FD.io VPP  v18.07.1-19-g511ce25
Vector Packet Processing
dns_packet.h
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1 /*
2  * Copyright (c) 2015 Cisco and/or its affiliates.
3  * Licensed under the Apache License, Version 2.0 (the "License");
4  * you may not use this file except in compliance with the License.
5  * You may obtain a copy of the License at:
6  *
7  * http://www.apache.org/licenses/LICENSE-2.0
8  *
9  * Unless required by applicable law or agreed to in writing, software
10  * distributed under the License is distributed on an "AS IS" BASIS,
11  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12  * See the License for the specific language governing permissions and
13  * limitations under the License.
14  */
15 
16 #ifndef included_dns_packet_h
17 #define included_dns_packet_h
18 
19 /**
20  * DNS packet header format
21  */
22 
23 /* *INDENT-OFF* */
24 typedef CLIB_PACKED (struct {
25  u16 id; /**< transaction ID */
26  u16 flags; /**< flags */
27  u16 qdcount; /**< number of questions */
28  u16 anscount; /**< number of answers */
29  u16 nscount; /**< number of name servers */
30  u16 arcount; /**< number of additional records */
31 }) dns_header_t;
32 /* *INDENT-ON* */
33 
34 #define DNS_RCODE_MASK (0xf)
35 #define DNS_RCODE_NO_ERROR 0
36 #define DNS_RCODE_FORMAT_ERROR 1
37 #define DNS_RCODE_SERVER_FAILURE 2
38 #define DNS_RCODE_NAME_ERROR 3
39 #define DNS_RCODE_NOT_IMPLEMENTED 4
40 #define DNS_RCODE_REFUSED 5
41 
42 #define DNS_RA (1<<7) /**< recursion available */
43 #define DNS_RD (1<<8) /**< recursion desired */
44 #define DNS_TC (1<<9) /**< truncation */
45 #define DNS_AA (1<<10) /**< authoritative answer */
46 #define DNS_OPCODE_MASK (0xf<<11) /**< opcode mask */
47 #define DNS_OPCODE_QUERY (0<<11) /**< standard query */
48 #define DNS_OPCODE_IQUERY (1<<11) /**< inverse query (deprecated) */
49 #define DNS_OPCODE_STATUS (2<<11) /**< server status */
50 #define DNS_QR (1<<15) /**< query=0, response=1 */
51 
52 
53 /*
54  * Note: in DNS-land, www.foobar.com is encoded as three "labels,"
55  * each of which amount to a 1 octet length followed by up to 63
56  * octets of name. Don't forget to add a "null root label" after the last
57  * real one, or the poor slob trying to parse the name will have
58  * no chance whatsoever.
59  *
60  * All RRs have the same top level format shown below:
61  *
62  * 1 1 1 1 1 1
63  * 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
64  * +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
65  * | |
66  * / /
67  * / NAME /
68  * | |
69  * +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
70  * | TYPE |
71  * +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
72  * | CLASS |
73  * +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
74  * | TTL |
75  * | |
76  * +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
77  * | RDLENGTH |
78  * +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--|
79  * / RDATA /
80  * / /
81  * +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
82  *
83  *
84  * DNS "questions" have the following format:
85  *
86  * 1 1 1 1 1 1
87  * 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
88  * +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
89  * | |
90  * / QNAME /
91  * / /
92  * +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
93  * | QTYPE |
94  * +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
95  * | QCLASS |
96  * +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
97  */
98 
99 /**
100  * DNS "question" fixed header.
101  */
102 /* *INDENT-OFF* */
103 typedef CLIB_PACKED (struct {
104  u16 type; /**< record type requested */
105  u16 class; /**< class, 1 = internet */
106 }) dns_query_t;
107 /* *INDENT-ON* */
108 
109 /**
110  * DNS RR fixed header.
111  */
112 /* *INDENT-OFF* */
113 typedef CLIB_PACKED (struct {
114  u16 type; /**< record type */
115  u16 class; /**< class, 1 = internet */
116  u32 ttl; /**< time to live, in seconds */
117  u16 rdlength;
118  /**< length of r */
119  u8 rdata[0];
120 }) dns_rr_t;
121 /* *INDENT-ON* */
122 
123 /*
124  * There are quite a number of DNS record types
125  * Feel free to add as needed
126  */
127 #define foreach_dns_type \
128 _(A, 1) /**< ip4 host address */ \
129 _(AAAA, 28) /**< ip6 host address */ \
130 _(ALL, 255) /**< all available data */ \
131 _(TEXT, 16) /**< a text string */ \
132 _(NAMESERVER, 2) /**< a nameserver */ \
133 _(CNAME, 5) /**< a CNAME (alias) */ \
134 _(MAIL_EXCHANGE, 15) /**< a mail exchange */ \
135 _(PTR, 12) /**< a PTR (pointer) record */ \
136 _(HINFO, 13) /**< Host info */
137 
138 typedef enum
139 {
140 #define _(name,value) DNS_TYPE_##name = value,
142 #undef _
143 } dns_type_t;
144 
145 #define DNS_CLASS_IN 1 /**< The Internet */
146 
147 
148 #endif /* included_dns_packet_h */
149 
150 /*
151  * fd.io coding-style-patch-verification: ON
152  *
153  * Local Variables:
154  * eval: (c-set-style "gnu")
155  * End:
156  */
unsigned char u8
Definition: types.h:56
unsigned int u32
Definition: types.h:88
dns_type_t
Definition: dns_packet.h:138
unsigned short u16
Definition: types.h:57
#define foreach_dns_type
Host info.
Definition: dns_packet.h:127
u32 flags
Definition: vhost_user.h:110
typedef CLIB_PACKED(struct{u16 id;u16 flags;u16 qdcount;u16 anscount;u16 nscount;u16 arcount;}) dns_header_t
DNS packet header format.