summaryrefslogtreecommitdiff
path: root/src/mod_auth.c
blob: 1cb6a22f1f30b465dd86ee419385a7ea27c6586d (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
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
#include "first.h"

#include "plugin.h"
#include "http_auth.h"
#include "log.h"

#include <stdlib.h>
#include <string.h>

/**
 * auth framework
 */

typedef struct {
	/* auth */
	array  *auth_require;
	buffer *auth_backend_conf;
	unsigned short auth_extern_authn;

	/* generated */
	const http_auth_backend_t *auth_backend;
} plugin_config;

typedef struct {
	PLUGIN_DATA;

	plugin_config **config_storage;

	plugin_config conf;
} plugin_data;

static handler_t mod_auth_check_basic(server *srv, connection *con, void *p_d, const struct http_auth_require_t *require, const struct http_auth_backend_t *backend);
static handler_t mod_auth_check_digest(server *srv, connection *con, void *p_d, const struct http_auth_require_t *require, const struct http_auth_backend_t *backend);
static handler_t mod_auth_check_extern(server *srv, connection *con, void *p_d, const struct http_auth_require_t *require, const struct http_auth_backend_t *backend);

INIT_FUNC(mod_auth_init) {
	static const http_auth_scheme_t http_auth_scheme_basic  = { "basic",  mod_auth_check_basic,  NULL };
	static const http_auth_scheme_t http_auth_scheme_digest = { "digest", mod_auth_check_digest, NULL };
	static const http_auth_scheme_t http_auth_scheme_extern = { "extern", mod_auth_check_extern, NULL };
	plugin_data *p;

	/* register http_auth_scheme_* */
	http_auth_scheme_set(&http_auth_scheme_basic);
	http_auth_scheme_set(&http_auth_scheme_digest);
	http_auth_scheme_set(&http_auth_scheme_extern);

	p = calloc(1, sizeof(*p));

	return p;
}

FREE_FUNC(mod_auth_free) {
	plugin_data *p = p_d;

	UNUSED(srv);

	if (!p) return HANDLER_GO_ON;

	if (p->config_storage) {
		size_t i;
		for (i = 0; i < srv->config_context->used; i++) {
			plugin_config *s = p->config_storage[i];

			if (NULL == s) continue;

			array_free(s->auth_require);
			buffer_free(s->auth_backend_conf);

			free(s);
		}
		free(p->config_storage);
	}

	free(p);

	return HANDLER_GO_ON;
}

/* data type for mod_auth structured data
 * (parsed from auth.require array of strings) */
typedef struct {
    DATA_UNSET;
    http_auth_require_t *require;
} data_auth;

static void data_auth_free(data_unset *d)
{
    data_auth * const dauth = (data_auth *)d;
    buffer_free(dauth->key);
    http_auth_require_free(dauth->require);
    free(dauth);
}

static data_auth *data_auth_init(void)
{
    data_auth * const dauth = calloc(1, sizeof(*dauth));
    force_assert(NULL != dauth);
    dauth->copy       = NULL; /* must not be called on this data */
    dauth->free       = data_auth_free;
    dauth->reset      = NULL; /* must not be called on this data */
    dauth->insert_dup = NULL; /* must not be called on this data */
    dauth->print      = NULL; /* must not be called on this data */
    dauth->type       = TYPE_OTHER;

    dauth->key = buffer_init();
    dauth->require = http_auth_require_init();

    return dauth;
}

static int mod_auth_require_parse (server *srv, http_auth_require_t * const require, const buffer *b)
{
    /* user=name1|user=name2|group=name3|host=name4 */

    const char *str = b->ptr;
    const char *p;

    if (buffer_is_equal_string(b, CONST_STR_LEN("valid-user"))) {
        require->valid_user = 1;
        return 1; /* success */
    }

    do {
        const char *eq;
        size_t len;
        p = strchr(str, '|');
        len = NULL != p ? (size_t)(p - str) : strlen(str);
        eq = memchr(str, '=', len);
        if (NULL == eq) {
            log_error_write(srv, __FILE__, __LINE__, "sssbss",
                            "error parsing auth.require 'require' field: missing '='",
                            "(expecting \"valid-user\" or \"user=a|user=b|group=g|host=h\").",
                            "error value:", b, "error near:", str);
            return 0;
        }
        if (p-1  == eq) {
            log_error_write(srv, __FILE__, __LINE__, "sssbss",
                            "error parsing auth.require 'require' field: missing token after '='",
                            "(expecting \"valid-user\" or \"user=a|user=b|group=g|host=h\").",
                            "error value:", b, "error near:", str);
            return 0;
        }

