bindresvport(3)

NAME

bindresvport, bindresvport_sa - bind a socket to a privi

leged 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 appro

priate 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 allo

cated (as
above). However, there is no way for bindresvport() to re

turn 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 success

ful; 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 ad

dress 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)

BSD November 22, 1987

BSD