📄 dns.h
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/* $Id: dns.h 1032 2007-03-02 14:46:15Z bennylp $ */
/*
* Copyright (C) 2003-2007 Benny Prijono <benny@prijono.org>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#ifndef __PJLIB_UTIL_DNS_H__
#define __PJLIB_UTIL_DNS_H__
/**
* @file dns.h
* @brief Low level DNS message parsing and packetization.
*/
#include <pjlib-util/types.h>
#include <pj/sock.h>
PJ_BEGIN_DECL
/**
* @defgroup PJ_DNS DNS and Asynchronous DNS Resolver
* @ingroup PJLIB_UTIL
*/
/**
* @defgroup PJ_DNS_PARSING Low-level DNS Message Parsing and Packetization
* @ingroup PJ_DNS
* @{
*
* This module provides low-level services to parse and packetize DNS queries
* and responses. The functions support building a DNS query packet and parse
* the data in the DNS response.
*
* To create a DNS query packet, application should call #pj_dns_make_query()
* function, specifying the desired DNS query type, the name to be resolved,
* and the buffer where the DNS packet will be built into.
*
* When incoming DNS query or response packet arrives, application can use
* #pj_dns_parse_packet() to parse the TCP/UDP payload into parsed DNS packet
* structure.
*
* This module does not provide any networking functionalities to send or
* receive DNS packets. This functionality should be provided by higher layer
* modules such as @ref PJ_DNS_RESOLVER.
*/
enum
{
PJ_DNS_CLASS_IN = 1 /**< DNS class IN. */
};
/**
* This enumeration describes standard DNS record types as described by
* RFC 1035, RFC 2782, and others.
*/
typedef enum pj_dns_type
{
PJ_DNS_TYPE_A = 1, /**< Host address (A) record. */
PJ_DNS_TYPE_NS = 2, /**< Authoritative name server (NS) */
PJ_DNS_TYPE_MD = 3, /**< Mail destination (MD) record. */
PJ_DNS_TYPE_MF = 4, /**< Mail forwarder (MF) record. */
PJ_DNS_TYPE_CNAME = 5, /**< Canonical name (CNAME) record. */
PJ_DNS_TYPE_SOA = 6, /**< Marks start of zone authority. */
PJ_DNS_TYPE_MB = 7, /**< Mailbox domain name (MB). */
PJ_DNS_TYPE_MG = 8, /**< Mail group member (MG). */
PJ_DNS_TYPE_MR = 9, /**< Mail rename domain name. */
PJ_DNS_TYPE_NULL = 10, /**< NULL RR. */
PJ_DNS_TYPE_WKS = 11, /**< Well known service description */
PJ_DNS_TYPE_PTR = 12, /**< Domain name pointer. */
PJ_DNS_TYPE_HINFO = 13, /**< Host information. */
PJ_DNS_TYPE_MINFO = 14, /**< Mailbox or mail list information. */
PJ_DNS_TYPE_MX = 15, /**< Mail exchange record. */
PJ_DNS_TYPE_TXT = 16, /**< Text string. */
PJ_DNS_TYPE_RP = 17, /**< Responsible person. */
PJ_DNS_TYPE_AFSB = 18, /**< AFS cell database. */
PJ_DNS_TYPE_X25 = 19, /**< X.25 calling address. */
PJ_DNS_TYPE_ISDN = 20, /**< ISDN calling address. */
PJ_DNS_TYPE_RT = 21, /**< Router. */
PJ_DNS_TYPE_NSAP = 22, /**< NSAP address. */
PJ_DNS_TYPE_NSAP_PTR= 23, /**< NSAP reverse address. */
PJ_DNS_TYPE_SIG = 24, /**< Signature. */
PJ_DNS_TYPE_KEY = 25, /**< Key. */
PJ_DNS_TYPE_PX = 26, /**< X.400 mail mapping. */
PJ_DNS_TYPE_GPOS = 27, /**< Geographical position (withdrawn) */
PJ_DNS_TYPE_AAAA = 28, /**< IPv6 address. */
