SIP-router core :: resolver/dns related functions, dns cache and failoverModule: SIP-router core. More...

#include "str.h"
#include "config.h"
#include "timer.h"
#include "ip_addr.h"
#include "atomic_ops.h"
#include "resolve.h"

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Data Structures

struct dns_rr
stripped down dns rr More...

Defines

#define DNS_SRV_LB
uncomment the define below for SRV weight based load balancing

#define DNS_FLAG_BAD_NAME 1
dns entry flags, shall be on the power of 2
#define DNS_FLAG_PERMANENT 2
permanent record, never times out, never deleted, never overwritten unless explicitely requested

dns requests flags

#define DNS_NO_FLAGS 0
#define DNS_IPV4_ONLY 1
#define DNS_IPV6_ONLY 2
#define DNS_IPV6_FIRST 4
#define DNS_SRV_RR_LB 8
SRV RR weight based load balancing.
#define DNS_TRY_NAPTR 16
enable naptr lookup

ip blacklist error flags

#define IP_ERR_BAD_DST 2
#define IP_ERR_SND 3
#define IP_ERR_TIMEOUT 4
#define IP_ERR_TCP_CON 5

Enumerations

enum dns_errors { ,
  E_DNS_EOR, E_DNS_UNKNOWN, E_DNS_INTERNAL_ERR , E_DNS_NO_SRV ,
  E_DNS_NO_IP, E_DNS_BAD_IP, E_DNS_BLACKLIST_IP, E_DNS_NAME_TOO_LONG,
  E_DNS_AF_MISMATCH, E_DNS_NO_NAPTR, E_DNS_CRITICAL
}
dns functions return them as negative values (e.g.
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Functions

int dns_cache_add_record (unsigned short type, str *name, int ttl, str *value, int priority, int weight, int port, int flags)
Adds a new record to the cache.
int dns_cache_delete_single_record (unsigned short type, str *name, str *value, int flags)
Delete a single record from the cache, i.e.
void dns_cache_flush (int del_permanent)
Delete all the entries from the cache.
int dns_get_ip (str *name, struct ip_addr *ip, int flags)
performs an A, AAAA (or both) query/queries Params: name - query target (e.g.
int dns_sip_resolve (struct dns_srv_handle *h, str *name, struct ip_addr *ip, unsigned short *port, char *proto, int flags)
resolve name to an ip, using srv record.
static int dns_sip_resolve2su (struct dns_srv_handle *h, union sockaddr_union *su, str *name, unsigned short port, char *proto, int flags)
same as above, but fills su intead of changing port and filling an ip
int dns_srv_get_ip (str *name, struct ip_addr *ip, unsigned short *port, int flags)
performes a srv query on name Params: name - srv query target (e.g.
static void dns_srv_handle_cpy (struct dns_srv_handle *dst, struct dns_srv_handle *src)
safe copy increases the refcnt, src must not change while in this function WARNING: the copy must be dns_srv_handle_put !
static int dns_srv_handle_next (struct dns_srv_handle *h, int err)
get "next" ip next time a dns_srv_handle function is called params: h - struct dns_srv_handler err - return code of the last dns_*_resolve* call returns: 0 if it doesn't make sense to try another record, 1 otherwise
static void dns_srv_handle_put_shm_unsafe (struct dns_srv_handle *h)
same as above but assume shm_lock held (for internal tm use only)
static void dns_srv_handle_ref (struct dns_srv_handle *h)
use it when copying, it manually increases the ref cound
const char * dns_strerror (int err)
return a short string, printable error description (err <=0)

Detailed Description

Definition in file dns_cache.h.

Define Documentation

#define DNS_FLAG_BAD_NAME 1

error flag: unresolvable

Definition at line 106 of file dns_cache.h.

Enumeration Type Documentation

enum dns_errors

return -E_DNS_NO_IP)

listed in the order of importance ( if more errors, only the most important is returned)

Enumerator:

E_DNS_EOR	no more records (not an error) -- returned only by the dns_resolve* functions when called iteratively,; it signals the end of the ip/records list
E_DNS_UNKNOWN	unkown error
E_DNS_INTERNAL_ERR	internal error
E_DNS_NO_SRV	unresolvable srv record
E_DNS_NO_IP	unresolvable a or aaaa records
E_DNS_BAD_IP	the ip is invalid
E_DNS_BLACKLIST_IP	the ip is blacklisted
E_DNS_NAME_TOO_LONG	try again with a shorter name
E_DNS_AF_MISMATCH	ipv4 or ipv6 only requested, but name contains an ip addr. of the opossite type
E_DNS_NO_NAPTR	unresolvable naptr record
E_DNS_CRITICAL	critical error, marks the end of the error table (always last)

Definition at line 75 of file dns_cache.h.

Function Documentation

int dns_cache_add_record	(	unsigned short	type,
		str *	name,
		int	ttl,
		str *	value,
		int	priority,
		int	weight,
		int	port,
		int	flags
	)

If there is an existing record with the same name and value (ip address in case of A/AAAA record, name in case of SRV record) only the remaining fields are updated.

Note that permanent records cannot be overwritten unless the new record is also permanent. A permanent record completely replaces a non-permanent one.

Currently only A, AAAA, and SRV records are supported.

int dns_cache_delete_single_record	(	unsigned short	type,
		str *	name,
		str *	value,
		int	flags
	)

the record with the same name and value (ip address in case of A/AAAA record, name in case of SRV record).

Currently only A, AAAA, and SRV records are supported.

void dns_cache_flush ( int del_permanent )

If del_permanent is 0, then only the non-permanent entries are deleted.

int dns_get_ip	(	str *	name,
		struct ip_addr *	ip,
		int	flags
	)

foo.bar) ip - result: first good ip found flags - resolve options (like ipv4 only, ipv6 prefered a.s.o) Returns: < 0 on error (can be passed to dns_strerror(), 0 on success

int dns_sip_resolve	(	struct dns_srv_handle *	h,
		str *	name,
		struct ip_addr *	ip,
		unsigned short *	port,
		char *	proto,
		int	flags
	)

Can be called multiple times to iterate on all the possible ips, e.g : dns_srv_handle_init(h); ret_code=dns_sip_resolve(h,...); while( dns_srv_handle_next(h, ret_code){ ret_code=dns_sip_resolve(h...); } dns_srv_handle_put(h); WARNING: dns_srv_handle_init() must be called to initialize h and dns_srv_handle_put(h) must be called when h is no longer needed

Referenced by dns_sip_resolve2su().

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int dns_srv_get_ip	(	str *	name,
		struct ip_addr *	ip,
		unsigned short *	port,
		int	flags
	)

_sip._udp.foo.bar) ip - result: first good ip found port - result: corresponding port number flags - resolve options (like ipv4 only, ipv6 prefered a.s.o) Returns: < 0 on error (can be passed to dns_strerror(), 0 on success

dns_cache.h File Reference