[PATCH] Honour sortlist from /etc/resolv.conf

[Jakub Jelinek]

Hi!

Although glibc reads sortlist directives in /etc/resolv.conf (it is
documented in resolv.conf man page btw) and records them in _res structure,
it does not use them.
This patch makes this work.
Tested with ftp.netscape.com lookup which gives 5 addresses in 2 different
networks.

2001-08-14  Jakub Jelinek  <jakub@redhat.com>

	* resolv/nss_dns/dns-host.c (RESOLVSORT): Define.
	(addrsort): New.
	* resolv/gethnamaddr.c (RESOLVSORT): Define.

--- libc/resolv/nss_dns/dns-host.c.jj	Mon Jul  9 14:57:48 2001
+++ libc/resolv/nss_dns/dns-host.c	Tue Aug 14 05:21:38 2001
@@ -1,4 +1,4 @@
-/* Copyright (C) 1996, 1997, 1998, 1999, 2000 Free Software Foundation, Inc.
+/* Copyright (C) 1996-2000, 2001 Free Software Foundation, Inc.
    This file is part of the GNU C Library.
    Extended from original form by Ulrich Drepper <drepper@cygnus.com>, 1996.
 
@@ -86,6 +86,8 @@
 #include <resolv/mapv4v6addr.h>
 #include <resolv/mapv4v6hostent.h>
 
+#define RESOLVSORT
+
 /* Maximum number of aliases we allow.  */
 #define MAX_NR_ALIASES	48
 #define MAX_NR_ADDRS	48
@@ -330,6 +332,51 @@ _nss_dns_gethostbyaddr_r (const void *ad
   return NSS_STATUS_SUCCESS;
 }
 
+#ifdef RESOLVSORT
+static void addrsort (char **ap, int num);
+
+static void
+addrsort (char **ap, int num)
+{
+  int i, j;
+  char **p;
+  short aval[MAX_NR_ADDRS];
+  int needsort = 0;
+
+  p = ap;
+  if (num > MAX_NR_ADDRS)
+    num = MAX_NR_ADDRS;
+  for (i = 0; i < num; i++, p++)
+    {
+      for (j = 0 ; (unsigned)j < _res.nsort; j++)
+	if (_res.sort_list[j].addr.s_addr ==
+	    (((struct in_addr *)(*p))->s_addr & _res.sort_list[j].mask))
+	  break;
+      aval[i] = j;
+      if (needsort == 0 && i > 0 && j < aval[i-1])
+	needsort = i;
+    }
+  if (!needsort)
+    return;
+
+  while (needsort++ < num)
+    for (j = needsort - 2; j >= 0; j--)
+      if (aval[j] > aval[j+1])
+	{
+	  char *hp;
+
+	  i = aval[j];
+	  aval[j] = aval[j+1];
+	  aval[j+1] = i;
+
+	  hp = ap[j];
+	  ap[j] = ap[j+1];
+	  ap[j+1] = hp;
+	}
+      else
+	break;
+}
+#endif
 
 static enum nss_status
 getanswer_r (const querybuf *answer, int anslen, const char *qname, int qtype,
--- libc/resolv/gethnamaddr.c.jj	Tue May  9 07:47:59 2000
+++ libc/resolv/gethnamaddr.c	Mon Aug 13 17:57:19 2001
@@ -68,6 +68,8 @@ static char rcsid[] = "$Id: gethnamaddr.
 #include <errno.h>
 #include <syslog.h>
 
+#define RESOLVSORT
+
 #ifndef LOG_AUTH
 # define LOG_AUTH 0
 #endif

	Jakub