bindresvport - bind a socket to a privileged IP port
int bindresvport(int sockfd, struct sockaddr_in *sin);
() 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
is not NULL, then sin->sin_port
returns the port number
can be NULL, in which case sin->sin_family
taken to be AF_INET
. However, in this case, bindresvport
no way to return the port number actually allocated. (This information can
later be obtained using getsockname(2)
() returns 0 on success; otherwise -1 is returned and
set to indicate the cause of the error.
() can fail for any of the same reasons as bind(2)
addition, the following errors may occur:
- The caller did not have superuser privilege (to be precise: the
CAP_NET_BIND_SERVICE capability is required).
- All privileged ports are in use.
- EAFNOSUPPORT (EPFNOSUPPORT in glibc 2.7 and earlier)
- sin is not NULL and sin->sin_family is not
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 the
static variable, so it is thread-safe.
Not in POSIX.1-2001. Present on the BSDs, Solaris, and many other systems.
Unlike some bindresvport
() implementations, the glibc implementation
ignores any value that the caller supplies in sin->sin_port
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