summaryrefslogtreecommitdiffstats
path: root/src/plugins/dns/dns_packet.h
blob: 13daf7849decb211f91a81e8012784f0de5e75a7 (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
/*
 * Copyright (c) 2015 Cisco and/or its affiliates.
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at:
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#ifndef included_dns_packet_h
#define included_dns_packet_h

/**
 * DNS packet header format
 */

typedef CLIB_PACKED (struct {
  u16 id;                       /**< transaction ID */
  u16 flags;                    /**< flags  */
  u16 qdcount;                  /**< number of questions */
  u16 anscount;                 /**< number of answers */
  u16 nscount;                  /**< number of name servers */
  u16 arcount;                  /**< number of additional records */
}) dns_header_t;

#define DNS_RCODE_MASK (0xf)
#define DNS_RCODE_NO_ERROR 0
#define DNS_RCODE_FORMAT_ERROR 1
#define DNS_RCODE_SERVER_FAILURE 2
#define DNS_RCODE_NAME_ERROR 3
#define DNS_RCODE_NOT_IMPLEMENTED 4
#define DNS_RCODE_REFUSED 5

#define DNS_RA (1<<7)		/**< recursion available */
#define DNS_RD (1<<8)		/**< recursion desired */
#define DNS_TC (1<<9)	       /**< truncation  */
#define DNS_AA (1<<10)		/**< authoritative answer  */
#define DNS_OPCODE_MASK (0xf<<11) /**< opcode mask */
#define DNS_OPCODE_QUERY (0<<11)  /**< standard query */
#define DNS_OPCODE_IQUERY (1<<11) /**< inverse query (deprecated) */
#define DNS_OPCODE_STATUS (2<<11) /**< server status  */
#define DNS_QR (1<<15)		/**< query=0, response=1  */


/*
 * Note: in DNS-land, www.foobar.com is encoded as three "labels,"
 * each of which amount to a 1 octet length followed by up to 63
 * octets of name. Don't forget to add a "null root label" after the last
 * real one, or the poor slob trying to parse the name will have
 * no chance whatsoever.
 *
 * All RRs have the same top level format shown below:
 *
 *                                    1  1  1  1  1  1
 *      0  1  2  3  4  5  6  7  8  9  0  1  2  3  4  5
 *    +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
 *    |                                               |
 *    /                                               /
 *    /                      NAME                     /
 *    |                                               |
 *    +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
 *    |                      TYPE                     |
 *    +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
 *    |                     CLASS                     |
 *    +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
 *    |                      TTL                      |
 *    |                                               |
 *    +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
 *    |                   RDLENGTH                    |
 *    +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--|
 *    /                     RDATA                     /
 *    /                                               /
 *    +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
 *
 *
 *  DNS "questions" have the following format:
 *
 *                                     1  1  1  1  1  1
 *       0  1  2  3  4  5  6  7  8  9  0  1  2  3  4  5
 *     +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
 *     |                                               |
 *     /                     QNAME                     /
 *     /                                               /
 *     +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
 *     |                     QTYPE                     |
 *     +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
 *     |                     QCLASS                    |
 *     +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
 */

/**
 * DNS "question" fixed header.
 */
typedef CLIB_PACKED (struct {
  u16 type;	/**< record type requested */
  u16 class;	/**< class, 1 = internet */
}) dns_query_t;

/**
 * DNS RR fixed header.
 */
typedef CLIB_PACKED (struct {
  u16 type;	/**< record type */
  u16 class;	/**< class, 1 = internet */
  u32 ttl;	/**< time to live, in seconds */
  u16 rdlength;
  /**< length of r */
  u8 rdata[0];
}) dns_rr_t;

/*
 * There are quite a number of DNS record types
 * Feel free to add as needed
 */
#define foreach_dns_type                        \
_(A, 1) 	/**< ip4 host address */        \
_(AAAA, 28)     /**< ip6 host address */        \
_(ALL, 255)     /**< all available data */      \
_(TEXT, 16)     /**< a text string */           \
_(NAMESERVER, 2) /**< a nameserver */           \
_(CNAME, 5)      /**< a CNAME (alias) */	\
_(MAIL_EXCHANGE, 15) /**< a mail exchange  */	\
_(PTR, 12)      /**< a PTR (pointer) record */	\
_(HINFO, 13)	/**< Host info */

typedef enum
{
#define _(name,value) DNS_TYPE_##name = value,
  foreach_dns_type
#undef _
} dns_type_t;

#define DNS_CLASS_IN	1	/**< The Internet */


#endif /* included_dns_packet_h */

/*
 * fd.io coding-style-patch-verification: ON
 *
 * Local Variables:
 * eval: (c-set-style "gnu")
 * End:
 */