busybox/networking/nslookup.c
Denys Vlasenko 9408978a43 nslookup: add support for search domains, closes 11161
function                                             old     new   delta
parse_resolvconf                                       -     311    +311
add_query_with_search                                  -     105    +105
nslookup_main                                        873     757    -116
------------------------------------------------------------------------------
(add/remove: 2/0 grow/shrink: 0/1 up/down: 416/-116)          Total: 300 bytes

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
2018-08-01 19:42:46 +02:00

995 lines
24 KiB
C

/* vi: set sw=4 ts=4: */
//config:config NSLOOKUP
//config: bool "nslookup (4.5 kb)"
//config: default y
//config: help
//config: nslookup is a tool to query Internet name servers.
//config:
//config:config FEATURE_NSLOOKUP_BIG
//config: bool "Use internal resolver code instead of libc"
//config: depends on NSLOOKUP
//config: default y
//config:
//config:config FEATURE_NSLOOKUP_LONG_OPTIONS
//config: bool "Enable long options"
//config: default y
//config: depends on FEATURE_NSLOOKUP_BIG && LONG_OPTS
//applet:IF_NSLOOKUP(APPLET(nslookup, BB_DIR_USR_BIN, BB_SUID_DROP))
//kbuild:lib-$(CONFIG_NSLOOKUP) += nslookup.o
//usage:#define nslookup_trivial_usage
//usage: IF_FEATURE_NSLOOKUP_BIG("[-type=QUERY_TYPE] [-debug] ") "HOST [DNS_SERVER]"
//usage:#define nslookup_full_usage "\n\n"
//usage: "Query DNS about HOST"
//usage: IF_FEATURE_NSLOOKUP_BIG("\n")
//usage: IF_FEATURE_NSLOOKUP_BIG("\nQUERY_TYPE: soa,ns,a,"IF_FEATURE_IPV6("aaaa,")"cname,mx,txt,ptr,any")
//usage:#define nslookup_example_usage
//usage: "$ 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 <net/if.h> /* for IFNAMSIZ */
//#include <arpa/inet.h>
//#include <netdb.h>
#include "libbb.h"
#include "common_bufsiz.h"
#if !ENABLE_FEATURE_NSLOOKUP_BIG
/*
* Mini nslookup implementation for busybox
*
* Copyright (C) 1999,2000 by Lineo, inc. and John Beppu
* Copyright (C) 1999,2000,2001 by John Beppu <beppu@codepoet.org>
*
* 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 source tree.
*/
/*
* 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
* $ nslookup yahoo.com
* Server: 128.193.0.10
* Address: 128.193.0.10#53
*
* Non-authoritative answer:
* Name: yahoo.com
* Address: 216.109.112.135
* Name: yahoo.com
* Address: 66.94.234.13
*
* $ nslookup 204.152.191.37
* Server: 128.193.4.20
* Address: 128.193.4.20#53
*
* Non-authoritative answer:
* 37.191.152.204.in-addr.arpa canonical name = 37.32-27.191.152.204.in-addr.arpa.
* 37.32-27.191.152.204.in-addr.arpa name = zeus-pub2.kernel.org.
*
* Authoritative answers can be found from:
* 32-27.191.152.204.in-addr.arpa nameserver = ns1.kernel.org.
* 32-27.191.152.204.in-addr.arpa nameserver = ns2.kernel.org.
* 32-27.191.152.204.in-addr.arpa nameserver = ns3.kernel.org.
* ns1.kernel.org internet address = 140.211.167.34
* ns2.kernel.org internet address = 204.152.191.4
* ns3.kernel.org internet address = 204.152.191.36
*/
static int print_host(const char *hostname, const char *header)
{
/* We can't use xhost2sockaddr() - 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 == 0) {
struct addrinfo *cur = result;
unsigned cnt = 0;
printf("%-10s %s\n", header, hostname);
// puts(cur->ai_canonname); ?
