evdns_compat(3) | Library Functions Manual | evdns_compat(3)

# NAME

evdns_compat - Potentially non-threadsafe versions of the functions in dns.h: provided only for backwards compatibility.

# SYNOPSIS

#include <event2/dns_compat.h>
#include <event2/event-config.h>
#include <event2/util.h>

## Functions

struct evdns_server_port * evdns_add_server_port (evutil_socket_t socket, int flags, evdns_request_callback_fn_type callback, void *user_data)
As evdns_server_new_with_base. int evdns_clear_nameservers_and_suspend (void)
Remove all configured nameservers, and suspend all pending resolves. int evdns_count_nameservers (void)
Get the number of configured nameservers. struct evdns_base * evdns_get_global_base (void)
Return the global evdns_base created by event_init() and used by the other deprecated functions. int evdns_init (void)
Initialize the asynchronous DNS library. int evdns_nameserver_add (unsigned long int address)
Add a nameserver. int evdns_nameserver_ip_add (const char *ip_as_string)
Add a nameserver. int evdns_resolv_conf_parse (int flags, const char *const filename)
Parse a resolv.conf file. int evdns_resolve_ipv4 (const char *name, int flags, evdns_callback_type callback, void *ptr)
Lookup an A record for a given name. int evdns_resolve_ipv6 (const char *name, int flags, evdns_callback_type callback, void *ptr)
Lookup an AAAA record for a given name. int evdns_resolve_reverse (const struct in_addr *in, int flags, evdns_callback_type callback, void *ptr)
Lookup a PTR record for a given IP address. int evdns_resolve_reverse_ipv6 (const struct in6_addr *in, int flags, evdns_callback_type callback, void *ptr)
Lookup a PTR record for a given IPv6 address. int evdns_resume (void)
Resume normal operation and continue any suspended resolve requests. void evdns_search_add (const char *domain)
Add a domain to the list of search domains. void evdns_search_clear (void)
Clear the list of search domains. void evdns_search_ndots_set (const int ndots)
Set the 'ndots' parameter for searches. int evdns_set_option (const char *option, const char *val, int flags)
Set the value of a configuration option. void evdns_shutdown (int fail_requests)
Shut down the asynchronous DNS resolver and terminate all active requests.

# Detailed Description

Potentially non-threadsafe versions of the functions in dns.h: provided only for backwards compatibility.

# Function Documentation

## struct evdns_server_port* evdns_add_server_port (evutil_socket_t socket, int flags, evdns_request_callback_fn_type callback, void * user_data)

As evdns_server_new_with_base.

Deprecated

This function is deprecated because it does not allow the caller to specify which even_base it uses. The recommended function is evdns_add_server_port_with_base().

## int evdns_clear_nameservers_and_suspend (void)

Remove all configured nameservers, and suspend all pending resolves. Resolves will not necessarily be re-attempted until evdns_resume() is called.

Deprecated

This function is deprecated because it does not allow the caller to specify which evdns_base it applies to. The recommended function is evdns_base_clear_nameservers_and_suspend().

Returns:

0 if successful, or -1 if an error occurred

See also:

evdns_resume()

## int evdns_count_nameservers (void)

Get the number of configured nameservers. This returns the number of configured nameservers (not necessarily the number of running nameservers). This is useful for double-checking whether our calls to the various nameserver configuration functions have been successful.

Deprecated

This function is deprecated because it does not allow the caller to specify which evdns_base it applies to. The recommended function is evdns_base_count_nameservers().

Returns:

the number of configured nameservers

See also:

evdns_nameserver_add()

## struct evdns_base* evdns_get_global_base (void)

Return the global evdns_base created by event_init() and used by the other deprecated functions.

Deprecated

This function is deprecated because use of the global evdns_base is error-prone.

## int evdns_init (void)

Initialize the asynchronous DNS library. This function initializes support for non-blocking name resolution by calling evdns_resolv_conf_parse() on UNIX and evdns_config_windows_nameservers() on Windows.

Deprecated

This function is deprecated because it always uses the current event base, and is easily confused by multiple calls to event_init(), and so is not safe for multithreaded use. Additionally, it allocates a global structure that only one thread can use. The replacement is evdns_base_new().

Returns:

0 if successful, or -1 if an error occurred

See also:

evdns_shutdown()

## int evdns_nameserver_add (unsigned long int address)

Add a nameserver. The address should be an IPv4 address in network byte order. The type of address is chosen so that it matches in_addr.s_addr.

Deprecated

This function is deprecated because it does not allow the caller to specify which evdns_base it applies to. The recommended function is evdns_base_nameserver_add().

Parameters:

address an IP address in network byte order

Returns:

0 if successful, or -1 if an error occurred

See also:

evdns_nameserver_ip_add()

## int evdns_nameserver_ip_add (const char * ip_as_string)

Add a nameserver. This wraps the evdns_nameserver_add() function by parsing a string as an IP address and adds it as a nameserver.

Deprecated

This function is deprecated because it does not allow the caller to specify which evdns_base it applies to. The recommended function is evdns_base_nameserver_ip_add().

Returns:

0 if successful, or -1 if an error occurred

See also:

evdns_nameserver_add()

## int evdns_resolv_conf_parse (int flags, const char *const filename)

Parse a resolv.conf file. The 'flags' parameter determines what information is parsed from the resolv.conf file. See the man page for resolv.conf for the format of this file.

The following directives are not parsed from the file: sortlist, rotate, no-check-names, inet6, debug.

