summaryrefslogtreecommitdiff
path: root/llmnr-query.c
blob: 5ee07ec91de38230eebd553e36e3e8cb8b7eac88 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
/*
 * 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;
}