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33 .Nd buffer incoming DNS requests until the whole first request is present
36 .Nm options ACCEPT_FILTER_DNS
39 This is a filter to be placed on a socket that will be using
41 to receive incoming connections.
43 It prevents the application from receiving the connected descriptor via
45 until a whole DNS request is available on the socket.
46 It does this by reading the first two bytes of the request,
47 to determine its size,
48 and waiting until the required amount of data is available to be read.
52 kernel option is also a module that can be enabled at runtime via
54 if the INET option has been compiled into the kernel.
58 module is available in the kernel,
59 the following code will enable the DNS accept filter
62 .Bd -literal -offset 0i
63 struct accept_filter_arg afa;
65 bzero(&afa, sizeof(afa));
66 strcpy(afa.af_name, "dnsready");
67 setsockopt(sok, SOL_SOCKET, SO_ACCEPTFILTER, &afa, sizeof(afa));
75 The accept filter mechanism was introduced in
78 This manual page and the filter were written by