NAME

       bindresvport - bind a socket to a privileged IP port

SYNOPSIS

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

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

DESCRIPTION

       bindresvport() is used to bind a socket descriptor to a privileged anonymous IP port, that
       is, a port number arbitrarily selected from the range 512 to 1023.

       If the bind(2) performed by bindresvport() is  successful,  and  sin  is  not  NULL,  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.
       However, in this case, bindresvport() has no  way  to  return  the  port  number  actually
       allocated.  (This information can later be obtained using getsockname(2).)

RETURN VALUE

       bindresvport()  returns  0  on success; 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).   In  addition,  the
       following errors may occur:

       EACCES The   caller   did   not   have   superuser   privilege   (to   be   precise:   the
              CAP_NET_BIND_SERVICE capability is required).

       EADDRINUSE
              All privileged ports are in use.

       EAFNOSUPPORT (EPFNOSUPPORT in glibc 2.7 and earlier)
              sin is not NULL and sin->sin_family is not AF_INET.

ATTRIBUTES

   Multithreading (see pthreads(7))
       Before glibc 2.17, the  bindresvport()  function  uses  a  static  variable  that  is  not
       protected, so it is not thread-safe.

       Since  glibc  2.17, the bindresvport() function uses a lock to protect static variable, so
       it is thread-safe.

CONFORMING TO

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

NOTES

       Unlike some bindresvport() implementations, the glibc  implementation  ignores  any  value
       that the caller supplies in sin->sin_port.

SEE ALSO

       bind(2), getsockname(2)

COLOPHON

       This  page  is  part of release 3.54 of the Linux man-pages project.  A description of the
       project,    and    information    about    reporting    bugs,    can    be    found     at
       http://www.kernel.org/doc/man-pages/.

                                            2013-06-21                            BINDRESVPORT(3)