil, errors.New("invalid proxy address")
		}
	}
	return proxyURL, nil
}

// ProxyURL returns a proxy function (for use in a Transport)
// that always returns the same URL.
func ProxyURL(fixedURL *url.URL) func(*Request) (*url.URL, error) {
	return func(*Request) (*url.URL, error) {
		return fixedURL, nil
	}
}

// transportRequest is a wrapper around a *Request that adds
// optional extra headers to write.
type transportRequest struct {
	*Request        // original request, not to be mutated
	extra    Header // extra headers to write, or nil
}

func (tr *transportRequest) extraHeaders() Header {
	if tr.extra == nil {
		tr.extra = make(Header)
	}
	return tr.extra
}

// RoundTrip implements the RoundTripper interface.
func (t *Transport) RoundTrip(req *Request) (resp *Response, err error) {
	if req.URL == nil {
		return nil, errors.New("http: nil Request.URL")
	}
	if req.Header == nil {
		return nil, errors.New("http: nil Request.Header")
	}
	if req.URL.Scheme != "http" && req.URL.Scheme != "https" {
		t.lk.Lock()
		var rt RoundTripper
		if t.altProto != nil {
			rt = t.altProto[req.URL.Scheme]
		}
		t.lk.Unlock()
		if rt == nil {
			return nil, &badStringError{"unsupported protocol scheme", req.URL.Scheme}
		}
		return rt.RoundTrip(req)
	}
	treq := &transportRequest{Request: req}
	cm, err := t.connectMethodForRequest(treq)
	if err != nil {
		return nil, err
	}

	// Get the cached or newly-created connection to either the
	// host (for http or https), the http proxy, or the http proxy
	// pre-CONNECTed to https server.  In any case, we'll be ready
	// to send it requests.
	pconn, err := t.getConn(cm)
	if err != nil {
		return nil, err
	}

	return pconn.roundTrip(treq)
}

// RegisterProtocol registers a new protocol with scheme.
// The Transport will pass requests using the given scheme to rt.
// It is rt's responsibility to simulate HTTP request semantics.
//
// RegisterProtocol can be used by other packages to provide
// implementations of protocol schemes like "ftp" or "file".
func (t *Transport) RegisterProtocol(scheme string, rt RoundTripper) {
	if scheme == "http" || scheme == "https" {
		panic("protocol " + scheme + " already registered")
	}
	t.lk.Lock()
	defer t.lk.Unlock()
	if t.altProto == nil {
		t.altProto = make(map[string]RoundTripper)
	}
	if _, exists := t.altProto[scheme]; exists {
		panic("protocol " + scheme + " already registered")
	}
	t.altProto[scheme] = rt
}

// CloseIdleConnections closes any connections which were previously
// connected from previous requests but are now sitting idle in
// a "keep-alive" state. It does not interrupt any connections currently
// in use.
func (t *Transport) CloseIdleConnections() {
	t.lk.Lock()
	defer t.lk.Unlock()
	if t.idleConn == nil {
		return
	}
	for _, conns := range t.idleConn {
		for _, pconn := range conns {
			pconn.close()
		}
	}
	t.idleConn = nil
}

//
// Private implementation past this point.
//

func getenvEitherCase(k string) string {
	if v := os.Getenv(strings.ToUpper(k)); v != "" {
		return v
	}
	return os.Getenv(strings.ToLower(k))
}

func (t *Transport) connectMethodForRequest(treq *transportRequest) (*connectMethod, error) {
	cm := &connectMethod{
		targetScheme: treq.URL.Scheme,
		targetAddr:   canonicalAddr(treq.URL),
	}
	if t.Proxy != nil {
		var err error
		cm.proxyURL, err = t.Proxy(treq.Request)
		if err != nil {
			return nil, err
		}
	}
	return cm, nil
}

// proxyAuth returns the Proxy-Authorization header to set
// on requests, if applicable.
func (cm *connectMethod) proxyAuth() string {
	if cm.proxyURL == nil {
		return ""
	}
	proxyInfo := cm.proxyURL.RawUserinfo
	if proxyInfo != "" {
		return "Basic " + base64.URLEncoding.EncodeToString([]byte(proxyInfo))
	}
	return ""
}

func (t *Transport) putIdleConn(pconn *persistConn) {
	t.lk.Lock()
	defer t.lk.Unlock()
	if t.DisableKeepAlives || t.MaxIdleConnsPerHost < 0 {
		pconn.close()
		return
	}
	if pconn.isBroken() {
		return
	}
	key := pconn.cacheKey
	max := t.MaxIdleConnsPerHost
	if max == 0 {
		max = DefaultMaxIdleConnsPerHost
	}
	if len(t.idleConn[key]) >= max {
		pconn.close()
		return
	}
	t.idleConn[key] = append(t.idleConn[key], pconn)
}

