bindresvport

BINDRESVPORT(3)            Linux Programmer's Manual           BINDRESVPORT(3)

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  allo-
       cated.

       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
       For   an   explanation   of   the  terms  used  in  this  section,  see
       attributes(7).

       +---------------+---------------+-------------------------+
       |Interface      | Attribute     | Value                   |
       +---------------+---------------+-------------------------+
       |bindresvport() | Thread safety | glibc >= 2.17: MT-Safe  |
       |               |               | glibc < 2.17: MT-Unsafe |
       +---------------+---------------+-------------------------+
       The bindresvport() function uses a static variable that  was  not  pro-
       tected by a lock before glibc 2.17, rendering the function MT-Unsafe.

CONFORMING TO
       Not in POSIX.1.  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 4.04 of the Linux  man-pages  project.   A
       description  of  the project, information about reporting bugs, and the
       latest    version    of    this    page,    can     be     found     at
       http://www.kernel.org/doc/man-pages/.

                                  2015-03-02                   BINDRESVPORT(3)
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