lwres_getnameinfo (3) - Linux Manuals

lwres_getnameinfo: lightweight resolver socket address structure to hostname and service name

NAME

lwres_getnameinfo - lightweight resolver socket address structure to hostname and service name

SYNOPSIS

#include <lwres/netdb.h>
int lwres_getnameinfo(const struct sockaddr *sa, size_t salen, char *host, size_t hostlen, char *serv, size_t servlen, int flags);

DESCRIPTION

This function is equivalent to the getnameinfo(3) function defined in RFC2133. lwres_getnameinfo() returns the hostname for the struct sockaddr sa which is salen bytes long. The hostname is of length hostlen and is returned via *host. The maximum length of the hostname is 1025 bytes: NI_MAXHOST.

The name of the service associated with the port number in sa is returned in *serv. It is servlen bytes long. The maximum length of the service name is NI_MAXSERV - 32 bytes.

The flags argument sets the following bits:

NI_NOFQDN

A fully qualified domain name is not required for local hosts. The local part of the fully qualified domain name is returned instead.

NI_NUMERICHOST

Return the address in numeric form, as if calling inet_ntop(), instead of a host name.

NI_NAMEREQD

A name is required. If the hostname cannot be found in the DNS and this flag is set, a non-zero error code is returned. If the hostname is not found and the flag is not set, the address is returned in numeric form.

NI_NUMERICSERV

The service name is returned as a digit string representing the port number.

NI_DGRAM

Specifies that the service being looked up is a datagram service, and causes getservbyport() to be called with a second argument of "udp" instead of its default of "tcp". This is required for the few ports (512-514) that have different services for UDP and TCP.

RETURN VALUES

lwres_getnameinfo() returns 0 on success or a non-zero error code if an error occurs.

BUGS

RFC2133 fails to define what the nonzero return values of getnameinfo(3) are.

COPYRIGHT

Copyright © 2004, 2005, 2007 Internet Systems Consortium, Inc. ("ISC")
Copyright © 2000, 2001 Internet Software Consortium.

SEE ALSO

RFC2133(), getservbyport(3), lwres(3), lwres_getnameinfo(3), lwres_getnamebyaddr(3). lwres_net_ntop(3).

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