        switch ((int)(eq - str)) {
          case 4:
            if (0 == memcmp(str, CONST_STR_LEN("user"))) {
                data_string *ds = data_string_init();
                buffer_copy_string_len(ds->key,str+5,len-5); /*("user=" is 5)*/
                array_insert_unique(require->user, (data_unset *)ds);
                continue;
            }
            else if (0 == memcmp(str, CONST_STR_LEN("host"))) {
                data_string *ds = data_string_init();
                buffer_copy_string_len(ds->key,str+5,len-5); /*("host=" is 5)*/
                array_insert_unique(require->host, (data_unset *)ds);
                log_error_write(srv, __FILE__, __LINE__, "ssb",
                                "warning parsing auth.require 'require' field: 'host' not implemented;",
                                "field value:", b);
                continue;
            }
            break; /* to error */
          case 5:
            if (0 == memcmp(str, CONST_STR_LEN("group"))) {
                data_string *ds = data_string_init();
                buffer_copy_string_len(ds->key,str+6,len-6); /*("group=" is 6)*/
                array_insert_unique(require->group, (data_unset *)ds);
              #if 0/*(supported by mod_authn_ldap, but not all other backends)*/
                log_error_write(srv, __FILE__, __LINE__, "ssb",
                                "warning parsing auth.require 'require' field: 'group' not implemented;",
                                "field value:", b);
              #endif
                continue;
            }
            break; /* to error */
          case 10:
            if (0 == memcmp(str, CONST_STR_LEN("valid-user"))) {
                log_error_write(srv, __FILE__, __LINE__, "sssb",
                                "error parsing auth.require 'require' field: valid user can not be combined with other require rules",
                                "(expecting \"valid-user\" or \"user=a|user=b|group=g|host=h\").",
                                "error value:", b);
                return 0;
            }
            break; /* to error */
          default:
            break; /* to error */
        }

        log_error_write(srv, __FILE__, __LINE__, "sssbss",
                        "error parsing auth.require 'require' field: invalid/unsupported token",
                        "(expecting \"valid-user\" or \"user=a|user=b|group=g|host=h\").",
                        "error value:", b, "error near:", str);
        return 0;

    } while (p && *((str = p+1)));

    return 1; /* success */
}

SETDEFAULTS_FUNC(mod_auth_set_defaults) {
	plugin_data *p = p_d;
	size_t i;

	config_values_t cv[] = {
		{ "auth.backend",                   NULL, T_CONFIG_STRING, T_CONFIG_SCOPE_CONNECTION }, /* 0 */
		{ "auth.require",                   NULL, T_CONFIG_LOCAL, T_CONFIG_SCOPE_CONNECTION },  /* 1 */
		{ "auth.extern-authn",              NULL, T_CONFIG_BOOLEAN, T_CONFIG_SCOPE_CONNECTION },/* 2 */
		{ NULL,                             NULL, T_CONFIG_UNSET, T_CONFIG_SCOPE_UNSET }
	};

	p->config_storage = calloc(1, srv->config_context->used * sizeof(plugin_config *));

	for (i = 0; i < srv->config_context->used; i++) {
		data_config const* config = (data_config const*)srv->config_context->data[i];
		plugin_config *s;
		size_t n;
		data_array *da;

		s = calloc(1, sizeof(plugin_config));
		s->auth_backend_conf = buffer_init();

		s->auth_require = array_init();

		cv[0].destination = s->auth_backend_conf;
		cv[1].destination = s->auth_require; /* T_CONFIG_LOCAL; not modified by config_insert_values_global() */
		cv[2].destination = &s->auth_extern_authn;

		p->config_storage[i] = s;

		if (0 != config_insert_values_global(srv, config->value, cv, i == 0 ? T_CONFIG_SCOPE_SERVER : T_CONFIG_SCOPE_CONNECTION)) {
			return HANDLER_ERROR;
		}

		if (!buffer_string_is_empty(s->auth_backend_conf)) {
			s->auth_backend = http_auth_backend_get(s->auth_backend_conf);
			if (NULL == s->auth_backend) {
				log_error_write(srv, __FILE__, __LINE__, "sb", "auth.backend not supported:", s->auth_backend_conf);