func (t *Transport) getIdleConn(cm *connectMethod) (pconn *persistConn) {
	t.lk.Lock()
	defer t.lk.Unlock()
	if t.idleConn == nil {
		t.idleConn = make(map[string][]*persistConn)
	}
	key := cm.String()
	for {
		pconns, ok := t.idleConn[key]
		if !ok {
			return nil
		}
		if len(pconns) == 1 {
			pconn = pconns[0]
			delete(t.idleConn, key)
		} else {
			// 2 or more cached connections; pop last
			// TODO: queue?
			pconn = pconns[len(pconns)-1]
			t.idleConn[key] = pconns[0 : len(pconns)-1]
		}
		if !pconn.isBroken() {
			return
		}
	}
	return
}

func (t *Transport) dial(network, addr string) (c net.Conn, err error) {
	if t.Dial != nil {
		return t.Dial(network, addr)
	}
	return net.Dial(network, addr)
}

// getConn dials and creates a new persistConn to the target as
// specified in the connectMethod.  This includes doing a proxy CONNECT
// and/or setting up TLS.  If this doesn't return an error, the persistConn
// is ready to write requests to.
func (t *Transport) getConn(cm *connectMethod) (*persistConn, error) {
	if pc := t.getIdleConn(cm); pc != nil {
		return pc, nil
	}

	conn, err := t.dial("tcp", cm.addr())
	if err != nil {
		if cm.proxyURL != nil {
			err = fmt.Errorf("http: error connecting to proxy %s: %v", cm.proxyURL, err)
		}
		return nil, err
	}

	pa := cm.proxyAuth()

	pconn := &persistConn{
		t:        t,
		cacheKey: cm.String(),
		conn:     conn,
		reqch:    make(chan requestAndChan, 50),
	}

	switch {
	case cm.proxyURL == nil:
		// Do nothing.
	case cm.targetScheme == "http":
		pconn.isProxy = true
		if pa != "" {
			pconn.mutateHeaderFunc = func(h Header) {
				h.Set("Proxy-Authorization", pa)
			}
		}
	case cm.targetScheme == "https":
		connectReq := &Request{
			Method: "CONNECT",
			URL:    &url.URL{RawPath: cm.targetAddr},
			Host:   cm.targetAddr,
			Header: make(Header),
		}
		if pa != "" {
			connectReq.Header.Set("Proxy-Authorization", pa)
		}
		connectReq.Write(conn)

		// Read response.
		// Okay to use and discard buffered reader here, because
		// TLS server will not speak until spoken to.
		br := bufio.NewReader(conn)
		resp, err := ReadResponse(br, connectReq)
		if err != nil {
			conn.Close()
			return nil, err
		}
		if resp.StatusCode != 200 {
			f := strings.SplitN(resp.Status, " ", 2)
			conn.Close()
			return nil, errors.New(f[1])
		}
	}

	if cm.targetScheme == "https" {
		// Initiate TLS and check remote host name against certificate.
		conn = tls.Client(conn, t.TLSClientConfig)
		if err = conn.(*tls.Conn).Handshake(); err != nil {
			return nil, err
		}
		if t.TLSClientConfig == nil || !t.TLSClientConfig.InsecureSkipVerify {
			if err = conn.(*tls.Conn).VerifyHostname(cm.tlsHost()); err != nil {
				return nil, err
			}
		}
		pconn.conn = conn
	}

	pconn.br = bufio.NewReader(pconn.conn)
	pconn.bw = bufio.NewWriter(pconn.conn)
	go pconn.readLoop()
	return pconn, nil
}

// useProxy returns true if requests to addr should use a proxy,
// according to the NO_PROXY or no_proxy environment variable.
// addr is always a canonicalAddr with a host and port.
func useProxy(addr string) bool {
	if len(addr) == 0 {
		return true
	}
	host, _, err := net.SplitHostPort(addr)
	if err != nil {
		return false
	}
	if host == "localhost" {
		return false
	}
	if ip := net.ParseIP(host); ip != nil {
		if ip.IsLoopback() {
			return false
		}
	}

	no_proxy := getenvEitherCase("NO_PROXY")
	if no_proxy == "*" {
		return false
	}

	addr = strings.ToLower(strings.TrimSpace(addr))
	if hasPort(addr) {
		addr = addr[:strings.LastIndex(addr, ":")]
	}

	for _, p := range strings.Split(no_proxy, ",") {
		p = strings.ToLower(strings.TrimSpace(p))
		if len(p) == 0 {
			continue
		}
		if hasPort(p) {
			p = p[:strings.LastIndex(p, ":")]
		}
		if addr == p || (p[0] == '.' && (strings.HasSuffix(addr, p) || addr == p[1:])) {
			return false
		}
	}
	return true
}

