SPF: only require "v=spf1" on TXT DNS records during lookups. Bug 2499
authorWolfgang Breyha <wbreyha@gmx.net>
Fri, 20 Dec 2019 14:01:23 +0000 (14:01 +0000)
committerJeremy Harris <jgh146exb@wizmail.org>
Sat, 21 Dec 2019 20:39:36 +0000 (20:39 +0000)
(cherry picked from commit 4a3709fb2cfb1ec26ac60bcdb8bbc078d3377ddc)

src/src/spf.c

index 1955b5d..b7041d3 100644 (file)
@@ -43,17 +43,15 @@ dns_answer * dnsa = store_get_dns_answer();
 dns_scan dnss;
 SPF_dns_rr_t * spfrr;
 
-DEBUG(D_receive) debug_printf("SPF_dns_exim_lookup\n");
+DEBUG(D_receive) debug_printf("SPF_dns_exim_lookup '%s'\n", domain);
 
 if (dns_lookup(dnsa, US domain, rr_type, NULL) == 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 == rr_type
-       && Ustrncmp(rr->data+1, "v=spf1", 6) == 0)
+       && (rr_type != T_TXT || Ustrncmp(rr->data+1, "v=spf1", 6) == 0))
       {
-      gstring * g = NULL;
-      uschar chunk_len;
-      uschar * s;
+      const uschar * s = rr->data;
       SPF_dns_rr_t srr = {
        .domain = CS rr->name,                  /* query information */
        .domain_buf_len = DNS_MAXNAME,
@@ -71,19 +69,49 @@ if (dns_lookup(dnsa, US domain, rr_type, NULL) == DNS_SUCCEED)
        .source = spf_dns_server
       };
 
-      for (int off = 0; off < rr->size; off += chunk_len)
+      switch(rr_type)
        {
-       chunk_len = (rr->data)[off++];
-       g = string_catn(g, US ((rr->data)+off), chunk_len);
+        case T_MX:
+          s += 2;                      /* skip the MX precedence field */
+        case T_PTR:
+         {
+          uschar * buf = store_malloc(256);
+          (void)dn_expand(dnsa->answer, dnsa->answer + dnsa->answerlen, s,
+            (DN_EXPAND_ARG4_TYPE)buf, 256);
+          s = buf;
+          break;
+         }
+
+        case T_TXT:
+         {
+         gstring * g = NULL;
+         uschar chunk_len;
+          for (int off = 0; off < rr->size; off += chunk_len)
+            {
+            if (!(chunk_len = s[off++])) break;
+            g = string_catn(g, s+off, chunk_len);
+            }
+          if (!g)
+            {
+            HDEBUG(D_host_lookup) debug_printf("IP address lookup yielded an "
+              "empty name: treated as non-existent host name\n");
+            continue;
+            }
+          gstring_release_unused(g);
+          s = string_copy_malloc(string_from_gstring(g));
+          break;
+         }
+
+        case T_A:
+        case T_AAAA:
+        default:
+         {
+          uschar * buf = store_malloc(dnsa->answerlen + 1);
+         s = memcpy(buf, s, dnsa->answerlen + 1);
+          break;
+         }
        }
-      if (!g)
-       {
-       HDEBUG(D_host_lookup) debug_printf("IP address lookup yielded an "
-         "empty name: treated as non-existent host name\n");
-       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);
       srr.rr = (void *) &s;
 
       /* spfrr->rr must have been malloc()d for this */