				return HANDLER_ERROR;
			}
		}

		/* no auth.require for this section */
		if (NULL == (da = (data_array *)array_get_element(config->value, "auth.require"))) continue;

		if (da->type != TYPE_ARRAY || !array_is_kvarray(da->value)) {
			log_error_write(srv, __FILE__, __LINE__, "ss",
					"unexpected value for auth.require; expected ",
					"auth.require = ( \"urlpath\" => ( \"option\" => \"value\" ) )");
			return HANDLER_ERROR;
		}


		for (n = 0; n < da->value->used; n++) {
			size_t m;
			data_array *da_file = (data_array *)da->value->data[n];
			const buffer *method = NULL, *realm = NULL, *require = NULL;
			const http_auth_scheme_t *auth_scheme;

			if (!array_is_kvstring(da_file->value)) {
				log_error_write(srv, __FILE__, __LINE__, "ss",
						"unexpected value for auth.require; expected ",
						"auth.require = ( \"urlpath\" => ( \"option\" => \"value\" ) )");

				return HANDLER_ERROR;
			}

			for (m = 0; m < da_file->value->used; m++) {
				if (da_file->value->data[m]->type == TYPE_STRING) {
					data_string *ds = (data_string *)da_file->value->data[m];
					if (buffer_is_equal_string(ds->key, CONST_STR_LEN("method"))) {
						method = ds->value;
					} else if (buffer_is_equal_string(ds->key, CONST_STR_LEN("realm"))) {
						realm = ds->value;
					} else if (buffer_is_equal_string(ds->key, CONST_STR_LEN("require"))) {
						require = ds->value;
					} else {
						log_error_write(srv, __FILE__, __LINE__, "ssbs",
							"the field is unknown in:",
							"auth.require = ( \"...\" => ( ..., -> \"",
							da_file->value->data[m]->key,
							"\" <- => \"...\" ) )");

						return HANDLER_ERROR;
					}
				} else {
					log_error_write(srv, __FILE__, __LINE__, "ssbs",
						"a string was expected for:",
						"auth.require = ( \"...\" => ( ..., -> \"",
						da_file->value->data[m]->key,
						"\" <- => \"...\" ) )");

					return HANDLER_ERROR;
				}
			}

			if (buffer_string_is_empty(method)) {
				log_error_write(srv, __FILE__, __LINE__, "ss",
						"the method field is missing or blank in:",
						"auth.require = ( \"...\" => ( ..., \"method\" => \"...\" ) )");
				return HANDLER_ERROR;
			} else {
				auth_scheme = http_auth_scheme_get(method);
				if (NULL == auth_scheme) {
					log_error_write(srv, __FILE__, __LINE__, "sbss",
							"unknown method", method, "(e.g. \"basic\", \"digest\" or \"extern\") in",
							"auth.require = ( \"...\" => ( ..., \"method\" => \"...\") )");
					return HANDLER_ERROR;
				}
			}

			if (buffer_is_empty(realm)) {
				log_error_write(srv, __FILE__, __LINE__, "ss",
						"the realm field is missing in:",
						"auth.require = ( \"...\" => ( ..., \"realm\" => \"...\" ) )");
				return HANDLER_ERROR;
			}

			if (buffer_string_is_empty(require)) {
				log_error_write(srv, __FILE__, __LINE__, "ss",
						"the require field is missing or blank in:",
						"auth.require = ( \"...\" => ( ..., \"require\" => \"...\" ) )");
				return HANDLER_ERROR;
			}

			if (require) { /*(always true at this point)*/
				data_auth * const dauth = data_auth_init();
				buffer_copy_buffer(dauth->key, da_file->key);
				dauth->require->scheme = auth_scheme;
				buffer_copy_buffer(dauth->require->realm, realm);
				if (!mod_auth_require_parse(srv, dauth->require, require)) {
					dauth->free((data_unset *)dauth);
					return HANDLER_ERROR;
				}
				array_insert_unique(s->auth_require, (data_unset *)dauth);
			}
		}
	}

	return HANDLER_GO_ON;
}

#define PATCH(x) \
	p->conf.x = s->x;
static int mod_auth_patch_connection(server *srv, connection *con, plugin_data *p) {
	size_t i, j;
	plugin_config *s = p->config_storage[0];

