diff options
author | lstewart <lstewart@FreeBSD.org> | 2011-02-11 07:26:17 +0000 |
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committer | lstewart <lstewart@FreeBSD.org> | 2011-02-11 07:26:17 +0000 |
commit | f7710268a23676069049c773e8c8a4b0caff7fa5 (patch) | |
tree | 96190b19ba4e8d77d1b14eb28d9373707e3efc9c /share/examples/kld/khelp | |
parent | febdd2ffbc8e4d9ad633968685747914f8729be4 (diff) | |
download | FreeBSD-src-f7710268a23676069049c773e8c8a4b0caff7fa5.zip FreeBSD-src-f7710268a23676069049c773e8c8a4b0caff7fa5.tar.gz |
Add an example Khelp module, which will be referenced in the forthcoming Khelp
documentation.
Sponsored by: FreeBSD Foundation
Discussed with: David Hayes <dahayes at swin edu au>
MFC after: 5 weeks
X-MFC with: r216615
Diffstat (limited to 'share/examples/kld/khelp')
-rw-r--r-- | share/examples/kld/khelp/Makefile | 11 | ||||
-rw-r--r-- | share/examples/kld/khelp/README | 6 | ||||
-rw-r--r-- | share/examples/kld/khelp/h_example.c | 154 |
3 files changed, 171 insertions, 0 deletions
diff --git a/share/examples/kld/khelp/Makefile b/share/examples/kld/khelp/Makefile new file mode 100644 index 0000000..e4cd80f --- /dev/null +++ b/share/examples/kld/khelp/Makefile @@ -0,0 +1,11 @@ +# $FreeBSD$ + +.include <bsd.own.mk> + +# Change if the src tree you are compiling for is not in /usr/src +#SYSDIR=/usr/src/sys + +KMOD= h_example +SRCS= h_example.c + +.include <bsd.kmod.mk> diff --git a/share/examples/kld/khelp/README b/share/examples/kld/khelp/README new file mode 100644 index 0000000..89a2a33 --- /dev/null +++ b/share/examples/kld/khelp/README @@ -0,0 +1,6 @@ +$FreeBSD$ + +An example Khelp module which 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. diff --git a/share/examples/kld/khelp/h_example.c b/share/examples/kld/khelp/h_example.c new file mode 100644 index 0000000..9f58f06 --- /dev/null +++ b/share/examples/kld/khelp/h_example.c @@ -0,0 +1,154 @@ +/*- + * 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); |