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 allocated.

       sin  can  be  NULL, in which case sin->sin_family is implicitly taken to be AF_INET.  How‐
       ever, in this case, bindresvport() has no way to return the  port  number  actually  allo‐
       cated.  (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  follow‐
       ing errors may occur:

       EACCES The  caller  did not have superuser privilege (to be precise: the CAP_NET_BIND_SER‐
              VICE 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  pro‐
       tected, so it is not thread-safe.

       Since  glibc 2.17, the bindresvport() function uses a lock to protect the 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 3.74 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/.



                                            2013-06-21                            BINDRESVPORT(3)