getnameinfo(SLIB)

Syntax

   cc ... -lsocket
   

   #include <sys/socket.h>
   #include <netdb.h>
   

   int
   getnameinfo(const struct sockaddr *sa, socklen_t salen, char *host,
           size_t hostlen, char *serv, size_t servlen, int flags);
   

Description

   The getnameinfo() function is defined for protocol-independent address-
   to-nodename translation.  It performs functionality of gethostbyaddr(SLIB)
   and getservbyport(SLIB) in more sophisticated manner.
   

   The sa argument is a pointer to a generic socket address structure of
   size salen. The arguments host and serv are pointers to buffers to hold
   the return values.  Their sizes are specified by hostlen and servlen
   repectively.  Either host or serv may be NULL if the hostname  or service
   name is not required.
   

   The flags argument modifies the behaviour of getnameinfo() as follows:
   

   If NI_NOFQDN is set only the unqualified hostname is returned for local
   fully qualified names.
   

   If NI_NUMERICHOST is set then the numeric form of the hostname is re-
   turned.
   

   If NI_NAMEREQD is set, then a error is returned if the hostname cannot be
   looked up.
   

   If NI_NUMERICSERV is set then the service is returned in numeric form.
   

   If NI_DGRAM is set then the service is UDP based rather than TCP based.
   

See also

   getaddrinfo(SLIB), gethostbyaddr(SLIB), getservbyport(SLIB), hosts(SFF),
   services(SFF), hostname(ADMN), named(ADMN).
   

   R. Gilligan, S. Thomson, J. Bound, and W. Stevens, "Basic Socket Inter-
   face Extensions for IPv6," RFC2133, April 1997.
   

Standards

   The getaddrinfo() function is defined IEEE POSIX 1003.1g draft specifica-
   tion, and documented in ``Basic Socket Interface Extensions for IPv6''
   (RFC2133).