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dns_packet.h
Go to the documentation of this file.
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/*
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* Copyright (c) 2015 Cisco and/or its affiliates.
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at:
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#ifndef included_dns_packet_h
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#define included_dns_packet_h
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/**
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* DNS packet header format
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*/
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/* *INDENT-OFF* */
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typedef
CLIB_PACKED
(
struct
{
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u16
id;
/**< transaction ID */
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u16
flags
;
/**< flags */
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u16
qdcount;
/**< number of questions */
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u16
anscount;
/**< number of answers */
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u16
nscount;
/**< number of name servers */
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u16
arcount;
/**< number of additional records */
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}) dns_header_t;
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/* *INDENT-ON* */
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#define DNS_RCODE_MASK (0xf)
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#define DNS_RCODE_NO_ERROR 0
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#define DNS_RCODE_FORMAT_ERROR 1
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#define DNS_RCODE_SERVER_FAILURE 2
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#define DNS_RCODE_NAME_ERROR 3
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#define DNS_RCODE_NOT_IMPLEMENTED 4
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#define DNS_RCODE_REFUSED 5
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#define DNS_RA (1<<7)
/**< recursion available */
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#define DNS_RD (1<<8)
/**< recursion desired */
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#define DNS_TC (1<<9)
/**< truncation */
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#define DNS_AA (1<<10)
/**< authoritative answer */
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#define DNS_OPCODE_MASK (0xf<<11)
/**< opcode mask */
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#define DNS_OPCODE_QUERY (0<<11)
/**< standard query */
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#define DNS_OPCODE_IQUERY (1<<11)
/**< inverse query (deprecated) */
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#define DNS_OPCODE_STATUS (2<<11)
/**< server status */
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#define DNS_QR (1<<15)
/**< query=0, response=1 */
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/*
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* Note: in DNS-land, www.foobar.com is encoded as three "labels,"
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* each of which amount to a 1 octet length followed by up to 63
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* octets of name. Don't forget to add a "null root label" after the last
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* real one, or the poor slob trying to parse the name will have
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* no chance whatsoever.
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*
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* All RRs have the same top level format shown below:
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*
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* 1 1 1 1 1 1
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* 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
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* +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
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* | |
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* / /
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* / NAME /
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* | |
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* +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
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* | TYPE |
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* +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
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* | CLASS |
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* +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
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* | TTL |
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* | |
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* +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
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* | RDLENGTH |
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* +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--|
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* / RDATA /
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* / /
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* +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
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*
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*
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* DNS "questions" have the following format:
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*
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* 1 1 1 1 1 1
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* 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
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* +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
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* | |
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* / QNAME /
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* / /
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* +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
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* | QTYPE |
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* +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
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* | QCLASS |
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* +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
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*/
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/**
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* DNS "question" fixed header.
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*/
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/* *INDENT-OFF* */
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typedef
CLIB_PACKED
(
struct
{
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u16
type;
/**< record type requested */
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u16
class
;
/**< class, 1 = internet */
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}) dns_query_t;
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/* *INDENT-ON* */
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/**
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* DNS RR fixed header.
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*/
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/* *INDENT-OFF* */
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typedef
CLIB_PACKED
(
struct
{
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u16
type;
/**< record type */
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u16
class
;
/**< class, 1 = internet */
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u32
ttl;
/**< time to live, in seconds */
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u16
rdlength;
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/**< length of r */
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u8
rdata[0];
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}) dns_rr_t;
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/* *INDENT-ON* */
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/*
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* There are quite a number of DNS record types
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* Feel free to add as needed
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*/
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#define foreach_dns_type \
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_(A, 1)
/**< ip4 host address */
\
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_(AAAA, 28)
/**< ip6 host address */
\
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_(ALL, 255)
/**< all available data */
\
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_(TEXT, 16)
/**< a text string */
\
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_(NAMESERVER, 2)
/**< a nameserver */
\
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_(CNAME, 5)
/**< a CNAME (alias) */
\
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_(MAIL_EXCHANGE, 15)
/**< a mail exchange */
\
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_(PTR, 12)
/**< a PTR (pointer) record */
\
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_(HINFO, 13)
/**< Host info */
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typedef
enum
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{
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#define _(name,value) DNS_TYPE_##name = value,
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foreach_dns_type
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#undef _
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}
dns_type_t
;
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#define DNS_CLASS_IN 1
/**< The Internet */
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#endif
/* included_dns_packet_h */
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/*
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* fd.io coding-style-patch-verification: ON
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*
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* Local Variables:
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* eval: (c-set-style "gnu")
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* End:
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*/
dns_type_t
dns_type_t
Definition:
dns_packet.h:138
foreach_dns_type
#define foreach_dns_type
Host info.
Definition:
dns_packet.h:127
u32
unsigned int u32
Definition:
types.h:88
u16
unsigned short u16
Definition:
types.h:57
u8
unsigned char u8
Definition:
types.h:56
CLIB_PACKED
typedef CLIB_PACKED(struct{u16 id;u16 flags;u16 qdcount;u16 anscount;u16 nscount;u16 arcount;}) dns_header_t
DNS packet header format.
flags
u32 flags
Definition:
vhost-user.h:77
src
vnet
dns
dns_packet.h
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