1// Copyright 2010 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
5package http
6
7import (
8	"bufio"
9	"bytes"
10	"errors"
11	"fmt"
12	"io"
13	"io/ioutil"
14	"net"
15	"net/url"
16	"strings"
17	"testing"
18	"time"
19)
20
21type reqWriteTest struct {
22	Req  Request
23	Body interface{} // optional []byte or func() io.ReadCloser to populate Req.Body
24
25	// Any of these three may be empty to skip that test.
26	WantWrite string // Request.Write
27	WantProxy string // Request.WriteProxy
28
29	WantError error // wanted error from Request.Write
30}
31
32var reqWriteTests = []reqWriteTest{
33	// HTTP/1.1 => chunked coding; no body; no trailer
34	0: {
35		Req: Request{
36			Method: "GET",
37			URL: &url.URL{
38				Scheme: "http",
39				Host:   "www.techcrunch.com",
40				Path:   "/",
41			},
42			Proto:      "HTTP/1.1",
43			ProtoMajor: 1,
44			ProtoMinor: 1,
45			Header: Header{
46				"Accept":           {"text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8"},
47				"Accept-Charset":   {"ISO-8859-1,utf-8;q=0.7,*;q=0.7"},
48				"Accept-Encoding":  {"gzip,deflate"},
49				"Accept-Language":  {"en-us,en;q=0.5"},
50				"Keep-Alive":       {"300"},
51				"Proxy-Connection": {"keep-alive"},
52				"User-Agent":       {"Fake"},
53			},
54			Body:  nil,
55			Close: false,
56			Host:  "www.techcrunch.com",
57			Form:  map[string][]string{},
58		},
59
60		WantWrite: "GET / HTTP/1.1\r\n" +
61			"Host: www.techcrunch.com\r\n" +
62			"User-Agent: Fake\r\n" +
63			"Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8\r\n" +
64			"Accept-Charset: ISO-8859-1,utf-8;q=0.7,*;q=0.7\r\n" +
65			"Accept-Encoding: gzip,deflate\r\n" +
66			"Accept-Language: en-us,en;q=0.5\r\n" +
67			"Keep-Alive: 300\r\n" +
68			"Proxy-Connection: keep-alive\r\n\r\n",
69
70		WantProxy: "GET http://www.techcrunch.com/ HTTP/1.1\r\n" +
71			"Host: www.techcrunch.com\r\n" +
72			"User-Agent: Fake\r\n" +
73			"Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8\r\n" +
74			"Accept-Charset: ISO-8859-1,utf-8;q=0.7,*;q=0.7\r\n" +
75			"Accept-Encoding: gzip,deflate\r\n" +
76			"Accept-Language: en-us,en;q=0.5\r\n" +
77			"Keep-Alive: 300\r\n" +
78			"Proxy-Connection: keep-alive\r\n\r\n",
79	},
80	// HTTP/1.1 => chunked coding; body; empty trailer
81	1: {
82		Req: Request{
83			Method: "GET",
84			URL: &url.URL{
85				Scheme: "http",
86				Host:   "www.google.com",
87				Path:   "/search",
88			},
89			ProtoMajor:       1,
90			ProtoMinor:       1,
91			Header:           Header{},
92			TransferEncoding: []string{"chunked"},
93		},
94
95		Body: []byte("abcdef"),
96
97		WantWrite: "GET /search HTTP/1.1\r\n" +
98			"Host: www.google.com\r\n" +
99			"User-Agent: Go-http-client/1.1\r\n" +
100			"Transfer-Encoding: chunked\r\n\r\n" +
101			chunk("abcdef") + chunk(""),
102
103		WantProxy: "GET http://www.google.com/search HTTP/1.1\r\n" +
104			"Host: www.google.com\r\n" +
105			"User-Agent: Go-http-client/1.1\r\n" +
106			"Transfer-Encoding: chunked\r\n\r\n" +
107			chunk("abcdef") + chunk(""),
108	},
109	// HTTP/1.1 POST => chunked coding; body; empty trailer
110	2: {
111		Req: Request{
112			Method: "POST",
113			URL: &url.URL{
114				Scheme: "http",
115				Host:   "www.google.com",
116				Path:   "/search",
117			},
118			ProtoMajor:       1,
119			ProtoMinor:       1,
120			Header:           Header{},
121			Close:            true,
