[BusyBox] bug#1182: [PATCH] - add explicit name server option to nslookup.c + minor other fix

[Benjamin Zeckel]

Package: busybox
Version: CVS
Severity: wishlist

This is a different patch than the one I just sent a few days ago.

This patch alters nslookup.c and usage.h to add a explicit nameserver 
option to nslookup

nslookup www.site.com = lookup www.site.com using /etc/resolv.conf DNS servers
nslookup www.site.com my.dns.server.net = lookup www.site.com with explicit 
DNS server my.dns.server.net
nslookup a b c ... = show usage for more than 2 arguments as according to 
standard nslookup, that is an error


It's output is the same as gnu (with minor whitespace variations which were 
in the original cvs version).

I have tested it against multibuild.pl script and it breaks nothing new

It increases the binary size (as compared to vanilla nslookup busybox 
version) by about 70 bytes

I tried to follow the style guide a little more closely this time around 
(as the first applied patch had been slightly altered which
is fine by me but a waste of time for someone)

Thanks much

Ben Zeckel
bzeckel at hmc.edu
bzeckel at cisco.com
-------------- next part --------------
Index: nslookup.c
===================================================================
RCS file: /var/cvs/busybox/nslookup.c,v
retrieving revision 1.23
diff -b -w -u -r1.23 nslookup.c
--- nslookup.c	2001/06/12 22:21:24	1.23
+++ nslookup.c	2001/06/13 02:18:24
@@ -5,6 +5,9 @@
  * Copyright (C) 1999,2000,2001 by Lineo, inc.
  * Written by John Beppu <beppu at lineo.com>
  *
+ * Correct default name server display and explicit name server option 
+ * added by Ben Zeckel <bzeckel at hmc.edu> June 2001
+ *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
  * the Free Software Foundation; either version 2 of the License, or
@@ -38,9 +41,6 @@
 /*
  |  I'm only implementing non-interactive mode;
  |  I totally forgot nslookup even had an interactive mode.
- |
- |  [ TODO ]
- |  + find out how to use non-default name servers
  */
 
 /* only works for IPv4 */
@@ -138,6 +138,19 @@
 	printf("\n");
 }
 
+/* alter the global _res nameserver structure to use
+   an explicit dns server instead of what is in /etc/resolv.h */
+static inline void set_default_dns(char *server)
+{
+	struct in_addr server_in_addr;
+
+	if(inet_aton(server,&server_in_addr))      
+	{
+		_res.nscount = 1;
+		_res.nsaddr_list[0].sin_addr = server_in_addr;
+	}
+}    
+
 /* naive function to check whether char *s is an ip address */
 static int is_ip_address(const char *s)
 {
@@ -156,11 +169,30 @@
 {
 	struct hostent *host;
 
+	/*
+	 * initialize DNS structure _res used in printing the default
+	 * name server and in the explicit name server option feature.
+	 */
+        
+	res_init();
+
+	/*
+	 * We allow 1 or 2 arguments. 
+	 * The first is the name to be looked up and the second is an 
+	 * optional DNS server with which to do the lookup. 
+	 * More than 3 arguments is an error to follow the pattern of the
+	 * standard nslookup
+	 */
+
+
 	if (argc < 2 || *argv[1]=='-') {
 		show_usage();
+	} else if(argc == 3) {
+		set_default_dns(argv[2]);
+	} else if(argc > 3) {
+		show_usage();
 	}
 
-	res_init();
 	server_print();
 	if (is_ip_address(argv[1])) {
 		host = gethostbyaddr_wrapper(argv[1]);
Index: usage.h
===================================================================
RCS file: /var/cvs/busybox/usage.h,v
retrieving revision 1.49
diff -b -w -u -r1.49 usage.h
--- usage.h	2001/06/03 05:41:59	1.49
+++ usage.h	2001/06/13 02:18:25
@@ -1154,9 +1154,10 @@
 	"221 foobar closing connection\n" 
 
 #define nslookup_trivial_usage \
-	"[HOST]"
+	"[HOST] [SERVER]"
 #define nslookup_full_usage \
-	"Queries the nameserver for the IP address of the given HOST"
+	"Queries the nameserver for the IP address of the given HOST\n" \
+	"optionally using a specified DNS server"
 #define nslookup_example_usage \
 	"$ nslookup localhost\n" \
 	"Server:     default\n" \