NAME
accf_dns —
buffer incoming DNS requests until the
whole first request is present
SYNOPSIS
options INET |
options ACCEPT_FILTER_DNS |
kldload accf_dns |
DESCRIPTION
This is a filter to be placed on a socket that will be usingaccept()
to receive incoming connections.
It prevents the application from receiving the
connected descriptor via
accept()
until a whole DNS request is available on the socket. It does this by
reading the first two bytes of the request, to determine its size, and
waiting until the required amount of data is available to be read.
The ACCEPT_FILTER_DNS kernel option is also a module that can be enabled at runtime via kldload(8) if the INET option has been compiled into the kernel.
EXAMPLES
If the accf_dns module is available in the
kernel, the following code will enable the DNS accept filter on a socket
sok.
struct accept_filter_arg afa; bzero(&afa, sizeof(afa)); strcpy(afa.af_name, "dnsready"); setsockopt(sok, SOL_SOCKET, SO_ACCEPTFILTER, &afa, sizeof(afa));
SEE ALSO
HISTORY
The accept filter mechanism was introduced in FreeBSD 4.0.
AUTHORS
This manual page and the filter were written by David Malone.