nslookup: full circle. Here we started IPv6 work. Use "new API"

and thus save a few bytes.

1 files changed, 88 insertions, 29 deletions

diff --git a/networking/nslookup.c b/networking/nslookup.c
index 5a08844..af08162 100644
--- a/networking/nslookup.c
+++ b/networking/nslookup.c
@@ -47,7 +47,7 @@
  * ns3.kernel.org  internet address = 204.152.191.36
  */
 
-static int sockaddr_to_dotted(struct sockaddr *saddr, char *buf, int buflen)
+/*static int sockaddr_to_dotted(struct sockaddr *saddr, char *buf, int buflen)
 {
 	if (buflen <= 0) return -1;
 	buf[0] = '\0';
@@ -61,9 +61,11 @@ static int sockaddr_to_dotted(struct sockaddr *saddr, char *buf, int buflen)
 	}
 	return -1;
 }
+*/
 
 static int print_host(const char *hostname, const char *header)
 {
+#if 0
 	char str[128];	/* IPv6 address will fit, hostnames hopefully too */
 	struct addrinfo *result = NULL;
 	int rc;
@@ -76,6 +78,7 @@ static int print_host(const char *hostname, const char *header)
 	hint.ai_socktype = SOCK_STREAM;
 	// hint.ai_flags = AI_CANONNAME;
 	rc = getaddrinfo(hostname, NULL /*service*/, &hint, &result);
+
 	if (!rc) {
 		struct addrinfo *cur = result;
 		// printf("%s\n", cur->ai_canonname); ?
@@ -93,6 +96,75 @@ static int print_host(const char *hostname, const char *header)
 	}
 	freeaddrinfo(result);
 	return (rc != 0);
+
+#else
+	/* We can't use host2sockaddr() - we want to get ALL addresses,
+	 * not just one */
+
+	struct addrinfo *result = NULL;
+	int rc;
+	struct addrinfo hint;
+
+	memset(&hint, 0 , sizeof(hint));
+	/* hint.ai_family = AF_UNSPEC; - zero anyway */
+	/* Needed. Or else we will get each address thrice (or more)
+	 * for each possible socket type (tcp,udp,raw...): */
+	hint.ai_socktype = SOCK_STREAM;
+	// hint.ai_flags = AI_CANONNAME;
+	rc = getaddrinfo(hostname, NULL /*service*/, &hint, &result);
+
+	if (!rc) {
+		struct addrinfo *cur = result;
+		unsigned cnt = 0;
+
+		printf("%-10s %s\n", header, hostname);
+		// printf("%s\n", 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);
+
+			printf("Address %u: %s%c", ++cnt, dotted, revhost ? ' ' : '\n');
+			if (revhost) {
+				puts(revhost);
+				if (ENABLE_FEATURE_CLEAN_UP)
+					free(revhost);
+			}
+			if (ENABLE_FEATURE_CLEAN_UP)
+				free(dotted);
+			cur = cur->ai_next;
+		}
+	} else {
+#if ENABLE_VERBOSE_RESOLUTION_ERRORS
+		bb_error_msg("getaddrinfo('%s') failed: %s", hostname, gai_strerror(rc));
+#else
+		bb_error_msg("can't resolve '%s'", hostname);
+#endif
+	}
+	if (ENABLE_FEATURE_CLEAN_UP)
+		freeaddrinfo(result);
+	return (rc != 0);
+#endif
+}
+
+
+/* lookup the default nameserver and display it */
+static void server_print(void)
+{
+	char *server;
+
+	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("");
 }
 
 
@@ -109,40 +181,27 @@ static void set_default_dns(char *server)
 }
 
 
-/* lookup the default nameserver and display it */
-static void server_print(void)
-{
-	char str[INET6_ADDRSTRLEN];
-
-	sockaddr_to_dotted((struct sockaddr*)&_res.nsaddr_list[0], str, sizeof(str));
-	print_host(str, "Server:");
-	puts("");
-}
-
-
 int nslookup_main(int argc, char **argv)
 {
-	/*
-	* 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
-	*/
+	/* 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] == '-' || argc > 3)
 		bb_show_usage();
-	else if(argc == 3)
+
+	/* 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|) */
+	/*_res.options |= RES_USE_INET6;*/
+
+	if(argc == 3)
 		set_default_dns(argv[2]);
 
 	server_print();
-	return print_host(argv[1], "Name:  ");
+	return print_host(argv[1], "Name:");
 }
-