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
|
/*
* packet.h -- low-level DNS packet encoding and decoding functions.
*
* Copyright (c) 2001-2006, NLnet Labs. All rights reserved.
*
* See LICENSE for the license.
*
*/
#ifndef PACKET_H
#define PACKET_H
#include <sys/types.h>
#include "dns.h"
#include "namedb.h"
struct query;
/*
* Set of macro's to deal with the dns message header as specified
* in RFC1035 in portable way.
*
*/
/*
*
* 1 1 1 1 1 1
* 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
* +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
* | ID |
* +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
* |QR| Opcode |AA|TC|RD|RA| Z|AD|CD| RCODE |
* +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
* | QDCOUNT |
* +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
* | ANCOUNT |
* +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
* | NSCOUNT |
* +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
* | ARCOUNT |
* +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
*
*/
/* The length of the header */
#define QHEADERSZ 12
/* First octet of flags */
#define RD_MASK 0x01U
#define RD_SHIFT 0
#define RD(packet) (*buffer_at((packet), 2) & RD_MASK)
#define RD_SET(packet) (*buffer_at((packet), 2) |= RD_MASK)
#define RD_CLR(packet) (*buffer_at((packet), 2) &= ~RD_MASK)
#define TC_MASK 0x02U
#define TC_SHIFT 1
#define TC(packet) (*buffer_at((packet), 2) & TC_MASK)
#define TC_SET(packet) (*buffer_at((packet), 2) |= TC_MASK)
#define TC_CLR(packet) (*buffer_at((packet), 2) &= ~TC_MASK)
#define AA_MASK 0x04U
#define AA_SHIFT 2
#define AA(packet) (*buffer_at((packet), 2) & AA_MASK)
#define AA_SET(packet) (*buffer_at((packet), 2) |= AA_MASK)
#define AA_CLR(packet) (*buffer_at((packet), 2) &= ~AA_MASK)
#define OPCODE_MASK 0x78U
#define OPCODE_SHIFT 3
#define OPCODE(packet) ((*buffer_at((packet), 2) & OPCODE_MASK) >> OPCODE_SHIFT)
#define OPCODE_SET(packet, opcode) \
(*buffer_at((packet), 2) = (*buffer_at((packet), 2) & ~OPCODE_MASK) | ((opcode) << OPCODE_SHIFT))
#define QR_MASK 0x80U
#define QR_SHIFT 7
#define QR(packet) (*buffer_at((packet), 2) & QR_MASK)
#define QR_SET(packet) (*buffer_at((packet), 2) |= QR_MASK)
#define QR_CLR(packet) (*buffer_at((packet), 2) &= ~QR_MASK)
/* Second octet of flags */
#define RCODE_MASK 0x0fU
#define RCODE_SHIFT 0
#define RCODE(packet) (*buffer_at((packet), 3) & RCODE_MASK)
#define RCODE_SET(packet, rcode) \
(*buffer_at((packet), 3) = (*buffer_at((packet), 3) & ~RCODE_MASK) | (rcode))
#define CD_MASK 0x10U
#define CD_SHIFT 4
#define CD(packet) (*buffer_at((packet), 3) & CD_MASK)
#define CD_SET(packet) (*buffer_at((packet), 3) |= CD_MASK)
#define CD_CLR(packet) (*buffer_at((packet), 3) &= ~CD_MASK)
#define AD_MASK 0x20U
#define AD_SHIFT 5
#define AD(packet) (*buffer_at((packet), 3) & AD_MASK)
#define AD_SET(packet) (*buffer_at((packet), 3) |= AD_MASK)
#define AD_CLR(packet) (*buffer_at((packet), 3) &= ~AD_MASK)
#define Z_MASK 0x40U
#define Z_SHIFT 6
#define Z(packet) (*buffer_at((packet), 3) & Z_MASK)
#define Z_SET(packet) (*buffer_at((packet), 3) |= Z_MASK)
#define Z_CLR(packet) (*buffer_at((packet), 3) &= ~Z_MASK)
#define RA_MASK 0x80U
#define RA_SHIFT 7
#define RA(packet) (*buffer_at((packet), 3) & RA_MASK)
