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
|
/* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
/*
* mod_setenvif.c
* Set environment variables based on matching request headers or
* attributes against regex strings
*
* Paul Sutton <paul@ukweb.com> 27 Oct 1996
* Based on mod_browser by Alexei Kosut <akosut@organic.com>
*/
/*
* Used to set environment variables based on the incoming request headers,
* or some selected other attributes of the request (e.g., the remote host
* name).
*
* Usage:
*
* SetEnvIf name regex var ...
*
* where name is either a HTTP request header name, or one of the
* special values (see below). 'name' may be a regex when it is used
* to specify an HTTP request header name. The 'value' of the header
& (or the value of the special value from below) are compared against
* the regex argument. If this is a simple string, a simple sub-string
* match is performed. Otherwise, a request expression match is
* done. If the value matches the string or regular expression, the
* environment variables listed as var ... are set. Each var can
* be in one of three formats: var, which sets the named variable
* (the value value "1"); var=value, which sets the variable to
* the given value; or !var, which unsets the variable is it has
* been previously set.
*
* Normally the strings are compared with regard to case. To ignore
* case, use the directive SetEnvIfNoCase instead.
*
* Special values for 'name' are:
*
* server_addr IP address of interface on which request arrived
* (analogous to SERVER_ADDR set in ap_add_common_vars())
* remote_host Remote host name (if available)
* remote_addr Remote IP address
* request_method Request method (GET, POST, etc)
* request_uri Requested URI
*
* Examples:
*
* To set the environment variable LOCALHOST if the client is the local
* machine:
*
* SetEnvIf remote_addr 127.0.0.1 LOCALHOST
*
* To set LOCAL if the client is the local host, or within our company's
* domain (192.168.10):
*
* SetEnvIf remote_addr 192.168.10. LOCAL
* SetEnvIf remote_addr 127.0.0.1 LOCALHOST
*
* This could be written as:
*
* SetEnvIf remote_addr (127.0.0.1|192.168.10.) LOCAL
*
* To set HAVE_TS if the client request contains any header beginning
* with "TS" with a value beginning with a lower case alphabet:
*
* SetEnvIf ^TS* ^[a-z].* HAVE_TS
*/
#include "apr.h"
#include "apr_strings.h"
#include "apr_strmatch.h"
#define APR_WANT_STRFUNC
#include "apr_want.h"
#include "ap_config.h"
#include "httpd.h"
#include "http_config.h"
#include "http_core.h"
#include "http_log.h"
#include "http_protocol.h"
enum special {
SPECIAL_NOT,
SPECIAL_REMOTE_ADDR,
SPECIAL_REMOTE_HOST,
SPECIAL_REQUEST_URI,
SPECIAL_REQUEST_METHOD,
SPECIAL_REQUEST_PROTOCOL,
SPECIAL_SERVER_ADDR
};
typedef struct {
char *name; /* header name */
ap_regex_t *pnamereg; /* compiled header name regex */
char *regex; /* regex to match against */
ap_regex_t *preg; /* compiled regex */
const apr_strmatch_pattern *pattern; /* non-regex pattern to match */
ap_expr_info_t *expr; /* parsed expression */
apr_table_t *features; /* env vars to set (or unset) */
enum special special_type; /* is it a "special" header ? */
int icase; /* ignoring case? */
} sei_entry;
typedef struct {
apr_array_header_t *conditionals;
} sei_cfg_rec;
module AP_MODULE_DECLARE_DATA setenvif_module;
/*
* These routines, the create- and merge-config functions, are called
* for both the server-wide and the per-directory contexts. This is
* because the different definitions are used at different times; the
* server-wide ones are used in the post-read-request phase, and the
* per-directory ones are used during the header-parse phase (after
* the URI has been mapped to a file and we have anything from the
* .htaccess file and <Directory> and <Files> containers).
