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/*
* include/haproxy/dns-t.h
* This file provides structures and types for DNS.
*
* Copyright (C) 2014 Baptiste Assmann <bedis9@gmail.com>
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation, version 2.1
* exclusively.
*
* This library 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
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#ifndef _HAPROXY_DNS_T_H
#define _HAPROXY_DNS_T_H
#include <import/eb32tree.h>
#include <haproxy/connection-t.h>
#include <haproxy/dgram-t.h>
#include <haproxy/obj_type-t.h>
#include <haproxy/stats-t.h>
#include <haproxy/task-t.h>
#include <haproxy/thread.h>
extern struct pool_head *dns_requester_pool;
/*DNS maximum values */
/*
* Maximum issued from RFC:
* RFC 1035: https://www.ietf.org/rfc/rfc1035.txt chapter 2.3.4
* RFC 2671: http://tools.ietf.org/html/rfc2671
*/
#define DNS_MAX_LABEL_SIZE 63
#define DNS_MAX_NAME_SIZE 255
#define DNS_MAX_UDP_MESSAGE 8192
/* DNS minimum record size: 1 char + 1 NULL + type + class */
#define DNS_MIN_RECORD_SIZE (1 + 1 + 2 + 2)
/* DNS smallest fqdn 'a.gl' size */
# define DNS_SMALLEST_FQDN_SIZE 4
/* maximum number of query records in a DNS response
* For now, we allow only one */
#define DNS_MAX_QUERY_RECORDS 1
/* maximum number of answer record in a DNS response */
#define DNS_MAX_ANSWER_RECORDS ((DNS_MAX_UDP_MESSAGE - DNS_HEADER_SIZE) / DNS_MIN_RECORD_SIZE)
/* size of dns_buffer used to store responses from the buffer
* dns_buffer is used to store data collected from records found in a response.
* Before using it, caller will always check that there is at least DNS_MAX_NAME_SIZE bytes
* available */
#define DNS_ANALYZE_BUFFER_SIZE DNS_MAX_UDP_MESSAGE + DNS_MAX_NAME_SIZE
/* DNS error messages */
#define DNS_TOO_LONG_FQDN "hostname too long"
#define DNS_LABEL_TOO_LONG "one label too long"
#define DNS_INVALID_CHARACTER "found an invalid character"
/* dns query class */
#define DNS_RCLASS_IN 1 /* internet class */
/* dns record types (non exhaustive list) */
#define DNS_RTYPE_A 1 /* IPv4 address */
#define DNS_RTYPE_CNAME 5 /* canonical name */
#define DNS_RTYPE_AAAA 28 /* IPv6 address */
#define DNS_RTYPE_SRV 33 /* SRV record */
#define DNS_RTYPE_OPT 41 /* OPT */
#define DNS_RTYPE_ANY 255 /* all records */
/* dns rcode values */
#define DNS_RCODE_NO_ERROR 0 /* no error */
#define DNS_RCODE_NX_DOMAIN 3 /* non existent domain */
#define DNS_RCODE_REFUSED 5 /* query refused */
/* dns flags masks */
#define DNS_FLAG_TRUNCATED 0x0200 /* mask for truncated flag */
#define DNS_FLAG_REPLYCODE 0x000F /* mask for reply code */
/* max number of network preference entries are available from the
* configuration file.
*/
#define SRV_MAX_PREF_NET 5
/* DNS header size */
#define DNS_HEADER_SIZE ((int)sizeof(struct dns_header))
/* DNS request or response header structure */
struct dns_header {
uint16_t id;
uint16_t flags;
uint16_t qdcount;
uint16_t ancount;
uint16_t nscount;
uint16_t arcount;
} __attribute__ ((packed));
/* short structure to describe a DNS question */
/* NOTE: big endian structure */
struct dns_question {
unsigned short qtype; /* question type */
unsigned short qclass; /* query class */
};
/* NOTE: big endian structure */
struct dns_query_item {
char name[DNS_MAX_NAME_SIZE+1]; /* query name */
unsigned short type; /* question type */
unsigned short class; /* query class */
struct list list;
};
/* NOTE: big endian structure */
struct dns_additional_record {
uint8_t name; /* domain name, must be 0 (RFC 6891) */
uint16_t type; /* record type DNS_RTYPE_OPT (41) */
uint16_t udp_payload_size; /* maximum size accepted for the response */
uint32_t extension; /* extended rcode and flags, not used for now */
uint16_t data_length; /* data length */
/* as of today, we don't support yet edns options, that said I already put a
* placeholder here for this purpose. We may need to define a dns_option_record
* structure which itself should point to different type of data, based on the
* extension set (client subnet, tcp keepalive, etc...)*/
// struct list options; /* list of option records */
} __attribute__ ((packed));
/* NOTE: big endian structure */
struct dns_answer_item {
/*For SRV type, name also includes service and protocol value */
char name[DNS_MAX_NAME_SIZE+1]; /* answer name */
int16_t type; /* question type */
int16_t class; /* query class */
int32_t ttl; /* response TTL */
int16_t priority; /* SRV type priority */
uint16_t weight; /* SRV type weight */
uint16_t port; /* SRV type port */
uint16_t data_len; /* number of bytes in target below */
struct sockaddr address; /* IPv4 or IPv6, network format */
char target[DNS_MAX_NAME_SIZE+1]; /* Response data: SRV or CNAME type target */
time_t last_seen; /* When was the answer was last seen */
struct dns_answer_item *ar_item; /* pointer to a RRset from the additional section, if exists */
struct list list;
};
struct dns_response_packet {
struct dns_header header;
struct list query_list;
struct list answer_list;
/* authority ignored for now */
};
/* Resolvers section and parameters. It is linked to the name servers
* servers points to it.
