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