zebra/sample_plugin.c

   1 /*
   2  * Sample plugin for the FRR zebra dataplane.
   3  *
   4  * Copyright (c) 2019 Volta Networks, Inc.
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License as published by
   8  * the Free Software Foundation; either version 2 of the License, or
   9  * (at your option) any later version.
  10  *
  11  * This program is distributed in the hope that it will be useful, but
  12  * WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14  * General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU General Public License along
  17  * with this program; see the file COPYING; if not, write to the Free Software
  18  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
  19  */
  20
  21 /*
  22  * Should be possible to build this plugin using this sort of command:
  23  *
  24  *    gcc -I ~/work/frr/ -I ~/work/frr/lib -I ~/work/frr/zebra \
  25  *        -g -O0 -o sample_plugin.so -shared -fPIC sample_plugin.c
  26  *
  27  * where 'frr' is a configured and built frr sandbox.
  28  *
  29  * Run zebra with '-M /path/to/sample_plugin.so' to load the module.
  30  */
  31
  32 #include "config.h" /* Include this explicitly */
  33 #include "lib/zebra.h"
  34 #include "lib/libfrr.h"
  35 #include "zebra/zebra_dplane.h"
  36 #include "zebra/debug.h"
  37
  38 static const char *plugin_name = "SAMPLE";
  39
  40 static struct zebra_dplane_provider *prov_p;
  41
  42 /*
  43  * Startup/init callback, called from the dataplane.
  44  */
  45 static int sample_start(struct zebra_dplane_provider *prov)
  46 {
  47         /* Nothing special to do - we don't allocate anything. */
  48         return 0;
  49 }
  50
  51
  52 /*
  53  * Shutdown/cleanup callback, called from the dataplane pthread.
  54  */
  55 static int sample_fini(struct zebra_dplane_provider *prov, bool early)
  56 {
  57         /* Nothing special to do. */
  58         return 0;
  59 }
  60
  61 /*
  62  * Callback from the dataplane to process incoming work; this runs in the
  63  * dplane pthread.
  64  */
  65 static int sample_process(struct zebra_dplane_provider *prov)
  66 {
  67         int counter, limit;
  68         struct zebra_dplane_ctx *ctx;
  69
  70         limit = dplane_provider_get_work_limit(prov_p);
  71
  72         /* Respect the configured limit on the amount of work to do in
  73          * any one call.
  74          */
  75         for (counter = 0; counter < limit; counter++) {
  76                 ctx = dplane_provider_dequeue_in_ctx(prov_p);
  77                 if (!ctx)
  78                         break;
  79
  80                 /* Just set 'success' status and return to the dataplane */
  81                 dplane_ctx_set_status(ctx, ZEBRA_DPLANE_REQUEST_SUCCESS);
  82                 dplane_provider_enqueue_out_ctx(prov_p, ctx);
  83         }
  84
  85         return 0;
  86 }
  87
  88 /*
  89  * Init entry point called during zebra startup. This is registered during
  90  * module init.
  91  */
  92 static int init_sample_plugin(struct thread_master *tm)
  93 {
  94         int ret;
  95         struct zebra_dplane_provider *prov = NULL;
  96
  97         /* Note that we don't use or store the thread_master 'tm'. We
  98          * don't use the zebra main pthread: our plugin code will run in
  99          * the zebra dataplane pthread context.
 100          */
 101
 102         /* Register the plugin with the dataplane infrastructure. We
 103          * register to be called before the kernel, and we register
 104          * our init, process work, and shutdown callbacks.
 105          */
 106         ret = dplane_provider_register(plugin_name, DPLANE_PRIO_PRE_KERNEL,
 107                                        DPLANE_PROV_FLAGS_DEFAULT,
 108                                        sample_start,
 109                                        sample_process,
 110                                        sample_fini,
 111                                        NULL,
 112                                        &prov_p);
 113
 114         if (IS_ZEBRA_DEBUG_DPLANE)
 115                 zlog_debug("sample plugin register => %d", ret);
 116
 117         return 0;
 118 }
 119
 120 /*
 121  * Base FRR loadable module info: basic info including module entry-point.
 122  */
 123 static int module_init(void)
 124 {
 125         hook_register(frr_late_init, init_sample_plugin);
 126         return 0;
 127 }
 128
 129 FRR_MODULE_SETUP(
 130         .name = "dplane_sample",
 131         .version = "0.0.1",
 132         .description = "Dataplane Sample Plugin",
 133         .init = module_init,
 134         )