bindresvport
Section: C Library Functions (3)
Updated: 202-0-08
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NAME
bindresvport - bind a socket to a privileged IP port
LIBRARY
Standard C library
(
libc,~
-lc)
SYNOPSIS
#include <sys/types.h>
#include <netinet/in.h>
int bindresvport(int sockfd, struct sockaddr_in *sin);
DESCRIPTION
bindresvport()
is used to bind the socket referred to by the
file descriptor
sockfd
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
is set to indicate the error.
ERRORS
bindresvport()
can fail for any of the same reasons as
bind(2).
In addition, the following errors may occur:
- EACCES
-
The calling process was not privileged
(on Linux: the calling process did not have the
CAP_NET_BIND_SERVICE
capability in the user namespace governing its network namespace).
- 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: M-Safe;
glibc < 2.17: M-Unsafe
|
The
bindresvport()
function uses a static variable that was not protected by a lock
before glibc 2.17, rendering the function M-Unsafe.
VERSIONS
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.
STANDARDS
BSD.
SEE ALSO
bind(2),
getsockname(2)
Index
- NAME
-
- LIBRARY
-
- SYNOPSIS
-
- DESCRIPTION
-
- RETURN VALUE
-
- ERRORS
-
- ATTRIBUTES
-
- VERSIONS
-
- NOTES
-
- STANDARDS
-
- SEE ALSO
-
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