src/src/spf.c

   1 /* $Cambridge: exim/src/src/spf.c,v 1.9 2009/11/11 10:08:02 nm4 Exp $ */
   2
   3 /*************************************************
   4 *     Exim - an Internet mail transport agent    *
   5 *************************************************/
   6
   7 /* Experimental SPF support.
   8    Copyright (c) Tom Kistner <tom@duncanthrax.net> 2004
   9    License: GPL */
  10
  11 /* Code for calling spf checks via libspf-alt. Called from acl.c. */
  12
  13 #include "exim.h"
  14 #ifdef EXPERIMENTAL_SPF
  15
  16 /* must be kept in numeric order */
  17 static spf_result_id spf_result_id_list[] = {
  18   { US"invalid", 0},
  19   { US"neutral", 1 },
  20   { US"pass", 2 },
  21   { US"fail", 3 },
  22   { US"softfail", 4 },
  23   { US"none", 5 },
  24   { US"err_temp", 6 },
  25   { US"err_perm", 7 }
  26 };
  27
  28 SPF_server_t    *spf_server = NULL;
  29 SPF_request_t   *spf_request = NULL;
  30 SPF_response_t  *spf_response = NULL;
  31 SPF_response_t  *spf_response_2mx = NULL;
  32
  33 /* spf_init sets up a context that can be re-used for several
  34    messages on the same SMTP connection (that come from the
  35    same host with the same HELO string) */
  36
  37 int spf_init(uschar *spf_helo_domain, uschar *spf_remote_addr) {
  38
  39   spf_server = SPF_server_new(SPF_DNS_CACHE, 0);
  40
  41   if ( spf_server == NULL ) {
  42     debug_printf("spf: SPF_server_new() failed.\n");
  43     return 0;
  44   }
  45
  46   if (SPF_server_set_rec_dom(spf_server, CS primary_hostname)) {
  47     debug_printf("spf: SPF_server_set_rec_dom() failed.\n");
  48     spf_server = NULL;
  49     return 0;
  50   }
  51
  52   spf_request = SPF_request_new(spf_server);
  53
  54   if (SPF_request_set_ipv4_str(spf_request, CS spf_remote_addr)) {
  55     debug_printf("spf: SPF_request_set_ipv4_str() failed.\n");
  56     spf_server = NULL;
  57     spf_request = NULL;
  58     return 0;
  59   }
  60
  61   if (SPF_request_set_helo_dom(spf_request, CS spf_helo_domain)) {
  62     debug_printf("spf: SPF_set_helo_dom() failed.\n");
  63     spf_server = NULL;
  64     spf_request = NULL;
  65     return 0;
  66   }
  67
  68   return 1;
  69 }
  70
  71
  72 /* spf_process adds the envelope sender address to the existing
  73    context (if any), retrieves the result, sets up expansion
  74    strings and evaluates the condition outcome. */
  75
  76 int spf_process(uschar **listptr, uschar *spf_envelope_sender, int action) {
  77   int sep = 0;
  78   uschar *list = *listptr;
  79   uschar *spf_result_id;
  80   uschar spf_result_id_buffer[128];
  81   int rc = SPF_RESULT_PERMERROR;
  82
  83   if (!(spf_server && spf_request)) {
  84     /* no global context, assume temp error and skip to evaluation */
  85     rc = SPF_RESULT_PERMERROR;
  86     goto SPF_EVALUATE;
  87   };
  88
  89   if (SPF_request_set_env_from(spf_request, CS spf_envelope_sender)) {
  90     /* Invalid sender address. This should be a real rare occurence */
  91     rc = SPF_RESULT_PERMERROR;
  92     goto SPF_EVALUATE;
  93   }
  94
  95   /* get SPF result */
  96   if (action == SPF_PROCESS_FALLBACK)
  97     SPF_request_query_fallback(spf_request, &spf_response, CS spf_guess);
  98   else
  99     SPF_request_query_mailfrom(spf_request, &spf_response);
 100
 101   /* set up expansion items */
 102   spf_header_comment     = (uschar *)SPF_response_get_header_comment(spf_response);
 103   spf_received           = (uschar *)SPF_response_get_received_spf(spf_response);
 104   spf_result             = (uschar *)SPF_strresult(SPF_response_result(spf_response));
 105   spf_smtp_comment       = (uschar *)SPF_response_get_smtp_comment(spf_response);
 106
 107   rc = SPF_response_result(spf_response);
 108
 109   /* We got a result. Now see if we should return OK or FAIL for it */
 110   SPF_EVALUATE:
 111   debug_printf("SPF result is %s (%d)\n", SPF_strresult(rc), rc);
 112
 113   if (action == SPF_PROCESS_GUESS && (!strcmp (SPF_strresult(rc), "none")))
 114     return spf_process(listptr, spf_envelope_sender, SPF_PROCESS_FALLBACK);
 115
 116   while ((spf_result_id = string_nextinlist(&list, &sep,
 117                                      spf_result_id_buffer,
 118                                      sizeof(spf_result_id_buffer))) != NULL) {
 119     int negate = 0;
 120     int result = 0;
 121
 122     /* Check for negation */
 123     if (spf_result_id[0] == '!') {
 124       negate = 1;
 125       spf_result_id++;
 126     };
 127
 128     /* Check the result identifier */
 129     result = Ustrcmp(spf_result_id, spf_result_id_list[rc].name);
 130     if (!negate && result==0) return OK;
 131     if (negate && result!=0) return OK;
 132   };
 133
 134   /* no match */
 135   return FAIL;
 136 }
 137
 138 #endif