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/*- * SPDX-License-Identifier: BSD-2-Clause-FreeBSD * * Copyright (c) 2010-2011 The FreeBSD Foundation * All rights reserved. * * This software was developed at the Centre for Advanced Internet * Architectures, Swinburne University of Technology, Melbourne, Australia by * Lawrence Stewart under sponsorship from the FreeBSD Foundation. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. */ /* * This example Khelp module uses the helper hook points available in the TCP * stack to calculate a per-connection count of inbound and outbound packets * when the connection is in the established state. The code is verbosely * documented in an attempt to explain how everything fits together. */ #include <sys/cdefs.h> __FBSDID("$FreeBSD$"); #include <sys/param.h> #include <sys/kernel.h> #include <sys/hhook.h> #include <sys/khelp.h> #include <sys/module.h> #include <sys/module_khelp.h> #include <sys/socket.h> #include <sys/socketvar.h> #include <netinet/tcp_var.h> #include <vm/uma.h> /* * Function prototype for our helper hook (man 9 hhook) compatible hook * function. */ static int example_hook(int hhook_type, int hhook_id, void *udata, void *ctx_data, void *hdata, struct osd *hosd); /* * Our per-connection persistent data storage struct. */ struct example { uint32_t est_in_count; uint32_t est_out_count; }; /* * Fill in the required bits of our module's struct helper (defined in * <sys/module_khelp.h>). * * - Our helper will be storing persistent state for each TCP connection, so we * request the use the Object Specific Data (OSD) feature from the framework by * setting the HELPER_NEEDS_OSD flag. * * - Our helper is related to the TCP subsystem, so tell the Khelp framework * this by setting an appropriate class for the module. When a new TCP * connection is created, the Khelp framework takes care of associating helper * modules of the appropriate class with the new connection. */ struct helper example_helper = { .h_flags = HELPER_NEEDS_OSD, .h_classes = HELPER_CLASS_TCP }; /* * Set which helper hook points our module wants to hook by creating an array of * hookinfo structs (defined in <sys/hhook.h>). We hook the TCP established * inbound/outbound hook points (TCP hhook points are defined in * <netinet/tcp_var.h>) with our example_hook() function. We don't require a user * data pointer to be passed to our hook function when called, so we set it to * NULL. */ struct hookinfo example_hooks[] = { { .hook_type = HHOOK_TYPE_TCP, .hook_id = HHOOK_TCP_EST_IN, .hook_udata = NULL, .hook_func = &example_hook }, { .hook_type = HHOOK_TYPE_TCP, .hook_id = HHOOK_TCP_EST_OUT, .hook_udata = NULL, .hook_func = &example_hook } }; /* * Very simple helper hook function. Here's a quick run through the arguments: * * - hhook_type and hhook_id are useful if you use a single function with many * hook points and want to know which hook point called the function. * * - udata will be NULL, because we didn't elect to pass a pointer in either of * the hookinfo structs we instantiated above in the example_hooks array. * * - ctx_data contains context specific data from the hook point call site. The * data type passed is subsystem dependent. In the case of TCP, the hook points * pass a pointer to a "struct tcp_hhook_data" (defined in <netinet/tcp_var.h>). * * - hdata is a pointer to the persistent per-object storage for our module. The * pointer is allocated automagically by the Khelp framework when the connection * is created, and comes from a dedicated UMA zone. It will never be NULL. * * - hosd can be used with the Khelp framework's khelp_get_osd() function to * access data belonging to a different Khelp module. */ static int example_hook(int hhook_type, int hhook_id, void *udata, void *ctx_data, void *hdata, struct osd *hosd) { struct example *data; data = hdata; if (hhook_id == HHOOK_TCP_EST_IN) data->est_in_count++; else if (hhook_id == HHOOK_TCP_EST_OUT) data->est_out_count++; return (0); } /* * We use a convenient macro which handles registering our module with the Khelp * framework. Note that Khelp modules which set the HELPER_NEEDS_OSD flag (i.e. * require persistent per-object storage) must use the KHELP_DECLARE_MOD_UMA() * macro. If you don't require per-object storage, use the KHELP_DECLARE_MOD() * macro instead. */ KHELP_DECLARE_MOD_UMA(example, &example_helper, example_hooks, 1, sizeof(struct example), NULL, NULL);
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