X-Git-Url: https://git.librecmc.org/?a=blobdiff_plain;ds=sidebyside;f=networking%2Fnslookup.c;h=26287114caee6b83c1c01de0633048979872a329;hb=4f731ce30ec2a9f5e9b231b47aa68f32b75feb35;hp=14c05b3e6c05f3b3268c2050157b89cbe0fb8dc9;hpb=06af2165288cd6516b89001ec9e24992619230e0;p=oweals%2Fbusybox.git

diff --git a/networking/nslookup.c b/networking/nslookup.c
index 14c05b3e6..26287114c 100644
--- a/networking/nslookup.c
+++ b/networking/nslookup.c
@@ -12,11 +12,14 @@
  */
 
 #include <resolv.h>
-#include "busybox.h"
+#include "libbb.h"
 
 /*
- *  I'm only implementing non-interactive mode;
- *  I totally forgot nslookup even had an interactive mode.
+ * I'm only implementing non-interactive mode;
+ * I totally forgot nslookup even had an interactive mode.
+ *
+ * This applet is the only user of res_init(). Without it,
+ * you may avoid pulling in _res global from libc.
  */
 
 /* Examples of 'standard' nslookup output
@@ -49,9 +52,8 @@
 
 static int print_host(const char *hostname, const char *header)
 {
-	/* We can't use host2sockaddr() - we want to get ALL addresses,
+	/* We can't use xhost2sockaddr() - we want to get ALL addresses,
 	 * not just one */
-
 	struct addrinfo *result = NULL;
 	int rc;
 	struct addrinfo hint;
@@ -69,11 +71,11 @@ static int print_host(const char *hostname, const char *header)
 		unsigned cnt = 0;
 
 		printf("%-10s %s\n", header, hostname);
-		// printf("%s\n", cur->ai_canonname); ?
+		// puts(cur->ai_canonname); ?
 		while (cur) {
 			char *dotted, *revhost;
-			dotted = xmalloc_sockaddr2dotted_noport(cur->ai_addr, cur->ai_addrlen);
-			revhost = xmalloc_sockaddr2hostonly_noport(cur->ai_addr, cur->ai_addrlen);
+			dotted = xmalloc_sockaddr2dotted_noport(cur->ai_addr);
+			revhost = xmalloc_sockaddr2hostonly_noport(cur->ai_addr);
 
 			printf("Address %u: %s%c", ++cnt, dotted, revhost ? ' ' : '\n');
 			if (revhost) {
@@ -101,34 +103,53 @@ static int print_host(const char *hostname, const char *header)
 static void server_print(void)
 {
 	char *server;
+	struct sockaddr *sa;
+
+#if ENABLE_FEATURE_IPV6
+	sa = (struct sockaddr*)_res._u._ext.nsaddrs[0];
+	if (!sa)
+#endif
+		sa = (struct sockaddr*)&_res.nsaddr_list[0];
+	server = xmalloc_sockaddr2dotted_noport(sa);
 
-	server = xmalloc_sockaddr2dotted_noport((struct sockaddr*)&_res.nsaddr_list[0],
-			sizeof(struct sockaddr_in));
-	/* I honestly don't know what to do if DNS server has _IPv6 address_.
-	 * Probably it is listed in
-	 * _res._u._ext_.nsaddrs[MAXNS] (of type "struct sockaddr_in6*" each)
-	 * but how to find out whether resolver uses
-	 * _res.nsaddr_list[] or _res._u._ext_.nsaddrs[], or both?
-	 * Looks like classic design from hell, BIND-grade. Hard to surpass. */
 	print_host(server, "Server:");
 	if (ENABLE_FEATURE_CLEAN_UP)
 		free(server);
-	puts("");
+	bb_putchar('\n');
 }
 
 /* alter the global _res nameserver structure to use
-   an explicit dns server instead of what is in /etc/resolv.h */
-static void set_default_dns(char *server)
+   an explicit dns server instead of what is in /etc/resolv.conf */
+static void set_default_dns(const char *server)
 {
-	struct in_addr server_in_addr;
+	len_and_sockaddr *lsa;
 
-	if (inet_pton(AF_INET, server, &server_in_addr) > 0) {
+	/* NB: this works even with, say, "[::1]:5353"! :) */
+	lsa = xhost2sockaddr(server, 53);
+
+	if (lsa->u.sa.sa_family == AF_INET) {
 		_res.nscount = 1;
-		_res.nsaddr_list[0].sin_addr = server_in_addr;
+		/* struct copy */
+		_res.nsaddr_list[0] = lsa->u.sin;
+	}
+#if ENABLE_FEATURE_IPV6
+	/* Hoped libc can cope with IPv4 address there too.
+	 * No such luck, glibc 2.4 segfaults even with IPv6,
+	 * maybe I misunderstand how to make glibc use IPv6 addr?
+	 * (uclibc 0.9.31+ should work) */
+	if (lsa->u.sa.sa_family == AF_INET6) {
+		// glibc neither SEGVs nor sends any dgrams with this
+		// (strace shows no socket ops):
+		//_res.nscount = 0;
+		_res._u._ext.nscount = 1;
+		/* store a pointer to part of malloc'ed lsa */
+		_res._u._ext.nsaddrs[0] = &lsa->u.sin6;
+		/* must not free(lsa)! */
 	}
+#endif
 }
 
-int nslookup_main(int argc, char **argv);
+int nslookup_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
 int nslookup_main(int argc, char **argv)
 {
 	/* We allow 1 or 2 arguments.
@@ -136,18 +157,17 @@ int nslookup_main(int argc, char **argv)
 	 * 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] == '-' || argc > 3)
+	if (!argv[1] || argv[1][0] == '-' || argc > 3)
 		bb_show_usage();
 
 	/* initialize DNS structure _res used in printing the default
 	 * name server and in the explicit name server option feature. */
 	res_init();
 	/* rfc2133 says this enables IPv6 lookups */
-	/* (but it also says "may be enabled in /etc/resolv.conf|) */
+	/* (but it also says "may be enabled in /etc/resolv.conf") */
 	/*_res.options |= RES_USE_INET6;*/
 
-	if(argc == 3)
+	if (argv[2])
 		set_default_dns(argv[2]);
 
 	server_print();