SPF: switch to NO_DATA for SPF-rr lookups. Bug 1294

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

diff --git a/src/src/spf.c b/src/src/spf.c
index 7192ef462912f21ff0889284e7014ee59a02454e..f120f722c81106274966517b09423ca6c920f2e0 100644 (file)
--- a/src/src/spf.c
+++ b/src/src/spf.c
@@ -5,7 +5,7 @@
 /* SPF support.
    Copyright (c) Tom Kistner <tom@duncanthrax.net> 2004 - 2014
    License: GPL
-   Copyright (c) The Exim Maintainers 2015 - 2019
+   Copyright (c) The Exim Maintainers 2015 - 2020
 */
 
 /* Code for calling spf checks via libspf-alt. Called from acl.c. */
@@ -34,6 +34,18 @@ SPF_response_t  *spf_response_2mx = NULL;
 SPF_dns_rr_t  * spf_nxdomain = NULL;
 
 
+void
+spf_lib_version_report(FILE * fp)
+{
+int maj, min, patch;
+SPF_get_lib_version(&maj, &min, &patch);
+fprintf(fp, "Library version: spf2: Compile: %d.%d.%d\n",
+       SPF_LIB_VERSION_MAJOR, SPF_LIB_VERSION_MINOR, SPF_LIB_VERSION_PATCH);
+fprintf(fp, "                       Runtime: %d.%d.%d\n",
+        maj, min, patch);
+}
+
+
 
 static SPF_dns_rr_t *
 SPF_dns_exim_lookup(SPF_dns_server_t *spf_dns_server,
@@ -60,11 +72,23 @@ int dns_rc;
 
 DEBUG(D_receive) debug_printf("SPF_dns_exim_lookup '%s'\n", domain);
 
+/* Shortcircuit SPF RR lookups by returning NO_DATA.  They were obsoleted by
+RFC 6686/7208 years ago. see bug #1294 */
+
+if (rr_type == T_SPF)
+  {
+  HDEBUG(D_host_lookup) debug_printf("faking NO_DATA for SPF RR(99) lookup\n");
+  srr.herrno = NO_DATA;
+  SPF_dns_rr_dup(&spfrr, &srr);
+  return spfrr;
+  }
+
 switch (dns_rc = dns_lookup(dnsa, US domain, rr_type, NULL))
   {
   case DNS_SUCCEED:    srr.herrno = NETDB_SUCCESS;     break;
   case DNS_AGAIN:      srr.herrno = TRY_AGAIN;         break;
   case DNS_NOMATCH:    srr.herrno = HOST_NOT_FOUND;    break;
+  case DNS_NODATA:     srr.herrno = NO_DATA;           break;
   case DNS_FAIL:
   default:             srr.herrno = NO_RECOVERY;       break;
   } 
@@ -107,9 +131,10 @@ for (dns_record * rr = dns_next_rr(dnsa, &dnss, RESET_ANSWERS); rr;
        gstring * g = NULL;
        uschar chunk_len;
 
-       if (strncmpic(rr->data+1, US"v=spf1", 6) != 0)
+       if (strncmpic(rr->data+1, US SPF_VER_STR, 6) != 0)
          {
-         HDEBUG(D_host_lookup) debug_printf("not an spf record\n");
+         HDEBUG(D_host_lookup) debug_printf("not an spf record: %.*s\n",
+           (int) s[0], s+1);
          continue;
          }
 
@@ -122,6 +147,7 @@ for (dns_record * rr = dns_next_rr(dnsa, &dnss, RESET_ANSWERS); rr;
          continue;
        gstring_release_unused(g);
        s = string_copy_malloc(string_from_gstring(g));
+       DEBUG(D_receive) debug_printf("SPF_dns_exim_lookup '%s'\n", s);
        break;
        }
 
@@ -134,11 +160,15 @@ for (dns_record * rr = dns_next_rr(dnsa, &dnss, RESET_ANSWERS); rr;
        break;
        }
       }
-    DEBUG(D_receive) debug_printf("SPF_dns_exim_lookup '%s'\n", s);
     srr.rr[found++] = (void *) s;
     }
 
-srr.num_rr = found;
+/* Did we filter out all TXT RRs? Return NO_DATA instead of SUCCESS with
+empty ANSWER section. */
+
+if (!(srr.num_rr = found))
+  srr.herrno = NO_DATA;
+
 /* spfrr->rr must have been malloc()d for this */
 SPF_dns_rr_dup(&spfrr, &srr);
 return spfrr;
@@ -270,6 +300,22 @@ return TRUE;
 }
 
 
+void
+spf_response_debug(SPF_response_t * spf_response)
+{
+if (SPF_response_messages(spf_response) == 0)
+  debug_printf(" (no errors)\n");
+else for (int i = 0; i < SPF_response_messages(spf_response); i++)
+  {
+  SPF_error_t * err = SPF_response_message(spf_response, i);
+  debug_printf( "%s_msg = (%d) %s\n",
+                 (SPF_error_errorp(err) ? "warn" : "err"),
+                 SPF_error_code(err),
+                 SPF_error_message(err));
+  }
+}
+
+
 /* spf_process adds the envelope sender address to the existing
    context (if any), retrieves the result, sets up expansion
    strings and evaluates the condition outcome.
@@ -312,6 +358,8 @@ else
   spf_smtp_comment       = US SPF_response_get_smtp_comment(spf_response);
 
   rc = SPF_response_result(spf_response);
+
+  DEBUG(D_acl) spf_response_debug(spf_response);
   }
 
 /* We got a result. Now see if we should return OK or FAIL for it */