src/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
  28 eximsrs_init()
  29 {
  30 const uschar *list = srs_config;
  31 uschar secret_buf[SRS_MAX_SECRET_LENGTH];
  32 uschar *secret = NULL;
  33 uschar sbuf[4];
  34 uschar *sbufp;
  35
  36 /* Check if this instance of Exim has not initialized SRS */
  37 if (srs == NULL)
  38   {
  39   int co = 0;
  40   int hashlen, maxage;
  41   BOOL usetimestamp, usehash;
  42
  43   /* Copy config vars */
  44   hashlen = srs_hashlength;
  45   maxage = srs_maxage;
  46   usetimestamp = srs_usetimestamp;
  47   usehash = srs_usehash;
  48
  49   /* Pass srs_config var (overrides new config vars) */
  50   co = 0;
  51   if (srs_config != NULL)
  52     {
  53     secret = string_nextinlist(&list, &co, secret_buf, SRS_MAX_SECRET_LENGTH);
  54
  55     if ((sbufp = string_nextinlist(&list, &co, sbuf, sizeof(sbuf))))
  56       maxage = atoi(sbuf);
  57
  58     if ((sbufp = string_nextinlist(&list, &co, sbuf, sizeof(sbuf))))
  59       hashlen = atoi(sbuf);
  60
  61     if ((sbufp = string_nextinlist(&list, &co, sbuf, sizeof(sbuf))))
  62       usetimestamp = atoi(sbuf);
  63
  64     if ((sbufp = string_nextinlist(&list, &co, sbuf, sizeof(sbuf))))
  65       usehash = atoi(sbuf);
  66     }
  67
  68   if (srs_hashmin == -1)
  69     srs_hashmin = hashlen;
  70
  71   /* First secret specified in secrets? */
  72   co = 0;
  73   list = srs_secrets;
  74   if (secret == NULL || *secret == '\0')
  75     if (!(secret = string_nextinlist(&list, &co, secret_buf, SRS_MAX_SECRET_LENGTH)))
  76       {
  77       log_write(0, LOG_MAIN | LOG_PANIC,
  78           "SRS Configuration Error: No secret specified");
  79       return DEFER;
  80       }
  81
  82   /* Check config */
  83   if (maxage < 0 || maxage > 365)
  84     {
  85     log_write(0, LOG_MAIN | LOG_PANIC,
  86         "SRS Configuration Error: Invalid maximum timestamp age");
  87     return DEFER;
  88     }
  89   if (hashlen < 1 || hashlen > 20 || srs_hashmin < 1 || srs_hashmin > 20)
  90     {
  91     log_write(0, LOG_MAIN | LOG_PANIC,
  92         "SRS Configuration Error: Invalid hash length");
  93     return DEFER;
  94     }
  95
  96   if (!(srs = srs_open(secret, Ustrlen(secret), maxage, hashlen, srs_hashmin)))
  97     {
  98     log_write(0, LOG_MAIN | LOG_PANIC,
  99         "Failed to allocate SRS memory");
 100     return DEFER;
 101     }
 102
 103   srs_set_option(srs, SRS_OPTION_USETIMESTAMP, usetimestamp);
 104   srs_set_option(srs, SRS_OPTION_USEHASH, usehash);
 105
 106   /* Extra secrets? */
 107   while((secret = string_nextinlist(&list, &co, secret_buf, SRS_MAX_SECRET_LENGTH)))
 108       srs_add_secret(srs, secret,
 109         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
 120 eximsrs_done()
 121 {
 122 if (srs) srs_close(srs);
 123 srs = NULL;
 124 return OK;
 125 }
 126
 127
 128 int
 129 eximsrs_forward(uschar **result, uschar *orig_sender, uschar *domain)
 130 {
 131 char res[512];
 132 int n;
 133
 134 if ((n = srs_forward(srs, orig_sender, domain, res, sizeof(res))) & SRS_RESULT_FAIL)
 135   {
 136   DEBUG(D_any)
 137     debug_printf("srs_forward failed (%s, %s): %s\n", orig_sender, domain, srs_geterrormsg(n));
 138   return DEFER;
 139   }
 140
 141 *result = string_copy(res);
 142 return OK;
 143 }
 144
 145
 146 int
 147 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
 169 eximsrs_db_set(BOOL reverse, uschar *srs_db)
 170 {
 171 if (reverse)
 172   srs_db_reverse = (srs_db == NULL ? NULL : string_copy(srs_db));
 173 else
 174   srs_db_forward = (srs_db == NULL ? NULL : string_copy(srs_db));
 175
 176 if (srs_set_db_functions(srs, (srs_db_forward ? eximsrs_db_insert : NULL),
 177                              (srs_db_reverse ? eximsrs_db_lookup : NULL)) & SRS_RESULT_FAIL)
 178   return DEFER;
 179
 180 return OK;
 181 }
 182
 183
 184 srs_result
 185 eximsrs_db_insert(srs_t *srs, char *data, uint data_len, char *result, uint result_len)
 186 {
 187 uschar *res;
 188 uschar buf[64];
 189
 190 if (srs_db_forward == NULL)
 191   return SRS_RESULT_DBERROR;
 192
 193 srs_db_address = string_copyn(data, data_len);
 194 if (srs_generate_unique_id(srs, srs_db_address, buf, 64) & SRS_RESULT_FAIL)
 195   return SRS_RESULT_DBERROR;
 196
 197 srs_db_key = string_copyn(buf, 16);
 198
 199 if ((res = expand_string(srs_db_forward)) == NULL)
 200   return SRS_RESULT_DBERROR;
 201
 202 if (result_len < 17)
 203   return SRS_RESULT_DBERROR;
 204
 205 Ustrncpy(result, srs_db_key, result_len);
 206
 207 return SRS_RESULT_OK;
 208 }
 209
 210
 211 srs_result
 212 eximsrs_db_lookup(srs_t *srs, char *data, uint data_len, char *result, uint result_len)
 213 {
 214 uschar *res;
 215
 216 if (srs_db_reverse == NULL)
 217   return SRS_RESULT_DBERROR;
 218
 219 srs_db_key = string_copyn(data, data_len);
 220 if ((res = expand_string(srs_db_reverse)) == NULL)
 221   return SRS_RESULT_DBERROR;
 222
 223 if (Ustrlen(res) >= result_len)
 224   return SRS_RESULT_ADDRESSTOOLONG;
 225
 226 strncpy(result, res, result_len);
 227
 228 return SRS_RESULT_OK;
 229 }
 230
 231
 232 #endif
 233