* Correct default name server display and explicit name server option
* added by Ben Zeckel <bzeckel@hmc.edu> June 2001
*
- * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
+ * Licensed under GPLv2 or later, see file LICENSE in this source tree.
*/
+//usage:#define nslookup_trivial_usage
+//usage: "[HOST] [SERVER]"
+//usage:#define nslookup_full_usage "\n\n"
+//usage: "Query the nameserver for the IP address of the given HOST\n"
+//usage: "optionally using a specified DNS server"
+//usage:
+//usage:#define nslookup_example_usage
+//usage: "$ nslookup localhost\n"
+//usage: "Server: default\n"
+//usage: "Address: default\n"
+//usage: "\n"
+//usage: "Name: debian\n"
+//usage: "Address: 127.0.0.1\n"
+
#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
* ns3.kernel.org internet address = 204.152.191.36
*/
-static int sockaddr_to_dotted(struct sockaddr *saddr, char *buf, int buflen)
-{
- if (buflen <= 0) return -1;
- buf[0] = '\0';
- if (saddr->sa_family == AF_INET) {
- inet_ntop(AF_INET, &((struct sockaddr_in*)saddr)->sin_addr, buf, buflen);
- return 0;
- }
- if (saddr->sa_family == AF_INET6) {
- inet_ntop(AF_INET6, &((struct sockaddr_in6*)saddr)->sin6_addr, buf, buflen);
- return 0;
- }
- return -1;
-}
-
static int print_host(const char *hostname, const char *header)
{
- char str[128]; /* IPv6 address will fit, hostnames hopefully too */
+ /* We can't use xhost2sockaddr() - we want to get ALL addresses,
+ * not just one */
struct addrinfo *result = NULL;
int rc;
struct addrinfo hint;
hint.ai_socktype = SOCK_STREAM;
// hint.ai_flags = AI_CANONNAME;
rc = getaddrinfo(hostname, NULL /*service*/, &hint, &result);
- if (!rc) {
+
+ if (rc == 0) {
struct addrinfo *cur = result;
- // printf("%s\n", cur->ai_canonname); ?
+ unsigned cnt = 0;
+
+ printf("%-10s %s\n", header, hostname);
+ // puts(cur->ai_canonname); ?
while (cur) {
- sockaddr_to_dotted(cur->ai_addr, str, sizeof(str));
- printf("%s %s\nAddress: %s", header, hostname, str);
- str[0] = ' ';
- if (getnameinfo(cur->ai_addr, cur->ai_addrlen, str+1, sizeof(str)-1, NULL, 0, NI_NAMEREQD))
- str[0] = '\0';
- puts(str);
+ char *dotted, *revhost;
+ 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) {
+ puts(revhost);
+ if (ENABLE_FEATURE_CLEAN_UP)
+ free(revhost);
+ }
+ if (ENABLE_FEATURE_CLEAN_UP)
+ free(dotted);
cur = cur->ai_next;
}
} else {
- bb_error_msg("getaddrinfo('%s') failed: %s", hostname, gai_strerror(rc));
+#if ENABLE_VERBOSE_RESOLUTION_ERRORS
+ bb_error_msg("can't resolve '%s': %s", hostname, gai_strerror(rc));
+#else
+ bb_error_msg("can't resolve '%s'", hostname);
+#endif
}
- freeaddrinfo(result);
+ if (ENABLE_FEATURE_CLEAN_UP && result)
+ freeaddrinfo(result);
return (rc != 0);
}
+/* lookup the default nameserver and display it */
+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);
+
+ print_host(server, "Server:");
+ if (ENABLE_FEATURE_CLEAN_UP)
+ free(server);
+ 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;
-
- if (inet_pton(AF_INET, server, &server_in_addr) > 0) {
- _res.nscount = 1;
- _res.nsaddr_list[0].sin_addr = server_in_addr;
- }
-}
+ len_and_sockaddr *lsa;
+ if (!server)
+ return;
-/* lookup the default nameserver and display it */
-static void server_print(void)
-{
- char str[INET6_ADDRSTRLEN];
+ /* NB: this works even with, say, "[::1]:5353"! :) */
+ lsa = xhost2sockaddr(server, 53);
- sockaddr_to_dotted((struct sockaddr*)&_res.nsaddr_list[0], str, sizeof(str));
- print_host(str, "Server:");
- puts("");
+ if (lsa->u.sa.sa_family == AF_INET) {
+ _res.nscount = 1;
+ /* 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) MAIN_EXTERNALLY_VISIBLE;
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.
- */
+ /* 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 (!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") */
+ /*_res.options |= RES_USE_INET6;*/
- /*
- * 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)
- set_default_dns(argv[2]);
+ set_default_dns(argv[2]);
server_print();
- return print_host(argv[1], "Name: ");
-}
+ /* getaddrinfo and friends are free to request a resolver
+ * reinitialization. Just in case, set_default_dns() again
+ * after getaddrinfo (in server_print). This reportedly helps
+ * with bug 675 "nslookup does not properly use second argument"
+ * at least on Debian Wheezy and Openwrt AA (eglibc based).
+ */
+ set_default_dns(argv[2]);
+
+ return print_host(argv[1], "Name:");
+}
projects / platform / upstream / busybox.git / blobdiff