Commit 091361f569dd86e8550c04afb193bfb516a21a74

Philip Kelley 2012-11-06T08:52:03

Basic authentication for http and winhttp

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
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
diff --git a/include/git2/remote.h b/include/git2/remote.h
index 1827e12..33b7dfd 100644
--- a/include/git2/remote.h
+++ b/include/git2/remote.h
@@ -287,6 +287,19 @@ GIT_EXTERN(int) git_remote_add(git_remote **out, git_repository *repo, const cha
 GIT_EXTERN(void) git_remote_check_cert(git_remote *remote, int check);
 
 /**
+ * Set a credentials acquisition callback for this remote. If the remote is
+ * not available for anonymous access, then you must set this callback in order
+ * to provide credentials to the transport at the time of authentication
+ * failure so that retry can be performed.
+ *
+ * @param remote the remote to configure
+ * @param The credentials acquisition callback to use (defaults to NULL)
+ */
+GIT_EXTERN(void) git_remote_set_cred_acquire_cb(
+	git_remote *remote,
+	git_cred_acquire_cb cred_acquire_cb);
+
+/**
  * Sets a custom transport for the remote. The caller can use this function
  * to bypass the automatic discovery of a transport by URL scheme (i.e.
  * http://, https://, git://) and supply their own transport to be used
@@ -297,7 +310,9 @@ GIT_EXTERN(void) git_remote_check_cert(git_remote *remote, int check);
  * @param remote the remote to configure
  * @param transport the transport object for the remote to use
  */
-GIT_EXTERN(int) git_remote_set_transport(git_remote *remote, git_transport *transport);
+GIT_EXTERN(int) git_remote_set_transport(
+	git_remote *remote,
+	git_transport *transport);
 
 /**
  * Argument to the completion callback which tells it which operation
diff --git a/include/git2/transport.h b/include/git2/transport.h
index fd0d56f..b2bdaae 100644
--- a/include/git2/transport.h
+++ b/include/git2/transport.h
@@ -20,6 +20,54 @@
 GIT_BEGIN_DECL
 
 /*
+ *** Begin interface for credentials acquisition ***
+ */
+
+typedef enum {
+	/* git_cred_userpass_plaintext */
+	GIT_CREDTYPE_USERPASS_PLAINTEXT = 1,
+} git_credtype_t;
+
+/* The base structure for all credential types */
+typedef struct git_cred {
+	git_credtype_t credtype;
+	void (*free)(
+		struct git_cred *cred);
+} git_cred;
+
+/* A plaintext username and password */
+typedef struct git_cred_userpass_plaintext {
+	git_cred parent;
+	char *username;
+	char *password;
+} git_cred_userpass_plaintext;
+
+/**
+ * Creates a new plain-text username and password credential object.
+ *
+ * @param cred The newly created credential object.
+ * @param username The username of the credential.
+ * @param password The password of the credential.
+ */
+GIT_EXTERN(int) git_cred_userpass_plaintext_new(
+	git_cred **cred,
+	const char *username,
+	const char *password);
+
+/**
+ * Signature of a function which acquires a credential object.
+ *
+ * @param cred The newly created credential object.
+ * @param url The resource for which we are demanding a credential.
+ * @param allowed_types A bitmask stating which cred types are OK to return.
+ */
+typedef int (*git_cred_acquire_cb)(
+	git_cred **cred,
+	const char *url,
+	int allowed_types);
+
+/*
+ *** End interface for credentials acquisition ***
  *** Begin base transport interface ***
  */
 
@@ -43,6 +91,7 @@ typedef struct git_transport {
 	 * direction. */
 	int (*connect)(struct git_transport *transport,
 		const char *url,
+		git_cred_acquire_cb cred_acquire_cb,
 		int direction,
 		int flags);
 
diff --git a/src/remote.c b/src/remote.c
index a873a27..98660fe 100644
--- a/src/remote.c
+++ b/src/remote.c
@@ -492,7 +492,7 @@ int git_remote_connect(git_remote *remote, int direction)
 	if (!remote->check_cert)
 		flags |= GIT_TRANSPORTFLAGS_NO_CHECK_CERT;
 
-	if (t->connect(t, url, direction, flags) < 0)
+	if (t->connect(t, url, remote->cred_acquire_cb, direction, flags) < 0)
 		goto on_error;
 
 	remote->transport = t;
@@ -809,6 +809,15 @@ void git_remote_set_callbacks(git_remote *remote, git_remote_callbacks *callback
 			remote->callbacks.data);
 }
 
