UTF8: Avoid treating a punycoded dns lookup as an implicit redirection

3 files changed, 26 insertions, 19 deletions

diff --git a/src/src/dns.c b/src/src/dns.c
index 6f75386ed..a9970d9fe 100644
--- a/src/src/dns.c
+++ b/src/src/dns.c
@@ -581,6 +581,8 @@ if (previous != NULL)
   {
   uschar * alabel;
   uschar * errstr = NULL;
+  DEBUG(D_dns) if (string_is_utf8(name))
+    debug_printf("convert utf8 '%s' to alabel for for lookup\n", name);
   if ((alabel = string_domain_utf8_to_alabel(name, &errstr)), errstr)
     {
     DEBUG(D_dns)
@@ -738,7 +740,8 @@ won't return any.
 If fully_qualified_name is not NULL, set it to point to the full name
 returned by the resolver, if this is different to what it is given, unless
 the returned name starts with "*" as some nameservers seem to be returning
-wildcards in this form.
+wildcards in this form.  In international mode "different" means "alabel
+forms are different".
 
 Arguments:
   dnsa                  pointer to dns_answer structure
@@ -799,18 +802,19 @@ for (i = 0; i < 10; i++)
 
   if (i == 0 && fully_qualified_name != NULL)
     {
-    if (cname_rr.data != NULL)
-      {
-      if (Ustrcmp(cname_rr.name, *fully_qualified_name) != 0 &&
-          cname_rr.name[0] != '*')
-        *fully_qualified_name = string_copy_dnsdomain(cname_rr.name);
-      }
-    else if (type_rr.data != NULL)
-      {
-      if (Ustrcmp(type_rr.name, *fully_qualified_name) != 0 &&
-          type_rr.name[0] != '*')
-        *fully_qualified_name = string_copy_dnsdomain(type_rr.name);
-      }
+    uschar * rr_name = cname_rr.data ? cname_rr.name
+      : type_rr.data ? type_rr.name : NULL;
+    if (  rr_name
+       && Ustrcmp(rr_name, *fully_qualified_name) != 0
+       && rr_name[0] != '*'
+#ifdef EXPERIMENTAL_INTERNATIONAL
+       && (  !string_is_utf8(*fully_qualified_name)
+	  || Ustrcmp(rr_name,
+	       string_domain_utf8_to_alabel(*fully_qualified_name, NULL)) != 0
+	  )
+#endif
+       )
+        *fully_qualified_name = string_copy_dnsdomain(rr_name);
     }
 
   /* If any data records of the correct type were found, we are done. */
diff --git a/test/dnszones-src/db.test.ex b/test/dnszones-src/db.test.ex
index ebf9a4021..ab1643452 100644
--- a/test/dnszones-src/db.test.ex
+++ b/test/dnszones-src/db.test.ex
@@ -38,9 +38,9 @@ dontqualify  A       V4NET.255.255.254
 
 UpperCase    A       127.0.0.1
 
-; A host with UTF-8 characters used for its lookup ( π.test.ex )
+; A host with punycoded UTF-8 characters used for its lookup ( mx.π.test.ex )
 
-mx.xn--1xa   A       V4NET.255.255.255
+mx.xn--1xa         A       V4NET.255.255.255
 
 ; A non-standard name for localhost
 
@@ -358,9 +358,13 @@ mxt97        MX  1  ten-1.test.ex.
 
 mxt1c        MX  1  dontqualify.
 
-; MX with UTF-8 characters used for its lookup ( π.test.ex )
+; MX with punycoded UTF-8 characters used for its lookup ( π.test.ex )
 
-xn--1xa      MX  0  mx.xn--1xa.test.ex.
+xn--1xa      MX  0  mx.π.test.ex.
+
+; MX with actual UTF-8 characters in its name, for allow_utf8_domains mode test
+
+π            MX  0  mx.xn--1xa.test.ex.
 
 ; -------- Testing SRV records --------
 
diff --git a/test/stdout/0405 b/test/stdout/0405
index f5b5dce41..8a0641056 100644
--- a/test/stdout/0405
+++ b/test/stdout/0405
@@ -1,5 +1,4 @@
 syntax error: domain missing or malformed
-bounce@xn--1xa.test.ex
-    <-- bounce@π.test.ex
+bounce@π.test.ex
   router = r1, transport = t1
   host mx.xn--1xa.test.ex [V4NET.255.255.255] MX=0