while (cur) {
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 {
#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
}
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.conf */
static void set_default_dns(const char *server)
{
len_and_sockaddr *lsa;
if (!server)
return;
/* NB: this works even with, say, "[::1]:5353"! :) */
lsa = xhost2sockaddr(server, 53);
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)
{
/* 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;*/
set_default_dns(argv[2]);
server_print();
/* 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:");
}
#else /****** A version from LEDE / OpenWRT ******/
/*
* musl compatible nslookup
*
* Copyright (C) 2017 Jo-Philipp Wich <jo@mein.io>
*
* Permission to use, copy, modify, and/or distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
#if 0
# define dbg(...) fprintf(stderr, __VA_ARGS__)
#else
# define dbg(...) ((void)0)
#endif
struct ns {
const char *name;
len_and_sockaddr *lsa;
int failures;
int replies;
};
struct query {
const char *name;
unsigned qlen;
// unsigned latency;
// uint8_t rcode;
unsigned char query[512];
// unsigned char reply[512];
};
static const struct {
unsigned char type;
char name[7];
} qtypes[] = {
{ ns_t_soa, "SOA" },
{ ns_t_ns, "NS" },
{ ns_t_a, "A" },
#if ENABLE_FEATURE_IPV6
{ ns_t_aaaa, "AAAA" },
#endif
{ ns_t_cname, "CNAME" },
{ ns_t_mx, "MX" },
{ ns_t_txt, "TXT" },
{ ns_t_ptr, "PTR" },
{ ns_t_any, "ANY" },
};
static const char *const rcodes[] = {
"NOERROR", // 0
"FORMERR", // 1
"SERVFAIL", // 2
"NXDOMAIN", // 3
"NOTIMP", // 4
"REFUSED", // 5
"YXDOMAIN", // 6
"YXRRSET", // 7
"NXRRSET", // 8
"NOTAUTH", // 9
"NOTZONE", // 10
"11", // 11 not assigned
"12", // 12 not assigned
"13", // 13 not assigned
"14", // 14 not assigned
"15", // 15 not assigned
};
#if ENABLE_FEATURE_IPV6
static const char v4_mapped[12] = { 0,0,0,0, 0,0,0,0, 0,0,0xff,0xff };
#endif
struct globals {
unsigned default_port;
unsigned default_retry;
unsigned default_timeout;
unsigned query_count;
unsigned serv_count;
struct ns *server;
struct query *query;
char *search;
smalluint have_search_directive;
} FIX_ALIASING;
#define G (*(struct globals*)bb_common_bufsiz1)
#define INIT_G() do { \
setup_common_bufsiz(); \
G.default_port = 53; \
G.default_retry = 2; \
G.default_timeout = 5; \
} while (0)
enum {
OPT_debug = (1 << 0),
};
static int parse_reply(const unsigned char *msg, size_t len)
{
HEADER *header;
ns_msg handle;
ns_rr rr;
int i, n, rdlen;
const char *format = NULL;
char astr[INET6_ADDRSTRLEN], dname[MAXDNAME];
const unsigned char *cp;
header = (HEADER *)msg;
if (!header->aa)
printf("Non-authoritative answer:\n");
if (ns_initparse(msg, len, &handle) != 0) {
//printf("Unable to parse reply: %s\n", strerror(errno));
return -1;
}
for (i = 0; i < ns_msg_count(handle, ns_s_an); i++) {
if (ns_parserr(&handle, ns_s_an, i, &rr) != 0) {
//printf("Unable to parse resource record: %s\n", strerror(errno));
return -1;
}
rdlen = ns_rr_rdlen(rr);
switch (ns_rr_type(rr))
{
case ns_t_a:
if (rdlen != 4) {
dbg("unexpected A record length %d\n", rdlen);
return -1;
}