+void git_remote_set_cred_acquire_cb(
+	git_remote *remote,
+	git_cred_acquire_cb cred_acquire_cb)
+{
+	assert(remote);
+
+	remote->cred_acquire_cb = cred_acquire_cb;
+}
+
 int git_remote_set_transport(git_remote *remote, git_transport *transport)
 {
 	assert(remote && transport);
diff --git a/src/remote.h b/src/remote.h
index b0df2d6..6a90bfc 100644
--- a/src/remote.h
+++ b/src/remote.h
@@ -22,6 +22,7 @@ struct git_remote {
 	git_vector refs;
 	struct git_refspec fetch;
 	struct git_refspec push;
+	git_cred_acquire_cb cred_acquire_cb;
 	git_transport *transport;
 	git_repository *repo;
 	git_remote_callbacks callbacks;
diff --git a/src/transports/cred.c b/src/transports/cred.c
new file mode 100644
index 0000000..5529537
--- /dev/null
+++ b/src/transports/cred.c
@@ -0,0 +1,57 @@
+/*
+ * Copyright (C) 2009-2012 the libgit2 contributors
+ *
+ * This file is part of libgit2, distributed under the GNU GPL v2 with
+ * a Linking Exception. For full terms see the included COPYING file.
+ */
+
+#include "git2.h"
+#include "smart.h"
+
+static void plaintext_free(struct git_cred *cred)
+{
+	git_cred_userpass_plaintext *c = (git_cred_userpass_plaintext *)cred;
+	int pass_len = strlen(c->password);
+
+	git__free(c->username);
+
+	/* Zero the memory which previously held the password */
+	memset(c->password, 0x0, pass_len);
+	git__free(c->password);
+
+	git__free(c);
+}
+
+int git_cred_userpass_plaintext_new(
+	git_cred **cred,
+	const char *username,
+	const char *password)
+{
+	git_cred_userpass_plaintext *c;
+
+	if (!cred)
+		return -1;
+
+	c = (git_cred_userpass_plaintext *)git__malloc(sizeof(git_cred_userpass_plaintext));
+	GITERR_CHECK_ALLOC(c);
+
+	c->parent.credtype = GIT_CREDTYPE_USERPASS_PLAINTEXT;
+	c->parent.free = plaintext_free;
+	c->username = git__strdup(username);
+
+	if (!c->username) {
+		git__free(c);
+		return -1;
+	}
+
+	c->password = git__strdup(password);
+
+	if (!c->password) {
+		git__free(c->username);
+		git__free(c);
+		return -1;
+	}
+
+	*cred = &c->parent;
+	return 0;
+}
\ No newline at end of file
diff --git a/src/transports/http.c b/src/transports/http.c
index f33cad7..4b48779 100644
--- a/src/transports/http.c
+++ b/src/transports/http.c
@@ -10,6 +10,7 @@
 #include "http_parser.h"
 #include "buffer.h"
 #include "netops.h"
+#include "smart.h"
 
 static const char *prefix_http = "http://";
 static const char *prefix_https = "https://";
@@ -18,15 +19,23 @@ static const char *upload_pack_ls_service_url = "/info/refs?service=git-upload-p
 static const char *upload_pack_service_url = "/git-upload-pack";
 static const char *get_verb = "GET";
 static const char *post_verb = "POST";
+static const char *basic_authtype = "Basic";
 
 #define OWNING_SUBTRANSPORT(s) ((http_subtransport *)(s)->parent.subtransport)
 
+#define PARSE_ERROR_GENERIC	-1
+#define PARSE_ERROR_REPLAY	-2
+
 enum last_cb {
 	NONE,
 	FIELD,
 	VALUE
 };
 
+typedef enum {
+	GIT_HTTP_AUTH_BASIC = 1,
+} http_authmechanism_t;
+
 typedef struct {
 	git_smart_subtransport_stream parent;
 	const char *service;
@@ -37,11 +46,13 @@ typedef struct {
 
 typedef struct {
 	git_smart_subtransport parent;
-	git_transport *owner;
+	transport_smart *owner;
 	gitno_socket socket;
 	const char *path;
 	char *host;
-	char *port;	
+	char *port;
+	git_cred *cred;
+	http_authmechanism_t auth_mechanism;
 	unsigned connected : 1,
 		use_ssl : 1,
 		no_check_cert : 1;
@@ -50,14 +61,14 @@ typedef struct {
 	http_parser parser;
 	http_parser_settings settings;
 	gitno_buffer parse_buffer;
-	git_buf parse_temp;
+	git_buf parse_header_name;
+	git_buf parse_header_value;
 	char parse_buffer_data[2048];
 	char *content_type;
+	git_vector www_authenticate;
 	enum last_cb last_cb;
-	int parse_error;	
-	unsigned parse_finished : 1,
-		ct_found : 1,
-		ct_finished : 1;
+	int parse_error;
+	unsigned parse_finished : 1;
 } http_subtransport;
 
 typedef struct {
@@ -70,10 +81,42 @@ typedef struct {
 	size_t *bytes_read;
 } parser_context;
 