*/
static void *create_setenvif_config(apr_pool_t *p)
{
sei_cfg_rec *new = (sei_cfg_rec *) apr_palloc(p, sizeof(sei_cfg_rec));
new->conditionals = apr_array_make(p, 20, sizeof(sei_entry));
return (void *) new;
}
static void *create_setenvif_config_svr(apr_pool_t *p, server_rec *dummy)
{
return create_setenvif_config(p);
}
static void *create_setenvif_config_dir(apr_pool_t *p, char *dummy)
{
return create_setenvif_config(p);
}
static void *merge_setenvif_config(apr_pool_t *p, void *basev, void *overridesv)
{
sei_cfg_rec *a = apr_pcalloc(p, sizeof(sei_cfg_rec));
sei_cfg_rec *base = basev, *overrides = overridesv;
a->conditionals = apr_array_append(p, base->conditionals,
overrides->conditionals);
return a;
}
/*
* any non-NULL magic constant will do... used to indicate if AP_REG_ICASE should
* be used
*/
#define ICASE_MAGIC ((void *)(&setenvif_module))
#define SEI_MAGIC_HEIRLOOM "setenvif-phase-flag"
static ap_regex_t *is_header_regex_regex;
static int is_header_regex(apr_pool_t *p, const char* name)
{
/* If a Header name contains characters other than:
* -,_,[A-Z\, [a-z] and [0-9].
* assume the header name is a regular expression.
*/
if (ap_regexec(is_header_regex_regex, name, 0, NULL, 0)) {
return 1;
}
return 0;
}
/* If the input string does not take advantage of regular
* expression metacharacters, return a pointer to an equivalent
* string that can be searched using apr_strmatch(). (The
* returned string will often be the input string. But if
* the input string contains escaped characters, the returned
* string will be a copy with the escapes removed.)
*/
static const char *non_regex_pattern(apr_pool_t *p, const char *s)
{
const char *src = s;
int escapes_found = 0;
int in_escape = 0;
while (*src) {
switch (*src) {
case '^':
case '.':
case '$':
case '|':
case '(':
case ')':
case '[':
case ']':
case '*':
case '+':
case '?':
case '{':
case '}':
if (!in_escape) {
return NULL;
}
in_escape = 0;
break;
case '\\':
if (!in_escape) {
in_escape = 1;
escapes_found = 1;
}
else {
in_escape = 0;
}
break;
default:
if (in_escape) {
return NULL;
}
break;
}
src++;
}
if (!escapes_found) {
return s;
}
else {
char *unescaped = (char *)apr_palloc(p, src - s + 1);
char *dst = unescaped;
src = s;
do {
if (*src == '\\') {
src++;
}
} while ((*dst++ = *src++));
return unescaped;
}
}
static const char *add_envvars(cmd_parms *cmd, const char *args, sei_entry *new)
{
const char *feature;
int beenhere = 0;
char *var;
for ( ; ; ) {
feature = ap_getword_conf(cmd->pool, &args);
if (!*feature) {
break;
}
beenhere++;
var = ap_getword(cmd->pool, &feature, '=');
if (*feature) {
apr_table_setn(new->features, var, feature);
}
else if (*var == '!') {
apr_table_setn(new->features, var + 1, "!");
}
else {
apr_table_setn(new->features, var, "1");
}
}
if (!beenhere) {
return apr_pstrcat(cmd->pool, "Missing envariable expression for ",
cmd->cmd->name, NULL);
}
return NULL;
}
static const char *add_setenvif_core(cmd_parms *cmd, void *mconfig,
char *fname, const char *args)
{
char *regex;
const char *simple_pattern;
sei_cfg_rec *sconf;
sei_entry *new;
sei_entry *entries;
int i;
int icase;
/*
* Determine from our context into which record to put the entry.
* cmd->path == NULL means we're in server-wide context; otherwise,
* we're dealing with a per-directory setting.