inet_ntop(AF_INET, ns_rr_rdata(rr), astr, sizeof(astr));
printf("Name:\t%s\nAddress: %s\n", ns_rr_name(rr), astr);
break;
#if ENABLE_FEATURE_IPV6
case ns_t_aaaa:
if (rdlen != 16) {
dbg("unexpected AAAA record length %d\n", rdlen);
return -1;
}
inet_ntop(AF_INET6, ns_rr_rdata(rr), astr, sizeof(astr));
/* bind-utils-9.11.3 uses the same format for A and AAAA answers */
printf("Name:\t%s\nAddress: %s\n", ns_rr_name(rr), astr);
break;
#endif
case ns_t_ns:
if (!format)
format = "%s\tnameserver = %s\n";
/* fall through */
case ns_t_cname:
if (!format)
format = "%s\tcanonical name = %s\n";
/* fall through */
case ns_t_ptr:
if (!format)
format = "%s\tname = %s\n";
if (ns_name_uncompress(ns_msg_base(handle), ns_msg_end(handle),
ns_rr_rdata(rr), dname, sizeof(dname)) < 0
) {
//printf("Unable to uncompress domain: %s\n", strerror(errno));
return -1;
}
printf(format, ns_rr_name(rr), dname);
break;
case ns_t_mx:
if (rdlen < 2) {
printf("MX record too short\n");
return -1;
}
n = ns_get16(ns_rr_rdata(rr));
if (ns_name_uncompress(ns_msg_base(handle), ns_msg_end(handle),
ns_rr_rdata(rr) + 2, dname, sizeof(dname)) < 0
) {
//printf("Cannot uncompress MX domain: %s\n", strerror(errno));
return -1;
}
printf("%s\tmail exchanger = %d %s\n", ns_rr_name(rr), n, dname);
break;
case ns_t_txt:
if (rdlen < 1) {
//printf("TXT record too short\n");
return -1;
}
n = *(unsigned char *)ns_rr_rdata(rr);
if (n > 0) {
memset(dname, 0, sizeof(dname));
memcpy(dname, ns_rr_rdata(rr) + 1, n);
printf("%s\ttext = \"%s\"\n", ns_rr_name(rr), dname);
}
break;
case ns_t_soa:
if (rdlen < 20) {
dbg("SOA record too short:%d\n", rdlen);
return -1;
}
printf("%s\n", ns_rr_name(rr));
cp = ns_rr_rdata(rr);
n = ns_name_uncompress(ns_msg_base(handle), ns_msg_end(handle),
cp, dname, sizeof(dname));
if (n < 0) {
//printf("Unable to uncompress domain: %s\n", strerror(errno));
return -1;
}
printf("\torigin = %s\n", dname);
cp += n;
n = ns_name_uncompress(ns_msg_base(handle), ns_msg_end(handle),
cp, dname, sizeof(dname));
if (n < 0) {
//printf("Unable to uncompress domain: %s\n", strerror(errno));
return -1;
}
printf("\tmail addr = %s\n", dname);
cp += n;
printf("\tserial = %lu\n", ns_get32(cp));
cp += 4;
printf("\trefresh = %lu\n", ns_get32(cp));
cp += 4;
printf("\tretry = %lu\n", ns_get32(cp));
cp += 4;
printf("\texpire = %lu\n", ns_get32(cp));
cp += 4;
printf("\tminimum = %lu\n", ns_get32(cp));
break;
default:
break;
}
}
return i;
}
/*
* Function logic borrowed & modified from musl libc, res_msend.c
* G.query_count is always > 0.
*/
static int send_queries(struct ns *ns)
{
unsigned char reply[512];
uint8_t rcode;
len_and_sockaddr *local_lsa;
struct pollfd pfd;
int servfail_retry = 0;
int n_replies = 0;
// int save_idx = 0;
unsigned retry_interval;
unsigned timeout = G.default_timeout * 1000;
unsigned tstart, tsent, tcur;
pfd.events = POLLIN;
pfd.fd = xsocket_type(&local_lsa, ns->lsa->u.sa.sa_family, SOCK_DGRAM);
/*
* local_lsa has "null" address and port 0 now.
* bind() ensures we have a *particular port* selected by kernel
* and remembered in fd, thus later recv(fd)
* receives only packets sent to this port.