-static int gen_request(git_buf *buf, const char *path, const char *host, const char *op,
-                       const char *service, const char *service_url, ssize_t content_length)
+static int apply_basic_credential(git_buf *buf, git_cred *cred)
+{
+	git_cred_userpass_plaintext *c = (git_cred_userpass_plaintext *)cred;
+	git_buf raw = GIT_BUF_INIT;
+	int error = -1;
+
+	git_buf_printf(&raw, "%s:%s", c->username, c->password);
+
+	if (git_buf_oom(&raw) ||
+		git_buf_puts(buf, "Authorization: Basic ") < 0 ||
+		git_buf_put_base64(buf, git_buf_cstr(&raw), raw.size) < 0 ||
+		git_buf_puts(buf, "\r\n") < 0)
+		goto on_error;
+
+	error = 0;
+
+on_error:
+	if (raw.size)
+		memset(raw.ptr, 0x0, raw.size);
+
+	git_buf_free(&raw);
+	return error;
+}
+
+static int gen_request(
+	git_buf *buf,
+	const char *path,
+	const char *host,
+	git_cred *cred,
+	http_authmechanism_t auth_mechanism,
+	const char *op,
+	const char *service,
+	const char *service_url,
+	ssize_t content_length)
 {
-	if (path == NULL) /* Is 'git fetch http://host.com/' valid? */
+	if (!path)
 		path = "/";
 
 	git_buf_printf(buf, "%s %s%s HTTP/1.1\r\n", op, path, service_url);
@@ -86,6 +129,13 @@ static int gen_request(git_buf *buf, const char *path, const char *host, const c
 	} else {
 		git_buf_puts(buf, "Accept: */*\r\n");
 	}
+
+	/* Apply credentials to the request */
+	if (cred && cred->credtype == GIT_CREDTYPE_USERPASS_PLAINTEXT &&
+		auth_mechanism == GIT_HTTP_AUTH_BASIC &&
+		apply_basic_credential(buf, cred) < 0)
+		return -1;
+
 	git_buf_puts(buf, "\r\n");
 
 	if (git_buf_oom(buf))
@@ -94,88 +144,157 @@ static int gen_request(git_buf *buf, const char *path, const char *host, const c
 	return 0;
 }
 
+static int parse_unauthorized_response(
+	git_vector *www_authenticate,
+	int *allowed_types,
+	http_authmechanism_t *auth_mechanism)
+{
+	unsigned i;
+	char *entry;
+
+	git_vector_foreach(www_authenticate, i, entry) {
+		if (!strncmp(entry, basic_authtype, 5) &&
+			(entry[5] == '\0' || entry[5] == ' ')) {
+			*allowed_types |= GIT_CREDTYPE_USERPASS_PLAINTEXT;
+			*auth_mechanism = GIT_HTTP_AUTH_BASIC;
+		}
+	}
+
+	return 0;
+}
+
+static int on_header_ready(http_subtransport *t)
+{
+	git_buf *name = &t->parse_header_name;
+	git_buf *value = &t->parse_header_value;
+	char *dup;
+
+	if (!t->content_type && !strcmp("Content-Type", git_buf_cstr(name))) {
+		t->content_type = git__strdup(git_buf_cstr(value));
+		GITERR_CHECK_ALLOC(t->content_type);
+	}
+	else if (!strcmp("WWW-Authenticate", git_buf_cstr(name))) {
+		dup = git__strdup(git_buf_cstr(value));
+		GITERR_CHECK_ALLOC(dup);
+		git_vector_insert(&t->www_authenticate, dup);
+	}
+
+	return 0;
+}
+
 static int on_header_field(http_parser *parser, const char *str, size_t len)
 {
 	parser_context *ctx = (parser_context *) parser->data;
 	http_subtransport *t = ctx->t;
-	git_buf *buf = &t->parse_temp;
 
-	if (t->last_cb == VALUE && t->ct_found) {
-		t->ct_finished = 1;
-		t->ct_found = 0;
-		t->content_type = git__strdup(git_buf_cstr(buf));
-		GITERR_CHECK_ALLOC(t->content_type);
-		git_buf_clear(buf);
-	}
+	/* Both parse_header_name and parse_header_value are populated
+	 * and ready for consumption */
+	if (VALUE == t->last_cb)
+		if (on_header_ready(t) < 0)
+			return t->parse_error = PARSE_ERROR_GENERIC;
 
-	if (t->ct_found) {
-		t->last_cb = FIELD;
-		return 0;
-	}
+	if (NONE == t->last_cb || VALUE == t->last_cb)
+		git_buf_clear(&t->parse_header_name);
 
-	if (t->last_cb != FIELD)
-		git_buf_clear(buf);
+	if (git_buf_put(&t->parse_header_name, str, len) < 0)
+		return t->parse_error = PARSE_ERROR_GENERIC;
 
-	git_buf_put(buf, str, len);
 	t->last_cb = FIELD;
-
-	return git_buf_oom(buf);
+	return 0;
 }
 
 static int on_header_value(http_parser *parser, const char *str, size_t len)
 {
 	parser_context *ctx = (parser_context *) parser->data;
 	http_subtransport *t = ctx->t;
-	git_buf *buf = &t->parse_temp;
 