*/
sconf = (cmd->path != NULL)
? (sei_cfg_rec *) mconfig
: (sei_cfg_rec *) ap_get_module_config(cmd->server->module_config,
&setenvif_module);
entries = (sei_entry *) sconf->conditionals->elts;
/* get regex */
regex = ap_getword_conf(cmd->pool, &args);
if (!*regex) {
return apr_pstrcat(cmd->pool, "Missing regular expression for ",
cmd->cmd->name, NULL);
}
/*
* If we've already got a sei_entry with the same name we want to
* just copy the name pointer... so that later on we can compare
* two header names just by comparing the pointers.
*/
for (i = 0; i < sconf->conditionals->nelts; ++i) {
new = &entries[i];
if (!strcasecmp(new->name, fname)) {
fname = new->name;
break;
}
}
/* if the last entry has an identical headername and regex then
* merge with it
*/
i = sconf->conditionals->nelts - 1;
icase = cmd->info == ICASE_MAGIC;
if (i < 0
|| entries[i].name != fname
|| entries[i].icase != icase
|| strcmp(entries[i].regex, regex)) {
/* no match, create a new entry */
new = apr_array_push(sconf->conditionals);
new->name = fname;
new->regex = regex;
new->icase = icase;
if ((simple_pattern = non_regex_pattern(cmd->pool, regex))) {
new->pattern = apr_strmatch_precompile(cmd->pool,
simple_pattern, !icase);
if (new->pattern == NULL) {
return apr_pstrcat(cmd->pool, cmd->cmd->name,
" pattern could not be compiled.", NULL);
}
new->preg = NULL;
}
else {
new->preg = ap_pregcomp(cmd->pool, regex,
(AP_REG_EXTENDED | (icase ? AP_REG_ICASE : 0)));
if (new->preg == NULL) {
return apr_pstrcat(cmd->pool, cmd->cmd->name,
" regex could not be compiled.", NULL);
}
new->pattern = NULL;
}
new->features = apr_table_make(cmd->pool, 2);
if (!strcasecmp(fname, "remote_addr")) {
new->special_type = SPECIAL_REMOTE_ADDR;
}
else if (!strcasecmp(fname, "remote_host")) {
new->special_type = SPECIAL_REMOTE_HOST;
}
else if (!strcasecmp(fname, "request_uri")) {
new->special_type = SPECIAL_REQUEST_URI;
}
else if (!strcasecmp(fname, "request_method")) {
new->special_type = SPECIAL_REQUEST_METHOD;
}
else if (!strcasecmp(fname, "request_protocol")) {
new->special_type = SPECIAL_REQUEST_PROTOCOL;
}
else if (!strcasecmp(fname, "server_addr")) {
new->special_type = SPECIAL_SERVER_ADDR;
}
else {
new->special_type = SPECIAL_NOT;
/* Handle fname as a regular expression.
* If fname a simple header string, identify as such
* (new->pnamereg = NULL) to avoid the overhead of searching
* through headers_in for a regex match.
*/
if (is_header_regex(cmd->temp_pool, fname)) {
new->pnamereg = ap_pregcomp(cmd->pool, fname,
(AP_REG_EXTENDED | AP_REG_NOSUB
| (icase ? AP_REG_ICASE : 0)));
if (new->pnamereg == NULL)
return apr_pstrcat(cmd->pool, cmd->cmd->name,
"Header name regex could not be "
"compiled.", NULL);
}
else {
new->pnamereg = NULL;
}
}
}
else {
new = &entries[i];
}
return add_envvars(cmd, args, new);
}
static const char *add_setenvif(cmd_parms *cmd, void *mconfig,
const char *args)
{
char *fname;
/* get header name */
fname = ap_getword_conf(cmd->pool, &args);
if (!*fname) {
return apr_pstrcat(cmd->pool, "Missing header-field name for ",
cmd->cmd->name, NULL);
}
return add_setenvif_core(cmd, mconfig, fname, args);
}
static const char *add_setenvifexpr(cmd_parms *cmd, void *mconfig,
const char *args)
{
char *expr;
sei_cfg_rec *sconf;
sei_entry *new;
const char *err;
/*
* Determine from our context into which record to put the entry.