*/
xbind(pfd.fd, &local_lsa->u.sa, local_lsa->len);
free(local_lsa);
/* Make read/writes know the destination */
xconnect(pfd.fd, &ns->lsa->u.sa, ns->lsa->len);
ndelay_on(pfd.fd);
retry_interval = timeout / G.default_retry;
tstart = tcur = monotonic_ms();
goto send;
while (tcur - tstart < timeout) {
int qn;
int recvlen;
if (tcur - tsent >= retry_interval) {
send:
for (qn = 0; qn < G.query_count; qn++) {
if (G.query[qn].qlen == 0)
continue; /* this one was replied already */
if (write(pfd.fd, G.query[qn].query, G.query[qn].qlen) < 0) {
bb_perror_msg("write to '%s'", ns->name);
n_replies = -1; /* "no go, try next server" */
goto ret;
}
dbg("query %u sent\n", qn);
}
tsent = tcur;
servfail_retry = 2 * G.query_count;
}
/* Wait for a response, or until time to retry */
if (poll(&pfd, 1, retry_interval - (tcur - tsent)) <= 0)
goto next;
recvlen = read(pfd.fd, reply, sizeof(reply));
if (recvlen < 0) {
bb_perror_msg("read");
next:
tcur = monotonic_ms();
continue;
}
if (ns->replies++ == 0) {
printf("Server:\t\t%s\n", ns->name);
printf("Address:\t%s\n\n",
auto_string(xmalloc_sockaddr2dotted(&ns->lsa->u.sa))
);
/* In "Address", bind-utils-9.11.3 show port after a hash: "1.2.3.4#53" */
/* Should we do the same? */
}
/* Non-identifiable packet */
if (recvlen < 4) {
dbg("read is too short:%d\n", recvlen);
goto next;
}
/* Find which query this answer goes with, if any */
// qn = save_idx;
qn = 0;
for (;;) {
if (memcmp(reply, G.query[qn].query, 2) == 0) {
dbg("response matches query %u\n", qn);
break;
}
if (++qn >= G.query_count) {
dbg("response does not match any query\n");
goto next;
}
}
if (G.query[qn].qlen == 0) {
dbg("dropped duplicate response to query %u\n", qn);
goto next;
}
rcode = reply[3] & 0x0f;
dbg("query %u rcode:%s\n", qn, rcodes[rcode]);
/* Retry immediately on SERVFAIL */
if (rcode == 2) {
ns->failures++;
if (servfail_retry) {
servfail_retry--;
write(pfd.fd, G.query[qn].query, G.query[qn].qlen);
dbg("query %u resent\n", qn);
goto next;
}
}
/* Process reply */
G.query[qn].qlen = 0; /* flag: "reply received" */
tcur = monotonic_ms();
#if 1
if (option_mask32 & OPT_debug) {
printf("Query #%d completed in %ums:\n", qn, tcur - tstart);
}
if (rcode != 0) {
printf("** server can't find %s: %s\n",
G.query[qn].name, rcodes[rcode]);
} else {
if (parse_reply(reply, recvlen) < 0)
printf("*** Can't find %s: Parse error\n", G.query[qn].name);
}
bb_putchar('\n');
n_replies++;
if (n_replies >= G.query_count)
goto ret;
#else
//used to store replies and process them later
G.query[qn].latency = tcur - tstart;
n_replies++;
if (qn != save_idx) {
/* "wrong" receive buffer, move to correct one */
memcpy(G.query[qn].reply, G.query[save_idx].reply, recvlen);
continue;
}
/* G.query[0..save_idx] have replies, move to next one, if exists */
for (;;) {
save_idx++;
if (save_idx >= G.query_count)
goto ret; /* all are full: we have all results */
if (!G.query[save_idx].rlen)
break; /* this one is empty */
}
#endif
} /* while() */
ret:
close(pfd.fd);
return n_replies;
}
static void add_ns(const char *addr)
{
struct ns *ns;
unsigned count;
dbg("%s: addr:'%s'\n", __func__, addr);
count = G.serv_count++;
G.server = xrealloc_vector(G.server, /*8=2^3:*/ 3, count);
ns = &G.server[count];
ns->name = addr;
ns->lsa = xhost2sockaddr(addr, G.default_port);
/*ns->replies = 0; - already is */
/*ns->failures = 0; - already is */
}
static void parse_resolvconf(void)
{
FILE *resolv;
resolv = fopen("/etc/resolv.conf", "r");
if (resolv) {
char line[512]; /* "search" is defined to be up to 256 chars */
while (fgets(line, sizeof(line), resolv)) {
char *p, *arg;
p = strtok(line, " \t\n");
if (!p)
continue;
dbg("resolv_key:'%s'\n", p);
arg = strtok(NULL, "\n");
dbg("resolv_arg:'%s'\n", arg);
if (!arg)
continue;
if (strcmp(p, "domain") == 0) {
/* domain DOM */
if (!G.have_search_directive)
goto set_search;
continue;
}
if (strcmp(p, "search") == 0) {
/* search DOM1 DOM2... */
G.have_search_directive = 1;
set_search:
free(G.search);
G.search = xstrdup(arg);
dbg("search='%s'\n", G.search);
continue;
}
if (strcmp(p, "nameserver") != 0)
continue;
/* nameserver DNS */
add_ns(xstrdup(arg));
}
fclose(resolv);
}
if (!G.search) {
/* default search domain is domain part of hostname */
char *h = safe_gethostname();
char *d = strchr(h, '.');
if (d) {
G.search = d + 1;
dbg("search='%s' (from hostname)\n", G.search);
}
/* else free(h); */
}
/* Cater for case of "domain ." in resolv.conf */
if (G.search && LONE_CHAR(G.search, '.'))
