lib/agentx.c

   1 /* SNMP support
   2  * Copyright (C) 2012 Vincent Bernat <bernat@luffy.cx>
   3  *
   4  * This file is part of GNU Zebra.
   5  *
   6  * GNU Zebra is free software; you can redistribute it and/or modify it
   7  * under the terms of the GNU General Public License as published by the
   8  * Free Software Foundation; either version 2, or (at your option) any
   9  * later version.
  10  *
  11  * GNU Zebra 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 #include <zebra.h>
  22
  23 #ifdef SNMP_AGENTX
  24 #include <net-snmp/net-snmp-config.h>
  25 #include <net-snmp/net-snmp-includes.h>
  26 #include <net-snmp/agent/net-snmp-agent-includes.h>
  27 #include <net-snmp/agent/snmp_vars.h>
  28
  29 #include "command.h"
  30 #include "smux.h"
  31 #include "memory.h"
  32 #include "linklist.h"
  33 #include "version.h"
  34 #include "lib_errors.h"
  35 #include "xref.h"
  36
  37 XREF_SETUP()
  38
  39 DEFINE_HOOK(agentx_enabled, (), ())
  40
  41 static int agentx_enabled = 0;
  42
  43 static struct thread_master *agentx_tm;
  44 static struct thread *timeout_thr = NULL;
  45 static struct list *events = NULL;
  46
  47 static void agentx_events_update(void);
  48
  49 static int agentx_timeout(struct thread *t)
  50 {
  51         timeout_thr = NULL;
  52
  53         snmp_timeout();
  54         run_alarms();
  55         netsnmp_check_outstanding_agent_requests();
  56         agentx_events_update();
  57         return 0;
  58 }
  59
  60 static int agentx_read(struct thread *t)
  61 {
  62         fd_set fds;
  63         int flags, new_flags = 0;
  64         int nonblock = false;
  65         struct listnode *ln = THREAD_ARG(t);
  66         list_delete_node(events, ln);
  67
  68         /* fix for non blocking socket */
  69         flags = fcntl(THREAD_FD(t), F_GETFL, 0);
  70         if (-1 == flags) {
  71                 flog_err(EC_LIB_SYSTEM_CALL, "Failed to get FD settings fcntl: %s(%d)",
  72                          strerror(errno), errno);
  73                 return -1;
  74         }
  75
  76         if (flags & O_NONBLOCK)
  77                 nonblock = true;
  78         else
  79                 new_flags = fcntl(THREAD_FD(t), F_SETFL, flags | O_NONBLOCK);
  80
  81         if (new_flags == -1)
  82                 flog_err(EC_LIB_SYSTEM_CALL, "Failed to set snmp fd non blocking: %s(%d)",
  83                          strerror(errno), errno);
  84
  85         FD_ZERO(&fds);
  86         FD_SET(THREAD_FD(t), &fds);
  87         snmp_read(&fds);
  88
  89         /* Reset the flag */
  90         if (!nonblock) {
  91                 new_flags = fcntl(THREAD_FD(t), F_SETFL, flags);
  92
  93                 if (new_flags == -1)
  94                         flog_err(
  95                                 EC_LIB_SYSTEM_CALL,
  96                                 "Failed to set snmp fd back to original settings: %s(%d)",
  97                                 strerror(errno), errno);
  98         }
  99
 100         netsnmp_check_outstanding_agent_requests();
 101         agentx_events_update();
 102         return 0;
 103 }
 104
 105 static void agentx_events_update(void)
 106 {
 107         int maxfd = 0;
 108         int block = 1;
 109         struct timeval timeout = {.tv_sec = 0, .tv_usec = 0};
 110         fd_set fds;
 111         struct listnode *ln;
 112         struct thread *thr;
 113         int fd, thr_fd;
 114
 115         thread_cancel(&timeout_thr);
 116
 117         FD_ZERO(&fds);
 118         snmp_select_info(&maxfd, &fds, &timeout, &block);
 119
 120         if (!block) {
 121                 timeout_thr = NULL;
 122                 thread_add_timer_tv(agentx_tm, agentx_timeout, NULL, &timeout,
 123                                     &timeout_thr);
 124         }
 125
 126         ln = listhead(events);