PJ_DNS_TYPE_LOC = 29, /**< Location. */
PJ_DNS_TYPE_NXT = 30, /**< Next valid name in the zone. */
PJ_DNS_TYPE_EID = 31, /**< Endpoint idenfitier. */
PJ_DNS_TYPE_NIMLOC = 32, /**< Nimrod locator. */
PJ_DNS_TYPE_SRV = 33, /**< Server selection (SRV) record. */
PJ_DNS_TYPE_ATMA = 34, /**< DNS ATM address record. */
PJ_DNS_TYPE_NAPTR = 35, /**< DNS Naming authority pointer record. */
PJ_DNS_TYPE_KX = 36, /**< DNS key exchange record. */
PJ_DNS_TYPE_CERT = 37, /**< DNS certificate record. */
PJ_DNS_TYPE_A6 = 38, /**< DNS IPv6 address (experimental) */
PJ_DNS_TYPE_DNAME = 39, /**< DNS non-terminal name redirection rec. */
PJ_DNS_TYPE_OPT = 41, /**< DNS options - contains EDNS metadata. */
PJ_DNS_TYPE_APL = 42, /**< DNS Address Prefix List (APL) record. */
PJ_DNS_TYPE_DS = 43, /**< DNS Delegation Signer (DS) */
PJ_DNS_TYPE_SSHFP = 44, /**< DNS SSH Key Fingerprint */
PJ_DNS_TYPE_IPSECKEY= 45, /**< DNS IPSEC Key. */
PJ_DNS_TYPE_RRSIG = 46, /**< DNS Resource Record signature. */
PJ_DNS_TYPE_NSEC = 47, /**< DNS Next Secure Name. */
PJ_DNS_TYPE_DNSKEY = 48 /**< DNSSEC Key. */
} pj_dns_type;
/**
* Standard DNS header, according to RFC 1035, which will be present in
* both DNS query and DNS response.
*
* Note that all values seen by application would be in
* host by order. The library would convert them to network
* byte order as necessary.
*/
typedef struct pj_dns_hdr
{
pj_uint16_t id; /**< Transaction ID. */
pj_uint16_t flags; /**< Flags. */
pj_uint16_t qdcount; /**< Nb. of queries. */
pj_uint16_t anscount; /**< Nb. of res records */
pj_uint16_t nscount; /**< Nb. of NS records. */
pj_uint16_t arcount; /**< Nb. of additional records */
} pj_dns_hdr;
/** Create RCODE flag */
#define PJ_DNS_SET_RCODE(c) ((pj_uint16_t)((c) & 0x0F))
/** Create RA (Recursion Available) bit */
#define PJ_DNS_SET_RA(on) ((pj_uint16_t)((on) << 7))
/** Create RD (Recursion Desired) bit */
#define PJ_DNS_SET_RD(on) ((pj_uint16_t)((on) << 8))
/** Create TC (Truncated) bit */
#define PJ_DNS_SET_TC(on) ((pj_uint16_t)((on) << 9))
/** Create AA (Authoritative Answer) bit */
#define PJ_DNS_SET_AA(on) ((pj_uint16_t)((on) << 10))
/** Create four bits opcode */
#define PJ_DNS_SET_OPCODE(o) ((pj_uint16_t)((o) << 11))
/** Create query/response bit */
#define PJ_DNS_SET_QR(on) ((pj_uint16_t)((on) << 15))
/** Get RCODE value */
#define PJ_DNS_GET_RCODE(val) (((val) & PJ_DNS_SET_RCODE(0x0F)) >> 0)
/** Get RA bit */
#define PJ_DNS_GET_RA(val) (((val) & PJ_DNS_SET_RA(1)) >> 7)
/** Get RD bit */
#define PJ_DNS_GET_RD(val) (((val) & PJ_DNS_SET_RD(1)) >> 8)
/** Get TC bit */
#define PJ_DNS_GET_TC(val) (((val) & PJ_DNS_SET_TC(1)) >> 9)
/** Get AA bit */
#define PJ_DNS_GET_AA(val) (((val) & PJ_DNS_SET_AA(1)) >> 10)
/** Get OPCODE value */
#define PJ_DNS_GET_OPCODE(val) (((val) & PJ_DNS_SET_OPCODE(0x0F)) >> 11)
/** Get QR bit */
#define PJ_DNS_GET_QR(val) (((val) & PJ_DNS_SET_QR(1)) >> 15)
/**
* These constants describe DNS RCODEs. Application can fold these constants
* into PJLIB pj_status_t namespace by calling #PJ_STATUS_FROM_DNS_RCODE()
* macro.
