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         timeout_thr = NULL;
  52
  53         snmp_timeout();
  54         run_alarms();
  55         netsnmp_check_outstanding_agent_requests();
  56         agentx_events_update();
  57 }
  58
  59 static void agentx_read(struct thread *t)
  60 {
  61         fd_set fds;
  62         int flags, new_flags = 0;
  63         int nonblock = false;
  64         struct listnode *ln = THREAD_ARG(t);
  65         struct thread **thr = listgetdata(ln);
  66         XFREE(MTYPE_TMP, thr);
  67         list_delete_node(events, ln);
  68
  69         /* fix for non blocking socket */
  70         flags = fcntl(THREAD_FD(t), F_GETFL, 0);
  71         if (-1 == flags) {
  72                 flog_err(EC_LIB_SYSTEM_CALL, "Failed to get FD settings fcntl: %s(%d)",
  73                          strerror(errno), errno);
  74                 return;
  75         }
  76
  77         if (flags & O_NONBLOCK)
  78                 nonblock = true;
  79         else
  80                 new_flags = fcntl(THREAD_FD(t), F_SETFL, flags | O_NONBLOCK);
  81
  82         if (new_flags == -1)
  83                 flog_err(EC_LIB_SYSTEM_CALL, "Failed to set snmp fd non blocking: %s(%d)",
  84                          strerror(errno), errno);
  85
  86         FD_ZERO(&fds);
  87         FD_SET(THREAD_FD(t), &fds);
  88         snmp_read(&fds);
  89
  90         /* Reset the flag */
  91         if (!nonblock) {
  92                 new_flags = fcntl(THREAD_FD(t), F_SETFL, flags);
  93
  94                 if (new_flags == -1)
  95                         flog_err(
  96                                 EC_LIB_SYSTEM_CALL,
  97                                 "Failed to set snmp fd back to original settings: %s(%d)",
  98                                 strerror(errno), errno);
  99         }
 100
 101         netsnmp_check_outstanding_agent_requests();
 102         agentx_events_update();
 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                                 XFREE(MTYPE_TMP, thr);
 140                                 list_delete_node(events, ln);
 141                         }
 142                         ln = nextln;
 143                         thr = ln ? listgetdata(ln) : NULL;
 144                         thr_fd = thr ? THREAD_FD(*thr) : -1;
 145                 }
 146                 /* need listener, but haven't hit one where it would be */
 147                 else if (FD_ISSET(fd, &fds)) {
 148                         struct listnode *newln;
 149                         thr = XCALLOC(MTYPE_TMP, sizeof(struct thread *));
 150                         thread_add_read(agentx_tm, agentx_read, NULL, fd, thr);
 151                         newln = listnode_add_before(events, ln, thr);
 152                         (*thr)->arg = newln;
 153                 }
 154         }
 155
 156         /* leftover event listeners at this point have fd > maxfd, delete them
 157          */
 158         while (ln) {
 159                 struct listnode *nextln = listnextnode(ln);
 160                 thr = listgetdata(ln);
 161                 thread_cancel(thr);
 162                 XFREE(MTYPE_TMP, thr);
 163                 list_delete_node(events, ln);
 164                 ln = nextln;
 165         }
 166 }
 167
 168 /* AgentX node. */
 169 static int config_write_agentx(struct vty *vty);
 170 static struct cmd_node agentx_node = {
 171         .name = "smux",
 172         .node = SMUX_NODE,
 173         .prompt = "",
 174         .config_write = config_write_agentx,
 175 };
 176
 177 /* Logging NetSNMP messages */
 178 static int agentx_log_callback(int major, int minor, void *serverarg,
 179                                void *clientarg)