122			TransferEncoding: []string{"chunked"},
123		},
124
125		Body: []byte("abcdef"),
126
127		WantWrite: "POST /search HTTP/1.1\r\n" +
128			"Host: www.google.com\r\n" +
129			"User-Agent: Go-http-client/1.1\r\n" +
130			"Connection: close\r\n" +
131			"Transfer-Encoding: chunked\r\n\r\n" +
132			chunk("abcdef") + chunk(""),
133
134		WantProxy: "POST http://www.google.com/search HTTP/1.1\r\n" +
135			"Host: www.google.com\r\n" +
136			"User-Agent: Go-http-client/1.1\r\n" +
137			"Connection: close\r\n" +
138			"Transfer-Encoding: chunked\r\n\r\n" +
139			chunk("abcdef") + chunk(""),
140	},
141
142	// HTTP/1.1 POST with Content-Length, no chunking
143	3: {
144		Req: Request{
145			Method: "POST",
146			URL: &url.URL{
147				Scheme: "http",
148				Host:   "www.google.com",
149				Path:   "/search",
150			},
151			ProtoMajor:    1,
152			ProtoMinor:    1,
153			Header:        Header{},
154			Close:         true,
155			ContentLength: 6,
156		},
157
158		Body: []byte("abcdef"),
159
160		WantWrite: "POST /search HTTP/1.1\r\n" +
161			"Host: www.google.com\r\n" +
162			"User-Agent: Go-http-client/1.1\r\n" +
163			"Connection: close\r\n" +
164			"Content-Length: 6\r\n" +
165			"\r\n" +
166			"abcdef",
167
168		WantProxy: "POST http://www.google.com/search HTTP/1.1\r\n" +
169			"Host: www.google.com\r\n" +
170			"User-Agent: Go-http-client/1.1\r\n" +
171			"Connection: close\r\n" +
172			"Content-Length: 6\r\n" +
173			"\r\n" +
174			"abcdef",
175	},
176
177	// HTTP/1.1 POST with Content-Length in headers
178	4: {
179		Req: Request{
180			Method: "POST",
181			URL:    mustParseURL("http://example.com/"),
182			Host:   "example.com",
183			Header: Header{
184				"Content-Length": []string{"10"}, // ignored
185			},
186			ContentLength: 6,
187		},
188
189		Body: []byte("abcdef"),
190
191		WantWrite: "POST / HTTP/1.1\r\n" +
192			"Host: example.com\r\n" +
193			"User-Agent: Go-http-client/1.1\r\n" +
194			"Content-Length: 6\r\n" +
195			"\r\n" +
196			"abcdef",
197
198		WantProxy: "POST http://example.com/ HTTP/1.1\r\n" +
199			"Host: example.com\r\n" +
200			"User-Agent: Go-http-client/1.1\r\n" +
201			"Content-Length: 6\r\n" +
202			"\r\n" +
203			"abcdef",
204	},
205
206	// default to HTTP/1.1
207	5: {
208		Req: Request{
209			Method: "GET",
210			URL:    mustParseURL("/search"),
211			Host:   "www.google.com",
212		},
213
214		WantWrite: "GET /search HTTP/1.1\r\n" +
215			"Host: www.google.com\r\n" +
216			"User-Agent: Go-http-client/1.1\r\n" +
217			"\r\n",
218	},
219
220	// Request with a 0 ContentLength and a 0 byte body.
221	6: {
222		Req: Request{
223			Method:        "POST",
224			URL:           mustParseURL("/"),
225			Host:          "example.com",
226			ProtoMajor:    1,
227			ProtoMinor:    1,
228			ContentLength: 0, // as if unset by user
229		},
230
231		Body: func() io.ReadCloser { return ioutil.NopCloser(io.LimitReader(strings.NewReader("xx"), 0)) },
232
233		WantWrite: "POST / HTTP/1.1\r\n" +
234			"Host: example.com\r\n" +
235			"User-Agent: Go-http-client/1.1\r\n" +
236			"Transfer-Encoding: chunked\r\n" +
237			"\r\n0\r\n\r\n",
238
239		WantProxy: "POST / HTTP/1.1\r\n" +
240			"Host: example.com\r\n" +
241			"User-Agent: Go-http-client/1.1\r\n" +
242			"Transfer-Encoding: chunked\r\n" +
243			"\r\n0\r\n\r\n",
244	},
245
246	// Request with a 0 ContentLength and a nil body.
