VMS Help TCPIP Services, Programming Interfaces, Sockets API, getpeername(), Arguments  *Conan The Librarian (sorry for the slow response - running on an old VAX)

 s
    A socket descriptor created using socket().
 name
    A pointer to a buffer where the peer name is to be returned.
 namelen
    An address of an integer that specifies the size of the name
    buffer. On return, it is modified to reflect the actual length,
    in bytes, of the name returned.