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() failed.\n");
  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     debug_printf("spf: SPF_request_set_ipv4_str() failed.\n");
  54     spf_server = NULL;
  55     spf_request = NULL;
  56     return 0;
  57   }
  58
  59   if (SPF_request_set_helo_dom(spf_request, CS spf_helo_domain)) {
  60     debug_printf("spf: SPF_set_helo_dom() failed.\n");
  61     spf_server = NULL;
  62     spf_request = NULL;
  63     return 0;
  64   }
  65
  66   return 1;
  67 }
  68
  69
  70 /* spf_process adds the envelope sender address to the existing
  71    context (if any), retrieves the result, sets up expansion
  72    strings and evaluates the condition outcome. */
  73
  74 int spf_process(uschar **listptr, uschar *spf_envelope_sender, int action) {
  75   int sep = 0;
  76   uschar *list = *listptr;
  77   uschar *spf_result_id;
  78   uschar spf_result_id_buffer[128];
  79   int rc = SPF_RESULT_PERMERROR;
  80
  81   if (!(spf_server && spf_request)) {
  82     /* no global context, assume temp error and skip to evaluation */
  83     rc = SPF_RESULT_PERMERROR;
  84     goto SPF_EVALUATE;
  85   };
  86
  87   if (SPF_request_set_env_from(spf_request, CS spf_envelope_sender)) {
  88     /* Invalid sender address. This should be a real rare occurence */
  89     rc = SPF_RESULT_PERMERROR;
  90     goto SPF_EVALUATE;
  91   }
  92
  93   /* get SPF result */
  94   if (action == SPF_PROCESS_FALLBACK)
  95     SPF_request_query_fallback(spf_request, &spf_response, CS spf_guess);
  96   else
  97     SPF_request_query_mailfrom(spf_request, &spf_response);
  98
  99   /* set up expansion items */
 100   spf_header_comment     = (uschar *)SPF_response_get_header_comment(spf_response);
 101   spf_received           = (uschar *)SPF_response_get_received_spf(spf_response);
 102   spf_result             = (uschar *)SPF_strresult(SPF_response_result(spf_response));
 103   spf_smtp_comment       = (uschar *)SPF_response_get_smtp_comment(spf_response);
 104
 105   rc = SPF_response_result(spf_response);
 106
 107   /* We got a result. Now see if we should return OK or FAIL for it */
 108   SPF_EVALUATE:
 109   debug_printf("SPF result is %s (%d)\n", SPF_strresult(rc), rc);
 110
 111   if (action == SPF_PROCESS_GUESS && (!strcmp (SPF_strresult(rc), "none")))
 112     return spf_process(listptr, spf_envelope_sender, SPF_PROCESS_FALLBACK);
 113
 114   while ((spf_result_id = string_nextinlist(&list, &sep,
 115                                      spf_result_id_buffer,
 116                                      sizeof(spf_result_id_buffer))) != NULL) {
 117     int negate = 0;
 118     int result = 0;
 119
 120     /* Check for negation */
 121     if (spf_result_id[0] == '!') {
 122       negate = 1;
 123       spf_result_id++;
 124     };
 125
 126     /* Check the result identifier */
 127     result = Ustrcmp(spf_result_id, spf_result_id_list[rc].name);
 128     if (!negate && result==0) return OK;
 129     if (negate && result!=0) return OK;
 130   };
 131
 132   /* no match */
 133   return FAIL;
 134 }
 135
 136 #endif