 127         thr = ln ? listgetdata(ln) : NULL;
 128         thr_fd = thr ? THREAD_FD(thr) : -1;
 129
 130         /* "two-pointer" / two-list simultaneous iteration
 131          * ln/thr/thr_fd point to the next existing event listener to hit while
 132          * fd counts to catch up */
 133         for (fd = 0; fd < maxfd; fd++) {
 134                 /* caught up */
 135                 if (thr_fd == fd) {
 136                         struct listnode *nextln = listnextnode(ln);
 137                         if (!FD_ISSET(fd, &fds)) {
 138                                 thread_cancel(&thr);
 139                                 list_delete_node(events, ln);
 140                         }
 141                         ln = nextln;
 142                         thr = ln ? listgetdata(ln) : NULL;
 143                         thr_fd = thr ? THREAD_FD(thr) : -1;
 144                 }
 145                 /* need listener, but haven't hit one where it would be */
 146                 else if (FD_ISSET(fd, &fds)) {
 147                         struct listnode *newln;
 148                         thr = NULL;
 149                         thread_add_read(agentx_tm, agentx_read, NULL, fd, &thr);
 150                         newln = listnode_add_before(events, ln, thr);
 151                         thr->arg = newln;
 152                 }
 153         }
 154
 155         /* leftover event listeners at this point have fd > maxfd, delete them
 156          */
 157         while (ln) {
 158                 struct listnode *nextln = listnextnode(ln);
 159                 thr = listgetdata(ln);
 160                 thread_cancel(&thr);
 161                 list_delete_node(events, ln);
 162                 ln = nextln;
 163         }
 164 }
 165
 166 /* AgentX node. */
 167 static int config_write_agentx(struct vty *vty);
 168 static struct cmd_node agentx_node = {
 169         .name = "smux",
 170         .node = SMUX_NODE,
 171         .prompt = "",
 172         .config_write = config_write_agentx,
 173 };
 174
 175 /* Logging NetSNMP messages */
 176 static int agentx_log_callback(int major, int minor, void *serverarg,
 177                                void *clientarg)
 178 {
 179         struct snmp_log_message *slm = (struct snmp_log_message *)serverarg;
 180         char *msg = XSTRDUP(MTYPE_TMP, slm->msg);
 181         if (msg)
 182                 msg[strlen(msg) - 1] = '\0';
 183         switch (slm->priority) {
 184         case LOG_EMERG:
 185                 flog_err(EC_LIB_SNMP, "snmp[emerg]: %s", msg ? msg : slm->msg);
 186                 break;
 187         case LOG_ALERT:
 188                 flog_err(EC_LIB_SNMP, "snmp[alert]: %s", msg ? msg : slm->msg);
 189                 break;
 190         case LOG_CRIT:
 191                 flog_err(EC_LIB_SNMP, "snmp[crit]: %s", msg ? msg : slm->msg);
 192                 break;
 193         case LOG_ERR:
 194                 flog_err(EC_LIB_SNMP, "snmp[err]: %s", msg ? msg : slm->msg);
 195                 break;
 196         case LOG_WARNING:
 197                 flog_warn(EC_LIB_SNMP, "snmp[warning]: %s",
 198                           msg ? msg : slm->msg);
 199                 break;
 200         case LOG_NOTICE:
 201                 zlog_notice("snmp[notice]: %s", msg ? msg : slm->msg);
 202                 break;
 203         case LOG_INFO:
 204                 zlog_info("snmp[info]: %s", msg ? msg : slm->msg);
 205                 break;
 206         case LOG_DEBUG:
 207                 zlog_debug("snmp[debug]: %s", msg ? msg : slm->msg);
 208                 break;
 209         }
 210         XFREE(MTYPE_TMP, msg);
 211         return SNMP_ERR_NOERROR;
 212 }
 213
 214 static int config_write_agentx(struct vty *vty)
 215 {
 216         if (agentx_enabled)
 217                 vty_out(vty, "agentx\n");
 218         return 1;
