ares_getnameinfo - Address-to-nodename translation in protocol-independent
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,
function is defined for protocol-independent address
translation. The function is a combination of ares_gethostbyaddr(3)
. The function will translate the address either by
executing a host query on the name service channel identified by
or it will attempt to resolve it locally if possible. The
give the address as a sockaddr structure,
gives the options that the function will use. Valid flags are
- Only the nodename portion of the FQDN is returned for local
- The numeric form of the hostname is returned rather than
- An error is returned if the hostname cannot be found in the
- The numeric form of the service is returned rather than the
- The service name is to be looked up for the TCP
- The service name is to be looked up for the UDP
- The service name is to be looked up for the SCTP
- The service name is to be looked up for the DCCP
- The numeric form of the scope ID is returned rather than
- A hostname lookup is being requested.
- A service name lookup is being requested.
When the query is complete or has failed, the ares library will invoke
. Completion or failure of the query may happen immediately, or
may happen during a later call to ares_process(3)
The callback argument arg
is copied from the ares_getnameinfo
. The callback argument status
indicates whether the
query succeeded and, if not, how it failed. It may have any of the following
- The host lookup completed successfully.
- The ares library does not know how to look up addresses of
- The address addr was not found.
- Memory was exhausted.
- The query was cancelled.
- The name service channel channel is being destroyed;
the query will not be completed.
- 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
was specified). Additionally, service
contains a string representing the service name (assuming
was specified). If the query did not complete
successfully, or one of the values was not requested, node
will be NULL
Copyright 2005 by Dominick Meglio.