* current resolution are stored in a FIFO list.
*/
struct dns_resolvers {
__decl_thread(HA_SPINLOCK_T lock);
unsigned int accepted_payload_size; /* maximum payload size we accept for responses */
int nb_nameservers; /* total number of active nameservers in a resolvers section */
int resolve_retries; /* number of retries before giving up */
struct { /* time to: */
int resolve; /* wait between 2 queries for the same resolution */
int retry; /* wait for a response before retrying */
} timeout;
struct { /* time to hold current data when */
int valid; /* a response is valid */
int nx; /* a response doesn't exist */
int timeout; /* no answer was delivered */
int refused; /* dns server refused to answer */
int other; /* other dns response errors */
int obsolete; /* an answer hasn't been seen */
} hold;
struct task *t; /* timeout management */
struct {
struct list wait; /* resolutions managed to this resolvers section */
struct list curr; /* current running resolutions */
} resolutions;
struct eb_root query_ids; /* tree to quickly lookup/retrieve query ids currently in use
* used by each nameserver, but stored in resolvers since there must
* be a unique relation between an eb_root and an eb_node (resolution) */
struct list list; /* resolvers list */
struct list nameservers; /* dns server list */
char *id; /* resolvers unique identifier */
struct {
const char *file; /* file where the section appears */
int line; /* line where the section appears */
} conf; /* config information */
};
/* Structure describing a name server used during name resolution.
* A name server belongs to a resolvers section.
*/
struct dns_nameserver {
char *id; /* nameserver unique identifier */
struct {
const char *file; /* file where the section appears */
int line; /* line where the section appears */
} conf; /* config information */
struct dns_resolvers *resolvers;
struct dgram_conn *dgram; /* transport layer */
struct sockaddr_storage addr; /* IP address */
EXTRA_COUNTERS(extra_counters);
struct dns_counters *counters;
struct list list; /* nameserver chained list */
};
struct dns_counters {
char *id;
long long sent; /* - queries sent */
long long snd_error; /* - sending errors */
long long valid; /* - valid response */
long long update; /* - valid response used to update server's IP */
long long cname; /* - CNAME response requiring new resolution */
long long cname_error; /* - error when resolving CNAMEs */
long long any_err; /* - void response (usually because ANY qtype) */
long long nx; /* - NX response */
long long timeout; /* - queries which reached timeout */
long long refused; /* - queries refused */
long long other; /* - other type of response */
long long invalid; /* - malformed DNS response */
long long too_big; /* - too big response */
long long outdated; /* - outdated response (server slower than the other ones) */
long long truncated; /* - truncated response */;
};
struct dns_options {
int family_prio; /* which IP family should the resolver use when both are returned */
struct {
int family;
union {
struct in_addr in4;
struct in6_addr in6;
} addr;
union {
struct in_addr in4;
struct in6_addr in6;
} mask;
} pref_net[SRV_MAX_PREF_NET];
int pref_net_nb; /* The number of registered preferred networks. */
int accept_duplicate_ip; /* flag to indicate whether the associated object can use an IP address
already set to an other object of the same group */
int ignore_weight; /* flag to indicate whether to ignore the weight within the record */
};
/* Resolution structure associated to single server and used to manage name
* resolution for this server.
* The only link between the resolution and a nameserver is through the
* query_id.
