ARES_GETNAMEINFO(3)ARES_GETNAMEINFO(3)NAMEares_getnameinfo - Address-to-nodename translation in protocol-indepen‐
dent manner
SYNOPSIS
#include <ares.h>
typedef void (*ares_nameinfo_callback)(void *arg, int status,
int timeouts, char *node, char *service)
void ares_getnameinfo(ares_channel channel, const struct sockaddr *sa,
ares_socklen_t salen, int flags, ares_nameinfo_callback callback,
void *arg)
DESCRIPTION
The ares_getnameinfo function is defined for protocol-independent
address translation. The function is a combination of ares_gethost‐
byaddr(3) and getservbyport(3). The function will translate the address
either by executing a host query on the name service channel identified
by channel or it will attempt to resolve it locally if possible. The
parameters sa and len give the address as a sockaddr structure, and
flags gives the options that the function will use. Valid flags are
listed below:
ARES_NI_NOFQDN Only the nodename portion of the FQDN is returned
for local hosts.
ARES_NI_NUMERICHOST
The numeric form of the hostname is returned rather
than the name.
ARES_NI_NAMEREQD An error is returned if the hostname cannot be found
in the DNS.
ARES_NI_NUMERICSERV
The numeric form of the service is returned rather
than the name.
ARES_NI_TCP The service name is to be looked up for the TCP pro‐
tocol.
ARES_NI_UDP The service name is to be looked up for the UDP pro‐
tocol.
ARES_NI_SCTP The service name is to be looked up for the SCTP
protocol.
ARES_NI_DCCP The service name is to be looked up for the DCCP
protocol.
ARES_NI_NUMERICSCOPE
The numeric form of the scope ID is returned rather
than the name.
ARES_NI_LOOKUPHOST A hostname lookup is being requested.
ARES_NI_LOOKUPSERVICE
A service name lookup is being requested.
When the query is complete or has failed, the ares library will invoke
callback. Completion or failure of the query may happen immediately,
or may happen during a later call to ares_process(3), ares_destroy(3)
or ares_cancel(3).
The callback argument arg is copied from the ares_getnameinfo argument
arg. The callback argument status indicates whether the query suc‐
ceeded and, if not, how it failed. It may have any of the following
values:
ARES_SUCCESS The host lookup completed successfully.
ARES_ENOTIMP The ares library does not know how to look up
addresses of type family.
ARES_ENOTFOUND The address addr was not found.
ARES_ENOMEM Memory was exhausted.
ARES_ECANCELLED The query was cancelled.
ARES_EDESTRUCTION The name service channel channel is being destroyed;
the query will not be completed.
ARES_EBADFLAGS The flags parameter contains an illegal value.
The callback argument timeouts reports how many times a query timed out
during the execution of the given request.
On successful completion of the query, the callback argument node con‐
tains a string representing the hostname (assuming ARES_NI_LOOKUPHOST
was specified). Additionally, service contains a string representing
the service name (assuming ARES_NI_LOOKUPSERVICE was specified). If
the query did not complete successfully, or one of the values was not
requested, node or service will be NULL.
SEE ALSOares_process(3), ares_getaddrinfo(3)AUTHOR
Dominick Meglio
Copyright 2005 by Dominick Meglio.
1 May 2009 ARES_GETNAMEINFO(3)