	PATCH(auth_backend);
	PATCH(auth_require);
	PATCH(auth_extern_authn);

	/* skip the first, the global context */
	for (i = 1; i < srv->config_context->used; i++) {
		data_config *dc = (data_config *)srv->config_context->data[i];
		s = p->config_storage[i];

		/* condition didn't match */
		if (!config_check_cond(srv, con, dc)) continue;

		/* merge config */
		for (j = 0; j < dc->value->used; j++) {
			data_unset *du = dc->value->data[j];

			if (buffer_is_equal_string(du->key, CONST_STR_LEN("auth.backend"))) {
				PATCH(auth_backend);
			} else if (buffer_is_equal_string(du->key, CONST_STR_LEN("auth.require"))) {
				PATCH(auth_require);
			} else if (buffer_is_equal_string(du->key, CONST_STR_LEN("auth.extern-authn"))) {
				PATCH(auth_extern_authn);
			}
		}
	}

	return 0;
}
#undef PATCH

static handler_t mod_auth_uri_handler(server *srv, connection *con, void *p_d) {
	size_t k;
	plugin_data *p = p_d;

	mod_auth_patch_connection(srv, con, p);

	if (p->conf.auth_require == NULL) return HANDLER_GO_ON;

	/* search auth directives for first prefix match against URL path */
	for (k = 0; k < p->conf.auth_require->used; k++) {
		const data_auth * const dauth = (data_auth *)p->conf.auth_require->data[k];
		const buffer *path = dauth->key;

		if (buffer_string_length(con->uri.path) < buffer_string_length(path)) continue;

		/* if we have a case-insensitive FS we have to lower-case the URI here too */

		if (!con->conf.force_lowercase_filenames
		    ? 0 == strncmp(con->uri.path->ptr, path->ptr, buffer_string_length(path))
		    : 0 == strncasecmp(con->uri.path->ptr, path->ptr, buffer_string_length(path))) {
			const http_auth_scheme_t * const scheme = dauth->require->scheme;
			if (p->conf.auth_extern_authn) {
				data_string *ds = (data_string *)array_get_element(con->environment, "REMOTE_USER");
				if (NULL != ds && http_auth_match_rules(dauth->require, ds->value->ptr, NULL, NULL)) {
					return HANDLER_GO_ON;
				}
			}
			return scheme->checkfn(srv, con, scheme->p_d, dauth->require, p->conf.auth_backend);
		}
	}

	/* nothing to do for us */
	return HANDLER_GO_ON;
}

int mod_auth_plugin_init(plugin *p);
int mod_auth_plugin_init(plugin *p) {
	p->version     = LIGHTTPD_VERSION_ID;
	p->name        = buffer_init_string("auth");
	p->init        = mod_auth_init;
	p->set_defaults = mod_auth_set_defaults;
	p->handle_uri_clean = mod_auth_uri_handler;
	p->cleanup     = mod_auth_free;

	p->data        = NULL;

	return 0;
}




/*
 * auth schemes (basic, digest, extern)
 *
 * (could be in separate file from mod_auth.c as long as registration occurs)
 */

#include "response.h"
#include "base64.h"
#include "md5.h"
#include "rand.h"

static handler_t mod_auth_send_400_bad_request(server *srv, connection *con) {
	UNUSED(srv);

	/* a field was missing or invalid */
	con->http_status = 400; /* Bad Request */
	con->mode = DIRECT;

	return HANDLER_FINISHED;
}

static handler_t mod_auth_send_401_unauthorized_basic(server *srv, connection *con, buffer *realm) {
	con->http_status = 401;
	con->mode = DIRECT;

	buffer_copy_string_len(srv->tmp_buf, CONST_STR_LEN("Basic realm=\""));
	buffer_append_string_buffer(srv->tmp_buf, realm);
	buffer_append_string_len(srv->tmp_buf, CONST_STR_LEN("\", charset=\"UTF-8\""));

	response_header_insert(srv, con, CONST_STR_LEN("WWW-Authenticate"), CONST_BUF_LEN(srv->tmp_buf));

	return HANDLER_FINISHED;
}

static handler_t mod_auth_check_basic(server *srv, connection *con, void *p_d, const struct http_auth_require_t *require, const struct http_auth_backend_t *backend) {
	data_string *ds = (data_string *)array_get_element(con->request.headers, "Authorization");
	buffer *username;
	buffer *b;
	char *pw;
	handler_t rc = HANDLER_UNSET;

