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 static int agentx_enabled = 0;
  40
  41 static struct thread_master *agentx_tm;
  42 static struct thread *timeout_thr = NULL;
  43 static struct list *events = NULL;
  44
  45 static void agentx_events_update(void);
  46
  47 static int agentx_timeout(struct thread *t)
  48 {
  49         timeout_thr = NULL;
  50
  51         snmp_timeout();
  52         run_alarms();
  53         netsnmp_check_outstanding_agent_requests();
  54         agentx_events_update();
  55         return 0;
  56 }
  57
  58 static int agentx_read(struct thread *t)
  59 {
  60         fd_set fds;
  61         int flags, new_flags = 0;
  62         int nonblock = false;
  63         struct listnode *ln = THREAD_ARG(t);
  64         list_delete_node(events, ln);
  65
  66         /* fix for non blocking socket */
  67         flags = fcntl(THREAD_FD(t), F_GETFL, 0);
  68         if (-1 == flags) {
  69                 flog_err(EC_LIB_SYSTEM_CALL, "Failed to get FD settings fcntl: %s(%d)",
  70                          strerror(errno), errno);
  71                 return -1;
  72         }
  73
  74         if (flags & O_NONBLOCK)
  75                 nonblock = true;
  76         else
  77                 new_flags = fcntl(THREAD_FD(t), F_SETFL, flags | O_NONBLOCK);
  78
  79         if (new_flags == -1)
  80                 flog_err(EC_LIB_SYSTEM_CALL, "Failed to set snmp fd non blocking: %s(%d)",
  81                          strerror(errno), errno);
  82
  83         FD_ZERO(&fds);
  84         FD_SET(THREAD_FD(t), &fds);
  85         snmp_read(&fds);
  86
  87         /* Reset the flag */
  88         if (!nonblock) {
  89                 new_flags = fcntl(THREAD_FD(t), F_SETFL, flags);
  90
  91                 if (new_flags == -1)
  92                         flog_err(
  93                                 EC_LIB_SYSTEM_CALL,
  94                                 "Failed to set snmp fd back to original settings: %s(%d)",
  95                                 strerror(errno), errno);
  96         }
  97
  98         netsnmp_check_outstanding_agent_requests();
  99         agentx_events_update();
 100         return 0;
 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                 timeout_thr = NULL;
 120                 thread_add_timer_tv(agentx_tm, agentx_timeout, NULL, &timeout,
 121                                     &timeout_thr);
 122         }
 123
 124         ln = listhead(events);
 125         thr = ln ? listgetdata(ln) : NULL;
 126         thr_fd = thr ? THREAD_FD(thr) : -1;
 127
 128         /* "two-pointer" / two-list simultaneous iteration
 129          * ln/thr/thr_fd point to the next existing event listener to hit while
 130          * fd counts to catch up */
 131         for (fd = 0; fd < maxfd; fd++) {
 132                 /* caught up */
 133                 if (thr_fd == fd) {
 134                         struct listnode *nextln = listnextnode(ln);
 135                         if (!FD_ISSET(fd, &fds)) {
 136                                 thread_cancel(&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 = NULL;
 147                         thread_add_read(agentx_tm, agentx_read, NULL, fd, &thr);
 148                         newln = listnode_add_before(events, ln, thr);
 149                         thr->arg = newln;
 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                 list_delete_node(events, ln);
 160                 ln = nextln;
 161         }
 162 }
 163
 164 /* AgentX node. */
 165 static int config_write_agentx(struct vty *vty);
 166 static struct cmd_node agentx_node = {
 167         .name = "smux",
 168         .node = SMUX_NODE,
 169         .prompt = "",
 170         .config_write = config_write_agentx,
 171 };
 172
 173 /* Logging NetSNMP messages */
 174 static int agentx_log_callback(int major, int minor, void *serverarg,
 175                                void *clientarg)
 176 {
 177         struct snmp_log_message *slm = (struct snmp_log_message *)serverarg;
 178         char *msg = XSTRDUP(MTYPE_TMP, slm->msg);
 179         if (msg)
 180                 msg[strlen(msg) - 1] = '\0';
 181         switch (slm->priority) {
 182         case LOG_EMERG:
