| GETSOCKNAME(2) | System Calls Manual | GETSOCKNAME(2) | 
getsockname —
#include <sys/socket.h>
int
  
  getsockname(int
    s, struct sockaddr *
    restrict name, socklen_t
    * restrict namelen);
getsockname() returns the locally bound address
  information for a specified socket.
Common uses of this function are as follows:
getsockname() is used to retrieve the
      kernel-assigned port number.getsockname() is used to
      retrieve the local IP address for the connection.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 family.
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.
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.
EBADF]EFAULT]EINVAL]ENOBUFS]ENOTCONN]ENOTSOCK]getsockname() function call appeared in
  4.2BSD.
| July 30, 2016 | NetBSD 10.0 |