mirror of https://github.com/mkerrisk/man-pages
129 lines
3.7 KiB
Groff
129 lines
3.7 KiB
Groff
.\" Copyright (C) 2007, Michael Kerrisk <mtk.manpages@gmail.com>
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.\" and Copyright (C) 2008, Linux Foundation, written by Michael Kerrisk
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.\" <mtk.manpages@gmail.com>
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.\"
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.\" %%%LICENSE_START(VERBATIM)
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.\" Permission is granted to make and distribute verbatim copies of this
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.\" manual provided the copyright notice and this permission notice are
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.\" preserved on all copies.
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.\"
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.\" Permission is granted to copy and distribute modified versions of this
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.\" manual under the conditions for verbatim copying, provided that the
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.\" entire resulting derived work is distributed under the terms of a
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.\" permission notice identical to this one.
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.\"
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.\" Since the Linux kernel and libraries are constantly changing, this
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.\" manual page may be incorrect or out-of-date. The author(s) assume no
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.\" responsibility for errors or omissions, or for damages resulting from
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.\" the use of the information contained herein. The author(s) may not
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.\" have taken the same level of care in the production of this manual,
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.\" which is licensed free of charge, as they might when working
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.\" professionally.
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.\"
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.\" Formatted or processed versions of this manual, if unaccompanied by
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.\" the source, must acknowledge the copyright and authors of this work.
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.\" %%%LICENSE_END
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.\"
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.\" 2007-05-31, mtk: Rewrite and substantial additional text.
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.\" 2008-12-03, mtk: Rewrote some pieces and fixed some errors
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.\"
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.TH BINDRESVPORT 3 2017-09-15 "" "Linux Programmer's Manual"
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.SH NAME
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bindresvport \- bind a socket to a privileged IP port
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.SH SYNOPSIS
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.nf
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.B #include <sys/types.h>
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.B #include <netinet/in.h>
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.PP
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.BI "int bindresvport(int " sockfd ", struct sockaddr_in *" sin );
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.fi
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.SH DESCRIPTION
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.BR bindresvport ()
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is used to bind the socket referred to by the
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file descriptor
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.I sockfd
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to a privileged anonymous IP port,
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that is, a port number arbitrarily selected from the range 512 to 1023.
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.\" Glibc actually starts searching with a port # in the range 600 to 1023
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.PP
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If the
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.BR bind (2)
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performed by
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.BR bindresvport ()
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is successful, and
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.I sin
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is not NULL, then
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.I sin\->sin_port
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returns the port number actually allocated.
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.PP
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.I sin
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can be NULL, in which case
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.I sin\->sin_family
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is implicitly taken to be
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.BR AF_INET .
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However, in this case,
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.BR bindresvport ()
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has no way to return the port number actually allocated.
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(This information can later be obtained using
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.BR getsockname (2).)
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.SH RETURN VALUE
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.BR bindresvport ()
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returns 0 on success; otherwise \-1 is returned and
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.I errno
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set to indicate the cause of the error.
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.SH ERRORS
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.BR bindresvport ()
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can fail for any of the same reasons as
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.BR bind (2).
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In addition, the following errors may occur:
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.TP
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.BR EACCES
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The calling process was not privileged
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(on Linux: the calling process did not have the
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.B CAP_NET_BIND_SERVICE
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capability in the user namespace governing its network namespace).
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.TP
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.B EADDRINUSE
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All privileged ports are in use.
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.TP
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.BR EAFNOSUPPORT " (" EPFNOSUPPORT " in glibc 2.7 and earlier)"
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.I sin
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is not NULL and
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.I sin->sin_family
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is not
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.BR AF_INET .
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.SH ATTRIBUTES
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For an explanation of the terms used in this section, see
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.BR attributes (7).
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.TS
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allbox;
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lb lb lb
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l l lw23.
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Interface Attribute Value
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T{
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.BR bindresvport ()
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T} Thread safety T{
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glibc >= 2.17: MT-Safe
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.\" commit f6da27e53695ad1cc0e2a9490358decbbfdff5e5
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.br
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glibc < 2.17: MT-Unsafe
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T}
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.TE
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.PP
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The
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.BR bindresvport ()
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function uses a static variable that was not protected by a lock
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before glibc 2.17, rendering the function MT-Unsafe.
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.SH CONFORMING TO
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Not in POSIX.1.
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Present on the BSDs, Solaris, and many other systems.
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.SH NOTES
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Unlike some
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.BR bindresvport ()
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implementations,
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the glibc implementation ignores any value that the caller supplies in
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.IR sin\->sin_port .
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.SH SEE ALSO
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.BR bind (2),
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.BR getsockname (2)
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