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/*
* Simple LLMNR query command.
*
* Copyright (C) 2015 Tobias Klauser <tklauser@distanz.ch>
*
* This file is part of llmnrd.
*
* llmnrd 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, version 2 of the License.
*
* llmnrd is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with llmnrd. If not, see <http://www.gnu.org/licenses/>.
*/
#include <errno.h>
#include <getopt.h>
#include <stdint.h>
#include <string.h>
#include <unistd.h>
#include <arpa/inet.h>
#include <sys/select.h>
#include <sys/socket.h>
#include <sys/time.h>
#include <sys/types.h>
#include "compiler.h"
#include "llmnr-packet.h"
#include "log.h"
#include "pkt.h"
static const char *short_ops = "c:i:p:T:h";
static const struct option long_opts[] = {
{ "count", required_argument, NULL, 'c' },
{ "interval", required_argument, NULL, 'i' },
{ "type", required_argument, NULL, 'T' },
{ "help", no_argument, NULL, 'h' },
{ NULL, 0, NULL, 0 },
};
static void __noreturn usage_and_exit(int status)
{
fprintf(stdout, "Usage: llmnr-query [OPTIONS...] <query-name>\n"
"Options:\n"
" -c, --count number of queries to send (default: 1)\n"
" -i, --interval interval between queries in ms (default: 500)\n"
" -T, --type LLMNR query type, must be one of A, AAAA, ANY (default: A)\n"
" -h, --help show this help and exit");
exit(status);
}
static const char *query_type(uint16_t qtype)
{
switch (qtype) {
case LLMNR_QTYPE_A:
return "A";
case LLMNR_QTYPE_AAAA:
return "AAAA";
case LLMNR_QTYPE_ANY:
return "ANY";
default:
return "<unknown>";
}
}
int main(int argc, char **argv)
{
int c, sock;
const char *query_name;
size_t query_name_len;
unsigned long i, count = 1, interval = 500;
uint16_t qtype = LLMNR_QTYPE_A;
struct pkt *p;
while ((c = getopt_long(argc, argv, short_ops, long_opts, NULL)) != -1) {
switch (c) {
case 'c':
count = strtoul(optarg, NULL, 0);
break;
case 'i':
interval = strtoul(optarg, NULL, 0);
break;
case 'T':
if (xstreq("A", optarg))
qtype = LLMNR_QTYPE_A;
else if (xstreq("AAAA", optarg))
qtype = LLMNR_QTYPE_AAAA;
else if (xstreq("ANY", optarg))
qtype = LLMNR_QTYPE_ANY;
else {
printf("Invalid query type: %s\n", optarg);
usage_and_exit(EXIT_FAILURE);
}
break;
case 'h':
usage_and_exit(EXIT_SUCCESS);
default:
usage_and_exit(EXIT_FAILURE);
}
}
if (optind >= argc)
usage_and_exit(EXIT_FAILURE);
query_name = argv[optind];
query_name_len = strlen(query_name);
if (query_name_len > UINT8_MAX) {
log_err("Query name too long\n");
return -1;
}
sock = socket(AF_INET, SOCK_DGRAM, 0);
if (sock < 0) {
log_err("Failed to open UDP socket: %s\n", strerror(errno));
return -1;
}
p = pkt_alloc(128);
log_info("LLMNR query: %s IN %s\n", query_name, query_type(qtype));
for (i = 0; i < count; i++) {
struct llmnr_hdr *hdr;
struct sockaddr_in sin;
size_t query_pkt_len;
fd_set rfds;
struct timeval tv;
int ret;
hdr = (struct llmnr_hdr *)pkt_put(p, sizeof(*hdr));
hdr->id = htons(i % UINT16_MAX);
hdr->flags = 0;
hdr->qdcount = htons(1);
hdr->ancount = 0;
hdr->nscount = 0;
hdr->arcount = 0;
pkt_put_u8(p, (uint8_t)query_name_len);
memcpy(pkt_put(p, query_name_len), query_name, query_name_len);
pkt_put_u8(p, 0);
pkt_put_u16(p, htons(qtype));
pkt_put_u16(p, htons(LLMNR_QCLASS_IN));
memset(&sin, 0, sizeof(sin));
sin.sin_family = AF_INET;
sin.sin_addr.s_addr = inet_addr(LLMNR_IPV4_MCAST_ADDR);
sin.sin_port = htons(LLMNR_UDP_PORT);
query_pkt_len = pkt_len(p) - sizeof(*hdr);
if (sendto(sock, p->data, pkt_len(p), 0, (struct sockaddr *)&sin, sizeof(sin)) < 0) {
log_err("Failed to send UDP packet: %s\n", strerror(errno));
break;
}
FD_ZERO(&rfds);
FD_SET(sock, &rfds);
/* wait up to one second for a response */
tv.tv_sec = 1;
tv.tv_usec = 0;
ret = select(sock + 1, &rfds, NULL, NULL, &tv);
if (ret < 0) {
log_err("Failed to select() on socket: %s\n", strerror(errno));
break;
} else if (ret) {
uint16_t j, ancount;
pkt_reset(p);
if (recv(sock, p->data, p->size, 0) < 0) {
log_err("Failed to receive from socket: %s\n", strerror(errno));
break;
}
hdr = (struct llmnr_hdr *)pkt_put(p, sizeof(*hdr));
ancount = htons(hdr->ancount);
/* skip the original query */
pkt_put(p, query_pkt_len);
for (j = 0; j < ancount; ++j) {
uint8_t nl = *pkt_put(p, 1);
char addr[INET6_ADDRSTRLEN];
uint16_t type, clss, addr_size;
uint32_t ttl;
char *name;
int af;
/* compression? */
if (nl & 0xC0) {
uint16_t ptr = (nl & 0x3F) << 8 | *pkt_put(p, 1);
name = (char *)p->data + ptr + 1;
} else
name = (char *)pkt_put(p, nl + 1);
type = htons(*(uint16_t *)pkt_put(p, sizeof(type)));
clss = htons(*(uint16_t *)pkt_put(p, sizeof(clss)));
ttl = htonl(*(uint32_t *)pkt_put(p, sizeof(ttl)));
addr_size = htons(*(uint16_t *)pkt_put(p, sizeof(addr_size)));
if (addr_size == sizeof(struct in_addr)) {
af = AF_INET;
} else if (addr_size == sizeof(struct in6_addr)) {
af = AF_INET6;
} else {
log_warn("Unexpected address size received: %d\n", addr_size);
break;
}
if (!inet_ntop(af, pkt_put(p, addr_size), addr, ARRAY_SIZE(addr)))
strncpy(addr, "<invalid>", sizeof(addr));
log_info("LLMNR response: %s IN %s %s (TTL %d)\n", name, query_type(type), addr, ttl);
}
} else
log_info("No LLMNR response received within timeout\n");
if (i < count - 1) {
pkt_reset(p);
usleep(interval * 1000);
}
}
pkt_free(p);
close(sock);
return 0;
}
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