BINDRESVPORT(3)

NAME
bindresvport - bind a socket to a privileged IP port

SYNOPSIS
#include <sys/types.h>
#include <netinet/in.h>

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

DESCRIPTION

bindresvport() is used to bind a socket descriptor to a privileged IP port, that is, a port number in the range 0-1023. If in->sin_port is 0 then an anonymous port in the range 600 to 1023 be chosen. If the bind(2) performed by bindresvport() is successful, then sin->sin_port returns the port number actually allocated. sin can be NULL, in which case sin->sin_family is implicitly taken to be AF_INET, and an anonymous port is allocated (as above). However, in this case, bindresvport() has no way to return the port number actually allocated.

RETURN VALUE
bindresvport() returns 0 if it is successful, otherwise -1 is returned and errno set to indicate the cause of the error.

ERRORS
bindresvport() can fail for any of the same reasons as bind(2).

CONFORMING TO
Not in POSIX.1-2001. Present on the BSDs, Solaris, and many other systems.

NOTES

Only root can bind to a privileged port; this call will fail for any other users. In addition, the following error may occur:

EPFNOSUPPORT
    sin is not NULL and sin->sin_family is not AF_INET.

SEE ALSO
bind(2)