 183                 flog_err(EC_LIB_SNMP, "snmp[emerg]: %s", msg ? msg : slm->msg);
 184                 break;
 185         case LOG_ALERT:
 186                 flog_err(EC_LIB_SNMP, "snmp[alert]: %s", msg ? msg : slm->msg);
 187                 break;
 188         case LOG_CRIT:
 189                 flog_err(EC_LIB_SNMP, "snmp[crit]: %s", msg ? msg : slm->msg);
 190                 break;
 191         case LOG_ERR:
 192                 flog_err(EC_LIB_SNMP, "snmp[err]: %s", msg ? msg : slm->msg);
 193                 break;
 194         case LOG_WARNING:
 195                 flog_warn(EC_LIB_SNMP, "snmp[warning]: %s",
 196                           msg ? msg : slm->msg);
 197                 break;
 198         case LOG_NOTICE:
 199                 zlog_notice("snmp[notice]: %s", msg ? msg : slm->msg);
 200                 break;
 201         case LOG_INFO:
 202                 zlog_info("snmp[info]: %s", msg ? msg : slm->msg);
 203                 break;
 204         case LOG_DEBUG:
 205                 zlog_debug("snmp[debug]: %s", msg ? msg : slm->msg);
 206                 break;
 207         }
 208         XFREE(MTYPE_TMP, msg);
 209         return SNMP_ERR_NOERROR;
 210 }
 211
 212 static int config_write_agentx(struct vty *vty)
 213 {
 214         if (agentx_enabled)
 215                 vty_out(vty, "agentx\n");
 216         return 1;
 217 }
 218
 219 DEFUN (agentx_enable,
 220        agentx_enable_cmd,
 221        "agentx",
 222        "SNMP AgentX protocol settings\n")
 223 {
 224         if (!agentx_enabled) {
 225                 init_snmp(FRR_SMUX_NAME);
 226                 events = list_new();
 227                 agentx_events_update();
 228                 agentx_enabled = 1;
 229         }
 230
 231         return CMD_SUCCESS;
 232 }
 233
 234 DEFUN (no_agentx,
 235        no_agentx_cmd,
 236        "no agentx",
 237        NO_STR
 238        "SNMP AgentX protocol settings\n")
 239 {
 240         if (!agentx_enabled)
 241                 return CMD_SUCCESS;
 242         vty_out(vty, "SNMP AgentX support cannot be disabled once enabled\n");
 243         return CMD_WARNING_CONFIG_FAILED;
 244 }
 245
 246 void smux_init(struct thread_master *tm)
 247 {
 248         agentx_tm = tm;
 249
 250         netsnmp_enable_subagent();
 251         snmp_disable_log();
 252         snmp_enable_calllog();
 253         snmp_register_callback(SNMP_CALLBACK_LIBRARY, SNMP_CALLBACK_LOGGING,
 254                                agentx_log_callback, NULL);
 255         init_agent(FRR_SMUX_NAME);
 256
 257         install_node(&agentx_node);
 258         install_element(CONFIG_NODE, &agentx_enable_cmd);
 259         install_element(CONFIG_NODE, &no_agentx_cmd);
 260 }
 261
 262 void smux_register_mib(const char *descr, struct variable *var, size_t width,
 263                        int num, oid name[], size_t namelen)
 264 {
 265         register_mib(descr, var, width, num, name, namelen);
 266 }
 267
 268 void smux_trap(struct variable *vp, size_t vp_len, const oid *ename,
 269                size_t enamelen, const oid *name, size_t namelen,
 270                const oid *iname, size_t inamelen,
 271                const struct trap_object *trapobj, size_t trapobjlen,
 272                uint8_t sptrap)
 273 {
 274         struct index_oid trap_index[1];
 275
 276         /* copy the single index into the multi-index format */
 277         oid_copy(trap_index[0].indexname, iname, inamelen);
 278         trap_index[0].indexlen = inamelen;
 279
 280         smux_trap_multi_index(vp, vp_len, ename, enamelen, name, namelen,
 281                               trap_index, array_size(trap_index), trapobj,
 282                               trapobjlen, sptrap);
 283 }
 284
 285 int smux_trap_multi_index(struct variable *vp, size_t vp_len, const oid *ename,
 286                           size_t enamelen, const oid *name, size_t namelen,
 287                           struct index_oid *iname, size_t index_len,
 288                           const struct trap_object *trapobj, size_t trapobjlen,
 289                           uint8_t sptrap)
 290 {
 291         oid objid_snmptrap[] = {1, 3, 6, 1, 6, 3, 1, 1, 4, 1, 0};
 292         size_t objid_snmptrap_len = sizeof(objid_snmptrap) / sizeof(oid);
 293         oid notification_oid[MAX_OID_LEN];