	UNUSED(p_d);

	if (NULL == backend) {
		log_error_write(srv, __FILE__, __LINE__, "sb", "auth.backend not configured for", con->uri.path);
		con->http_status = 500;
		con->mode = DIRECT;
		return HANDLER_FINISHED;
	}

	if (NULL == ds || buffer_is_empty(ds->value)) {
		return mod_auth_send_401_unauthorized_basic(srv, con, require->realm);
	}

	if (0 != strncasecmp(ds->value->ptr, "Basic ", sizeof("Basic ")-1)) {
		return mod_auth_send_400_bad_request(srv, con);
	}
      #ifdef __COVERITY__
	if (buffer_string_length(ds->value) < sizeof("Basic ")-1) {
		return mod_auth_send_400_bad_request(srv, con);
	}
      #endif

	username = buffer_init();

	b = ds->value;
	/* coverity[overflow_sink : FALSE] */
	if (!buffer_append_base64_decode(username, b->ptr+sizeof("Basic ")-1, buffer_string_length(b)-(sizeof("Basic ")-1), BASE64_STANDARD)) {
		log_error_write(srv, __FILE__, __LINE__, "sb", "decoding base64-string failed", username);

		buffer_free(username);
		return mod_auth_send_400_bad_request(srv, con);
	}

	/* r2 == user:password */
	if (NULL == (pw = strchr(username->ptr, ':'))) {
		log_error_write(srv, __FILE__, __LINE__, "sb", "missing ':' in", username);

		buffer_free(username);
		return mod_auth_send_400_bad_request(srv, con);
	}

	buffer_string_set_length(username, pw - username->ptr);
	pw++;

	rc = backend->basic(srv, con, backend->p_d, require, username, pw);
	switch (rc) {
	case HANDLER_GO_ON:
		http_auth_setenv(con->environment, CONST_BUF_LEN(username), CONST_STR_LEN("Basic"));
		break;
	case HANDLER_WAIT_FOR_EVENT:
	case HANDLER_FINISHED:
		break;
	case HANDLER_ERROR:
	default:
		log_error_write(srv, __FILE__, __LINE__, "sbsBsB", "password doesn't match for", con->uri.path, "username:", username, ", IP:", con->dst_addr_buf);
		rc = HANDLER_UNSET;
		break;
	}

	buffer_free(username);
	return (HANDLER_UNSET != rc) ? rc : mod_auth_send_401_unauthorized_basic(srv, con, require->realm);
}

#define HASHLEN 16
#define HASHHEXLEN 32
typedef unsigned char HASH[HASHLEN];
typedef char HASHHEX[HASHHEXLEN+1];

static void CvtHex(const HASH Bin, char (*Hex)[33]) {
	li_tohex(*Hex, sizeof(*Hex), (const char*) Bin, 16);
}

typedef struct {
	const char *key;
	int key_len;
	char **ptr;
} digest_kv;

static handler_t mod_auth_send_401_unauthorized_digest(server *srv, connection *con, buffer *realm, int nonce_stale);

static handler_t mod_auth_check_digest(server *srv, connection *con, void *p_d, const struct http_auth_require_t *require, const struct http_auth_backend_t *backend) {
	data_string *ds = (data_string *)array_get_element(con->request.headers, "Authorization");

	char a1[33];
	char a2[33];

	char *username = NULL;
	char *realm = NULL;
	char *nonce = NULL;
	char *uri = NULL;
	char *algorithm = NULL;
	char *qop = NULL;
	char *cnonce = NULL;
	char *nc = NULL;
	char *respons = NULL;

	char *e, *c;
	const char *m = NULL;
	int i;
	buffer *b;

	li_MD5_CTX Md5Ctx;
	HASH HA1;
	HASH HA2;
	HASH RespHash;
	HASHHEX HA2Hex;


	/* init pointers */
#define S(x) \
	x, sizeof(x)-1, NULL
	digest_kv dkv[10] = {
		{ S("username=") },
		{ S("realm=") },
		{ S("nonce=") },
		{ S("uri=") },
		{ S("algorithm=") },
		{ S("qop=") },
		{ S("cnonce=") },
		{ S("nc=") },
		{ S("response=") },

