src/src/regex.c

   1 /* $Cambridge: exim/src/src/regex.c,v 1.8 2010/06/05 11:13:30 pdp Exp $ */
   2
   3 /*************************************************
   4 *     Exim - an Internet mail transport agent    *
   5 *************************************************/
   6
   7 /* Copyright (c) Tom Kistner <tom@duncanthrax.net> 2003-???? */
   8 /* License: GPL */
   9
  10 /* Code for matching regular expressions against headers and body.
  11  Called from acl.c. */
  12
  13 #include "exim.h"
  14 #ifdef WITH_CONTENT_SCAN
  15 #include <unistd.h>
  16 #include <sys/mman.h>
  17
  18 /* Structure to hold a list of Regular expressions */
  19 typedef struct pcre_list {
  20   pcre *re;
  21   uschar *pcre_text;
  22   struct pcre_list *next;
  23 } pcre_list;
  24
  25 uschar regex_match_string_buffer[1024];
  26
  27 extern FILE *mime_stream;
  28 extern uschar *mime_current_boundary;
  29
  30 int regex(uschar **listptr) {
  31   int sep = 0;
  32   uschar *list = *listptr;
  33   uschar *regex_string;
  34   uschar regex_string_buffer[1024];
  35   unsigned long mbox_size;
  36   FILE *mbox_file;
  37   pcre *re;
  38   pcre_list *re_list_head = NULL;
  39   pcre_list *re_list_item;
  40   const char *pcre_error;
  41   int pcre_erroffset;
  42   uschar *linebuffer;
  43   long f_pos = 0;
  44
  45   /* reset expansion variable */
  46   regex_match_string = NULL;
  47
  48   if (mime_stream == NULL) {
  49     /* We are in the DATA ACL */
  50     mbox_file = spool_mbox(&mbox_size, NULL);
  51     if (mbox_file == NULL) {
  52       /* error while spooling */
  53       log_write(0, LOG_MAIN|LOG_PANIC,
  54              "regex acl condition: error while creating mbox spool file");
  55       return DEFER;
  56     };
  57   }
  58   else {
  59     f_pos = ftell(mime_stream);
  60     mbox_file = mime_stream;
  61   };
  62
  63   /* precompile our regexes */
  64   while ((regex_string = string_nextinlist(&list, &sep,
  65                                            regex_string_buffer,
  66                                            sizeof(regex_string_buffer))) != NULL) {
  67
  68     /* parse option */
  69     if ( (strcmpic(regex_string,US"false") == 0) ||
  70          (Ustrcmp(regex_string,"0") == 0) ) {
  71       /* explicitly no matching */
  72       continue;
  73     };
  74
  75     /* compile our regular expression */
  76     re = pcre_compile( CS regex_string,
  77                        0,
  78                        &pcre_error,
  79                        &pcre_erroffset,
  80                        NULL );
  81
  82     if (re == NULL) {
  83       log_write(0, LOG_MAIN,
  84            "regex acl condition warning - error in regex '%s': %s at offset %d, skipped.", regex_string, pcre_error, pcre_erroffset);
  85       continue;
  86     }
  87     else {
  88       re_list_item = store_get(sizeof(pcre_list));
  89       re_list_item->re = re;
  90       re_list_item->pcre_text = string_copy(regex_string);
  91       re_list_item->next = re_list_head;
  92       re_list_head = re_list_item;
  93     };
  94   };
  95
  96   /* no regexes -> nothing to do */
  97   if (re_list_head == NULL) {
  98     return FAIL;
  99   };
 100
 101   /* match each line against all regexes */
 102   linebuffer = store_get(32767);
 103   while (fgets(CS linebuffer, 32767, mbox_file) != NULL) {
 104     if ( (mime_stream != NULL) && (mime_current_boundary != NULL) ) {
 105       /* check boundary */
 106       if (Ustrncmp(linebuffer,"--",2) == 0) {
 107         if (Ustrncmp((linebuffer+2),mime_current_boundary,Ustrlen(mime_current_boundary)) == 0)
 108           /* found boundary */
 109           break;
 110       };
 111     };
 112     re_list_item = re_list_head;
 113     do {
 114       /* try matcher on the line */
 115       if (pcre_exec(re_list_item->re, NULL, CS linebuffer,
 116       (int)Ustrlen(linebuffer), 0, 0, NULL, 0) >= 0) {
 117         Ustrncpy(regex_match_string_buffer, re_list_item->pcre_text, 1023);
 118         regex_match_string = regex_match_string_buffer;