G.search = NULL;
}
static void add_query(int type, const char *dname)
{
struct query *new_q;
unsigned count;
ssize_t qlen;
count = G.query_count++;
G.query = xrealloc_vector(G.query, /*4=2^2:*/ 2, count);
new_q = &G.query[count];
dbg("new query#%u type %u for '%s'\n", count, type, dname);
new_q->name = dname;
qlen = res_mkquery(QUERY, dname, C_IN, type,
/*data:*/ NULL, /*datalen:*/ 0,
/*newrr:*/ NULL,
new_q->query, sizeof(new_q->query)
);
new_q->qlen = qlen;
}
static void add_query_with_search(int type, const char *dname)
{
char *s;
if (type == T_PTR || !G.search || strchr(dname, '.')) {
add_query(type, dname);
return;
}
s = G.search;
for (;;) {
char *fullname, *e;
e = skip_non_whitespace(s);
fullname = xasprintf("%s.%.*s", dname, (int)(e - s), s);
add_query(type, fullname);
s = skip_whitespace(e);
if (!*s)
break;
}
}
static char *make_ptr(const char *addrstr)
{
unsigned char addr[16];
#if ENABLE_FEATURE_IPV6
if (inet_pton(AF_INET6, addrstr, addr)) {
if (memcmp(addr, v4_mapped, 12) != 0) {
int i;
char resbuf[80];
char *ptr = resbuf;
for (i = 0; i < 16; i++) {
*ptr++ = 0x20 | bb_hexdigits_upcase[(unsigned char)addr[15 - i] & 0xf];
*ptr++ = '.';
*ptr++ = 0x20 | bb_hexdigits_upcase[(unsigned char)addr[15 - i] >> 4];
*ptr++ = '.';
}
strcpy(ptr, "ip6.arpa");
return xstrdup(resbuf);
}
return xasprintf("%u.%u.%u.%u.in-addr.arpa",
addr[15], addr[14], addr[13], addr[12]);
}
#endif
if (inet_pton(AF_INET, addrstr, addr)) {
return xasprintf("%u.%u.%u.%u.in-addr.arpa",
addr[3], addr[2], addr[1], addr[0]);
}
return NULL;
}
int nslookup_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
int nslookup_main(int argc UNUSED_PARAM, char **argv)
{
unsigned types;
int rc;
int err;
INIT_G();
/* manpage: "Options can also be specified on the command line
* if they precede the arguments and are prefixed with a hyphen."
