src/srs.c

   1 /*************************************************
   2 *     Exim - an Internet mail transport agent    *
   3 *************************************************/
   4
   5 /* SRS - Sender rewriting scheme support
   6   (C)2004 Miles Wilton <miles@mirtol.com>
   7   Copyright (c) The Exim Maintainers 2016
   8
   9   SRS Support Version: 1.0a
  10
  11   License: GPL */
  12
  13 #include "exim.h"
  14 #ifdef EXPERIMENTAL_SRS
  15
  16 #include <srs_alt.h>
  17 #include "srs.h"
  18
  19 srs_t    *srs                   = NULL;
  20 uschar   *srs_db_forward        = NULL;
  21 uschar   *srs_db_reverse        = NULL;
  22
  23
  24 /* srs_init just initialises libsrs and creates (if necessary)
  25    an srs object to use for all srs calls in this instance */
  26
  27 int eximsrs_init()
  28 {
  29   const uschar *list = srs_config;
  30   uschar secret_buf[SRS_MAX_SECRET_LENGTH];
  31   uschar *secret = NULL;
  32   uschar sbuf[4];
  33   uschar *sbufp;
  34
  35   /* Check if this instance of Exim has not initialized SRS */
  36   if(srs == NULL)
  37   {
  38     int co = 0;
  39     int hashlen, maxage;
  40     BOOL usetimestamp, usehash;
  41
  42     /* Copy config vars */
  43     hashlen = srs_hashlength;
  44     maxage = srs_maxage;
  45     usetimestamp = srs_usetimestamp;
  46     usehash = srs_usehash;
  47
  48     /* Pass srs_config var (overrides new config vars) */
  49     co = 0;
  50     if(srs_config != NULL)
  51     {
  52       secret = string_nextinlist(&list, &co, secret_buf, SRS_MAX_SECRET_LENGTH);
  53
  54       if((sbufp = string_nextinlist(&list, &co, sbuf, sizeof(sbuf))) != NULL)
  55         maxage = atoi(sbuf);
  56
  57       if((sbufp = string_nextinlist(&list, &co, sbuf, sizeof(sbuf))) != NULL)
  58         hashlen = atoi(sbuf);
  59
  60       if((sbufp = string_nextinlist(&list, &co, sbuf, sizeof(sbuf))) != NULL)
  61         usetimestamp = atoi(sbuf);
  62
  63       if((sbufp = string_nextinlist(&list, &co, sbuf, sizeof(sbuf))) != NULL)
  64         usehash = atoi(sbuf);
  65     }
  66
  67     if(srs_hashmin == -1)
  68       srs_hashmin = hashlen;
  69
  70     /* First secret specified in secrets? */
  71     co = 0;
  72     list = srs_secrets;
  73     if(secret == NULL || *secret == '\0')
  74     {
  75       if((secret = string_nextinlist(&list, &co, secret_buf, SRS_MAX_SECRET_LENGTH)) == NULL)
  76       {
  77         log_write(0, LOG_MAIN | LOG_PANIC,
  78             "SRS Configuration Error: No secret specified");
  79         return DEFER;
  80       }
  81     }
  82
  83     /* Check config */
  84     if(maxage < 0 || maxage > 365)
  85     {
  86       log_write(0, LOG_MAIN | LOG_PANIC,
  87           "SRS Configuration Error: Invalid maximum timestamp age");
  88       return DEFER;
  89     }
  90     if(hashlen < 1 || hashlen > 20 || srs_hashmin < 1 || srs_hashmin > 20)
  91     {
  92       log_write(0, LOG_MAIN | LOG_PANIC,
  93           "SRS Configuration Error: Invalid hash length");
  94       return DEFER;
  95     }
  96
  97     if((srs = srs_open(secret, Ustrlen(secret), maxage, hashlen, srs_hashmin)) == NULL)
  98     {
  99       log_write(0, LOG_MAIN | LOG_PANIC,
 100           "Failed to allocate SRS memory");
 101       return DEFER;
 102     }
 103
 104     srs_set_option(srs, SRS_OPTION_USETIMESTAMP, usetimestamp);
 105     srs_set_option(srs, SRS_OPTION_USEHASH, usehash);