		{ NULL, 0, NULL }
	};
#undef S

	dkv[0].ptr = &username;
	dkv[1].ptr = &realm;
	dkv[2].ptr = &nonce;
	dkv[3].ptr = &uri;
	dkv[4].ptr = &algorithm;
	dkv[5].ptr = &qop;
	dkv[6].ptr = &cnonce;
	dkv[7].ptr = &nc;
	dkv[8].ptr = &respons;

	UNUSED(p_d);

	if (NULL == backend) {
		log_error_write(srv, __FILE__, __LINE__, "sb", "auth.backend not configured for", con->uri.path);
		con->http_status = 500;
		con->mode = DIRECT;
		return HANDLER_FINISHED;
	}

	if (NULL == ds || buffer_is_empty(ds->value)) {
		return mod_auth_send_401_unauthorized_digest(srv, con, require->realm, 0);
	}

	if (0 != strncasecmp(ds->value->ptr, "Digest ", sizeof("Digest ")-1)) {
		return mod_auth_send_400_bad_request(srv, con);
	} else {
		size_t n = buffer_string_length(ds->value);
	      #ifdef __COVERITY__
		if (n < sizeof("Digest ")-1) {
			return mod_auth_send_400_bad_request(srv, con);
		}
	      #endif
		n -= (sizeof("Digest ")-1);
		b = buffer_init();
		buffer_copy_string_len(b,ds->value->ptr+sizeof("Digest ")-1,n);
	}

	/* parse credentials from client */
	for (c = b->ptr; *c; c++) {
		/* skip whitespaces */
		while (*c == ' ' || *c == '\t') c++;
		if (!*c) break;

		for (i = 0; dkv[i].key; i++) {
			if ((0 == strncmp(c, dkv[i].key, dkv[i].key_len))) {
				if ((c[dkv[i].key_len] == '"') &&
				    (NULL != (e = strchr(c + dkv[i].key_len + 1, '"')))) {
					/* value with "..." */
					*(dkv[i].ptr) = c + dkv[i].key_len + 1;
					c = e;

					*e = '\0';
				} else if (NULL != (e = strchr(c + dkv[i].key_len, ','))) {
					/* value without "...", terminated by ',' */
					*(dkv[i].ptr) = c + dkv[i].key_len;
					c = e;

					*e = '\0';
				} else {
					/* value without "...", terminated by EOL */
					*(dkv[i].ptr) = c + dkv[i].key_len;
					c += strlen(c) - 1;
				}
				break;
			}
		}
	}

	/* check if everything is transmitted */
	if (!username ||
	    !realm ||
	    !nonce ||
	    !uri ||
	    (qop && (!nc || !cnonce)) ||
	    !respons ) {
		/* missing field */

		log_error_write(srv, __FILE__, __LINE__, "s",
				"digest: missing field");

		buffer_free(b);
		return mod_auth_send_400_bad_request(srv, con);
	}

	/**
	 * protect the md5-sess against missing cnonce and nonce
	 */
	if (algorithm &&
	    0 == strcasecmp(algorithm, "md5-sess") &&
	    (!nonce || !cnonce)) {
		log_error_write(srv, __FILE__, __LINE__, "s",
				"digest: (md5-sess: missing field");

		buffer_free(b);
		return mod_auth_send_400_bad_request(srv, con);
	}

	if (qop && strcasecmp(qop, "auth-int") == 0) {
		log_error_write(srv, __FILE__, __LINE__, "s",
				"digest: qop=auth-int not supported");

		buffer_free(b);
		return mod_auth_send_400_bad_request(srv, con);
	}

	m = get_http_method_name(con->request.http_method);
	force_assert(m);

	/* detect if attacker is attempting to reuse valid digest for one uri
	 * on a different request uri.  Might also happen if intermediate proxy
	 * altered client request line.  (Altered request would not result in
	 * the same digest as that calculated by the client.)
	 * Internal redirects such as with mod_rewrite will modify request uri.
	 * Reauthentication is done to detect crossing auth realms, but this
	 * uri validation step is bypassed.  con->request.orig_uri is original
	 * uri sent in client request. */
	{
		const size_t ulen = strlen(uri);
		const size_t rlen = buffer_string_length(con->request.orig_uri);
		if (!buffer_is_equal_string(con->request.orig_uri, uri, ulen)
		    && !(rlen < ulen && 0 == memcmp(con->request.orig_uri->ptr, uri, rlen) && uri[rlen] == '?')) {
			log_error_write(srv, __FILE__, __LINE__, "sbsssB",
					"digest: auth failed: uri mismatch (", con->request.orig_uri, "!=", uri, "), IP:", con->dst_addr_buf);
			buffer_free(b);
			return mod_auth_send_400_bad_request(srv, con);
		}
	}