* cmd->path == NULL means we're in server-wide context; otherwise,
* we're dealing with a per-directory setting.
*/
sconf = (cmd->path != NULL)
? (sei_cfg_rec *) mconfig
: (sei_cfg_rec *) ap_get_module_config(cmd->server->module_config,
&setenvif_module);
/* get expr */
expr = ap_getword_conf(cmd->pool, &args);
if (!*expr) {
return apr_pstrcat(cmd->pool, "Missing expression for ",
cmd->cmd->name, NULL);
}
new = apr_array_push(sconf->conditionals);
new->features = apr_table_make(cmd->pool, 2);
new->name = NULL;
new->regex = NULL;
new->pattern = NULL;
new->preg = NULL;
new->expr = ap_expr_parse_cmd(cmd, expr, 0, &err, NULL);
if (err)
return apr_psprintf(cmd->pool, "Could not parse expression \"%s\": %s",
expr, err);
return add_envvars(cmd, args, new);
}
/*
* This routine handles the BrowserMatch* directives. It simply turns around
* and feeds them, with the appropriate embellishments, to the general-purpose
* command handler.
*/
static const char *add_browser(cmd_parms *cmd, void *mconfig, const char *args)
{
return add_setenvif_core(cmd, mconfig, "User-Agent", args);
}
static const command_rec setenvif_module_cmds[] =
{
AP_INIT_RAW_ARGS("SetEnvIf", add_setenvif, NULL, OR_FILEINFO,
"A header-name, regex and a list of variables."),
AP_INIT_RAW_ARGS("SetEnvIfNoCase", add_setenvif, ICASE_MAGIC, OR_FILEINFO,
"a header-name, regex and a list of variables."),
AP_INIT_RAW_ARGS("SetEnvIfExpr", add_setenvifexpr, NULL, OR_FILEINFO,
"an expression and a list of variables."),
AP_INIT_RAW_ARGS("BrowserMatch", add_browser, NULL, OR_FILEINFO,
"A browser regex and a list of variables."),
AP_INIT_RAW_ARGS("BrowserMatchNoCase", add_browser, ICASE_MAGIC,
OR_FILEINFO,
"A browser regex and a list of variables."),
{ NULL },
};
/*
* This routine gets called at two different points in request processing:
* once before the URI has been translated (during the post-read-request
* phase) and once after (during the header-parse phase). We use different
* config records for the two different calls to reduce overhead (by not
* re-doing the server-wide settings during directory processing), and
* signal which call it is by having the earlier one pass a flag to the
* later one.
*/
static int match_headers(request_rec *r)
{
sei_cfg_rec *sconf;
sei_entry *entries;
const apr_table_entry_t *elts;
const char *val, *err;
apr_size_t val_len = 0;
int i, j;
char *last_name;
ap_regmatch_t regm[AP_MAX_REG_MATCH];
if (!ap_get_module_config(r->request_config, &setenvif_module)) {
ap_set_module_config(r->request_config, &setenvif_module,
SEI_MAGIC_HEIRLOOM);
sconf = (sei_cfg_rec *) ap_get_module_config(r->server->module_config,
&setenvif_module);
}
else {
sconf = (sei_cfg_rec *) ap_get_module_config(r->per_dir_config,
&setenvif_module);
}
entries = (sei_entry *) sconf->conditionals->elts;
last_name = NULL;
val = NULL;
for (i = 0; i < sconf->conditionals->nelts; ++i) {
sei_entry *b = &entries[i];
if (!b->expr) {
/* Optimize the case where a bunch of directives in a row use the
* same header. Remember we don't need to strcmp the two header
* names because we made sure the pointers were equal during
* configuration.
