support EDNS0 (RFC2671) buffer size notification on DNS queries.

"options edns0" in /etc/resolv.conf will enable the behavior.  no behavior
change if you don't have the line.  see resolv.conf(5) for more details.

EDNS0 is useful for avoiding TCP DNS queries/replies on larger DNS responses.
also, draft-ietf-dnsext-message-size-* plans to mandate EDNS0 support for DNS
clients that support IPv6 transport.

1 files changed, 4 insertions, 1 deletions

diff --git a/src/lib/libc/net/getaddrinfo.c b/src/lib/libc/net/getaddrinfo.c
index 1326473fb7..0a0b112589 100644
--- a/src/lib/libc/net/getaddrinfo.c
+++ b/src/lib/libc/net/getaddrinfo.c
@@ -1,4 +1,4 @@
-/*      $OpenBSD: getaddrinfo.c,v 1.27 2000/08/31 17:41:51 itojun Exp $ */
+/*      $OpenBSD: getaddrinfo.c,v 1.28 2001/06/11 10:05:58 itojun Exp $ */
 /*      $KAME: getaddrinfo.c,v 1.31 2000/08/31 17:36:43 itojun Exp $    */
 
 /*
@@ -1511,6 +1511,7 @@ _yp_getaddrinfo(name, pai)
 
 extern const char *__hostalias __P((const char *));
 extern int h_errno;
+extern int res_opt __P((int, u_char *, int, int));
 
 /*
  * Formulate a normal query, send, and await answer.
@@ -1562,6 +1563,8 @@ res_queryN(name, target)
 
                 n = res_mkquery(QUERY, name, class, type, NULL, 0, NULL,
                     buf, sizeof(buf));
+                if (n > 0 && (_res.options & RES_USE_EDNS0) != 0)
+                        n = res_opt(n, buf, sizeof(buf), anslen);
                 if (n <= 0) {
 #ifdef DEBUG
                         if (_res.options & RES_DEBUG)