ARC: relax restriction on building without SPF

[users/jgh/exim.git] / src / src / dmarc.c

diff --git a/src/src/dmarc.c b/src/src/dmarc.c
index c4edc9159b72f5e0880d02950152a7c1268e271b..2e43f846d39155e8116a7f067bc20a30a4292e2e 100644 (file)
--- a/src/src/dmarc.c
+++ b/src/src/dmarc.c
@@ -1,8 +1,9 @@
 /*************************************************
 *     Exim - an Internet mail transport agent    *
 *************************************************/
-/* Experimental DMARC support.
+/* DMARC support.
    Copyright (c) Todd Lyons <tlyons@exim.org> 2012 - 2014
+   Copyright (c) The Exim Maintainers 2019
    License: GPL */
 
 /* Portions Copyright (c) 2012, 2013, The Trusted Domain Project;
@@ -11,7 +12,7 @@
 /* Code for calling dmarc checks via libopendmarc. Called from acl.c. */
 
 #include "exim.h"
-#ifdef EXPERIMENTAL_DMARC
+#ifdef SUPPORT_DMARC
 # if !defined SUPPORT_SPF
 #  error SPF must also be enabled for DMARC
 # elif defined DISABLE_DKIM
@@ -109,15 +110,15 @@ if (libdm_status != DMARC_PARSE_OKAY)
                       opendmarc_policy_status_to_str(libdm_status));
   dmarc_abort = TRUE;
   }
-if (!dmarc_tld_file)
+if (!dmarc_tld_file || !*dmarc_tld_file)
   {
   DEBUG(D_receive) debug_printf("DMARC: no dmarc_tld_file\n");
   dmarc_abort = TRUE;
   }
 else if (opendmarc_tld_read_file(CS dmarc_tld_file, NULL, NULL, NULL))
   {
-  log_write(0, LOG_MAIN|LOG_PANIC, "DMARC failure to load tld list %s: %d",
-                      dmarc_tld_file, errno);
+  log_write(0, LOG_MAIN|LOG_PANIC, "DMARC failure to load tld list '%s': %s",
+                      dmarc_tld_file, strerror(errno));
   dmarc_abort = TRUE;
   }
 if (!sender_host_address)
@@ -203,6 +204,25 @@ if (  dmarc_policy == DMARC_POLICY_REJECT     && action == DMARC_RESULT_REJECT
     }
 }
 
+
+/* Look up a DNS dmarc record for the given domain.  Return it or NULL */
+
+static uschar *
+dmarc_dns_lookup(uschar * dom)
+{
+dns_answer * dnsa = store_get_dns_answer();
+dns_scan dnss;
+int rc = dns_lookup(dnsa, string_sprintf("_dmarc.%s", dom), T_TXT, NULL);
+
+if (rc == DNS_SUCCEED)
+  for (dns_record * rr = dns_next_rr(dnsa, &dnss, RESET_ANSWERS); rr;
+       rr = dns_next_rr(dnsa, &dnss, RESET_NEXT))
+    if (rr->type == T_TXT && rr->size > 3)
+      return string_copyn(US rr->data, rr->size);
+return NULL;
+}
+
+
 /* dmarc_process adds the envelope sender address to the existing
 context (if any), retrieves the result, sets up expansion
 strings and evaluates the condition outcome. */
@@ -214,6 +234,7 @@ int sr, origin;             /* used in SPF section */
 int dmarc_spf_result  = 0;  /* stores spf into dmarc conn ctx */
 int tmp_ans, c;
 pdkim_signature * sig = dkim_signatures;
+uschar * rr;
 BOOL has_dmarc_record = TRUE;
 u_char **ruf; /* forensic report addressees, if called for */
 
@@ -358,7 +379,15 @@ if (!dmarc_abort && !sender_host_authenticated)
                                         sig->domain, dkim_ares_result);
     sig = sig->next;
     }
-  libdm_status = opendmarc_policy_query_dmarc(dmarc_pctx, US"");
+
+  /* Look up DMARC policy record in DNS.  We do this explicitly, rather than
+  letting the dmarc library do it with opendmarc_policy_query_dmarc(), so that
+  our dns access path is used for debug tracing and for the testsuite
+  diversion. */
+
+  libdm_status = (rr = dmarc_dns_lookup(header_from_sender))
+    ? opendmarc_policy_store_dmarc(dmarc_pctx, rr, header_from_sender, NULL)
+    : DMARC_DNS_ERROR_NO_RECORD;
   switch (libdm_status)
     {
     case DMARC_DNS_ERROR_NXDOMAIN:
@@ -398,11 +427,11 @@ if (!dmarc_abort && !sender_host_authenticated)
   /* Can't use exim's string manipulation functions so allocate memory
   for libopendmarc using its max hostname length definition. */
 
-  dmarc_domain = US calloc(DMARC_MAXHOSTNAMELEN, sizeof(uschar));
+  dmarc_domain = store_get(DMARC_MAXHOSTNAMELEN, TRUE);
   libdm_status = opendmarc_policy_fetch_utilized_domain(dmarc_pctx,
     dmarc_domain, DMARC_MAXHOSTNAMELEN-1);
-  dmarc_used_domain = string_copy(dmarc_domain);
-  free(dmarc_domain);
+  store_release_above(dmarc_domain + Ustrlen(dmarc_domain)+1);
+  dmarc_used_domain = dmarc_domain;
 
   if (libdm_status != DMARC_PARSE_OKAY)
     log_write(0, LOG_MAIN|LOG_PANIC,
@@ -606,6 +635,6 @@ return g;
 }
 
 # endif /* SUPPORT_SPF */
-#endif /* EXPERIMENTAL_DMARC */
+#endif /* SUPPORT_DMARC */
 /* vi: aw ai sw=2
  */