src/src/spf.c

   1 /*************************************************
   2 *     Exim - an Internet mail transport agent    *
   3 *************************************************/
   4
   5 /* Experimental SPF support.
   6    Copyright (c) Tom Kistner <tom@duncanthrax.net> 2004
   7    License: GPL */
   8
   9 /* Code for calling spf checks via libspf-alt. Called from acl.c. */
  10
  11 #include "exim.h"
  12 #ifdef EXPERIMENTAL_SPF
  13
  14 /* must be kept in numeric order */
  15 static spf_result_id spf_result_id_list[] = {
  16   { US"invalid", 0},
  17   { US"neutral", 1 },
  18   { US"pass", 2 },
  19   { US"fail", 3 },
  20   { US"softfail", 4 },
  21   { US"none", 5 },
  22   { US"err_temp", 6 },
  23   { US"err_perm", 7 }
  24 };
  25
  26 SPF_server_t    *spf_server = NULL;
  27 SPF_request_t   *spf_request = NULL;
  28 SPF_response_t  *spf_response = NULL;
  29 SPF_response_t  *spf_response_2mx = NULL;
  30
  31 /* spf_init sets up a context that can be re-used for several
  32    messages on the same SMTP connection (that come from the
  33    same host with the same HELO string) */
  34
  35 int spf_init(uschar *spf_helo_domain, uschar *spf_remote_addr) {
  36
  37   spf_server = SPF_server_new(SPF_DNS_CACHE, 0);
  38
  39   if ( spf_server == NULL ) {
  40     debug_printf("spf: SPF_server_new() failed.\n");
  41     return 0;
  42   }
  43
  44   if (SPF_server_set_rec_dom(spf_server, CS primary_hostname)) {
  45     debug_printf("spf: SPF_server_set_rec_dom(\"%s\") failed.\n", primary_hostname);
  46     spf_server = NULL;
  47     return 0;
  48   }
  49
  50   spf_request = SPF_request_new(spf_server);
  51
  52   if (SPF_request_set_ipv4_str(spf_request, CS spf_remote_addr)
  53       && SPF_request_set_ipv6_str(spf_request, CS spf_remote_addr)) {
  54     debug_printf("spf: SPF_request_set_ipv4_str() and SPF_request_set_ipv6_str() failed [%s]\n", spf_remote_addr);
  55     spf_server = NULL;
  56     spf_request = NULL;
  57     return 0;
  58   }
  59
  60   if (SPF_request_set_helo_dom(spf_request, CS spf_helo_domain)) {
  61     debug_printf("spf: SPF_set_helo_dom(\"%s\") failed.\n", spf_helo_domain);
  62     spf_server = NULL;
  63     spf_request = NULL;
  64     return 0;
  65   }
  66
  67   return 1;
  68 }
  69
  70
  71 /* spf_process adds the envelope sender address to the existing
  72    context (if any), retrieves the result, sets up expansion
  73    strings and evaluates the condition outcome. */
  74
  75 int spf_process(uschar **listptr, uschar *spf_envelope_sender, int action) {
  76   int sep = 0;
  77   uschar *list = *listptr;
  78   uschar *spf_result_id;
  79   uschar spf_result_id_buffer[128];
  80   int rc = SPF_RESULT_PERMERROR;
  81
  82   if (!(spf_server && spf_request)) {
  83     /* no global context, assume temp error and skip to evaluation */
  84     rc = SPF_RESULT_PERMERROR;
  85     goto SPF_EVALUATE;
  86   };
  87
  88   if (SPF_request_set_env_from(spf_request, CS spf_envelope_sender)) {
  89     /* Invalid sender address. This should be a real rare occurence */
  90     rc = SPF_RESULT_PERMERROR;
  91     goto SPF_EVALUATE;
  92   }
  93
  94   /* get SPF result */
  95   if (action == SPF_PROCESS_FALLBACK)
  96     SPF_request_query_fallback(spf_request, &spf_response, CS spf_guess);
  97   else
  98     SPF_request_query_mailfrom(spf_request, &spf_response);
  99
 100   /* set up expansion items */
 101   spf_header_comment     = (uschar *)SPF_response_get_header_comment(spf_response);
 102   spf_received           = (uschar *)SPF_response_get_received_spf(spf_response);
 103   spf_result             = (uschar *)SPF_strresult(SPF_response_result(spf_response));
 104   spf_smtp_comment       = (uschar *)SPF_response_get_smtp_comment(spf_response);
 105
 106   rc = SPF_response_result(spf_response);
 107
 108   /* We got a result. Now see if we should return OK or FAIL for it */
 109   SPF_EVALUATE:
 110   debug_printf("SPF result is %s (%d)\n", SPF_strresult(rc), rc);
 111
 112   if (action == SPF_PROCESS_GUESS && (!strcmp (SPF_strresult(rc), "none")))
 113     return spf_process(listptr, spf_envelope_sender, SPF_PROCESS_FALLBACK);
 114
 115   while ((spf_result_id = string_nextinlist(&list, &sep,
 116                                      spf_result_id_buffer,
 117                                      sizeof(spf_result_id_buffer))) != NULL) {
 118     int negate = 0;
 119     int result = 0;
 120
 121     /* Check for negation */
 122     if (spf_result_id[0] == '!') {
 123       negate = 1;
 124       spf_result_id++;
 125     };
 126
 127     /* Check the result identifier */
 128     result = Ustrcmp(spf_result_id, spf_result_id_list[rc].name);
 129     if (!negate && result==0) return OK;
 130     if (negate && result!=0) return OK;
 131   };
 132
 133   /* no match */
 134   return FAIL;
 135 }
 136
 137 #endif