247	7: {
248		Req: Request{
249			Method:        "POST",
250			URL:           mustParseURL("/"),
251			Host:          "example.com",
252			ProtoMajor:    1,
253			ProtoMinor:    1,
254			ContentLength: 0, // as if unset by user
255		},
256
257		Body: func() io.ReadCloser { return nil },
258
259		WantWrite: "POST / HTTP/1.1\r\n" +
260			"Host: example.com\r\n" +
261			"User-Agent: Go-http-client/1.1\r\n" +
262			"Content-Length: 0\r\n" +
263			"\r\n",
264
265		WantProxy: "POST / HTTP/1.1\r\n" +
266			"Host: example.com\r\n" +
267			"User-Agent: Go-http-client/1.1\r\n" +
268			"Content-Length: 0\r\n" +
269			"\r\n",
270	},
271
272	// Request with a 0 ContentLength and a 1 byte body.
273	8: {
274		Req: Request{
275			Method:        "POST",
276			URL:           mustParseURL("/"),
277			Host:          "example.com",
278			ProtoMajor:    1,
279			ProtoMinor:    1,
280			ContentLength: 0, // as if unset by user
281		},
282
283		Body: func() io.ReadCloser { return ioutil.NopCloser(io.LimitReader(strings.NewReader("xx"), 1)) },
284
285		WantWrite: "POST / HTTP/1.1\r\n" +
286			"Host: example.com\r\n" +
287			"User-Agent: Go-http-client/1.1\r\n" +
288			"Transfer-Encoding: chunked\r\n\r\n" +
289			chunk("x") + chunk(""),
290
291		WantProxy: "POST / HTTP/1.1\r\n" +
292			"Host: example.com\r\n" +
293			"User-Agent: Go-http-client/1.1\r\n" +
294			"Transfer-Encoding: chunked\r\n\r\n" +
295			chunk("x") + chunk(""),
296	},
297
298	// Request with a ContentLength of 10 but a 5 byte body.
299	9: {
300		Req: Request{
301			Method:        "POST",
302			URL:           mustParseURL("/"),
303			Host:          "example.com",
304			ProtoMajor:    1,
305			ProtoMinor:    1,
306			ContentLength: 10, // but we're going to send only 5 bytes
307		},
308		Body:      []byte("12345"),
309		WantError: errors.New("http: ContentLength=10 with Body length 5"),
310	},
311
312	// Request with a ContentLength of 4 but an 8 byte body.
313	10: {
314		Req: Request{
315			Method:        "POST",
316			URL:           mustParseURL("/"),
317			Host:          "example.com",
318			ProtoMajor:    1,
319			ProtoMinor:    1,
320			ContentLength: 4, // but we're going to try to send 8 bytes
321		},
322		Body:      []byte("12345678"),
323		WantError: errors.New("http: ContentLength=4 with Body length 8"),
324	},
325
326	// Request with a 5 ContentLength and nil body.
327	11: {
328		Req: Request{
329			Method:        "POST",
330			URL:           mustParseURL("/"),
331			Host:          "example.com",
332			ProtoMajor:    1,
333			ProtoMinor:    1,
334			ContentLength: 5, // but we'll omit the body
335		},
336		WantError: errors.New("http: Request.ContentLength=5 with nil Body"),
337	},
338
339	// Request with a 0 ContentLength and a body with 1 byte content and an error.
340	12: {
341		Req: Request{
342			Method:        "POST",
343			URL:           mustParseURL("/"),
344			Host:          "example.com",
345			ProtoMajor:    1,
346			ProtoMinor:    1,
347			ContentLength: 0, // as if unset by user
348		},
349
350		Body: func() io.ReadCloser {
351			err := errors.New("Custom reader error")
352			errReader := &errorReader{err}
353			return ioutil.NopCloser(io.MultiReader(strings.NewReader("x"), errReader))
354		},
355
356		WantError: errors.New("Custom reader error"),
357	},
358
359	// Request with a 0 ContentLength and a body without content and an error.
