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#include <sys/types.h>
#include <sys/module.h>
#include <sys/socket.h>
#include <sys/socketvar.h>
struct accept_filter { char accf_name[16]; void (*accf_callback)(struct socket *so, void *arg, int waitflag); void * (*accf_create)(struct socket *so, char *arg); void (*accf_destroy)(struct socket *so); SLIST_ENTRY(accept_filter) accf_next; /* next on the list */ };
The module should register it with the function accept_filt_add(), passing a pointer to a struct accept_filter, allocated with malloc(9).
The fields of struct accept_filter are as follows:
accf_name | |
Name of the filter; this is how it will be accessed from userland. | |
accf_callback | |
The callback that the kernel will do once the connection is established. It is the same as a socket upcall and will be called when the connection is established and whenever new data arrives on the socket, unless the callback modifies the socket's flags. | |
accf_create | |
Called whenever a setsockopt(2) installs the filter onto a listening socket. | |
accf_destroy | |
Called whenever the user removes the accept filter on the socket. | |
The accept_filt_del() function passed the same string used in accept_filter.accf_name during registration with accept_filt_add(), the kernel will then disallow and further userland use of the filter.
The accept_filt_get() function is used internally to locate which accept filter to use via the setsockopt(2) system call.
The accept_filt_generic_mod_event() function provides a simple way to avoid duplication of code for accept filters which do not use the argument field to load and unload themselves. This function can be used in the moduledata_t struct for the DECLARE_MODULE(9) macro.
The accept filter concept was pioneered by David Filo at Yahoo!amp; and refined to be a loadable module system by Alfred Perlstein.
ACCEPT_FILTER (9) | June 25, 2000 |
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