	/* password-string == HA1 */
	switch (backend->digest(srv, con, backend->p_d, username, realm, HA1)) {
	case HANDLER_GO_ON:
		break;
	case HANDLER_WAIT_FOR_EVENT:
		buffer_free(b);
		return HANDLER_WAIT_FOR_EVENT;
	case HANDLER_FINISHED:
		buffer_free(b);
		return HANDLER_FINISHED;
	case HANDLER_ERROR:
	default:
		buffer_free(b);
		return mod_auth_send_401_unauthorized_digest(srv, con, require->realm, 0);
	}

	if (algorithm &&
	    strcasecmp(algorithm, "md5-sess") == 0) {
		li_MD5_Init(&Md5Ctx);
		/* Errata ID 1649: http://www.rfc-editor.org/errata_search.php?rfc=2617 */
		CvtHex(HA1, &a1);
		li_MD5_Update(&Md5Ctx, (unsigned char *)a1, HASHHEXLEN);
		li_MD5_Update(&Md5Ctx, CONST_STR_LEN(":"));
		li_MD5_Update(&Md5Ctx, (unsigned char *)nonce, strlen(nonce));
		li_MD5_Update(&Md5Ctx, CONST_STR_LEN(":"));
		li_MD5_Update(&Md5Ctx, (unsigned char *)cnonce, strlen(cnonce));
		li_MD5_Final(HA1, &Md5Ctx);
	}

	CvtHex(HA1, &a1);

	/* calculate H(A2) */
	li_MD5_Init(&Md5Ctx);
	li_MD5_Update(&Md5Ctx, (unsigned char *)m, strlen(m));
	li_MD5_Update(&Md5Ctx, CONST_STR_LEN(":"));
	li_MD5_Update(&Md5Ctx, (unsigned char *)uri, strlen(uri));
	/* qop=auth-int not supported, already checked above */
/*
	if (qop && strcasecmp(qop, "auth-int") == 0) {
		li_MD5_Update(&Md5Ctx, CONST_STR_LEN(":"));
		li_MD5_Update(&Md5Ctx, (unsigned char *) [body checksum], HASHHEXLEN);
	}
*/
	li_MD5_Final(HA2, &Md5Ctx);
	CvtHex(HA2, &HA2Hex);

	/* calculate response */
	li_MD5_Init(&Md5Ctx);
	li_MD5_Update(&Md5Ctx, (unsigned char *)a1, HASHHEXLEN);
	li_MD5_Update(&Md5Ctx, CONST_STR_LEN(":"));
	li_MD5_Update(&Md5Ctx, (unsigned char *)nonce, strlen(nonce));
	li_MD5_Update(&Md5Ctx, CONST_STR_LEN(":"));
	if (qop && *qop) {
		li_MD5_Update(&Md5Ctx, (unsigned char *)nc, strlen(nc));
		li_MD5_Update(&Md5Ctx, CONST_STR_LEN(":"));
		li_MD5_Update(&Md5Ctx, (unsigned char *)cnonce, strlen(cnonce));
		li_MD5_Update(&Md5Ctx, CONST_STR_LEN(":"));
		li_MD5_Update(&Md5Ctx, (unsigned char *)qop, strlen(qop));
		li_MD5_Update(&Md5Ctx, CONST_STR_LEN(":"));
	};
	li_MD5_Update(&Md5Ctx, (unsigned char *)HA2Hex, HASHHEXLEN);
	li_MD5_Final(RespHash, &Md5Ctx);
	CvtHex(RespHash, &a2);

	if (0 != strcmp(a2, respons)) {
		/* digest not ok */
		log_error_write(srv, __FILE__, __LINE__, "sssB",
				"digest: auth failed for ", username, ": wrong password, IP:", con->dst_addr_buf);

		buffer_free(b);
		return mod_auth_send_401_unauthorized_digest(srv, con, require->realm, 0);
	}