360	13: {
361		Req: Request{
362			Method:        "POST",
363			URL:           mustParseURL("/"),
364			Host:          "example.com",
365			ProtoMajor:    1,
366			ProtoMinor:    1,
367			ContentLength: 0, // as if unset by user
368		},
369
370		Body: func() io.ReadCloser {
371			err := errors.New("Custom reader error")
372			errReader := &errorReader{err}
373			return ioutil.NopCloser(errReader)
374		},
375
376		WantError: errors.New("Custom reader error"),
377	},
378
379	// Verify that DumpRequest preserves the HTTP version number, doesn't add a Host,
380	// and doesn't add a User-Agent.
381	14: {
382		Req: Request{
383			Method:     "GET",
384			URL:        mustParseURL("/foo"),
385			ProtoMajor: 1,
386			ProtoMinor: 0,
387			Header: Header{
388				"X-Foo": []string{"X-Bar"},
389			},
390		},
391
392		WantWrite: "GET /foo HTTP/1.1\r\n" +
393			"Host: \r\n" +
394			"User-Agent: Go-http-client/1.1\r\n" +
395			"X-Foo: X-Bar\r\n\r\n",
396	},
397
398	// If no Request.Host and no Request.URL.Host, we send
399	// an empty Host header, and don't use
400	// Request.Header["Host"]. This is just testing that
401	// we don't change Go 1.0 behavior.
402	15: {
403		Req: Request{
404			Method: "GET",
405			Host:   "",
406			URL: &url.URL{
407				Scheme: "http",
408				Host:   "",
409				Path:   "/search",
410			},
411			ProtoMajor: 1,
412			ProtoMinor: 1,
413			Header: Header{
414				"Host": []string{"bad.example.com"},
415			},
416		},
417
418		WantWrite: "GET /search HTTP/1.1\r\n" +
419			"Host: \r\n" +
420			"User-Agent: Go-http-client/1.1\r\n\r\n",
421	},
422
423	// Opaque test #1 from golang.org/issue/4860
424	16: {
425		Req: Request{
426			Method: "GET",
427			URL: &url.URL{
428				Scheme: "http",
429				Host:   "www.google.com",
430				Opaque: "/%2F/%2F/",
431			},
432			ProtoMajor: 1,
433			ProtoMinor: 1,
434			Header:     Header{},
435		},
436
437		WantWrite: "GET /%2F/%2F/ HTTP/1.1\r\n" +
438			"Host: www.google.com\r\n" +
439			"User-Agent: Go-http-client/1.1\r\n\r\n",
440	},
441
442	// Opaque test #2 from golang.org/issue/4860
443	17: {
444		Req: Request{
445			Method: "GET",
446			URL: &url.URL{
447				Scheme: "http",
448				Host:   "x.google.com",
449				Opaque: "//y.google.com/%2F/%2F/",
450			},
451			ProtoMajor: 1,
452			ProtoMinor: 1,
453			Header:     Header{},
454		},
455
456		WantWrite: "GET http://y.google.com/%2F/%2F/ HTTP/1.1\r\n" +
457			"Host: x.google.com\r\n" +
458			"User-Agent: Go-http-client/1.1\r\n\r\n",
459	},
460
461	// Testing custom case in header keys. Issue 5022.
