LWRES_GETNAMEINFOSection: (3)Updated: Jun 30, 2000 |
NAME
lwres_getnameinfo - lightweight resolver socket address structure to hostname and service nameSYNOPSIS
#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.