src/src/regex.c

   1 /*************************************************
   2 *     Exim - an Internet mail transport agent    *
   3 *************************************************/
   4
   5 /* Copyright (c) Tom Kistner <tom@duncanthrax.net> 2003-2015 */
   6 /* License: GPL */
   7
   8 /* Code for matching regular expressions against headers and body.
   9  Called from acl.c. */
  10
  11 #include "exim.h"
  12 #ifdef WITH_CONTENT_SCAN
  13 #include <unistd.h>
  14 #include <sys/mman.h>
  15
  16 /* Structure to hold a list of Regular expressions */
  17 typedef struct pcre_list {
  18   pcre *re;
  19   uschar *pcre_text;
  20   struct pcre_list *next;
  21 } pcre_list;
  22
  23 uschar regex_match_string_buffer[1024];
  24
  25 extern FILE *mime_stream;
  26 extern uschar *mime_current_boundary;
  27
  28 static pcre_list *
  29 compile(const uschar * list)
  30 {
  31   int sep = 0;
  32   uschar *regex_string;
  33   uschar regex_string_buffer[1024];
  34   const char *pcre_error;
  35   int pcre_erroffset;
  36   pcre_list *re_list_head = NULL;
  37   pcre_list *ri;
  38
  39   /* precompile our regexes */
  40   while ((regex_string = string_nextinlist(&list, &sep,
  41                                            regex_string_buffer,
  42                                            sizeof(regex_string_buffer))) != NULL) {
  43     pcre *re;
  44
  45     /* parse option */
  46     if ( (strcmpic(regex_string,US"false") == 0) ||
  47          (Ustrcmp(regex_string,"0") == 0) )
  48       continue;                         /* explicitly no matching */
  49
  50     /* compile our regular expression */
  51     if (!(re = pcre_compile( CS regex_string,
  52                        0, &pcre_error, &pcre_erroffset, NULL ))) {
  53       log_write(0, LOG_MAIN,
  54            "regex acl condition warning - error in regex '%s': %s at offset %d, skipped.",
  55            regex_string, pcre_error, pcre_erroffset);
  56       continue;
  57     }
  58
  59     ri = store_get(sizeof(pcre_list));
  60     ri->re = re;
  61     ri->pcre_text = string_copy(regex_string);
  62     ri->next = re_list_head;
  63     re_list_head = ri;
  64   }
  65   return re_list_head;
  66 }
  67
  68 static int
  69 matcher(pcre_list * re_list_head, uschar * linebuffer, int len)
  70 {
  71   pcre_list * ri;
  72
  73   for(ri = re_list_head; ri; ri = ri->next)
  74     {
  75     int ovec[3*(REGEX_VARS+1)];
  76     int n, nn;
  77
  78     /* try matcher on the line */
  79     n = pcre_exec(ri->re, NULL,
  80          CS linebuffer, len, 0, 0,
  81          ovec, nelem(ovec));
  82     if (n > 0)
  83       {
  84       Ustrncpy(regex_match_string_buffer, ri->pcre_text, 1023);
  85       regex_match_string = regex_match_string_buffer;
  86
  87       for (nn = 1; nn < n; nn++)
  88         regex_vars[nn-1] =
  89           string_copyn(linebuffer + ovec[nn*2], ovec[nn*2+1] - ovec[nn*2]);
  90
  91       return OK;
  92       }
  93     }
  94   return FAIL;
  95 }
  96
  97 int
  98 regex(const uschar **listptr)
  99 {
 100   unsigned long mbox_size;
 101   FILE *mbox_file;
 102   pcre_list *re_list_head;
 103   uschar *linebuffer;
 104   long f_pos = 0;
 105   int ret = FAIL;
 106
 107   /* reset expansion variable */
 108   regex_match_string = NULL;
 109
 110   if (mime_stream == NULL) {                    /* We are in the DATA ACL */
 111     mbox_file = spool_mbox(&mbox_size, NULL);
 112     if (mbox_file == NULL) {                    /* error while spooling */
 113       log_write(0, LOG_MAIN|LOG_PANIC,
 114              "regex acl condition: error while creating mbox spool file");
 115       return DEFER;
 116     }
 117   }
 118   else {
 119     f_pos = ftell(mime_stream);
 120     mbox_file = mime_stream;
 121   }
 122
 123   /* precompile our regexes */
 124   if (!(re_list_head = compile(*listptr)))
 125     return FAIL;                        /* no regexes -> nothing to do */
 126
 127   /* match each line against all regexes */
 128   linebuffer = store_get(32767);
 129   while (fgets(CS linebuffer, 32767, mbox_file) != NULL) {
 130
 131     if (  mime_stream && mime_current_boundary          /* check boundary */
 132        && Ustrncmp(linebuffer,"--",2) == 0
 133        && Ustrncmp((linebuffer+2),mime_current_boundary,Ustrlen(mime_current_boundary)) == 0)
 134         break;                                          /* found boundary */
 135
 136     if ((ret = matcher(re_list_head, linebuffer, (int)Ustrlen(linebuffer))) == OK)
 137       goto done;
 138   }
 139   /* no matches ... */
 140
 141 done:
 142   if (mime_stream == NULL)
 143     (void)fclose(mbox_file);
 144   else {
 145     clearerr(mime_stream);
 146     fseek(mime_stream,f_pos,SEEK_SET);
 147   };
 148
 149   return ret;
 150 }
 151
 152
 153 int
 154 mime_regex(const uschar **listptr)
 155 {
 156   pcre_list *re_list_head = NULL;
 157   FILE *f;
 158   uschar *mime_subject = NULL;
 159   int mime_subject_len = 0;
 160   int ret;
 161
 162   /* reset expansion variable */
 163   regex_match_string = NULL;
 164
 165   /* precompile our regexes */
 166   if (!(re_list_head = compile(*listptr)))
 167     return FAIL;                        /* no regexes -> nothing to do */
 168
 169   /* check if the file is already decoded */
 170   if (mime_decoded_filename == NULL) {
 171     const uschar *empty = US"";
 172     /* no, decode it first */
 173     mime_decode(&empty);
 174     if (mime_decoded_filename == NULL) {
 175       /* decoding failed */
 176       log_write(0, LOG_MAIN,
 177            "mime_regex acl condition warning - could not decode MIME part to file.");
 178       return DEFER;
 179     }
 180   }
 181
 182   /* open file */
 183   if (!(f = fopen(CS mime_decoded_filename, "rb"))) {
 184     log_write(0, LOG_MAIN,
 185          "mime_regex acl condition warning - can't open '%s' for reading.",
 186          mime_decoded_filename);
 187     return DEFER;
 188   }
 189
 190   /* get 32k memory */
 191   mime_subject = (uschar *)store_get(32767);
 192
 193   mime_subject_len = fread(mime_subject, 1, 32766, f);
 194
 195   ret = matcher(re_list_head, mime_subject, mime_subject_len);
 196   (void)fclose(f);
 197   return ret;
 198 }
 199
 200 #endif /* WITH_CONTENT_SCAN */