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/*************************************************
* Exim - an Internet mail transport agent *
*************************************************/
/*
* Copyright (c) The Exim Maintainers 2016 - 2022
* Copyright (c) Tom Kistner <tom@duncanthrax.net> 2003-2015
* License: GPL
*/
/* Code for matching regular expressions against headers and body.
Called from acl.c. */
#include "exim.h"
#ifdef WITH_CONTENT_SCAN
#include <unistd.h>
#include <sys/mman.h>
/* Structure to hold a list of Regular expressions */
typedef struct pcre_list {
pcre2_code *re;
uschar *pcre_text;
struct pcre_list *next;
} pcre_list;
uschar regex_match_string_buffer[1024];
extern FILE *mime_stream;
extern uschar *mime_current_boundary;
static pcre_list *
compile(const uschar * list)
{
int sep = 0;
uschar *regex_string;
pcre_list *re_list_head = NULL;
pcre_list *ri;
/* precompile our regexes */
while ((regex_string = string_nextinlist(&list, &sep, NULL, 0)))
if (strcmpic(regex_string, US"false") != 0 && Ustrcmp(regex_string, "0") != 0)
{
pcre2_code * re;
int err;
PCRE2_SIZE pcre_erroffset;
/* compile our regular expression */
if (!(re = pcre2_compile( (PCRE2_SPTR) regex_string, PCRE2_ZERO_TERMINATED,
0, &err, &pcre_erroffset, pcre_cmp_ctx)))
{
uschar errbuf[128];
pcre2_get_error_message(err, errbuf, sizeof(errbuf));
log_write(0, LOG_MAIN,
"regex acl condition warning - error in regex '%s': %s at offset %ld, skipped.",
regex_string, errbuf, (long)pcre_erroffset);
continue;
}
ri = store_get(sizeof(pcre_list), GET_UNTAINTED);
ri->re = re;
ri->pcre_text = regex_string;
ri->next = re_list_head;
re_list_head = ri;
}
return re_list_head;
}
static int
matcher(pcre_list * re_list_head, uschar * linebuffer, int len)
{
pcre2_match_data * md = pcre2_match_data_create(REGEX_VARS + 1, pcre_gen_ctx);
for (pcre_list * ri = re_list_head; ri; ri = ri->next)
{
int n;
/* try matcher on the line */
if ((n = pcre2_match(ri->re, (PCRE2_SPTR)linebuffer, len, 0, 0, md, pcre_mtc_ctx)) > 0)
{
Ustrncpy(regex_match_string_buffer, ri->pcre_text,
sizeof(regex_match_string_buffer)-1);
regex_match_string = regex_match_string_buffer;
for (int nn = 1; nn < n; nn++)
{
PCRE2_UCHAR * cstr;
PCRE2_SIZE cslen;
pcre2_substring_get_bynumber(md, nn, &cstr, &cslen);
regex_vars[nn-1] = CUS cstr;
}
return OK;
}
}
pcre2_match_data_free(md);
return FAIL;
}
int
regex(const uschar **listptr)
{
unsigned long mbox_size;
FILE *mbox_file;
pcre_list *re_list_head;
uschar *linebuffer;
long f_pos = 0;
int ret = FAIL;
/* reset expansion variable */
regex_match_string = NULL;
if (!mime_stream) /* We are in the DATA ACL */
{
if (!(mbox_file = spool_mbox(&mbox_size, NULL, NULL)))
{ /* error while spooling */
log_write(0, LOG_MAIN|LOG_PANIC,
"regex acl condition: error while creating mbox spool file");
return DEFER;
}
}
else
{
if ((f_pos = ftell(mime_stream)) < 0)
{
log_write(0, LOG_MAIN|LOG_PANIC,
"regex acl condition: mime_stream: %s", strerror(errno));
return DEFER;
}
mbox_file = mime_stream;
}
/* precompile our regexes */
if (!(re_list_head = compile(*listptr)))
return FAIL; /* no regexes -> nothing to do */
/* match each line against all regexes */
linebuffer = store_get(32767, GET_TAINTED);
while (fgets(CS linebuffer, 32767, mbox_file))
{
if ( mime_stream && mime_current_boundary /* check boundary */
&& Ustrncmp(linebuffer, "--", 2) == 0
&& Ustrncmp((linebuffer+2), mime_current_boundary,
Ustrlen(mime_current_boundary)) == 0)
break; /* found boundary */
if ((ret = matcher(re_list_head, linebuffer, (int)Ustrlen(linebuffer))) == OK)
goto done;
}
/* no matches ... */
done:
if (!mime_stream)
(void)fclose(mbox_file);
else
{
clearerr(mime_stream);
if (fseek(mime_stream, f_pos, SEEK_SET) == -1)
{
log_write(0, LOG_MAIN|LOG_PANIC,
"regex acl condition: mime_stream: %s", strerror(errno));
clearerr(mime_stream);
}
}
return ret;
}
int
mime_regex(const uschar **listptr)
{
pcre_list *re_list_head = NULL;
FILE *f;
uschar *mime_subject = NULL;
int mime_subject_len = 0;
int ret;
/* reset expansion variable */
regex_match_string = NULL;
/* precompile our regexes */
if (!(re_list_head = compile(*listptr)))
return FAIL; /* no regexes -> nothing to do */
/* check if the file is already decoded */
if (!mime_decoded_filename)
{ /* no, decode it first */
const uschar *empty = US"";
mime_decode(&empty);
if (!mime_decoded_filename)
{ /* decoding failed */
log_write(0, LOG_MAIN,
"mime_regex acl condition warning - could not decode MIME part to file");
return DEFER;
}
}
/* open file */
if (!(f = fopen(CS mime_decoded_filename, "rb")))
{
log_write(0, LOG_MAIN,
"mime_regex acl condition warning - can't open '%s' for reading",
mime_decoded_filename);
return DEFER;
}
/* get 32k memory, tainted */
mime_subject = store_get(32767, GET_TAINTED);
mime_subject_len = fread(mime_subject, 1, 32766, f);
ret = matcher(re_list_head, mime_subject, mime_subject_len);
(void)fclose(f);
return ret;
}
#endif /* WITH_CONTENT_SCAN */
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