-	if (t->ct_finished) {
-		t->last_cb = VALUE;
-		return 0;
-	}
+	assert(NONE != t->last_cb);
 
-	if (t->last_cb == VALUE)
-		git_buf_put(buf, str, len);
+	if (FIELD == t->last_cb)
+		git_buf_clear(&t->parse_header_value);
 
-	if (t->last_cb == FIELD && !strcmp(git_buf_cstr(buf), "Content-Type")) {
-		t->ct_found = 1;
-		git_buf_clear(buf);
-		git_buf_put(buf, str, len);
-	}
+	if (git_buf_put(&t->parse_header_value, str, len) < 0)
+		return t->parse_error = PARSE_ERROR_GENERIC;
 
 	t->last_cb = VALUE;
-
-	return git_buf_oom(buf);
+	return 0;
 }
 
 static int on_headers_complete(http_parser *parser)
 {
 	parser_context *ctx = (parser_context *) parser->data;
 	http_subtransport *t = ctx->t;
-	git_buf *buf = &t->parse_temp;
+	http_stream *s = ctx->s;
+	git_buf buf = GIT_BUF_INIT;
 
-	/* The content-type is text/plain for 404, so don't validate */
-	if (parser->status_code == 404) {
-		git_buf_clear(buf);
-		return 0;
+	/* Both parse_header_name and parse_header_value are populated
+	 * and ready for consumption. */
+	if (VALUE == t->last_cb)
+		if (on_header_ready(t) < 0)
+			return t->parse_error = PARSE_ERROR_GENERIC;
+
+	/* Check for an authentication failure. */
+	if (parser->status_code == 401 &&
+		get_verb == s->verb &&
+		t->owner->cred_acquire_cb) {
+		int allowed_types = 0;
+
+		if (parse_unauthorized_response(&t->www_authenticate,
+			&allowed_types, &t->auth_mechanism) < 0)
+			return t->parse_error = PARSE_ERROR_GENERIC;
+
+		if (allowed_types &&
+			(!t->cred || 0 == (t->cred->credtype & allowed_types))) {
+
+			if (t->owner->cred_acquire_cb(&t->cred,
+					t->owner->url,
+					allowed_types) < 0)
+				return PARSE_ERROR_GENERIC;
+
+			assert(t->cred);
+
+			/* Successfully acquired a credential. */
+			return t->parse_error = PARSE_ERROR_REPLAY;
+		}
 	}
 
-	if (t->content_type == NULL) {
-		t->content_type = git__strdup(git_buf_cstr(buf));
-		if (t->content_type == NULL)
-			return t->parse_error = -1;
+	/* Check for a 200 HTTP status code. */
+	if (parser->status_code != 200) {
+		giterr_set(GITERR_NET,
+			"Unexpected HTTP status code: %d",
+			parser->status_code);
+		return t->parse_error = PARSE_ERROR_GENERIC;
 	}
 
-	git_buf_clear(buf);
-	git_buf_printf(buf, "application/x-git-%s-advertisement", ctx->s->service);
-	if (git_buf_oom(buf))
-		return t->parse_error = -1;
+	/* The response must contain a Content-Type header. */
+	if (!t->content_type) {
+		giterr_set(GITERR_NET, "No Content-Type header in response");
+		return t->parse_error = PARSE_ERROR_GENERIC;
+	}
 
-	if (strcmp(t->content_type, git_buf_cstr(buf))) {
-		giterr_set(GITERR_NET, "Invalid content-type: %s", t->content_type);
-		return t->parse_error = -1;
+	/* The Content-Type header must match our expectation. */
+	if (get_verb == s->verb)
+		git_buf_printf(&buf,
+			"application/x-git-%s-advertisement",
+			ctx->s->service);
+	else
+		git_buf_printf(&buf,
+			"application/x-git-%s-result",
+			ctx->s->service);
+
+	if (git_buf_oom(&buf))
+		return t->parse_error = PARSE_ERROR_GENERIC;
+
+	if (strcmp(t->content_type, git_buf_cstr(&buf))) {
+		git_buf_free(&buf);
+		giterr_set(GITERR_NET,
+			"Invalid Content-Type: %s",
+			t->content_type);
+		return t->parse_error = PARSE_ERROR_GENERIC;
 	}
 
-	git_buf_clear(buf);
+	git_buf_free(&buf);
+
 	return 0;
 }
 
@@ -186,11 +305,6 @@ static int on_message_complete(http_parser *parser)
 
 	t->parse_finished = 1;
 
-	if (parser->status_code == 404) {
-		giterr_set(GITERR_NET, "Remote error: %s", git_buf_cstr(&t->parse_temp));
-		t->parse_error = -1;
-	}
-
 	return 0;
 }
 