 219 }
 220
 221 DEFUN (agentx_enable,
 222        agentx_enable_cmd,
 223        "agentx",
 224        "SNMP AgentX protocol settings\n")
 225 {
 226         if (!agentx_enabled) {
 227                 init_snmp(FRR_SMUX_NAME);
 228                 events = list_new();
 229                 agentx_events_update();
 230                 agentx_enabled = 1;
 231                 hook_call(agentx_enabled);
 232         }
 233
 234         return CMD_SUCCESS;
 235 }
 236
 237 DEFUN (no_agentx,
 238        no_agentx_cmd,
 239        "no agentx",
 240        NO_STR
 241        "SNMP AgentX protocol settings\n")
 242 {
 243         if (!agentx_enabled)
 244                 return CMD_SUCCESS;
 245         vty_out(vty, "SNMP AgentX support cannot be disabled once enabled\n");
 246         return CMD_WARNING_CONFIG_FAILED;
 247 }
 248
 249 int smux_enabled(void)
 250 {
 251         return agentx_enabled;
 252 }
 253
 254 void smux_init(struct thread_master *tm)
 255 {
 256         agentx_tm = tm;
 257
 258         netsnmp_enable_subagent();
 259         snmp_disable_log();
 260         snmp_enable_calllog();
 261         snmp_register_callback(SNMP_CALLBACK_LIBRARY, SNMP_CALLBACK_LOGGING,
 262                                agentx_log_callback, NULL);
 263         init_agent(FRR_SMUX_NAME);
 264
 265         install_node(&agentx_node);
 266         install_element(CONFIG_NODE, &agentx_enable_cmd);
 267         install_element(CONFIG_NODE, &no_agentx_cmd);
 268 }
 269
 270 void smux_agentx_enable(void)
 271 {
 272         if (!agentx_enabled) {
 273                 init_snmp(FRR_SMUX_NAME);
 274                 events = list_new();
 275                 agentx_events_update();
 276                 agentx_enabled = 1;
 277         }
 278 }
 279
 280 void smux_register_mib(const char *descr, struct variable *var, size_t width,
 281                        int num, oid name[], size_t namelen)
 282 {
 283         register_mib(descr, var, width, num, name, namelen);
 284 }
 285
 286 void smux_trap(struct variable *vp, size_t vp_len, const oid *ename,
 287                size_t enamelen, const oid *name, size_t namelen,
 288                const oid *iname, size_t inamelen,
 289                const struct trap_object *trapobj, size_t trapobjlen,
 290                uint8_t sptrap)
 291 {
 292         struct index_oid trap_index[1];
 293
 294         /* copy the single index into the multi-index format */
 295         oid_copy(trap_index[0].indexname, iname, inamelen);
 296         trap_index[0].indexlen = inamelen;
 297
 298         smux_trap_multi_index(vp, vp_len, ename, enamelen, name, namelen,
 299                               trap_index, array_size(trap_index), trapobj,
 300                               trapobjlen, sptrap);
 301 }
 302
 303 int smux_trap_multi_index(struct variable *vp, size_t vp_len, const oid *ename,
 304                           size_t enamelen, const oid *name, size_t namelen,
 305                           struct index_oid *iname, size_t index_len,
 306                           const struct trap_object *trapobj, size_t trapobjlen,
 307                           uint8_t sptrap)
 308 {
 309         oid objid_snmptrap[] = {1, 3, 6, 1, 6, 3, 1, 1, 4, 1, 0};
 310         size_t objid_snmptrap_len = sizeof(objid_snmptrap) / sizeof(oid);
 311         oid notification_oid[MAX_OID_LEN];
 312         size_t notification_oid_len;
 313         unsigned int i;
 314
 315         netsnmp_variable_list *notification_vars = NULL;
 316         if (!agentx_enabled)
 317                 return 0;
 318
 319         /* snmpTrapOID */
 320         oid_copy(notification_oid, ename, enamelen);
 321         notification_oid[enamelen] = sptrap;
 322         notification_oid_len = enamelen + 1;
 323         snmp_varlist_add_variable(&notification_vars, objid_snmptrap,
