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/* tinyproxy - A fast light-weight HTTP proxy
* Copyright (C) 1999 George Talusan <gstalusan@uwaterloo.ca>
* Copyright (C) 2002 James E. Flemer <jflemer@acm.jhu.edu>
* Copyright (C) 2002 Robert James Kaes <rjkaes@users.sourceforge.net>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
/* A substring of the domain to be filtered goes into the file
* pointed at by DEFAULT_FILTER.
*/
#include "main.h"
#include "filter.h"
#include "heap.h"
#include "log.h"
#include "reqs.h"
#define FILTER_BUFFER_LEN (512)
static int err;
struct filter_list {
struct filter_list *next;
char *pat;
regex_t *cpat;
};
static struct filter_list *fl = NULL;
static int already_init = 0;
static filter_policy_t default_policy = FILTER_DEFAULT_ALLOW;
/*
* Initializes a linked list of strings containing hosts/urls to be filtered
*/
void filter_init (void)
{
FILE *fd;
struct filter_list *p;
char buf[FILTER_BUFFER_LEN];
char *s;
int cflags;
if (fl || already_init) {
return;
}
fd = fopen (config.filter, "r");
if (!fd) {
return;
}
p = NULL;
cflags = REG_NEWLINE | REG_NOSUB;
if (config.filter_extended)
cflags |= REG_EXTENDED;
if (!config.filter_casesensitive)
cflags |= REG_ICASE;
while (fgets (buf, FILTER_BUFFER_LEN, fd)) {
/*
* Remove any trailing white space and
* comments.
*/
s = buf;
while (*s) {
if (isspace ((unsigned char) *s))
break;
if (*s == '#') {
/*
* If the '#' char is preceeded by
* an escape, it's not a comment
* string.
*/
if (s == buf || *(s - 1) != '\\')
break;
}
++s;
}
*s = '\0';
/* skip leading whitespace */
s = buf;
while (*s && isspace ((unsigned char) *s))
s++;
/* skip blank lines and comments */
if (*s == '\0')
continue;
if (!p) /* head of list */
fl = p =
(struct filter_list *)
safecalloc (1, sizeof (struct filter_list));
else { /* next entry */
p->next =
(struct filter_list *)
safecalloc (1, sizeof (struct filter_list));
p = p->next;
}
p->pat = safestrdup (s);
p->cpat = (regex_t *) safemalloc (sizeof (regex_t));
err = regcomp (p->cpat, p->pat, cflags);
if (err != 0) {
fprintf (stderr,
"Bad regex in %s: %s\n",
config.filter, p->pat);
exit (EX_DATAERR);
}
}
if (ferror (fd)) {
perror ("fgets");
exit (EX_DATAERR);
}
fclose (fd);
already_init = 1;
}
/* unlink the list */
void filter_destroy (void)
{
struct filter_list *p, *q;
if (already_init) {
for (p = q = fl; p; p = q) {
regfree (p->cpat);
safefree (p->cpat);
safefree (p->pat);
q = p->next;
safefree (p);
}
fl = NULL;
already_init = 0;
}
}
/**
* reload the filter file if filtering is enabled
*/
void filter_reload (void)
{
if (config.filter) {
log_message (LOG_NOTICE, "Re-reading filter file.");
filter_destroy ();
filter_init ();
}
}
/* Return 0 to allow, non-zero to block */
int filter_domain (const char *host)
{
struct filter_list *p;
int result;
if (!fl || !already_init)
goto COMMON_EXIT;
for (p = fl; p; p = p->next) {
result =
regexec (p->cpat, host, (size_t) 0, (regmatch_t *) 0, 0);
if (result == 0) {
if (default_policy == FILTER_DEFAULT_ALLOW)
return 1;
else
return 0;
}
}
COMMON_EXIT:
if (default_policy == FILTER_DEFAULT_ALLOW)
return 0;
else
return 1;
}
/* returns 0 to allow, non-zero to block */
int filter_url (const char *url)
{
struct filter_list *p;
int result;
if (!fl || !already_init)
goto COMMON_EXIT;
for (p = fl; p; p = p->next) {
result =
regexec (p->cpat, url, (size_t) 0, (regmatch_t *) 0, 0);
if (result == 0) {
if (default_policy == FILTER_DEFAULT_ALLOW)
return 1;
else
return 0;
}
}
COMMON_EXIT:
if (default_policy == FILTER_DEFAULT_ALLOW)
return 0;
else
return 1;
}
/*
* Set the default filtering policy
*/
void filter_set_default_policy (filter_policy_t policy)
{
default_policy = policy;
}
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