@@ -201,7 +315,7 @@ static int on_body_fill_buffer(http_parser *parser, const char *str, size_t len)
 
 	if (ctx->buf_size < len) {
 		giterr_set(GITERR_NET, "Can't fit data in the buffer");
-		return t->parse_error = -1;
+		return t->parse_error = PARSE_ERROR_GENERIC;
 	}
 
 	memcpy(ctx->buffer, str, len);
@@ -212,6 +326,36 @@ static int on_body_fill_buffer(http_parser *parser, const char *str, size_t len)
 	return 0;
 }
 
+static void clear_parser_state(http_subtransport *t)
+{
+	unsigned i;
+	char *entry;
+
+	http_parser_init(&t->parser, HTTP_RESPONSE);
+	gitno_buffer_setup(&t->socket,
+		&t->parse_buffer,
+		t->parse_buffer_data,
+		sizeof(t->parse_buffer_data));
+
+	t->last_cb = NONE;
+	t->parse_error = 0;
+	t->parse_finished = 0;
+
+	git_buf_free(&t->parse_header_name);
+	git_buf_init(&t->parse_header_name, 0);
+
+	git_buf_free(&t->parse_header_value);
+	git_buf_init(&t->parse_header_value, 0);
+
+	git__free(t->content_type);
+	t->content_type = NULL;
+
+	git_vector_foreach(&t->www_authenticate, i, entry)
+		git__free(entry);
+
+	git_vector_free(&t->www_authenticate);
+}
+
 static int http_stream_read(
 	git_smart_subtransport_stream *stream,
 	char *buffer,
@@ -219,17 +363,22 @@ static int http_stream_read(
 	size_t *bytes_read)
 {
 	http_stream *s = (http_stream *)stream;
-	http_subtransport *t = OWNING_SUBTRANSPORT(s);	
+	http_subtransport *t = OWNING_SUBTRANSPORT(s);
 	git_buf request = GIT_BUF_INIT;
 	parser_context ctx;
 
+replay:
 	*bytes_read = 0;
 
 	assert(t->connected);
 
 	if (!s->sent_request) {
-		if (gen_request(&request, t->path, t->host, s->verb, s->service, s->service_url, 0) < 0) {
-			giterr_set(GITERR_NET, "Failed to generate request");			
+		clear_parser_state(t);
+
+		if (gen_request(&request, t->path, t->host,
+				t->cred, t->auth_mechanism, s->verb,
+				s->service, s->service_url, 0) < 0) {
+			giterr_set(GITERR_NET, "Failed to generate request");
 			return -1;
 		}
 
@@ -239,7 +388,7 @@ static int http_stream_read(
 		}
 
 		git_buf_free(&request);
-		s->sent_request = 1;		
+		s->sent_request = 1;
 	}
 
 	t->parse_buffer.offset = 0;
@@ -250,10 +399,11 @@ static int http_stream_read(
 	if (gitno_recv(&t->parse_buffer) < 0)
 		return -1;
 
-	/* This call to http_parser_execute will result in invocations of the on_* family of
-		* callbacks. The most interesting of these is on_body_fill_buffer, which is called
-		* when data is ready to be copied into the target buffer. We need to marshal the
-		* buffer, buf_size, and bytes_read parameters to this callback. */
+	/* This call to http_parser_execute will result in invocations of the on_*
+	 * family of callbacks. The most interesting of these is
+	 * on_body_fill_buffer, which is called when data is ready to be copied
+	 * into the target buffer. We need to marshal the buffer, buf_size, and
+	 * bytes_read parameters to this callback. */
 	ctx.t = t;
 	ctx.s = s;
 	ctx.buffer = buffer;
@@ -262,11 +412,23 @@ static int http_stream_read(
 
 	/* Set the context, call the parser, then unset the context. */
 	t->parser.data = &ctx;
-	http_parser_execute(&t->parser, &t->settings, t->parse_buffer.data, t->parse_buffer.offset);
+
+	http_parser_execute(&t->parser,
+		&t->settings,
+		t->parse_buffer.data,
+		t->parse_buffer.offset);
+
 	t->parser.data = NULL;
 
+	/* If there was a handled authentication failure, then parse_error
+	 * will have signaled us that we should replay the request. */
+	if (PARSE_ERROR_REPLAY == t->parse_error) {
+		s->sent_request = 0;
+		goto replay;
+	}
+
 	if (t->parse_error < 0)
-		return t->parse_error;
+		return -1;
 
 	return 0;
 }
@@ -277,7 +439,7 @@ static int http_stream_write(
 	size_t len)
 {
 	http_stream *s = (http_stream *)stream;
-	http_subtransport *t = OWNING_SUBTRANSPORT(s);	
+	http_subtransport *t = OWNING_SUBTRANSPORT(s);
 	git_buf request = GIT_BUF_INIT;
 
 	assert(t->connected);
@@ -287,7 +449,11 @@ static int http_stream_write(
 	assert(!s->sent_request);
 
 	if (!s->sent_request) {
-		if (gen_request(&request, t->path, t->host, s->verb, s->service, s->service_url, len) < 0) {
+		clear_parser_state(t);
+
+		if (gen_request(&request, t->path, t->host,
+				t->cred, t->auth_mechanism, s->verb,
+				s->service, s->service_url, len) < 0) {
 			giterr_set(GITERR_NET, "Failed to generate request");
 			return -1;
 		}
@@ -316,9 +482,10 @@ static void http_stream_free(git_smart_subtransport_stream *stream)
 	git__free(s);
 }
 