 294         size_t notification_oid_len;
 295         unsigned int i;
 296
 297         netsnmp_variable_list *notification_vars = NULL;
 298         if (!agentx_enabled)
 299                 return 0;
 300
 301         /* snmpTrapOID */
 302         oid_copy(notification_oid, ename, enamelen);
 303         notification_oid[enamelen] = sptrap;
 304         notification_oid_len = enamelen + 1;
 305         snmp_varlist_add_variable(&notification_vars, objid_snmptrap,
 306                                   objid_snmptrap_len, ASN_OBJECT_ID,
 307                                   (uint8_t *)notification_oid,
 308                                   notification_oid_len * sizeof(oid));
 309
 310         /* Provided bindings */
 311         for (i = 0; i < trapobjlen; i++) {
 312                 unsigned int j;
 313                 oid oid[MAX_OID_LEN];
 314                 size_t oid_len, onamelen;
 315                 uint8_t *val;
 316                 size_t val_len;
 317                 WriteMethod *wm = NULL;
 318                 struct variable cvp;
 319                 unsigned int iindex;
 320                 /*
 321                  * this allows the behaviour of smux_trap with a singe index
 322                  * for all objects to be maintained whilst allowing traps which
 323                  * have different indices per object to be supported
 324                  */
 325                 iindex = (index_len == 1) ? 0 : i;
 326
 327                 /* Make OID. */
 328                 if (trapobj[i].namelen > 0) {
 329                         /* Columnar object */
 330                         onamelen = trapobj[i].namelen;
 331                         oid_copy(oid, name, namelen);
 332                         oid_copy(oid + namelen, trapobj[i].name, onamelen);
 333                         oid_copy(oid + namelen + onamelen,
 334                                  iname[iindex].indexname,
 335                                  iname[iindex].indexlen);
 336                         oid_len = namelen + onamelen + iname[iindex].indexlen;
 337                 } else {
 338                         /* Scalar object */
 339                         onamelen = trapobj[i].namelen * (-1);
 340                         oid_copy(oid, name, namelen);
 341                         oid_copy(oid + namelen, trapobj[i].name, onamelen);
 342                         oid[onamelen + namelen] = 0;
 343                         oid_len = namelen + onamelen + 1;
 344                 }
 345
 346                 /* Locate the appropriate function and type in the MIB registry.
 347                  */
 348                 for (j = 0; j < vp_len; j++) {
 349                         if (oid_compare(trapobj[i].name, onamelen, vp[j].name,
 350                                         vp[j].namelen)
 351                             != 0)
 352                                 continue;
 353                         /* We found the appropriate variable in the MIB
 354                          * registry. */
 355                         oid_copy(cvp.name, name, namelen);
 356                         oid_copy(cvp.name + namelen, vp[j].name, vp[j].namelen);
 357                         cvp.namelen = namelen + vp[j].namelen;
 358                         cvp.type = vp[j].type;
 359                         cvp.magic = vp[j].magic;
 360                         cvp.acl = vp[j].acl;
 361                         cvp.findVar = vp[j].findVar;
 362
 363                         /* Grab the result. */
 364                         val = cvp.findVar(&cvp, oid, &oid_len, 1, &val_len,
 365                                           &wm);
 366                         if (!val)
 367                                 break;
 368                         snmp_varlist_add_variable(&notification_vars, oid,
 369                                                   oid_len, vp[j].type, val,
 370                                                   val_len);
 371                         break;
 372                 }
 373         }
 374
 375
 376         send_v2trap(notification_vars);
 377         snmp_free_varbind(notification_vars);
 378         agentx_events_update();
 379         return 1;
 380 }
 381
 382 #endif /* SNMP_AGENTX */