#define RA_SET(packet) (*buffer_at((packet), 3) |= RA_MASK)
#define RA_CLR(packet) (*buffer_at((packet), 3) &= ~RA_MASK)
/* Query ID */
#define ID(packet) (buffer_read_u16_at((packet), 0))
#define ID_SET(packet, id) (buffer_write_u16_at((packet), 0, (id)))
/* Flags, RCODE, and OPCODE. */
#define FLAGS(packet) (buffer_read_u16_at((packet), 2))
#define FLAGS_SET(packet, f) (buffer_write_u16_at((packet), 2, (f)))
/* Counter of the question section */
#define QDCOUNT(packet) (buffer_read_u16_at((packet), 4))
#define QDCOUNT_SET(packet, c) (buffer_write_u16_at((packet), 4, (c)))
/* Counter of the answer section */
#define ANCOUNT(packet) (buffer_read_u16_at((packet), 6))
#define ANCOUNT_SET(packet, c) (buffer_write_u16_at((packet), 6, (c)))
/* Counter of the authority section */
#define NSCOUNT(packet) (buffer_read_u16_at((packet), 8))
#define NSCOUNT_SET(packet, c) (buffer_write_u16_at((packet), 8, (c)))
/* Counter of the additional section */
#define ARCOUNT(packet) (buffer_read_u16_at((packet), 10))
#define ARCOUNT_SET(packet, c) (buffer_write_u16_at((packet), 10, (c)))
/* Miscellaneous limits */
#define MAX_PACKET_SIZE 65535 /* Maximum supported size of DNS packets. */
#define QIOBUFSZ (MAX_PACKET_SIZE + MAX_RR_SIZE)
#define MAXRRSPP 10240 /* Maximum number of rr's per packet */
#define MAX_COMPRESSED_DNAMES MAXRRSPP /* Maximum number of compressed domains. */
#define MAX_COMPRESSION_OFFSET 16383 /* Compression pointers are 14 bit. */
#define IPV4_MINIMAL_RESPONSE_SIZE 1232 /* Recommended minimal edns size for IPv4 */
#define IPV6_MINIMAL_RESPONSE_SIZE 1220 /* Recommended minimal edns size for IPv6 */
/* use round robin rotation */
extern int round_robin;
/* use minimal responses (more minimal, with additional only for referrals) */
extern int minimal_responses;
/*
* Encode RR with OWNER as owner name into QUERY. Returns the number
* of RRs successfully encoded.
*/
int packet_encode_rr(struct query *query,
domain_type *owner,
rr_type *rr,
uint32_t ttl);
/*
* Encode RRSET with OWNER as the owner name into QUERY. Returns the
* number of RRs successfully encoded. If TRUNCATE_RRSET the entire
* RRset is truncated in case an RR (or the RRsets signature) does not
* fit.
*/
int packet_encode_rrset(struct query *query,
domain_type *owner,
rrset_type *rrset,
int truncate_rrset,
size_t minimal_respsize,
int* done);
/*
* Skip the RR at the current position in PACKET.
*/
int packet_skip_rr(buffer_type *packet, int question_section);
/*
* Skip the dname at the current position in PACKET.
*/
int packet_skip_dname(buffer_type *packet);
/*
* Read the RR at the current position in PACKET.
*/
rr_type *packet_read_rr(region_type *region,
domain_table_type *owners,
buffer_type *packet,
int question_section);
/*
* read a query entry from network packet given in buffer.
* does not follow compression ptrs, checks for errors (returns 0).
* Dest must be at least MAXDOMAINLEN long.
*/
int packet_read_query_section(buffer_type *packet,
uint8_t* dest,
uint16_t* qtype,
uint16_t* qclass);
/* read notify SOA serial from packet. buffer position is unmodified on return.
* returns false on no-serial found or parse failure. */
int packet_find_notify_serial(buffer_type *packet, uint32_t* serial);
#endif /* PACKET_H */
|