462	18: {
463		Req: Request{
464			Method: "GET",
465			URL: &url.URL{
466				Scheme: "http",
467				Host:   "www.google.com",
468				Path:   "/",
469			},
470			Proto:      "HTTP/1.1",
471			ProtoMajor: 1,
472			ProtoMinor: 1,
473			Header: Header{
474				"ALL-CAPS": {"x"},
475			},
476		},
477
478		WantWrite: "GET / HTTP/1.1\r\n" +
479			"Host: www.google.com\r\n" +
480			"User-Agent: Go-http-client/1.1\r\n" +
481			"ALL-CAPS: x\r\n" +
482			"\r\n",
483	},
484
485	// Request with host header field; IPv6 address with zone identifier
486	19: {
487		Req: Request{
488			Method: "GET",
489			URL: &url.URL{
490				Host: "[fe80::1%en0]",
491			},
492		},
493
494		WantWrite: "GET / HTTP/1.1\r\n" +
495			"Host: [fe80::1]\r\n" +
496			"User-Agent: Go-http-client/1.1\r\n" +
497			"\r\n",
498	},
499
500	// Request with optional host header field; IPv6 address with zone identifier
501	20: {
502		Req: Request{
503			Method: "GET",
504			URL: &url.URL{
505				Host: "www.example.com",
506			},
507			Host: "[fe80::1%en0]:8080",
508		},
509
510		WantWrite: "GET / HTTP/1.1\r\n" +
511			"Host: [fe80::1]:8080\r\n" +
512			"User-Agent: Go-http-client/1.1\r\n" +
513			"\r\n",
514	},
515}
516
517func TestRequestWrite(t *testing.T) {
518	for i := range reqWriteTests {
519		tt := &reqWriteTests[i]
520
521		setBody := func() {
522			if tt.Body == nil {
523				return
524			}
525			switch b := tt.Body.(type) {
526			case []byte:
527				tt.Req.Body = ioutil.NopCloser(bytes.NewReader(b))
528			case func() io.ReadCloser:
529				tt.Req.Body = b()
530			}
531		}
532		setBody()
533		if tt.Req.Header == nil {
534			tt.Req.Header = make(Header)
535		}
536
537		var braw bytes.Buffer
538		err := tt.Req.Write(&braw)
539		if g, e := fmt.Sprintf("%v", err), fmt.Sprintf("%v", tt.WantError); g != e {
540			t.Errorf("writing #%d, err = %q, want %q", i, g, e)
541			continue
542		}
543		if err != nil {
544			continue
545		}
546
547		if tt.WantWrite != "" {
548			sraw := braw.String()
549			if sraw != tt.WantWrite {
550				t.Errorf("Test %d, expecting:\n%s\nGot:\n%s\n", i, tt.WantWrite, sraw)
551				continue
552			}
553		}
554
555		if tt.WantProxy != "" {
556			setBody()
557			var praw bytes.Buffer
558			err = tt.Req.WriteProxy(&praw)
559			if err != nil {
560				t.Errorf("WriteProxy #%d: %s", i, err)
561				continue
562			}
563			sraw := praw.String()
564			if sraw != tt.WantProxy {
565				t.Errorf("Test Proxy %d, expecting:\n%s\nGot:\n%s\n", i, tt.WantProxy, sraw)
566				continue
567			}
568		}
569	}
570}
571
572func TestRequestWriteTransport(t *testing.T) {
573	t.Parallel()
574
575	matchSubstr := func(substr string) func(string) error {
576		return func(written string) error {
577			if !strings.Contains(written, substr) {
578				return fmt.Errorf("expected substring %q in request: %s", substr, written)
579			}
580			return nil
581		}
582	}
583
584	noContentLengthOrTransferEncoding := func(req string) error {
585		if strings.Contains(req, "Content-Length: ") {
586			return fmt.Errorf("unexpected Content-Length in request: %s", req)
587		}
588		if strings.Contains(req, "Transfer-Encoding: ") {
589			return fmt.Errorf("unexpected Transfer-Encoding in request: %s", req)
590		}
591		return nil
592	}
593
594	all := func(checks ...func(string) error) func(string) error {
595		return func(req string) error {
596			for _, c := range checks {
597				if err := c(req); err != nil {
598					return err
599				}
600			}
601			return nil
602		}
603	}
604
605	type testCase struct {
606		method string
607		clen   int64 // ContentLength
608		body   io.ReadCloser
609		want   func(string) error
610
611		// optional:
612		init         func(*testCase)
613		afterReqRead func()
614	}
615
616	tests := []testCase{
617		{
618			method: "GET",
619			want:   noContentLengthOrTransferEncoding,
620		},
621		{
622			method: "GET",
623			body:   ioutil.NopCloser(strings.NewReader("")),
624			want:   noContentLengthOrTransferEncoding,
625		},
626		{
627			method: "GET",
628			clen:   -1,
629			body:   ioutil.NopCloser(strings.NewReader("")),
630			want:   noContentLengthOrTransferEncoding,
631		},
632		// A GET with a body, with explicit content length:
633		{
634			method: "GET",
635			clen:   7,
636			body:   ioutil.NopCloser(strings.NewReader("foobody")),
637			want: all(matchSubstr("Content-Length: 7"),
638				matchSubstr("foobody")),
639		},
640		// A GET with a body, sniffing the leading "f" from "foobody".