*/
types = 0;
argv++;
for (;;) {
const char *options =
// bind-utils-9.11.3 accept these:
// class= cl=
// type= ty= querytype= query= qu= q=
// domain= do=
// port= po=
// timeout= t=
// retry= ret=
// ndots=
// recurse
// norecurse
// defname
// nodefname
// vc
// novc
// debug
// nodebug
// d2
// nod2
// search
// nosearch
// sil
// fail
// nofail
// ver (prints version and exits)
"type\0" /* 0 */
"querytype\0" /* 1 */
"port\0" /* 2 */
"retry\0" /* 3 */
"debug\0" /* 4 */
"t\0" /* disambiguate with "type": else -t=2 fails */
"timeout\0" /* 6 */
"";
int i;
char *arg;
char *val;
if (!*argv)
bb_show_usage();
if (argv[0][0] != '-')
break;
/* Separate out "=val" part */
arg = (*argv++) + 1;
val = strchrnul(arg, '=');
if (*val)
*val++ = '\0';
i = index_in_substrings(options, arg);
//bb_error_msg("i:%d arg:'%s' val:'%s'", i, arg, val);
if (i < 0)
bb_show_usage();
if (i <= 1) {
for (i = 0;; i++) {
if (i == ARRAY_SIZE(qtypes))
bb_error_msg_and_die("invalid query type \"%s\"", val);
if (strcasecmp(qtypes[i].name, val) == 0)
break;
}
types |= (1 << i);
continue;
}
if (i == 2) {
G.default_port = xatou_range(val, 1, 0xffff);
}
if (i == 3) {
G.default_retry = xatou_range(val, 1, INT_MAX);
}
if (i == 4) {
option_mask32 |= OPT_debug;
}
if (i > 4) {
G.default_timeout = xatou_range(val, 1, INT_MAX / 1000);
}
}
/* Use given DNS server if present */
if (argv[1]) {
if (argv[2])
bb_show_usage();
add_ns(argv[1]);
} else {
parse_resolvconf();
/* Fall back to localhost if we could not find NS in resolv.conf */
if (G.serv_count == 0)
add_ns("127.0.0.1");
}
if (types == 0) {
/* No explicit type given, guess query type.
* If we can convert the domain argument into a ptr (means that
* inet_pton() could read it) we assume a PTR request, else
* we issue A+AAAA queries and switch to an output format
* mimicking the one of the traditional nslookup applet.
*/
char *ptr;
ptr = make_ptr(argv[0]);
if (ptr) {
add_query(T_PTR, ptr);
} else {
add_query_with_search(T_A, argv[0]);
#if ENABLE_FEATURE_IPV6
add_query_with_search(T_AAAA, argv[0]);
#endif
}
} else {
int c;
for (c = 0; c < ARRAY_SIZE(qtypes); c++) {
if (types & (1 << c))
add_query_with_search(qtypes[c].type, argv[0]);
}
}
for (rc = 0; rc < G.serv_count;) {
int c;
c = send_queries(&G.server[rc]);
if (c > 0) {
/* more than zero replies received */
#if 0 /* which version does this? */
if (option_mask32 & OPT_debug) {
printf("Replies:\t%d\n", G.server[rc].replies);
printf("Failures:\t%d\n\n", G.server[rc].failures);
}
#endif
break;
//FIXME: we "break" even though some queries may still be not answered, and other servers may know them?
}
/* c = 0: timed out waiting for replies */
/* c < 0: error (message already printed) */
rc++;
if (rc >= G.serv_count) {
//
// NB: bind-utils-9.11.3 behavior (all to stdout, not stderr):
//
// $ nslookup gmail.com 8.8.8.8
// ;; connection timed out; no servers could be reached
//
// Using TCP mode:
// $ nslookup -vc gmail.com 8.8.8.8; echo EXITCODE:$?
// <~10 sec>
// ;; Connection to 8.8.8.8#53(8.8.8.8) for gmail.com failed: timed out.
// <~10 sec>
// ;; Connection to 8.8.8.8#53(8.8.8.8) for gmail.com failed: timed out.
// <~10 sec>
// ;; connection timed out; no servers could be reached
// ;; Connection to 8.8.8.8#53(8.8.8.8) for gmail.com failed: timed out.
// <empty line>
// EXITCODE:1
// $ _
printf(";; connection timed out; no servers could be reached\n\n");
return EXIT_FAILURE;
}
}
err = 0;
for (rc = 0; rc < G.query_count; rc++) {
if (G.query[rc].qlen) {
printf("*** Can't find %s: No answer\n", G.query[rc].name);
err = 1;
}
}
if (err) /* should this affect exicode too? */
bb_putchar('\n');
if (ENABLE_FEATURE_CLEAN_UP) {
free(G.server);
free(G.query);
}
return EXIT_SUCCESS;
}
#endif