ARES_GETNAMEINFO(3)

NAME

ares_getnameinfo - Address-to-nodename translation in protocol-independent 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_gethostbyaddr(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 succeeded 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_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 contains 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 ALSO

ares_process(3), ares_getaddrinfo(3)

AUTHOR

Dominick Meglio
Copyright 2005 by Dominick Meglio.

1 May 2009 ARES_GETNAMEINFO(3)