getsockname(2) [netbsd man page]

GETSOCKNAME(2)						      BSD System Calls Manual						    GETSOCKNAME(2)

NAME

     getsockname -- get socket name

LIBRARY

     Standard C Library (libc, -lc)

SYNOPSIS

     #include <sys/socket.h>

     int
     getsockname(int s, struct sockaddr * restrict name, socklen_t * restrict namelen);

DESCRIPTION

     getsockname() returns the locally bound address information for a specified socket.

     Common uses of this function are as follows:

     o	 When bind(2) is called with a port number of 0 (indicating the kernel should pick an ephemeral port) getsockname() is used to retrieve
	 the kernel-assigned port number.

     o	 When a process calls bind(2) on a wildcard IP address, getsockname() is used to retrieve the local IP address for the connection.

     o	 When a function wishes to know the address family of a socket, getsockname() can be used.

     getsockname() takes three parameters:

     s, Contains the file descriptor for the socket to be looked up.

     name points to a sockaddr structure which will hold the resulting address information.  Normal use requires one to use a structure specific
     to the protocol family in use, such as sockaddr_in (IPv4) or sockaddr_in6 (IPv6), cast to a (struct sockaddr *).

     For greater portability (such as newer protocol families) the new structure sockaddr_storage exists.  sockaddr_storage is large enough to
     hold any of the other sockaddr_* variants.  On return, it should be cast to the correct sockaddr type, according to the current protocol fam-
     ily.

     namelen indicates the amount of space pointed to by name, in bytes.  Upon return, namelen is set to the actual size of the returned address
     information.

     If the address of the destination socket for a given socket connection is needed, the getpeername(2) function should be used instead.

     If name does not point to enough space to hold the entire socket address, the result will be truncated to namelen bytes.

RETURN VALUES

     On success, getsockname() returns a 0, and namelen is set to the actual size of the socket address returned in name.  Otherwise, errno is
     set, and a value of -1 is returned.

ERRORS

     The call succeeds unless:

     [EBADF]		The argument s is not a valid descriptor.

     [ENOTSOCK] 	The argument s is a file, not a socket.

     [EINVAL]		The socket has been shut down.

     [ENOBUFS]		Insufficient resources were available in the system to perform the operation.

     [EFAULT]		The name parameter points to memory not in a valid part of the process address space.

SEE ALSO

     bind(2), socket(2)

HISTORY

     The getsockname() function call appeared in 4.2BSD.

BUGS

     Names bound to sockets in the UNIX domain are inaccessible; getsockname() returns a zero length name.

BSD
								  August 11, 2002							       BSD

getsockname(2)							System Calls Manual						    getsockname(2)

NAME

       getsockname - Gets the socket name

SYNOPSIS

       #include <sys/socket.h>
       int getsockname(
	    int socket,      struct sockaddr *address,	    socklen_t *address_len );

       [XNS4.0]  The  definition  of the getsockname() function in XNS4.0 uses a size_t data type instead of a socklen_t data type as specified in
       XNS5.0 (the previous definition).

       [Tru64 UNIX]  The following definition of the getsockname() function does not conform to current standards and is supported only for  back-
       ward compatibility (see standards(5)):

       #include <sys/socket.h>
       int getsockname(
	    int socket,      struct sockaddr *address,	    int *address_len );

STANDARDS

       Interfaces documented on this reference page conform to industry standards as follows:

       getsockname():  XNS5.0

       Refer to the standards(5) reference page for more information about industry standards and associated tags.

PARAMETERS

       Specifies  the socket file descriptor for which the local address is needed.  Points to a sockaddr structure, the format of which is deter-
       mined by the domain and by the behavior requested for the socket.  The sockaddr structure is an overlay for a  sockaddr_in  or  sockaddr_un
       structure, depending on which of the supported address families is active.

	      [Tru64  UNIX]    If  the	compile-time option _SOCKADDR_LEN is defined before the sys/socket.h header file is included, the sockaddr
	      structure takes 4.4BSD behavior, with a field for specifying the length of the socket address.  Otherwise, the default 4.3BSD  sock-
	      addr structure is used, with the length of the socket address assumed to be 14 bytes or less.

	      If _SOCKADDR_LEN is defined, the 4.3BSD sockaddr structure is defined with the name osockaddr.  Specifies the length of the sockaddr
	      structure pointed to by the address parameter.

DESCRIPTION

       The getsockname() function retrieves the locally bound address of the specified socket.

       If the actual length of the address is greater than the length of the sockaddr structure, the address is truncated.

       If the socket is not bound to a local name, the value pointed to by address is unspecified.

       A process created by another process can inherit open sockets.  To use the inherited sockets, the created process may need to identify  its
       address.  The getsockname() function allows a process to retrieve the local address bound to the specified socket.

       A process can use the getpeername() function to determine the address of a destination socket in a socket connection.

NOTES

       [Tru64  UNIX]  When  compiled  in  the  X/Open UNIX environment or the POSIX.1g socket environment, calls to the getsockname() function are
       internally renamed by prepending _E to the function name.  When you are debugging a module that includes the getsockname() function and for
       which _XOPEN_SOURCE_EXTENDED or _POSIX_PII_SOCKET has been defined, use _Egetsockname to refer to the getsockname() call.  See standards(5)
       for further information.

RETURN VALUES

       Upon successful completion, a value of 0 (zero) is returned, and the address_len parameter points to the size of the socket address.   Oth-
       erwise, a value of -1 is returned and errno is set to indicate the error.

ERRORS

       If  the	getsockname()  function fails, errno may be set to one of the following values: The socket parameter is not valid.  The address or
       address_len parameter is not in a readable or writable part of the user address space.  The socket is shut  down.   Insufficient  resources
       are  available  in  the system to complete the call.  The available STREAMS resources were insufficient for the operation to complete.  The
       socket parameter refers to a file, not a socket.  The operation is not supported for this socket's protocol.

RELATED INFORMATION

       Functions: accept(2), bind(2), getpeername(2), socket(2).

       Standards: standards(5).  delim off

																    getsockname(2)