// connectMethod is the map key (in its String form) for keeping persistent
// TCP connections alive for subsequent HTTP requests.
//
// A connect method may be of the following types:
//
// Cache key form                Description
// -----------------             -------------------------
// ||http|foo.com                http directly to server, no proxy
// ||https|foo.com               https directly to server, no proxy
// http://proxy.com|https|foo.com  http to proxy, then CONNECT to foo.com
// http://proxy.com|http           http to proxy, http to anywhere after that
//
// Note: no support to https to the proxy yet.
//
type connectMethod struct {
	proxyURL     *url.URL // nil for no proxy, else full proxy URL
	targetScheme string   // "http" or "https"
	targetAddr   string   // Not used if proxy + http targetScheme (4th example in table)
}

func (ck *connectMethod) String() string {
	proxyStr := ""
	if ck.proxyURL != nil {
		proxyStr = ck.proxyURL.String()
	}
	return strings.Join([]string{proxyStr, ck.targetScheme, ck.targetAddr}, "|")
}

// addr returns the first hop "host:port" to which we need to TCP connect.
func (cm *connectMethod) addr() string {
	if cm.proxyURL != nil {
		return canonicalAddr(cm.proxyURL)
	}
	return cm.targetAddr
}

// tlsHost returns the host name to match against the peer's
// TLS certificate.
func (cm *connectMethod) tlsHost() string {
	h := cm.targetAddr
	if hasPort(h) {
		h = h[:strings.LastIndex(h, ":")]
	}
	return h
}

// persistConn wraps a connection, usually a persistent one
// (but may be used for non-keep-alive requests as well)
type persistConn struct {
	t        *Transport
	cacheKey string // its connectMethod.String()
	conn     net.Conn
	br       *bufio.Reader       // from conn
	bw       *bufio.Writer       // to conn
	reqch    chan requestAndChan // written by roundTrip(); read by readLoop()
	isProxy  bool

	// mutateHeaderFunc is an optional func to modify extra
	// headers on each outbound request before it's written. (the
	// original Request given to RoundTrip is not modified)
	mutateHeaderFunc func(Header)

	lk                   sync.Mutex // guards numExpectedResponses and broken
	numExpectedResponses int
	broken               bool // an error has happened on this connection; marked broken so it's not reused.
}

func (pc *persistConn) isBroken() bool {
	pc.lk.Lock()
	defer pc.lk.Unlock()
	return pc.broken
}

func (pc *persistConn) expectingResponse() bool {
	pc.lk.Lock()
	defer pc.lk.Unlock()
	return pc.numExpectedResponses > 0
}

var remoteSideClosedFunc func(error) bool // or nil to use default

func remoteSideClosed(err error) bool {
	if err == io.EOF {
		return true
	}
	if remoteSideClosedFunc != nil {
		return remoteSideClosedFunc(err)
	}
	return false
}

func (pc *persistConn) readLoop() {
	alive := true
	var lastbody io.ReadCloser // last response body, if any, read on this connection

	for alive {
		pb, err := pc.br.Peek(1)
		if !pc.expectingResponse() {
			if len(pb) > 0 {
				log.Printf("Unsolicited response received on idle HTTP channel starting with %q; err=%v",
					string(pb), err)
			}
			pc.close()
			return
		}

		rc := <-pc.reqch

		// Advance past the previous response's body, if the
		// caller hasn't done so.
		if lastbody != nil {
			lastbody.Close() // assumed idempotent
			lastbody = nil
		}
		resp, err := ReadResponse(pc.br, rc.req)

		if err == nil {
			if rc.addedGzip && resp.Header.Get("Content-Encoding") == "gzip" {
				resp.Header.Del("Content-Encoding")
				resp.Header.Del("Content-Length")
				resp.ContentLength = -1
				gzReader, zerr := gzip.NewReader(resp.Body)
				if err != nil {
					pc.close()
					err = zerr
				} else {
					resp.Body = &readFirstCloseBoth{&discardOnCloseReadCloser{gzReader}, resp.Body}
				}
			}
			resp.Body = &bodyEOFSignal{body: resp.Body}
		}

