NAME

     bindresvport, bindresvport_sa — bind a socket to a privileged IP port

LIBRARY

     Standard C Library (libc, -lc)

SYNOPSIS

     #include <sys/types.h>
     #include <rpc/rpc.h>

     int
     bindresvport(int sd, struct sockaddr_in *sin);

     int
     bindresvport_sa(int sd, struct sockaddr *sa);

DESCRIPTION

     The bindresvport() and bindresvport_sa() functions are used to bind a socket descriptor to a
     privileged IP port, that is, a port number in the range 0-1023.

     If sin is a pointer to a struct sockaddr_in then the appropriate fields in the structure
     should be defined.  Note that sin->sin_family must be initialized to the address family of
     the socket, passed by sd.  If sin->sin_port is ‘0’ then an anonymous port (in the range
     600-1023) will be chosen, and if bind(2) is successful, the sin->sin_port will be updated to
     contain the allocated port.

     If sin is the NULL pointer, an anonymous port will be allocated (as above).  However, there
     is no way for bindresvport() to return the allocated port in this case.

     Only root can bind to a privileged port; this call will fail for any other users.

     Function prototype of bindresvport() is biased to AF_INET socket.  The bindresvport_sa()
     function acts exactly the same, with more neutral function prototype.  Note that both
     functions behave exactly the same, and both support AF_INET6 sockets as well as AF_INET
     sockets.

RETURN VALUES

     The bindresvport() function returns the value 0 if successful; otherwise the value -1 is
     returned and the global variable errno is set to indicate the error.

ERRORS

     [EPFNOSUPPORT]     If second argument was supplied, and address family did not match between
                        arguments.

     The bindresvport() function may also fail and set errno for any of the errors specified for
     the calls bind(2), getsockopt(2), or setsockopt(2).

SEE ALSO

     bind(2), getsockopt(2), setsockopt(2), ip(4)