summaryrefslogtreecommitdiff
path: root/usr.sbin/nsd/packet.c
blob: c3c9a8a1aadcd6151e2896da538ee86b137b45f9 (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
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
/*
 * packet.c -- low-level DNS packet encoding and decoding functions.
 *
 * Copyright (c) 2001-2006, NLnet Labs. All rights reserved.
 *
 * See LICENSE for the license.
 *
 */

#include <config.h>

#include <string.h>

#include "packet.h"
#include "query.h"
#include "rdata.h"

static void
encode_dname(query_type *q, domain_type *domain)
{
	while (domain->parent && query_get_dname_offset(q, domain) == 0) {
		query_put_dname_offset(q, domain, buffer_position(q->packet));
		DEBUG(DEBUG_NAME_COMPRESSION, 2,
		      (LOG_INFO, "dname: %s, number: %lu, offset: %u\n",
		       dname_to_string(domain_dname(domain), NULL),
		       (unsigned long) domain->number,
		       query_get_dname_offset(q, domain)));
		buffer_write(q->packet, dname_name(domain_dname(domain)),
			     label_length(dname_name(domain_dname(domain))) + 1U);
		domain = domain->parent;
	}
	if (domain->parent) {
		DEBUG(DEBUG_NAME_COMPRESSION, 2,
		      (LOG_INFO, "dname: %s, number: %lu, pointer: %u\n",
		       dname_to_string(domain_dname(domain), NULL),
		       (unsigned long) domain->number,
		       query_get_dname_offset(q, domain)));
		assert(query_get_dname_offset(q, domain) <= MAX_COMPRESSION_OFFSET);
		buffer_write_u16(q->packet,
				 0xc000 | query_get_dname_offset(q, domain));
	} else {
		buffer_write_u8(q->packet, 0);
	}
}

int
packet_encode_rr(query_type *q, domain_type *owner, rr_type *rr)
{
	size_t truncation_mark;
	uint16_t rdlength = 0;
	size_t rdlength_pos;
	uint16_t j;

	assert(q);
	assert(owner);
	assert(rr);

	/*
	 * If the record does not in fit in the packet the packet size
	 * will be restored to the mark.
	 */
	truncation_mark = buffer_position(q->packet);

	encode_dname(q, owner);
	buffer_write_u16(q->packet, rr->type);
	buffer_write_u16(q->packet, rr->klass);
	buffer_write_u32(q->packet, rr->ttl);

	/* Reserve space for rdlength. */
	rdlength_pos = buffer_position(q->packet);
	buffer_skip(q->packet, sizeof(rdlength));

	for (j = 0; j < rr->rdata_count; ++j) {
		switch (rdata_atom_wireformat_type(rr->type, j)) {
		case RDATA_WF_COMPRESSED_DNAME:
			encode_dname(q, rdata_atom_domain(rr->rdatas[j]));
			break;
		case RDATA_WF_UNCOMPRESSED_DNAME:
		{
			const dname_type *dname = domain_dname(
				rdata_atom_domain(rr->rdatas[j]));
			buffer_write(q->packet,
				     dname_name(dname), dname->name_size);
			break;
		}
		default:
			buffer_write(q->packet,
				     rdata_atom_data(rr->rdatas[j]),
				     rdata_atom_size(rr->rdatas[j]));
			break;
		}
	}

	if (!query_overflow(q)) {
		rdlength = (buffer_position(q->packet) - rdlength_pos
			    - sizeof(rdlength));
		buffer_write_u16_at(q->packet, rdlength_pos, rdlength);
		return 1;
	} else {
		buffer_set_position(q->packet, truncation_mark);
		query_clear_dname_offsets(q, truncation_mark);
		assert(!query_overflow(q));
		return 0;
	}
}

int
packet_encode_rrset(query_type *query,
		    domain_type *owner,
		    rrset_type *rrset,
		    int section)
{
	uint16_t i;
	size_t truncation_mark;
	uint16_t added = 0;
	int all_added = 1;
	int truncate_rrset = (section == ANSWER_SECTION ||
							section == AUTHORITY_SECTION);
	rrset_type *rrsig;

	assert(rrset->rr_count > 0);

	truncation_mark = buffer_position(query->packet);

	for (i = 0; i < rrset->rr_count; ++i) {
		if (packet_encode_rr(query, owner, &rrset->rrs[i])) {
			++added;
		} else {
			all_added = 0;
			break;
		}
	}