		if err != nil || resp.Close || rc.req.Close {
			alive = false
		}

		hasBody := resp != nil && resp.ContentLength != 0
		var waitForBodyRead chan bool
		if alive {
			if hasBody {
				lastbody = resp.Body
				waitForBodyRead = make(chan bool)
				resp.Body.(*bodyEOFSignal).fn = func() {
					pc.t.putIdleConn(pc)
					waitForBodyRead <- true
				}
			} else {
				// When there's no response body, we immediately
				// reuse the TCP connection (putIdleConn), but
				// we need to prevent ClientConn.Read from
				// closing the Response.Body on the next
				// loop, otherwise it might close the body
				// before the client code has had a chance to
				// read it (even though it'll just be 0, EOF).
				lastbody = nil

				pc.t.putIdleConn(pc)
			}
		}

		rc.ch <- responseAndError{resp, err}

		// Wait for the just-returned response body to be fully consumed
		// before we race and peek on the underlying bufio reader.
		if waitForBodyRead != nil {
			<-waitForBodyRead
		}
	}
}

type responseAndError struct {
	res *Response
	err error
}

type requestAndChan struct {
	req *Request
	ch  chan responseAndError

	// did the Transport (as opposed to the client code) add an
	// Accept-Encoding gzip header? only if it we set it do
	// we transparently decode the gzip.
	addedGzip bool
}

func (pc *persistConn) roundTrip(req *transportRequest) (resp *Response, err error) {
	if pc.mutateHeaderFunc != nil {
		pc.mutateHeaderFunc(req.extraHeaders())
	}

	// Ask for a compressed version if the caller didn't set their
	// own value for Accept-Encoding. We only attempted to
	// uncompress the gzip stream if we were the layer that
	// requested it.
	requestedGzip := false
	if !pc.t.DisableCompression && req.Header.Get("Accept-Encoding") == "" {
		// Request gzip only, not deflate. Deflate is ambiguous and 
		// not as universally supported anyway.
		// See: http://www.gzip.org/zlib/zlib_faq.html#faq38
		requestedGzip = true
		req.extraHeaders().Set("Accept-Encoding", "gzip")
	}

	pc.lk.Lock()
	pc.numExpectedResponses++
	pc.lk.Unlock()

	err = req.Request.write(pc.bw, pc.isProxy, req.extra)
	if err != nil {
		pc.close()
		return
	}
	pc.bw.Flush()

	ch := make(chan responseAndError, 1)
	pc.reqch <- requestAndChan{req.Request, ch, requestedGzip}
	re := <-ch
	pc.lk.Lock()
	pc.numExpectedResponses--
	pc.lk.Unlock()

	return re.res, re.err
}

func (pc *persistConn) close() {
	pc.lk.Lock()
	defer pc.lk.Unlock()
	pc.broken = true
	pc.conn.Close()
	pc.mutateHeaderFunc = nil
}

var portMap = map[string]string{
	"http":  "80",
	"https": "443",
}

// canonicalAddr returns url.Host but always with a ":port" suffix
func canonicalAddr(url *url.URL) string {
	addr := url.Host
	if !hasPort(addr) {
		return addr + ":" + portMap[url.Scheme]
	}
	return addr
}

func responseIsKeepAlive(res *Response) bool {
	// TODO: implement.  for now just always shutting down the connection.
	return false
}

// bodyEOFSignal wraps a ReadCloser but runs fn (if non-nil) at most
// once, right before the final Read() or Close() call returns, but after
// EOF has been seen.
type bodyEOFSignal struct {
	body     io.ReadCloser
	fn       func()
	isClosed bool
}

func (es *bodyEOFSignal) Read(p []byte) (n int, err error) {
	n, err = es.body.Read(p)
	if es.isClosed && n > 0 {
		panic("http: unexpected bodyEOFSignal Read after Close; see issue 1725")
	}
	if err == io.EOF && es.fn != nil {
		es.fn()
		es.fn = nil
	}
	return
}

func (es *bodyEOFSignal) Close() (err error) {
	if es.isClosed {
		return nil
	}
	es.isClosed = true
	err = es.body.Close()
	if err == nil && es.fn != nil {
		es.fn()
		es.fn = nil
	}
	return
}

type readFirstCloseBoth struct {
	io.ReadCloser
	io.Closer
}

func (r *readFirstCloseBoth) Close() error {
	if err := r.ReadCloser.Close(); err != nil {
		r.Closer.Close()
		return err
	}
	if err := r.Closer.Close(); err != nil {
		return err
	}
	return nil
}

// discardOnCloseReadCloser consumes all its input on Close.
type discardOnCloseReadCloser struct {
	io.ReadCloser
}

func (d *discardOnCloseReadCloser) Close() error {
	io.Copy(ioutil.Discard, d.ReadCloser) // ignore errors; likely invalid or already closed
	return d.ReadCloser.Close()
}