osf1 man page for getnameinfo

getnameinfo(3)						     Library Functions Manual						    getnameinfo(3)

NAME
       getnameinfo - Get a node name and service name for an address and port number

LIBRARY
       Standard C Library (libc.so, libc.a)

SYNOPSIS
       #include <netdb.h>

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

PARAMETERS
       Points either to a sockaddr_in structure (for IPv4) or to a sockaddr_in6 structure (for IPv6) that holds the IP address	and  port  number.
       Specifies  the  length of either the sockaddr_in structure or the sockaddr_in6 structure.  Points to a buffer in which to receive the null-
       terminated network node name or alias corresponding to the address contained in sa.  A NULL pointer instructs the routine not to  return  a
       node  name.   Both  node  and  serv cannot be zero.  Specifies the length of the node buffer.  A value of zero instructs the routine not to
       return a node name.  Points to a buffer in which to receive the null-terminated network service name associated with the port  number  con-
       tained in sa.  A NULL pointer instructs the routine not to return a service name.  Both node and serv cannot be zero.  Specifies the length
       of the serv buffer.  A value of zero instructs the routine not to return a service  name.   Specifies  changes  to  the	routine's  default
       actions.   By  default, the routine searches for the fully-qualified domain name of the node in the hosts database and returns it.  See the
       "Flag Bits" section for additional flags.

DESCRIPTION
       The getnameinfo() routine looks up an IP address and port number in a sockaddr structure specified by sa and returns node name and  service
       name text strings in the buffers pointed to by the host and serv parameters, respectively.

       If  the	node's name is not found, the routine returns the numeric form of the node's address, regardless of the value of the flags parame-
       ter.  If the service's name is not found, the routine returns the numeric form of the service's address (port  number)  regardless  of  the
       value of the flag parameter.

       The  application  must provide buffers large enough to hold the fully-qualified domain name and the service name, including the terminating
       null characters.  To assist in initializing the buffers, the following constants are defined in <netdb.h>: #define NI_MAXHOST  1025 #define
       NI_MAXSERV    32

   Flag Bits
       The flag bits and their meanings, if set, are as follows: Specifies that the service is a datagram service (SOCK_DGRAM).  The default is to
       assume a stream service (SOCK_STREAM).  This is required for the few ports (512-514) that have different services for UDP and TCP.  Returns
       an  error if the host's name cannot be located in the hosts database.  Searches the hosts database and returns the node name portion of the
       fully-qualified domain name for local hosts.  Returns the numeric form of the host's address instead of its name.  No host name	resolution
       is performed.  Returns the numeric form (port number) of the service address instead of its name.  No service name resolution is performed.

       The two NI_NUMERIC* flags are required to support the -n flag that many commands provide.  All flags are defined in <netdb.h> header file.

RETURN VALUES
       Upon successful completion, the getnameinfo() function returns 0 (zero).  Upon failure, it returns a non-zero value.

ERRORS
       If  the	getnameinfo() function fails, it returns one of the following values: The nodename parameter could not be resolved this time.  Try
       the request again.  The value of the flags parameter is invalid.  A non-recoverable error occurred.  The address family (ai_family  in  the
       hints  structure)  was  not recognized, or the address length was invalid.  A memory allocation failure occurred.  Name does not resolve to
       supplied parameters.

	      The NI_NAMEREQD flag was set and the node's name was not found.

	      You did not pass either the nodename or servname parameter.  You must pass at least one.	A system error occurred; errno is  set	to
	      the error value.

FILES
       The  Internet  network  hostname  database.   Each  record  in  the file occupies a single line and has three fields consisting of the host
       address, official hostname, and aliases.  The resolver configuration file.  The database service selection configuration file.

RELATED INFORMATION
       Functions: getaddrinfo(3), getservbyname(3), gethostbyport(3), inet_ntop(3), socket(3).

       Files: hostname(5), resolv.conf(4), svc.conf(4).

       Networks: bind_intro(7), nis_intro(7).  delim off

																    getnameinfo(3)