bindresvport, bindresvport_sa - bind a socket to a privileged IP port
Standard C Library (libc, -lc)
bindresvport(int sd, struct sockaddr_in *sin);
bindresvport_sa(int sd, struct sockaddr *sa);
bindresvport() and bindresvport_sa() are used to bind a socket descriptor
to a privileged IP port, that is, a port number in the range 0-1023. The
routine returns 0 if it is successful, otherwise -1 is returned and errno
set to reflect the cause of the error.
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
Function prototype of bindresvport() is biased to AF_INET socket.
bindresvport_sa() 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.
If the bind is successful, a 0 value is returned. A return value of -1
indicates an error, which is further specified in the global errno.
[EPFNOSUPPORT] If second argument was supplied, and address family
did not match between arguments.
bindresvport() may also fail and set errno for any of the errors specified
for the calls bind(2), getsockopt(2), or setsockopt(2).
bind(2), getsockopt(2), setsockopt(2), ip(4)
BSD November 22, 1987 BSD
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