-static int http_stream_alloc(http_subtransport *t, git_smart_subtransport_stream **stream)
+static int http_stream_alloc(http_subtransport *t,
+	git_smart_subtransport_stream **stream)
 {
-	http_stream *s;	
+	http_stream *s;
 
 	if (!stream)
 		return -1;
@@ -396,7 +563,8 @@ static int http_action(
 			t->use_ssl = 1;
 		}
 
-		if ((ret = gitno_extract_host_and_port(&t->host, &t->port, url, default_port)) < 0)
+		if ((ret = gitno_extract_host_and_port(&t->host, &t->port,
+				url, default_port)) < 0)
 			return ret;
 
 		t->path = strchr(url, '/');
@@ -412,15 +580,10 @@ static int http_action(
 
 		if (gitno_connect(&t->socket, t->host, t->port, flags) < 0)
 			return -1;
-	
-		t->parser.data = t;
-
-		http_parser_init(&t->parser, HTTP_RESPONSE);
-		gitno_buffer_setup(&t->socket, &t->parse_buffer, t->parse_buffer_data, sizeof(t->parse_buffer_data));
 
 		t->connected = 1;
 	}
-	
+
 	t->parse_finished = 0;
 	t->parse_error = 0;
 
@@ -432,7 +595,7 @@ static int http_action(
 		case GIT_SERVICE_UPLOADPACK:
 			return http_uploadpack(t, stream);
 	}
-	
+
 	*stream = NULL;
 	return -1;
 }
@@ -441,14 +604,20 @@ static void http_free(git_smart_subtransport *smart_transport)
 {
 	http_subtransport *t = (http_subtransport *) smart_transport;
 
-	git_buf_free(&t->parse_temp);
-	git__free(t->content_type);
+	clear_parser_state(t);
+
+	if (t->cred) {
+		t->cred->free(t->cred);
+		t->cred = NULL;
+	}
+
 	git__free(t->host);
 	git__free(t->port);
 	git__free(t);
 }
 
-int git_smart_subtransport_http(git_smart_subtransport **out, git_transport *owner)
+int git_smart_subtransport_http(git_smart_subtransport **out,
+	git_transport *owner)
 {
 	http_subtransport *t;
 	int flags;
@@ -459,7 +628,7 @@ int git_smart_subtransport_http(git_smart_subtransport **out, git_transport *own
 	t = (http_subtransport *)git__calloc(sizeof(http_subtransport), 1);
 	GITERR_CHECK_ALLOC(t);
 
-	t->owner = owner;
+	t->owner = (transport_smart *)owner;
 	t->parent.action = http_action;
 	t->parent.free = http_free;
 
diff --git a/src/transports/local.c b/src/transports/local.c
index 5a279ef..0a63a12 100644
--- a/src/transports/local.c
+++ b/src/transports/local.c
@@ -130,7 +130,11 @@ on_error:
  * Try to open the url as a git directory. The direction doesn't
  * matter in this case because we're calulating the heads ourselves.
  */
-static int local_connect(git_transport *transport, const char *url, int direction, int flags)
+static int local_connect(
+	git_transport *transport,
+	const char *url,
+	git_cred_acquire_cb cred_acquire_cb,
+	int direction, int flags)
 {
 	git_repository *repo;
 	int error;
@@ -138,6 +142,8 @@ static int local_connect(git_transport *transport, const char *url, int directio
 	const char *path;
 	git_buf buf = GIT_BUF_INIT;
 
+	GIT_UNUSED(cred_acquire_cb);
+
 	t->url = git__strdup(url);
 	GITERR_CHECK_ALLOC(t->url);
 	t->direction = direction;
diff --git a/src/transports/smart.c b/src/transports/smart.c
index b9c90df..8f9715a 100644
--- a/src/transports/smart.c
+++ b/src/transports/smart.c
@@ -52,7 +52,12 @@ static int git_smart__set_callbacks(
 	return 0;
 }
 