641		{
642			method: "GET",
643			clen:   -1,
644			body:   ioutil.NopCloser(strings.NewReader("foobody")),
645			want: all(matchSubstr("Transfer-Encoding: chunked"),
646				matchSubstr("\r\n1\r\nf\r\n"),
647				matchSubstr("oobody")),
648		},
649		// But a POST request is expected to have a body, so
650		// no sniffing happens:
651		{
652			method: "POST",
653			clen:   -1,
654			body:   ioutil.NopCloser(strings.NewReader("foobody")),
655			want: all(matchSubstr("Transfer-Encoding: chunked"),
656				matchSubstr("foobody")),
657		},
658		{
659			method: "POST",
660			clen:   -1,
661			body:   ioutil.NopCloser(strings.NewReader("")),
662			want:   all(matchSubstr("Transfer-Encoding: chunked")),
663		},
664		// Verify that a blocking Request.Body doesn't block forever.
665		{
666			method: "GET",
667			clen:   -1,
668			init: func(tt *testCase) {
669				pr, pw := io.Pipe()
670				tt.afterReqRead = func() {
671					pw.Close()
672				}
673				tt.body = ioutil.NopCloser(pr)
674			},
675			want: matchSubstr("Transfer-Encoding: chunked"),
676		},
677	}
678
679	for i, tt := range tests {
680		if tt.init != nil {
681			tt.init(&tt)
682		}
683		req := &Request{
684			Method: tt.method,
685			URL: &url.URL{
686				Scheme: "http",
687				Host:   "example.com",
688			},
689			Header:        make(Header),
690			ContentLength: tt.clen,
691			Body:          tt.body,
692		}
693		got, err := dumpRequestOut(req, tt.afterReqRead)
694		if err != nil {
695			t.Errorf("test[%d]: %v", i, err)
696			continue
697		}
698		if err := tt.want(string(got)); err != nil {
699			t.Errorf("test[%d]: %v", i, err)
700		}
701	}
702}
703
704type closeChecker struct {
705	io.Reader
706	closed bool
707}
708
709func (rc *closeChecker) Close() error {
710	rc.closed = true
711	return nil
712}
713
714// TestRequestWriteClosesBody tests that Request.Write closes its request.Body.
715// It also indirectly tests NewRequest and that it doesn't wrap an existing Closer
716// inside a NopCloser, and that it serializes it correctly.
717func TestRequestWriteClosesBody(t *testing.T) {
718	rc := &closeChecker{Reader: strings.NewReader("my body")}
719	req, err := NewRequest("POST", "http://foo.com/", rc)
720	if err != nil {
721		t.Fatal(err)
722	}
723	buf := new(bytes.Buffer)
724	if err := req.Write(buf); err != nil {
725		t.Error(err)
726	}
727	if !rc.closed {
728		t.Error("body not closed after write")
729	}
730	expected := "POST / HTTP/1.1\r\n" +
731		"Host: foo.com\r\n" +
732		"User-Agent: Go-http-client/1.1\r\n" +
733		"Transfer-Encoding: chunked\r\n\r\n" +
734		chunk("my body") +
735		chunk("")
736	if buf.String() != expected {
737		t.Errorf("write:\n got: %s\nwant: %s", buf.String(), expected)
738	}
739}
740
741func chunk(s string) string {
742	return fmt.Sprintf("%x\r\n%s\r\n", len(s), s)
743}
744
745func mustParseURL(s string) *url.URL {
746	u, err := url.Parse(s)
747	if err != nil {
748		panic(fmt.Sprintf("Error parsing URL %q: %v", s, err))
749	}
750	return u
751}
752
753type writerFunc func([]byte) (int, error)
754
755func (f writerFunc) Write(p []byte) (int, error) { return f(p) }
756
757// TestRequestWriteError tests the Write err != nil checks in (*Request).write.
758func TestRequestWriteError(t *testing.T) {
759	failAfter, writeCount := 0, 0
760	errFail := errors.New("fake write failure")
761
762	// w is the buffered io.Writer to write the request to. It
763	// fails exactly once on its Nth Write call, as controlled by
764	// failAfter. It also tracks the number of calls in
765	// writeCount.