 106
 107     /* Extra secrets? */
 108     while((secret = string_nextinlist(&list, &co, secret_buf, SRS_MAX_SECRET_LENGTH)) != NULL)
 109         srs_add_secret(srs, secret, (Ustrlen(secret) > SRS_MAX_SECRET_LENGTH) ? SRS_MAX_SECRET_LENGTH :  Ustrlen(secret));
 110
 111     DEBUG(D_any)
 112       debug_printf("SRS initialized\n");
 113   }
 114
 115   return OK;
 116 }
 117
 118
 119 int eximsrs_done()
 120 {
 121   if(srs != NULL)
 122     srs_close(srs);
 123
 124   srs = NULL;
 125
 126   return OK;
 127 }
 128
 129
 130 int eximsrs_forward(uschar **result, uschar *orig_sender, uschar *domain)
 131 {
 132   char res[512];
 133   int n;
 134
 135   if((n = srs_forward(srs, orig_sender, domain, res, sizeof(res))) & SRS_RESULT_FAIL)
 136   {
 137     DEBUG(D_any)
 138       debug_printf("srs_forward failed (%s, %s): %s\n", orig_sender, domain, srs_geterrormsg(n));
 139     return DEFER;
 140   }
 141
 142   *result = string_copy(res);
 143   return OK;
 144 }
 145
 146
 147 int eximsrs_reverse(uschar **result, uschar *address)
 148 {
 149   char res[512];
 150   int n;
 151
 152   if((n = srs_reverse(srs, address, res, sizeof(res))) & SRS_RESULT_FAIL)
 153   {
 154     DEBUG(D_any)
 155       debug_printf("srs_reverse failed (%s): %s\n", address, srs_geterrormsg(n));
 156     if(n == SRS_RESULT_NOTSRS || n == SRS_RESULT_BADSRS)
 157       return DECLINE;
 158     if(n == SRS_RESULT_BADHASH || n == SRS_RESULT_BADTIMESTAMP || n == SRS_RESULT_TIMESTAMPEXPIRED)
 159       return FAIL;
 160     return DEFER;
 161   }
 162
 163   *result = string_copy(res);
 164   return OK;
 165 }
 166
 167
 168 int eximsrs_db_set(BOOL reverse, uschar *srs_db)
 169 {
 170   if(reverse)
 171     srs_db_reverse = (srs_db == NULL ? NULL : string_copy(srs_db));
 172   else
 173     srs_db_forward = (srs_db == NULL ? NULL : string_copy(srs_db));
 174
 175   if(srs_set_db_functions(srs, (srs_db_forward ? eximsrs_db_insert : NULL),
 176                                (srs_db_reverse ? eximsrs_db_lookup : NULL)) & SRS_RESULT_FAIL)
 177     return DEFER;
 178
 179   return OK;
 180 }
 181
 182
 183 srs_result eximsrs_db_insert(srs_t *srs, char *data, uint data_len, char *result, uint result_len)
 184 {
 185   uschar *res;
 186   uschar buf[64];
 187
 188   if(srs_db_forward == NULL)
 189     return SRS_RESULT_DBERROR;
 190
 191   srs_db_address = string_copyn(data, data_len);
 192   if(srs_generate_unique_id(srs, srs_db_address, buf, 64) & SRS_RESULT_FAIL)
 193     return SRS_RESULT_DBERROR;
 194
 195   srs_db_key = string_copyn(buf, 16);
 196
 197   if((res = expand_string(srs_db_forward)) == NULL)
 198     return SRS_RESULT_DBERROR;
 199
 200   if(result_len < 17)
 201     return SRS_RESULT_DBERROR;
 202
 203   Ustrncpy(result, srs_db_key, result_len);
 204
 205   return SRS_RESULT_OK;
 206 }
 207
 208
 209 srs_result eximsrs_db_lookup(srs_t *srs, char *data, uint data_len, char *result, uint result_len)
 210 {
 211   uschar *res;
 212
 213   if(srs_db_reverse == NULL)
 214     return SRS_RESULT_DBERROR;
 215
 216   srs_db_key = string_copyn(data, data_len);
 217   if((res = expand_string(srs_db_reverse)) == NULL)
 218     return SRS_RESULT_DBERROR;
 219
 220   if(Ustrlen(res) >= result_len)
 221     return SRS_RESULT_ADDRESSTOOLONG;
 222
 223   strncpy(result, res, result_len);
 224
 225   return SRS_RESULT_OK;
 226 }
 227
 228
 229 #endif
 230