If this function encounters an error, the possible return values are: 1 = failed to open file, 2 = failed to stat file, 3 = file too large, 4 = out of memory, 5 = short read from file, 6 = no nameservers listed in the file

Deprecated

This function is deprecated because it does not allow the caller to specify which evdns_base it applies to. The recommended function is evdns_base_resolv_conf_parse().

Parameters:

flags any of DNS_OPTION_NAMESERVERS|DNS_OPTION_SEARCH|DNS_OPTION_MISC| DNS_OPTIONS_ALL
filename the path to the resolv.conf file

Returns:

0 if successful, or various positive error codes if an error occurred (see above)

See also:

resolv.conf(3), evdns_config_windows_nameservers()

## int evdns_resolve_ipv4 (const char * name, int flags, evdns_callback_type callback, void * ptr)

Lookup an A record for a given name.

Deprecated

This function is deprecated because it does not allow the caller to specify which evdns_base it applies to. The recommended function is evdns_base_resolve_ipv4().

Parameters:

name a DNS hostname
flags either 0, or DNS_QUERY_NO_SEARCH to disable searching for this query.
callback a callback function to invoke when the request is completed
ptr an argument to pass to the callback function

Returns:

0 if successful, or -1 if an error occurred

See also:

evdns_resolve_ipv6(), evdns_resolve_reverse(), evdns_resolve_reverse_ipv6()

## int evdns_resolve_ipv6 (const char * name, int flags, evdns_callback_type callback, void * ptr)

Lookup an AAAA record for a given name.

Parameters:

name a DNS hostname
flags either 0, or DNS_QUERY_NO_SEARCH to disable searching for this query.
callback a callback function to invoke when the request is completed
ptr an argument to pass to the callback function

Returns:

0 if successful, or -1 if an error occurred

See also:

evdns_resolve_ipv4(), evdns_resolve_reverse(), evdns_resolve_reverse_ipv6()

## int evdns_resolve_reverse (const struct in_addr * in, int flags, evdns_callback_type callback, void * ptr)

Lookup a PTR record for a given IP address.

Deprecated

This function is deprecated because it does not allow the caller to specify which evdns_base it applies to. The recommended function is evdns_base_resolve_reverse().

Parameters:

in an IPv4 address
flags either 0, or DNS_QUERY_NO_SEARCH to disable searching for this query.
callback a callback function to invoke when the request is completed
ptr an argument to pass to the callback function

Returns:

0 if successful, or -1 if an error occurred

See also:

evdns_resolve_reverse_ipv6()

## int evdns_resolve_reverse_ipv6 (const struct in6_addr * in, int flags, evdns_callback_type callback, void * ptr)

Lookup a PTR record for a given IPv6 address.

Deprecated

This function is deprecated because it does not allow the caller to specify which evdns_base it applies to. The recommended function is evdns_base_resolve_reverse_ipv6().

Parameters:

in an IPv6 address
flags either 0, or DNS_QUERY_NO_SEARCH to disable searching for this query.
callback a callback function to invoke when the request is completed
ptr an argument to pass to the callback function

Returns:

0 if successful, or -1 if an error occurred

See also:

evdns_resolve_reverse_ipv6()

## int evdns_resume (void)

Resume normal operation and continue any suspended resolve requests. Re-attempt resolves left in limbo after an earlier call to evdns_clear_nameservers_and_suspend().

Deprecated

This function is deprecated because it does not allow the caller to specify which evdns_base it applies to. The recommended function is evdns_base_resume().

Returns:

0 if successful, or -1 if an error occurred

See also:

evdns_clear_nameservers_and_suspend()

## void evdns_search_add (const char * domain)

Add a domain to the list of search domains.

Deprecated

This function is deprecated because it does not allow the caller to specify which evdns_base it applies to. The recommended function is evdns_base_search_add().

Parameters:

domain the domain to be added to the search list

## void evdns_search_clear (void)

Clear the list of search domains.

Deprecated

This function is deprecated because it does not allow the caller to specify which evdns_base it applies to. The recommended function is evdns_base_search_clear().

## void evdns_search_ndots_set (const int ndots)

Set the 'ndots' parameter for searches. Sets the number of dots which, when found in a name, causes the first query to be without any search domain.

Deprecated

This function is deprecated because it does not allow the caller to specify which evdns_base it applies to. The recommended function is evdns_base_search_ndots_set().

Parameters:

ndots the new ndots parameter

## int evdns_set_option (const char * option, const char * val, int flags)

Set the value of a configuration option. The currently available configuration options are:

ndots, timeout, max-timeouts, max-inflight, and attempts

Deprecated

This function is deprecated because it does not allow the caller to specify which evdns_base it applies to. The recommended function is evdns_base_set_option().

Parameters:

option the name of the configuration option to be modified
val the value to be set
flags Ignored.

Returns:

0 if successful, or -1 if an error occurred

## void evdns_shutdown (int fail_requests)

Shut down the asynchronous DNS resolver and terminate all active requests. If the 'fail_requests' option is enabled, all active requests will return an empty result with the error flag set to DNS_ERR_SHUTDOWN. Otherwise, the requests will be silently discarded.

Deprecated

This function is deprecated because it does not allow the caller to specify which evdns_base it applies to. The recommended function is evdns_base_shutdown().

Parameters:

fail_requests if zero, active requests will be aborted; if non-zero, active requests will return DNS_ERR_SHUTDOWN.

See also:

evdns_init()

# Author

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Tue Jan 31 2017 | libevent