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 - 2014
   7    License: GPL
   8    Copyright (c) The Exim Maintainers 2015 - 2018
   9 */
  10
  11 /* Code for calling spf checks via libspf-alt. Called from acl.c. */
  12
  13 #include "exim.h"
  14 #ifdef SUPPORT_SPF
  15
  16 /* must be kept in numeric order */
  17 static spf_result_id spf_result_id_list[] = {
  18   /* name               value */
  19   { US"invalid",        0},
  20   { US"neutral",        1 },
  21   { US"pass",           2 },
  22   { US"fail",           3 },
  23   { US"softfail",       4 },
  24   { US"none",           5 },
  25   { US"err_temp",       6 },  /* Deprecated Apr 2014 */
  26   { US"err_perm",       7 },  /* Deprecated Apr 2014 */
  27   { US"temperror",      6 }, /* RFC 4408 defined */
  28   { US"permerror",      7 }  /* RFC 4408 defined */
  29 };
  30
  31 SPF_server_t    *spf_server = NULL;
  32 SPF_request_t   *spf_request = NULL;
  33 SPF_response_t  *spf_response = NULL;
  34 SPF_response_t  *spf_response_2mx = NULL;
  35
  36
  37 /* spf_init sets up a context that can be re-used for several
  38    messages on the same SMTP connection (that come from the
  39    same host with the same HELO string)
  40
  41 Return: Boolean success */
  42
  43 BOOL
  44 spf_init(uschar *spf_helo_domain, uschar *spf_remote_addr)
  45 {
  46 spf_server = SPF_server_new(SPF_DNS_CACHE, 0);
  47
  48 if (!spf_server)
  49   {
  50   DEBUG(D_receive) debug_printf("spf: SPF_server_new() failed.\n");
  51   return FALSE;
  52   }
  53
  54 if (SPF_server_set_rec_dom(spf_server, CS primary_hostname))
  55   {
  56   DEBUG(D_receive) debug_printf("spf: SPF_server_set_rec_dom(\"%s\") failed.\n",
  57     primary_hostname);
  58   spf_server = NULL;
  59   return FALSE;
  60   }
  61
  62 spf_request = SPF_request_new(spf_server);
  63
  64 if (  SPF_request_set_ipv4_str(spf_request, CS spf_remote_addr)
  65    && SPF_request_set_ipv6_str(spf_request, CS spf_remote_addr)
  66    )
  67   {
  68   DEBUG(D_receive)
  69     debug_printf("spf: SPF_request_set_ipv4_str() and "
  70       "SPF_request_set_ipv6_str() failed [%s]\n", spf_remote_addr);
  71   spf_server = NULL;
  72   spf_request = NULL;
  73   return FALSE;
  74   }
  75
  76 if (SPF_request_set_helo_dom(spf_request, CS spf_helo_domain))
  77   {
  78   DEBUG(D_receive) debug_printf("spf: SPF_set_helo_dom(\"%s\") failed.\n",
  79     spf_helo_domain);
  80   spf_server = NULL;
  81   spf_request = NULL;
  82   return FALSE;
  83   }
  84
  85 return TRUE;
  86 }
  87
  88
  89 /* spf_process adds the envelope sender address to the existing
  90    context (if any), retrieves the result, sets up expansion
  91    strings and evaluates the condition outcome.
  92
  93 Return: OK/FAIL  */
  94
  95 int
  96 spf_process(const uschar **listptr, uschar *spf_envelope_sender, int action)
  97 {
  98 int sep = 0;
  99 const uschar *list = *listptr;
 100 uschar *spf_result_id;
 101 int rc = SPF_RESULT_PERMERROR;
 102
 103 if (!(spf_server && spf_request))
 104   /* no global context, assume temp error and skip to evaluation */
 105   rc = SPF_RESULT_PERMERROR;
 106
 107 else if (SPF_request_set_env_from(spf_request, CS spf_envelope_sender))
 108   /* Invalid sender address. This should be a real rare occurence */
 109   rc = SPF_RESULT_PERMERROR;
 110
 111 else
 112   {
 113   /* get SPF result */
 114   if (action == SPF_PROCESS_FALLBACK)
 115     {
 116     SPF_request_query_fallback(spf_request, &spf_response, CS spf_guess);
 117     spf_result_guessed = TRUE;
 118     }
 119   else
 120     SPF_request_query_mailfrom(spf_request, &spf_response);
 121
 122   /* set up expansion items */
 123   spf_header_comment     = US SPF_response_get_header_comment(spf_response);
 124   spf_received           = US SPF_response_get_received_spf(spf_response);
 125   spf_result             = US SPF_strresult(SPF_response_result(spf_response));
 126   spf_smtp_comment       = US SPF_response_get_smtp_comment(spf_response);
 127
 128   rc = SPF_response_result(spf_response);
 129   }
 130
 131 /* We got a result. Now see if we should return OK or FAIL for it */
 132 DEBUG(D_acl) debug_printf("SPF result is %s (%d)\n", SPF_strresult(rc), rc);
 133
 134 if (action == SPF_PROCESS_GUESS && (!strcmp (SPF_strresult(rc), "none")))
 135   return spf_process(listptr, spf_envelope_sender, SPF_PROCESS_FALLBACK);
 136
 137 while ((spf_result_id = string_nextinlist(&list, &sep, NULL, 0)))
 138   {
 139   BOOL negate, result;
 140
 141   if ((negate = spf_result_id[0] == '!'))
 142     spf_result_id++;
 143
 144   result = Ustrcmp(spf_result_id, spf_result_id_list[rc].name) == 0;
 145   if (negate != result) return OK;
 146   }
 147
 148 /* no match */
 149 return FAIL;
 150 }
 151
 152
 153
 154 gstring *
 155 authres_spf(gstring * g)
 156 {
 157 uschar * s;
 158 if (!spf_result) return g;
 159
 160 g = string_append(g, 2, US";\n\tspf=", spf_result);
 161 if (spf_result_guessed)
 162   g = string_cat(g, US" (best guess record for domain)");
 163
 164 s = expand_string(US"$sender_address_domain");
 165 return s && *s
 166   ? string_append(g, 2, US" smtp.mailfrom=", s)
 167   : string_cat(g, US" smtp.mailfrom=<>");
 168 }
 169
 170
 171 #endif