-static int git_smart__connect(git_transport *transport, const char *url, int direction, int flags)
+static int git_smart__connect(
+	git_transport *transport,
+	const char *url,
+	git_cred_acquire_cb cred_acquire_cb,
+	int direction,
+	int flags)
 {
 	transport_smart *t = (transport_smart *)transport;
 	git_smart_subtransport_stream *stream;
@@ -66,6 +71,7 @@ static int git_smart__connect(git_transport *transport, const char *url, int dir
 
 	t->direction = direction;
 	t->flags = flags;
+	t->cred_acquire_cb = cred_acquire_cb;
 
 	if (GIT_DIR_FETCH == direction)
 	{
diff --git a/src/transports/smart.h b/src/transports/smart.h
index 5784713..046bc89 100644
--- a/src/transports/smart.h
+++ b/src/transports/smart.h
@@ -99,6 +99,7 @@ typedef void (*packetsize_cb)(int received, void *payload);
 typedef struct {
 	git_transport parent;
 	char *url;
+	git_cred_acquire_cb cred_acquire_cb;
 	int direction;
 	int flags;
 	git_transport_message_cb progress_cb;
diff --git a/src/transports/winhttp.c b/src/transports/winhttp.c
index 0411a70..ef47616 100644
--- a/src/transports/winhttp.c
+++ b/src/transports/winhttp.c
@@ -30,6 +30,7 @@ static const char *upload_pack_ls_service_url = "/info/refs?service=git-upload-p
 static const char *upload_pack_service_url = "/git-upload-pack";
 static const wchar_t *get_verb = L"GET";
 static const wchar_t *post_verb = L"POST";
+static const wchar_t *basic_authtype = L"Basic";
 static const wchar_t *pragma_nocache = L"Pragma: no-cache";
 static const int no_check_cert_flags = SECURITY_FLAG_IGNORE_CERT_CN_INVALID |
 	SECURITY_FLAG_IGNORE_CERT_DATE_INVALID |
@@ -37,6 +38,10 @@ static const int no_check_cert_flags = SECURITY_FLAG_IGNORE_CERT_CN_INVALID |
 
 #define OWNING_SUBTRANSPORT(s) ((winhttp_subtransport *)(s)->parent.subtransport)
 
+typedef enum {
+	GIT_WINHTTP_AUTH_BASIC = 1,
+} winhttp_authmechanism_t;
+
 typedef struct {
 	git_smart_subtransport_stream parent;
 	const char *service;
@@ -49,16 +54,75 @@ typedef struct {
 
 typedef struct {
 	git_smart_subtransport parent;
-	git_transport *owner;
+	transport_smart *owner;
 	const char *path;
 	char *host;
 	char *port;
+	git_cred *cred;
+	int auth_mechanism;
 	HINTERNET session;
 	HINTERNET connection;
 	unsigned use_ssl : 1,
 		no_check_cert : 1;
 } winhttp_subtransport;
 
+static int apply_basic_credential(HINTERNET request, git_cred *cred)
+{
+	git_cred_userpass_plaintext *c = (git_cred_userpass_plaintext *)cred;
+	git_buf buf = GIT_BUF_INIT, raw = GIT_BUF_INIT;
+	wchar_t *wide = NULL;
+	int error = -1, wide_len;
+
+	git_buf_printf(&raw, "%s:%s", c->username, c->password);
+
+	if (git_buf_oom(&raw) ||
+		git_buf_puts(&buf, "Authorization: Basic ") < 0 ||
+		git_buf_put_base64(&buf, git_buf_cstr(&raw), raw.size) < 0)
+		goto on_error;
+
+	wide_len = MultiByteToWideChar(CP_UTF8,	MB_ERR_INVALID_CHARS,
+		git_buf_cstr(&buf),	-1, NULL, 0);
+
+	if (!wide_len) {
+		giterr_set(GITERR_OS, "Failed to measure string for wide conversion");
+		goto on_error;
+	}
+
+	wide = (wchar_t *)git__malloc(wide_len * sizeof(wchar_t));
+
+	if (!wide)
+		goto on_error;
+
+	if (!MultiByteToWideChar(CP_UTF8, MB_ERR_INVALID_CHARS,
+		git_buf_cstr(&buf), -1, wide, wide_len)) {
+		giterr_set(GITERR_OS, "Failed to convert string to wide form");
+		goto on_error;
+	}
+
+	if (!WinHttpAddRequestHeaders(request, wide, (ULONG) -1L, WINHTTP_ADDREQ_FLAG_ADD)) {
+		giterr_set(GITERR_OS, "Failed to add a header to the request");
+		goto on_error;
+	}
+
+	error = 0;
+
+on_error:
+	/* We were dealing with plaintext passwords, so clean up after ourselves a bit. */
+	if (wide)
+		memset(wide, 0x0, wide_len * sizeof(wchar_t));
+
+	if (buf.size)
+		memset(buf.ptr, 0x0, buf.size);
+
+	if (raw.size)
+		memset(raw.ptr, 0x0, raw.size);
+
+	git__free(wide);
+	git_buf_free(&buf);
+	git_buf_free(&raw);
+	return error;
+}
+
 static int winhttp_stream_connect(winhttp_stream *s)
 {
 	winhttp_subtransport *t = OWNING_SUBTRANSPORT(s);
@@ -127,6 +191,13 @@ static int winhttp_stream_connect(winhttp_stream *s)
 		}
 	}
 
