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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.

SEE ALSO

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

BUGS

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