 324                                   objid_snmptrap_len, ASN_OBJECT_ID,
 325                                   (uint8_t *)notification_oid,
 326                                   notification_oid_len * sizeof(oid));
 327
 328         /* Provided bindings */
 329         for (i = 0; i < trapobjlen; i++) {
 330                 unsigned int j;
 331                 oid oid[MAX_OID_LEN];
 332                 size_t oid_len, onamelen;
 333                 uint8_t *val;
 334                 size_t val_len;
 335                 WriteMethod *wm = NULL;
 336                 struct variable cvp;
 337                 unsigned int iindex;
 338                 /*
 339                  * this allows the behaviour of smux_trap with a singe index
 340                  * for all objects to be maintained whilst allowing traps which
 341                  * have different indices per object to be supported
 342                  */
 343                 iindex = (index_len == 1) ? 0 : i;
 344
 345                 /* Make OID. */
 346                 if (trapobj[i].namelen > 0) {
 347                         /* Columnar object */
 348                         onamelen = trapobj[i].namelen;
 349                         oid_copy(oid, name, namelen);
 350                         oid_copy(oid + namelen, trapobj[i].name, onamelen);
 351                         oid_copy(oid + namelen + onamelen,
 352                                  iname[iindex].indexname,
 353                                  iname[iindex].indexlen);
 354                         oid_len = namelen + onamelen + iname[iindex].indexlen;
 355                 } else {
 356                         /* Scalar object */
 357                         onamelen = trapobj[i].namelen * (-1);
 358                         oid_copy(oid, name, namelen);
 359                         oid_copy(oid + namelen, trapobj[i].name, onamelen);
 360                         oid[onamelen + namelen] = 0;
 361                         oid_len = namelen + onamelen + 1;
 362                 }
 363
 364                 /* Locate the appropriate function and type in the MIB registry.
 365                  */
 366                 for (j = 0; j < vp_len; j++) {
 367                         if (oid_compare(trapobj[i].name, onamelen, vp[j].name,
 368                                         vp[j].namelen)
 369                             != 0)
 370                                 continue;
 371                         /* We found the appropriate variable in the MIB
 372                          * registry. */
 373                         oid_copy(cvp.name, name, namelen);
 374                         oid_copy(cvp.name + namelen, vp[j].name, vp[j].namelen);
 375                         cvp.namelen = namelen + vp[j].namelen;
 376                         cvp.type = vp[j].type;
 377                         cvp.magic = vp[j].magic;
 378                         cvp.acl = vp[j].acl;
 379                         cvp.findVar = vp[j].findVar;
 380
 381                         /* Grab the result. */
 382                         val = cvp.findVar(&cvp, oid, &oid_len, 1, &val_len,
 383                                           &wm);
 384                         if (!val)
 385                                 break;
 386                         snmp_varlist_add_variable(&notification_vars, oid,
 387                                                   oid_len, vp[j].type, val,
 388                                                   val_len);
 389                         break;
 390                 }
 391         }
 392
 393
 394         send_v2trap(notification_vars);
 395         snmp_free_varbind(notification_vars);
 396         agentx_events_update();
 397         return 1;
 398 }
 399
 400 void smux_events_update(void)
 401 {
 402         agentx_events_update();
 403 }
 404
 405 #endif /* SNMP_AGENTX */