+	/* If we have a credential on the subtransport, apply it to the request */
+	if (t->cred &&
+		t->cred->credtype == GIT_CREDTYPE_USERPASS_PLAINTEXT &&
+		t->auth_mechanism == GIT_WINHTTP_AUTH_BASIC &&
+		apply_basic_credential(s->request, t->cred) < 0)
+		goto on_error;
+
 	/* We've done everything up to calling WinHttpSendRequest. */
 
 	return 0;
@@ -136,6 +207,64 @@ on_error:
 	return -1;
 }
 
+static int parse_unauthorized_response(
+	HINTERNET request,
+	int *allowed_types,
+	int *auth_mechanism)
+{
+	DWORD index, buf_size, last_error;
+	int error = 0;
+	wchar_t *buf = NULL;
+
+	*allowed_types = 0;
+
+	for (index = 0; ; index++) {
+		/* Make a first call to ask for the size of the buffer to allocate
+		 * to hold the WWW-Authenticate header */
+		if (!WinHttpQueryHeaders(request, WINHTTP_QUERY_WWW_AUTHENTICATE,
+			WINHTTP_HEADER_NAME_BY_INDEX, WINHTTP_NO_OUTPUT_BUFFER,
+			&buf_size, &index))
+		{
+			last_error = GetLastError();
+
+			if (ERROR_WINHTTP_HEADER_NOT_FOUND == last_error) {
+				/* End of enumeration */
+				break;
+			} else if (ERROR_INSUFFICIENT_BUFFER == last_error) {
+				git__free(buf);
+				buf = (wchar_t *)git__malloc(buf_size);
+
+				if (!buf) {
+					error = -1;
+					break;
+				}
+			} else {
+				giterr_set(GITERR_OS, "Failed to read WWW-Authenticate header");
+				error = -1;
+				break;
+			}
+		}
+
+		/* Actually receive the data into our now-allocated buffer */
+		if (!WinHttpQueryHeaders(request, WINHTTP_QUERY_WWW_AUTHENTICATE,
+			WINHTTP_HEADER_NAME_BY_INDEX, buf,
+			&buf_size, &index)) {
+			giterr_set(GITERR_OS, "Failed to read WWW-Authenticate header");
+			error = -1;
+			break;
+		}
+
+		if (!wcsncmp(buf, basic_authtype, 5) &&
+			(buf[5] == L'\0' || buf[5] == L' ')) {
+			*allowed_types |= GIT_CREDTYPE_USERPASS_PLAINTEXT;
+			*auth_mechanism = GIT_WINHTTP_AUTH_BASIC;
+		}
+	}
+
+	git__free(buf);
+	return error;
+}
+
 static int winhttp_stream_read(
 	git_smart_subtransport_stream *stream,
 	char *buffer,
@@ -145,6 +274,7 @@ static int winhttp_stream_read(
 	winhttp_stream *s = (winhttp_stream *)stream;
 	winhttp_subtransport *t = OWNING_SUBTRANSPORT(s);
 
+replay:
 	/* Connect if necessary */
 	if (!s->request && winhttp_stream_connect(s) < 0)
 		return -1;
@@ -182,6 +312,31 @@ static int winhttp_stream_read(
 				return -1;
 		}
 
+		/* Handle authentication failures */
+		if (HTTP_STATUS_DENIED == status_code &&
+			get_verb == s->verb && t->owner->cred_acquire_cb) {
+			int allowed_types;
+
+			if (parse_unauthorized_response(s->request, &allowed_types, &t->auth_mechanism) < 0)
+				return -1;
+
+			if (allowed_types &&
+				(!t->cred || 0 == (t->cred->credtype & allowed_types))) {
+
+				if (t->owner->cred_acquire_cb(&t->cred, t->owner->url, allowed_types) < 0)
+					return -1;
+
+				assert(t->cred);
+
+				WinHttpCloseHandle(s->request);
+				s->request = NULL;
+				s->sent_request = 0;
+
+				/* Successfully acquired a credential */
+				goto replay;
+			}
+		}
+
 		if (HTTP_STATUS_OK != status_code) {
 			giterr_set(GITERR_NET, "Request failed with status code: %d", status_code);
 			return -1;
@@ -432,6 +587,11 @@ static void winhttp_free(git_smart_subtransport *smart_transport)
 	git__free(t->host);
 	git__free(t->port);
 
+	if (t->cred) {
+		t->cred->free(t->cred);
+		t->cred = NULL;
+	}
+
 	if (t->connection) {
 		WinHttpCloseHandle(t->connection);
 		t->connection = NULL;
@@ -456,7 +616,7 @@ int git_smart_subtransport_http(git_smart_subtransport **out, git_transport *own
 	t = (winhttp_subtransport *)git__calloc(sizeof(winhttp_subtransport), 1);
 	GITERR_CHECK_ALLOC(t);
 
-	t->owner = owner;
+	t->owner = (transport_smart *)owner;
 	t->parent.action = winhttp_action;
 	t->parent.free = winhttp_free;