	/* value is our allow-rules */
	if (!http_auth_match_rules(require, username, NULL, NULL)) {
		buffer_free(b);
		return mod_auth_send_401_unauthorized_digest(srv, con, require->realm, 0);
	}

	/* check age of nonce.  Note, random data is used in nonce generation
	 * in mod_auth_send_401_unauthorized_digest().  If that were replaced
	 * with nanosecond time, then nonce secret would remain unique enough
	 * for the purposes of Digest auth, and would be reproducible (and
	 * verifiable) if nanoseconds were inclued with seconds as part of the
	 * nonce "timestamp:secret".  Since that is not done, timestamp in
	 * nonce could theoretically be modified and still produce same md5sum,
	 * but that is highly unlikely within a 10 min (moving) window of valid
	 * time relative to current time (now) */
	{
		time_t ts = 0;
		const unsigned char * const nonce_uns = (unsigned char *)nonce;
		for (i = 0; i < 8 && light_isxdigit(nonce_uns[i]); ++i) {
			ts = (ts << 4) + hex2int(nonce_uns[i]);
		}
		if (nonce[i] != ':'
		    || ts > srv->cur_ts || srv->cur_ts - ts > 600) { /*(10 mins)*/
			/* nonce is stale; have client regenerate digest */
			buffer_free(b);
			return mod_auth_send_401_unauthorized_digest(srv, con, require->realm, 1);
		} /*(future: might send nextnonce when expiration is imminent)*/
	}

	http_auth_setenv(con->environment, username, strlen(username), CONST_STR_LEN("Digest"));

	buffer_free(b);

	return HANDLER_GO_ON;
}

static handler_t mod_auth_send_401_unauthorized_digest(server *srv, connection *con, buffer *realm, int nonce_stale) {
	li_MD5_CTX Md5Ctx;
	HASH h;
	char hh[33];

	force_assert(33 >= LI_ITOSTRING_LENGTH); /*(buffer used for both li_itostrn() and CvtHex())*/

	/* generate nonce */

	/* generate shared-secret */
	li_MD5_Init(&Md5Ctx);

	li_itostrn(hh, sizeof(hh), srv->cur_ts);
	li_MD5_Update(&Md5Ctx, (unsigned char *)hh, strlen(hh));
	li_itostrn(hh, sizeof(hh), li_rand_pseudo_bytes());
	li_MD5_Update(&Md5Ctx, (unsigned char *)hh, strlen(hh));

	li_MD5_Final(h, &Md5Ctx);

	CvtHex(h, &hh);

	/* generate WWW-Authenticate */

	con->http_status = 401;
	con->mode = DIRECT;

	buffer_copy_string_len(srv->tmp_buf, CONST_STR_LEN("Digest realm=\""));
	buffer_append_string_buffer(srv->tmp_buf, realm);
	buffer_append_string_len(srv->tmp_buf, CONST_STR_LEN("\", charset=\"UTF-8\", nonce=\""));
	buffer_append_uint_hex(srv->tmp_buf, (uintmax_t)srv->cur_ts);
	buffer_append_string_len(srv->tmp_buf, CONST_STR_LEN(":"));
	buffer_append_string(srv->tmp_buf, hh);
	buffer_append_string_len(srv->tmp_buf, CONST_STR_LEN("\", qop=\"auth\""));
	if (nonce_stale) {
		buffer_append_string_len(srv->tmp_buf, CONST_STR_LEN(", stale=true"));
	}

	response_header_insert(srv, con, CONST_STR_LEN("WWW-Authenticate"), CONST_BUF_LEN(srv->tmp_buf));

	return HANDLER_FINISHED;
}

static handler_t mod_auth_check_extern(server *srv, connection *con, void *p_d, const struct http_auth_require_t *require, const struct http_auth_backend_t *backend) {
	/* require REMOTE_USER already set */
	data_string *ds = (data_string *)array_get_element(con->environment, "REMOTE_USER");
	UNUSED(srv);
	UNUSED(p_d);
	UNUSED(backend);
	if (NULL != ds && http_auth_match_rules(require, ds->value->ptr, NULL, NULL)) {
		return HANDLER_GO_ON;
	} else {
		con->http_status = 401;
		con->mode = DIRECT;
		return HANDLER_FINISHED;
	}
}