*/
if (b->name != last_name) {
last_name = b->name;
switch (b->special_type) {
case SPECIAL_REMOTE_ADDR:
val = r->useragent_ip;
break;
case SPECIAL_SERVER_ADDR:
val = r->connection->local_ip;
break;
case SPECIAL_REMOTE_HOST:
val = ap_get_remote_host(r->connection, r->per_dir_config,
REMOTE_NAME, NULL);
break;
case SPECIAL_REQUEST_URI:
val = r->uri;
break;
case SPECIAL_REQUEST_METHOD:
val = r->method;
break;
case SPECIAL_REQUEST_PROTOCOL:
val = r->protocol;
break;
case SPECIAL_NOT:
if (b->pnamereg) {
/* Matching headers_in against a regex. Iterate through
* the headers_in until we find a match or run out of
* headers.
*/
const apr_array_header_t
*arr = apr_table_elts(r->headers_in);
elts = (const apr_table_entry_t *) arr->elts;
val = NULL;
for (j = 0; j < arr->nelts; ++j) {
if (!ap_regexec(b->pnamereg, elts[j].key, 0, NULL, 0)) {
val = elts[j].val;
}
}
}
else {
/* Not matching against a regex */
val = apr_table_get(r->headers_in, b->name);
if (val == NULL) {
val = apr_table_get(r->subprocess_env, b->name);
}
}
}
val_len = val ? strlen(val) : 0;
}
}
/*
* A NULL value indicates that the header field or special entity
* wasn't present or is undefined. Represent that as an empty string
* so that REs like "^$" will work and allow envariable setting
* based on missing or empty field. This is also necessary to make
* ap_pregsub work after evaluating an ap_expr_t which does set the
* regexp backref data.
*/
if (val == NULL) {
val = "";
val_len = 0;
}
if ((b->pattern && apr_strmatch(b->pattern, val, val_len)) ||
(b->preg && !ap_regexec(b->preg, val, AP_MAX_REG_MATCH, regm, 0)) ||
(b->expr && ap_expr_exec_re(r, b->expr, AP_MAX_REG_MATCH, regm, &val, &err) > 0))
{
const apr_array_header_t *arr = apr_table_elts(b->features);
elts = (const apr_table_entry_t *) arr->elts;
for (j = 0; j < arr->nelts; ++j) {
if (*(elts[j].val) == '!') {
apr_table_unset(r->subprocess_env, elts[j].key);
}
else {
if (!b->pattern) {
char *replaced = ap_pregsub(r->pool, elts[j].val, val,
AP_MAX_REG_MATCH, regm);
if (replaced) {
apr_table_setn(r->subprocess_env, elts[j].key,
replaced);
}
else {
ap_log_rerror(APLOG_MARK, APLOG_CRIT, 0, r, APLOGNO(01505)
"Regular expression replacement "
"failed for '%s', value too long?",
elts[j].key);
return HTTP_INTERNAL_SERVER_ERROR;
}
}
else {
apr_table_setn(r->subprocess_env, elts[j].key,
elts[j].val);
}
}
ap_log_rerror(APLOG_MARK, APLOG_TRACE2, 0, r, "Setting %s",
elts[j].key);
}
}
}
return DECLINED;
}
static void register_hooks(apr_pool_t *p)
{
ap_hook_header_parser(match_headers, NULL, NULL, APR_HOOK_MIDDLE);
ap_hook_post_read_request(match_headers, NULL, NULL, APR_HOOK_MIDDLE);
is_header_regex_regex = ap_pregcomp(p, "^[-A-Za-z0-9_]*$",
(AP_REG_EXTENDED | AP_REG_NOSUB ));
ap_assert(is_header_regex_regex != NULL);
}
AP_DECLARE_MODULE(setenvif) =
{
STANDARD20_MODULE_STUFF,
create_setenvif_config_dir, /* dir config creater */
merge_setenvif_config, /* dir merger --- default is to override */
create_setenvif_config_svr, /* server config */
merge_setenvif_config, /* merge server configs */
setenvif_module_cmds, /* command apr_table_t */
register_hooks /* register hooks */
};
|