*/
typedef enum pj_dns_rcode
{
PJ_DNS_RCODE_FORMERR = 1, /**< Format error. */
PJ_DNS_RCODE_SERVFAIL = 2, /**< Server failure. */
PJ_DNS_RCODE_NXDOMAIN = 3, /**< Name Error. */
PJ_DNS_RCODE_NOTIMPL = 4, /**< Not Implemented. */
PJ_DNS_RCODE_REFUSED = 5, /**< Refused. */
PJ_DNS_RCODE_YXDOMAIN = 6, /**< The name exists. */
PJ_DNS_RCODE_YXRRSET = 7, /**< The RRset (name, type) exists. */
PJ_DNS_RCODE_NXRRSET = 8, /**< The RRset (name, type) doesn't exist*/
PJ_DNS_RCODE_NOTAUTH = 9, /**< Not authorized. */
PJ_DNS_RCODE_NOTZONE = 10 /**< The zone specified is not a zone. */
} pj_dns_rcode;
/**
* This structure describes a DNS query record.
*/
typedef struct pj_dns_parsed_query
{
pj_str_t name; /**< The domain in the query. */
pj_uint16_t type; /**< Type of the query (pj_dns_type) */
pj_uint16_t dnsclass; /**< Network class (PJ_DNS_CLASS_IN=1) */
} pj_dns_parsed_query;
/**
* This structure describes a Resource Record parsed from the DNS packet.
* All integral values are in host byte order.
*/
typedef struct pj_dns_parsed_rr
{
pj_str_t name; /**< The domain name which this rec pertains. */
pj_uint16_t type; /**< RR type code. */
pj_uint16_t dnsclass; /**< Class of data (PJ_DNS_CLASS_IN=1). */
pj_uint32_t ttl; /**< Time to live. */
pj_uint16_t rdlength; /**< Resource data length. */
void *data; /**< Pointer to the raw resource data, only
when the type is not known. If it is known,
the data will be put in rdata below. */
/** For resource types that are recognized/supported by this library,
* the parsed resource data will be placed in this rdata union.
*/
union rdata
{
/** SRV Resource Data (PJ_DNS_TYPE_SRV, 33) */
struct srv {
pj_uint16_t prio; /**< Target priority (lower is higher). */
pj_uint16_t weight; /**< Weight/proportion */
pj_uint16_t port; /**< Port number of the service */
pj_str_t target; /**< Target name. */
} srv;
/** CNAME Resource Data (PJ_DNS_TYPE_CNAME, 5) */
struct cname {
pj_str_t name; /**< Primary canonical name for an alias. */
} cname;
/** NS Resource Data (PJ_DNS_TYPE_NS, 2) */
struct ns {
pj_str_t name; /**< Primary name server. */
} ns;
/** PTR Resource Data (PJ_DNS_TYPE_PTR, 12) */
struct ptr {
pj_str_t name; /**< PTR name. */
} ptr;
/** A Resource Data (PJ_DNS_TYPE_A, 1) */
struct a {
pj_in_addr ip_addr;/**< IP host address string. */
} a;
} rdata;
} pj_dns_parsed_rr;
/**
* This structure describes the parsed repersentation of the raw DNS packet.
