ACCF_DNS(9) 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 In rc.conf(5): kld_list="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 ac- cept() 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 ker- nel. 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_data(9), accf_http(9) HISTORY The accept filter mechanism was introduced in FreeBSD 4.0. AUTHORS This manual page and the filter were written by David Malone. FreeBSD 15.1 July 16, 2008 ACCF_DNS(9)
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