SPF: only require "v=spf1" on TXT DNS records during lookups. Bug 2499

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

diff --git a/src/src/spf.c b/src/src/spf.c
index 8b7bf4bc9428a52f9fe271bf65ef6182fe48ad41..b7041d3e3493b2bd0172eaca2842ae3022657233 100644 (file)
--- a/src/src/spf.c
+++ b/src/src/spf.c
@@ -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 */
@@ -133,25 +161,18 @@ return spf_dns_server;
 
 
 
-/* spf_init sets up a context that can be re-used for several
-   messages on the same SMTP connection (that come from the
-   same host with the same HELO string).
-XXX the spf_server layer could usefully be separately init'd
-given that it sets up a dns cache.
 
-Return: Boolean success */
+/* Construct the SPF library stack.
+   Return: Boolean success.
+*/
 
 BOOL
-spf_init(uschar *spf_helo_domain, uschar *spf_remote_addr)
+spf_init(void)
 {
-int debug = 0;
 SPF_dns_server_t * dc;
+int debug = 0;
 
-DEBUG(D_receive)
-  {
-  debug_printf("spf_init: %s %s\n", spf_helo_domain, spf_remote_addr);
-  debug = 1;
-  }
+DEBUG(D_receive) debug = 1;
 
 /* We insert our own DNS access layer rather than letting the spf library
 do it, so that our dns access path is used for debug tracing and for the
@@ -172,6 +193,30 @@ if (!(spf_server = SPF_server_new_dns(dc, debug)))
   DEBUG(D_receive) debug_printf("spf: SPF_server_new() failed.\n");
   return FALSE;
   }
+  /* Quick hack to override the outdated explanation URL.
+  See https://www.mail-archive.com/mailop@mailop.org/msg08019.html */
+  SPF_server_set_explanation(spf_server, "Please%_see%_http://www.open-spf.org/Why?id=%{S}&ip=%{C}&receiver=%{R}", &spf_response);
+  if (SPF_response_errcode(spf_response) != SPF_E_SUCCESS)
+    log_write(0, LOG_MAIN|LOG_PANIC_DIE, "%s", SPF_strerror(SPF_response_errcode(spf_response)));
+
+return TRUE;
+}
+
+
+/* Set up a context that can be re-used for several
+   messages on the same SMTP connection (that come from the
+   same host with the same HELO string).
+
+Return: Boolean success
+*/
+
+BOOL
+spf_conn_init(uschar * spf_helo_domain, uschar * spf_remote_addr)
+{
+DEBUG(D_receive)
+  debug_printf("spf_conn_init: %s %s\n", spf_helo_domain, spf_remote_addr);
+
+if (!spf_server && !spf_init()) return FALSE;
 
 if (SPF_server_set_rec_dom(spf_server, CS primary_hostname))
   {