	if (all_added &&
	    query->edns.dnssec_ok &&
	    zone_is_secure(rrset->zone) &&
	    rrset_rrtype(rrset) != TYPE_RRSIG &&
	    (rrsig = domain_find_rrset(owner, rrset->zone, TYPE_RRSIG)))
	{
		for (i = 0; i < rrsig->rr_count; ++i) {
			if (rr_rrsig_type_covered(&rrsig->rrs[i])
			    == rrset_rrtype(rrset))
			{
				if (packet_encode_rr(query, owner,
						     &rrsig->rrs[i]))
				{
					++added;
				} else {
					all_added = 0;
					break;
				}
			}
		}
	}

	if (!all_added && truncate_rrset) {
		/* Truncate entire RRset and set truncate flag. */
		buffer_set_position(query->packet, truncation_mark);
		query_clear_dname_offsets(query, truncation_mark);
		TC_SET(query->packet);
		added = 0;
	}

	return added;
}

int
packet_skip_dname(buffer_type *packet)
{
	while (1) {
		uint8_t label_size;
		if (!buffer_available(packet, 1))
			return 0;

		label_size = buffer_read_u8(packet);
		if (label_size == 0) {
			return 1;
		} else if ((label_size & 0xc0) != 0) {
			if (!buffer_available(packet, 1))
				return 0;
			buffer_skip(packet, 1);
			return 1;
		} else if (!buffer_available(packet, label_size)) {
			return 0;
		} else {
			buffer_skip(packet, label_size);
		}
	}
}

int
packet_skip_rr(buffer_type *packet, int question_section)
{
	if (!packet_skip_dname(packet))
		return 0;

	if (question_section) {
		if (!buffer_available(packet, 4))
			return 0;
		buffer_skip(packet, 4);
	} else {
		uint16_t rdata_size;
		if (!buffer_available(packet, 10))
			return 0;
		buffer_skip(packet, 8);
		rdata_size = buffer_read_u16(packet);
		if (!buffer_available(packet, rdata_size))
			return 0;
		buffer_skip(packet, rdata_size);
	}

	return 1;
}

rr_type *
packet_read_rr(region_type *region, domain_table_type *owners,
	       buffer_type *packet, int question_section)
{
	const dname_type *owner;
	uint16_t rdlength;
	ssize_t rdata_count;
	rdata_atom_type *rdatas;
	rr_type *result = (rr_type *) region_alloc(region, sizeof(rr_type));

	owner = dname_make_from_packet(region, packet, 1, 1);
	if (!owner || !buffer_available(packet, 2*sizeof(uint16_t))) {
		return NULL;
	}

	result->owner = domain_table_insert(owners, owner);
	result->type = buffer_read_u16(packet);
	result->klass = buffer_read_u16(packet);

	if (question_section) {
		result->ttl = 0;
		result->rdata_count = 0;
		result->rdatas = NULL;
		return result;
	} else if (!buffer_available(packet, sizeof(uint32_t) + sizeof(uint16_t))) {
		return NULL;
	}

	result->ttl = buffer_read_u32(packet);
	rdlength = buffer_read_u16(packet);

	if (!buffer_available(packet, rdlength)) {
		return NULL;
	}

	rdata_count = rdata_wireformat_to_rdata_atoms(
		region, owners, result->type, rdlength, packet, &rdatas);
	if (rdata_count == -1) {
		return NULL;
	}
	result->rdata_count = rdata_count;
	result->rdatas = rdatas;

	return result;
}

int packet_read_query_section(buffer_type *packet,
	uint8_t* dst, uint16_t* qtype, uint16_t* qclass)
{
	uint8_t *query_name = buffer_current(packet);
	uint8_t *src = query_name;
	size_t len;

	while (*src) {
		/*
		 * If we are out of buffer limits or we have a pointer
		 * in question dname or the domain name is longer than
		 * MAXDOMAINLEN ...
		 */
		if ((*src & 0xc0) ||
		    (src + *src + 2 > buffer_end(packet)) ||
		    (src + *src + 2 > query_name + MAXDOMAINLEN))
		{
			return 0;
		}
		memcpy(dst, src, *src + 1);
		dst += *src + 1;
		src += *src + 1;
	}
	*dst++ = *src++;

	/* Make sure name is not too long or we have stripped packet... */
	len = src - query_name;
	if (len > MAXDOMAINLEN ||
	    (src + 2*sizeof(uint16_t) > buffer_end(packet)))
	{
		return 0;
	}
	buffer_set_position(packet, src - buffer_begin(packet));

	*qtype = buffer_read_u16(packet);
	*qclass = buffer_read_u16(packet);
	return 1;
}