SIMPLE SOLUTIONS

ACCF_DNS(9FREEBSD) - man page online | system kernel interfaces

Buffer incoming DNS requests until the whole first request is present.

Chapter
July 16, 2008
ACCF_DNS(9)                       BSD Kernel Developer's Manual                       ACCF_DNS(9)

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 using accept() 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 setsockopt(2), accept_filter(9), accf_http(9) accf_data(9)
HISTORY The accept filter mechanism was introduced in FreeBSD 4.0.
AUTHORS This manual page and the filter were written by David Malone.
BSD July 16, 2008 BSD
This manual Reference Other manuals
accf_dns(9freebsd) referred by accept_filter(9freebsd) | accf_data(9freebsd)
refer to accept_filter(9freebsd) | accf_data(9freebsd) | accf_http(9freebsd) | getsockopt(2)