766	w := struct {
767		io.ByteWriter // to avoid being wrapped by a bufio.Writer
768		io.Writer
769	}{
770		nil,
771		writerFunc(func(p []byte) (n int, err error) {
772			writeCount++
773			if failAfter == 0 {
774				err = errFail
775			}
776			failAfter--
777			return len(p), err
778		}),
779	}
780
781	req, _ := NewRequest("GET", "http://example.com/", nil)
782	const writeCalls = 4 // number of Write calls in current implementation
783	sawGood := false
784	for n := 0; n <= writeCalls+2; n++ {
785		failAfter = n
786		writeCount = 0
787		err := req.Write(w)
788		var wantErr error
789		if n < writeCalls {
790			wantErr = errFail
791		}
792		if err != wantErr {
793			t.Errorf("for fail-after %d Writes, err = %v; want %v", n, err, wantErr)
794			continue
795		}
796		if err == nil {
797			sawGood = true
798			if writeCount != writeCalls {
799				t.Fatalf("writeCalls constant is outdated in test")
800			}
801		}
802		if writeCount > writeCalls || writeCount > n+1 {
803			t.Errorf("for fail-after %d, saw unexpectedly high (%d) write calls", n, writeCount)
804		}
805	}
806	if !sawGood {
807		t.Fatalf("writeCalls constant is outdated in test")
808	}
809}
810
811// dumpRequestOut is a modified copy of net/http/httputil.DumpRequestOut.
812// Unlike the original, this version doesn't mutate the req.Body and
813// try to restore it. It always dumps the whole body.
814// And it doesn't support https.
815func dumpRequestOut(req *Request, onReadHeaders func()) ([]byte, error) {
816
817	// Use the actual Transport code to record what we would send
818	// on the wire, but not using TCP.  Use a Transport with a
819	// custom dialer that returns a fake net.Conn that waits
820	// for the full input (and recording it), and then responds
821	// with a dummy response.
822	var buf bytes.Buffer // records the output
823	pr, pw := io.Pipe()
824	defer pr.Close()
825	defer pw.Close()
826	dr := &delegateReader{c: make(chan io.Reader)}
827
828	t := &Transport{
829		Dial: func(net, addr string) (net.Conn, error) {
830			return &dumpConn{io.MultiWriter(&buf, pw), dr}, nil
831		},
832	}
833	defer t.CloseIdleConnections()
834
835	// Wait for the request before replying with a dummy response:
836	go func() {
837		req, err := ReadRequest(bufio.NewReader(pr))
838		if err == nil {
839			if onReadHeaders != nil {
840				onReadHeaders()
841			}
842			// Ensure all the body is read; otherwise
843			// we'll get a partial dump.
844			io.Copy(ioutil.Discard, req.Body)
845			req.Body.Close()
846		}
847		dr.c <- strings.NewReader("HTTP/1.1 204 No Content\r\nConnection: close\r\n\r\n")
848	}()
849
850	_, err := t.RoundTrip(req)
851	if err != nil {
852		return nil, err
853	}
854	return buf.Bytes(), nil
855}
856
857// delegateReader is a reader that delegates to another reader,
858// once it arrives on a channel.
859type delegateReader struct {
860	c chan io.Reader
861	r io.Reader // nil until received from c
862}
863
864func (r *delegateReader) Read(p []byte) (int, error) {
865	if r.r == nil {
866		r.r = <-r.c
867	}
868	return r.r.Read(p)
869}
870
871// dumpConn is a net.Conn that writes to Writer and reads from Reader.
872type dumpConn struct {
873	io.Writer
874	io.Reader
875}
876
877func (c *dumpConn) Close() error                       { return nil }
878func (c *dumpConn) LocalAddr() net.Addr                { return nil }
879func (c *dumpConn) RemoteAddr() net.Addr               { return nil }
880func (c *dumpConn) SetDeadline(t time.Time) error      { return nil }
881func (c *dumpConn) SetReadDeadline(t time.Time) error  { return nil }
882func (c *dumpConn) SetWriteDeadline(t time.Time) error { return nil }
883