*/
struct dns_resolution {
struct dns_resolvers *resolvers; /* pointer to the resolvers structure owning the resolution */
struct list requesters; /* list of requesters using this resolution */
int uuid; /* unique id (used for debugging purpose) */
char *hostname_dn; /* server hostname in domain name label format */
int hostname_dn_len; /* server domain name label len */
unsigned int last_resolution; /* time of the last resolution */
unsigned int last_query; /* time of the last query sent */
unsigned int last_valid; /* time of the last valid response */
int query_id; /* DNS query ID dedicated for this resolution */
struct eb32_node qid; /* ebtree query id */
int prefered_query_type; /* preferred query type */
int query_type; /* current query type */
int status; /* status of the resolution being processed RSLV_STATUS_* */
int step; /* RSLV_STEP_* */
int try; /* current resolution try */
int nb_queries; /* count number of queries sent */
int nb_responses; /* count number of responses received */
struct dns_response_packet response; /* structure hosting the DNS response */
struct dns_query_item response_query_records[DNS_MAX_QUERY_RECORDS]; /* <response> query records */
struct list list; /* resolution list */
};
/* Structure used to describe the owner of a DNS resolution. */
struct dns_requester {
enum obj_type *owner; /* pointer to the owner (server or dns_srvrq) */
struct dns_resolution *resolution; /* pointer to the owned DNS resolution */
int (*requester_cb)(struct dns_requester *, struct dns_nameserver *); /* requester callback for valid response */
int (*requester_error_cb)(struct dns_requester *, int); /* requester callback, for error management */
struct list list; /* requester list */
};
/* Last resolution status code */
enum {
RSLV_STATUS_NONE = 0, /* no resolution occurred yet */
RSLV_STATUS_VALID, /* no error */
RSLV_STATUS_INVALID, /* invalid responses */
RSLV_STATUS_ERROR, /* error */
RSLV_STATUS_NX, /* NXDOMAIN */
RSLV_STATUS_REFUSED, /* server refused our query */
RSLV_STATUS_TIMEOUT, /* no response from DNS servers */
RSLV_STATUS_OTHER, /* other errors */
};
/* Current resolution step */
enum {
RSLV_STEP_NONE = 0, /* nothing happening currently */
RSLV_STEP_RUNNING, /* resolution is running */
};
/* Return codes after analyzing a DNS response */
enum {
DNS_RESP_VALID = 0, /* valid response */
DNS_RESP_INVALID, /* invalid response (various type of errors can trigger it) */
DNS_RESP_ERROR, /* DNS error code */
DNS_RESP_NX_DOMAIN, /* resolution unsuccessful */
DNS_RESP_REFUSED, /* DNS server refused to answer */
DNS_RESP_ANCOUNT_ZERO, /* no answers in the response */
DNS_RESP_WRONG_NAME, /* response does not match query name */
DNS_RESP_CNAME_ERROR, /* error when resolving a CNAME in an atomic response */
DNS_RESP_TIMEOUT, /* DNS server has not answered in time */
DNS_RESP_TRUNCATED, /* DNS response is truncated */
DNS_RESP_NO_EXPECTED_RECORD, /* No expected records were found in the response */
DNS_RESP_QUERY_COUNT_ERROR, /* we did not get the expected number of queries in the response */
DNS_RESP_INTERNAL, /* internal resolver error */
};
/* Return codes after searching an IP in a DNS response buffer, using a family
* preference
*/
enum {
DNS_UPD_NO = 1, /* provided IP was found and preference is matched
* OR provided IP found and preference is not matched, but no IP
* matching preference was found */
DNS_UPD_SRVIP_NOT_FOUND, /* provided IP not found
* OR provided IP found and preference is not match and an IP
* matching preference was found */
DNS_UPD_CNAME, /* CNAME without any IP provided in the response */
DNS_UPD_NAME_ERROR, /* name in the response did not match the query */
DNS_UPD_NO_IP_FOUND, /* no IP could be found in the response */
DNS_UPD_OBSOLETE_IP, /* The server IP was obsolete, and no other IP was found */
};
struct proxy;
struct dns_srvrq {
enum obj_type obj_type; /* object type == OBJ_TYPE_SRVRQ */
struct dns_resolvers *resolvers; /* pointer to the resolvers structure used for this server template */
struct proxy *proxy; /* associated proxy */
char *name;
char *hostname_dn; /* server hostname in Domain Name format */
int hostname_dn_len; /* string length of the server hostname in Domain Name format */
struct dns_requester *dns_requester; /* used to link to its DNS resolution */
struct list list; /* Next SRV RQ for the same proxy */
};
#endif /* _HAPROXY_DNS_T_H */