 119         if (mime_stream == NULL)
 120           (void)fclose(mbox_file);
 121         else {
 122           clearerr(mime_stream);
 123           fseek(mime_stream,f_pos,SEEK_SET);
 124         };
 125         return OK;
 126       };
 127       re_list_item = re_list_item->next;
 128     } while (re_list_item != NULL);
 129   };
 130
 131   if (mime_stream == NULL)
 132     (void)fclose(mbox_file);
 133   else {
 134     clearerr(mime_stream);
 135     fseek(mime_stream,f_pos,SEEK_SET);
 136   };
 137
 138   /* no matches ... */
 139   return FAIL;
 140 }
 141
 142
 143 int mime_regex(uschar **listptr) {
 144   int sep = 0;
 145   uschar *list = *listptr;
 146   uschar *regex_string;
 147   uschar regex_string_buffer[1024];
 148   pcre *re;
 149   pcre_list *re_list_head = NULL;
 150   pcre_list *re_list_item;
 151   const char *pcre_error;
 152   int pcre_erroffset;
 153   FILE *f;
 154   uschar *mime_subject = NULL;
 155   int mime_subject_len = 0;
 156
 157   /* reset expansion variable */
 158   regex_match_string = NULL;
 159
 160   /* precompile our regexes */
 161   while ((regex_string = string_nextinlist(&list, &sep,
 162                                            regex_string_buffer,
 163                                            sizeof(regex_string_buffer))) != NULL) {
 164
 165     /* parse option */
 166     if ( (strcmpic(regex_string,US"false") == 0) ||
 167          (Ustrcmp(regex_string,"0") == 0) ) {
 168       /* explicitly no matching */
 169       continue;
 170     };
 171
 172     /* compile our regular expression */
 173     re = pcre_compile( CS regex_string,
 174                        0,
 175                        &pcre_error,
 176                        &pcre_erroffset,
 177                        NULL );
 178
 179     if (re == NULL) {
 180       log_write(0, LOG_MAIN,
 181            "regex acl condition warning - error in regex '%s': %s at offset %d, skipped.", regex_string, pcre_error, pcre_erroffset);
 182       continue;
 183     }
 184     else {
 185       re_list_item = store_get(sizeof(pcre_list));
 186       re_list_item->re = re;
 187       re_list_item->pcre_text = string_copy(regex_string);
 188       re_list_item->next = re_list_head;
 189       re_list_head = re_list_item;
 190     };
 191   };
 192
 193   /* no regexes -> nothing to do */
 194   if (re_list_head == NULL) {
 195     return FAIL;
 196   };
 197
 198   /* check if the file is already decoded */
 199   if (mime_decoded_filename == NULL) {
 200     uschar *empty = US"";
 201     /* no, decode it first */
 202     mime_decode(&empty);
 203     if (mime_decoded_filename == NULL) {
 204       /* decoding failed */
 205       log_write(0, LOG_MAIN,
 206            "mime_regex acl condition warning - could not decode MIME part to file.");
 207       return DEFER;
 208     };
 209   };
 210
 211
 212   /* open file */
 213   f = fopen(CS mime_decoded_filename, "rb");
 214   if (f == NULL) {
 215     /* open failed */
 216     log_write(0, LOG_MAIN,
 217          "mime_regex acl condition warning - can't open '%s' for reading.", mime_decoded_filename);
 218     return DEFER;
 219   };
 220
 221   /* get 32k memory */
 222   mime_subject = (uschar *)store_get(32767);
 223
 224   /* read max 32k chars from file */
 225   mime_subject_len = fread(mime_subject, 1, 32766, f);
 226
 227   re_list_item = re_list_head;
 228   do {
 229     /* try matcher on the mmapped file */
 230     debug_printf("Matching '%s'\n", re_list_item->pcre_text);
 231     if (pcre_exec(re_list_item->re, NULL, CS mime_subject,
 232                   mime_subject_len, 0, 0, NULL, 0) >= 0) {
 233       Ustrncpy(regex_match_string_buffer, re_list_item->pcre_text, 1023);
 234       regex_match_string = regex_match_string_buffer;
 235       (void)fclose(f);
 236       return OK;
 237     };
 238     re_list_item = re_list_item->next;
 239   } while (re_list_item != NULL);
 240
 241   (void)fclose(f);
 242
 243   /* no matches ... */
 244   return FAIL;
 245 }
 246
 247 #endif