* Note that all integral values in the parsed packet are represented in
* host byte order.
*/
typedef struct pj_dns_parsed_packet
{
pj_dns_hdr hdr; /**< Pointer to DNS hdr, in host byte order */
pj_dns_parsed_query *q; /**< Array of DNS queries. */
pj_dns_parsed_rr *ans; /**< Array of DNS RR answer. */
pj_dns_parsed_rr *ns; /**< Array of NS record in the answer. */
pj_dns_parsed_rr *arr; /**< Array of additional RR answer. */
} pj_dns_parsed_packet;
/**
* Option flags to be specified when calling #pj_dns_packet_dup() function.
* These flags can be combined with bitwise OR operation.
*/
enum pj_dns_dup_options
{
PJ_DNS_NO_QD = 1, /**< Do not duplicate the query section. */
PJ_DNS_NO_ANS = 2, /**< Do not duplicate the answer section. */
PJ_DNS_NO_NS = 4, /**< Do not duplicate the NS section. */
PJ_DNS_NO_AR = 8 /**< Do not duplicate the additional rec section */
};
/**
* Create DNS query packet to resolve the specified names. This function
* can be used to build any types of DNS query, such as A record or DNS SRV
* record.
*
* Application specifies the type of record and the name to be queried,
* and the function will build the DNS query packet into the buffer
* specified. Once the packet is successfully built, application can send
* the packet via TCP or UDP connection.
*
* @param packet The buffer to put the DNS query packet.
* @param size On input, it specifies the size of the buffer.
* On output, it will be filled with the actual size of
* the DNS query packet.
* @param id DNS query ID to associate DNS response with the
* query.
* @param qtype DNS type of record to be queried (see #pj_dns_type).
* @param name Name to be queried from the DNS server.
*
* @return PJ_SUCCESS on success, or the appropriate error code.
*/
PJ_DECL(pj_status_t) pj_dns_make_query(void *packet,
unsigned *size,
pj_uint16_t id,
int qtype,
const pj_str_t *name);
/**
* Parse raw DNS packet into parsed DNS packet structure. This function is
* able to parse few DNS resource records such as A record, PTR record,
* CNAME record, NS record, and SRV record.
*
* @param pool Pool to allocate memory for the parsed packet.
* @param packet Pointer to the DNS packet (the TCP/UDP payload of
* the raw packet).
* @param size The size of the DNS packet.
* @param p_res Pointer to store the resulting parsed packet.
*
* @return PJ_SUCCESS on success, or the appropriate error code.
*/
PJ_DECL(pj_status_t) pj_dns_parse_packet(pj_pool_t *pool,
const void *packet,
unsigned size,
pj_dns_parsed_packet **p_res);
/**
* Duplicate DNS packet.
*
* @param pool The pool to allocate memory for the duplicated packet.
* @param p The DNS packet to be cloned.
* @param options Option flags, from pj_dns_dup_options.
* @param p_dst Pointer to store the cloned DNS packet.
*/
PJ_DECL(void) pj_dns_packet_dup(pj_pool_t *pool,
const pj_dns_parsed_packet*p,
unsigned options,
pj_dns_parsed_packet **p_dst);
/**
* Utility function to get the type name string of the specified DNS type.
*
* @param type DNS type (see #pj_dns_type).
*
* @return String name of the type (e.g. "A", "SRV", etc.).
*/
PJ_DECL(const char *) pj_dns_get_type_name(int type);
/**
* Dump DNS packet to standard log.
*
* @param res The DNS packet.
*/
PJ_DECL(void) pj_dns_dump_packet(const pj_dns_parsed_packet *res);
/**
* @}
*/
PJ_END_DECL
#endif /* __PJLIB_UTIL_DNS_H__ */
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