 180 {
 181         struct snmp_log_message *slm = (struct snmp_log_message *)serverarg;
 182         char *msg = XSTRDUP(MTYPE_TMP, slm->msg);
 183         if (msg)
 184                 msg[strlen(msg) - 1] = '\0';
 185         switch (slm->priority) {
 186         case LOG_EMERG:
 187                 flog_err(EC_LIB_SNMP, "snmp[emerg]: %s", msg ? msg : slm->msg);
 188                 break;
 189         case LOG_ALERT:
 190                 flog_err(EC_LIB_SNMP, "snmp[alert]: %s", msg ? msg : slm->msg);
 191                 break;
 192         case LOG_CRIT:
 193                 flog_err(EC_LIB_SNMP, "snmp[crit]: %s", msg ? msg : slm->msg);
 194                 break;
 195         case LOG_ERR:
 196                 flog_err(EC_LIB_SNMP, "snmp[err]: %s", msg ? msg : slm->msg);
 197                 break;
 198         case LOG_WARNING:
 199                 flog_warn(EC_LIB_SNMP, "snmp[warning]: %s",
 200                           msg ? msg : slm->msg);
 201                 break;
 202         case LOG_NOTICE:
 203                 zlog_notice("snmp[notice]: %s", msg ? msg : slm->msg);
 204                 break;
 205         case LOG_INFO:
 206                 zlog_info("snmp[info]: %s", msg ? msg : slm->msg);
 207                 break;
 208         case LOG_DEBUG:
 209                 zlog_debug("snmp[debug]: %s", msg ? msg : slm->msg);
 210                 break;
 211         }
 212         XFREE(MTYPE_TMP, msg);
 213         return SNMP_ERR_NOERROR;
 214 }
 215
 216 static int config_write_agentx(struct vty *vty)
 217 {
 218         if (agentx_enabled)
 219                 vty_out(vty, "agentx\n");
 220         return 1;
 221 }
 222
 223 DEFUN (agentx_enable,
 224        agentx_enable_cmd,
 225        "agentx",
 226        "SNMP AgentX protocol settings\n")
 227 {
 228         if (!agentx_enabled) {
 229                 init_snmp(FRR_SMUX_NAME);
 230                 events = list_new();
 231                 agentx_events_update();
 232                 agentx_enabled = 1;
 233                 hook_call(agentx_enabled);
 234         }
 235
 236         return CMD_SUCCESS;
 237 }
 238
 239 DEFUN (no_agentx,
 240        no_agentx_cmd,
 241        "no agentx",
 242        NO_STR
 243        "SNMP AgentX protocol settings\n")
 244 {
 245         if (!agentx_enabled)
 246                 return CMD_SUCCESS;
 247         vty_out(vty, "SNMP AgentX support cannot be disabled once enabled\n");
 248         return CMD_WARNING_CONFIG_FAILED;
 249 }
 250
 251 int smux_enabled(void)
 252 {
 253         return agentx_enabled;
 254 }
 255
 256 void smux_init(struct thread_master *tm)
 257 {
 258         agentx_tm = tm;
 259
 260         netsnmp_enable_subagent();
 261         snmp_disable_log();
 262         snmp_enable_calllog();
 263         snmp_register_callback(SNMP_CALLBACK_LIBRARY, SNMP_CALLBACK_LOGGING,
 264                                agentx_log_callback, NULL);
 265         init_agent(FRR_SMUX_NAME);
 266
 267         install_node(&agentx_node);
 268         install_element(CONFIG_NODE, &agentx_enable_cmd);
 269         install_element(CONFIG_NODE, &no_agentx_cmd);
 270 }
 271
 272 void smux_agentx_enable(void)
 273 {
 274         if (!agentx_enabled) {
 275                 init_snmp(FRR_SMUX_NAME);
 276                 events = list_new();
 277                 agentx_events_update();
 278                 agentx_enabled = 1;
 279         }
 280 }
 281
 282 void smux_register_mib(const char *descr, struct variable *var, size_t width,
 283                        int num, oid name[], size_t namelen)
 284 {
 285         register_mib(descr, var, width, num, name, namelen);
 286 }
 287
 288 void smux_trap(struct variable *vp, size_t vp_len, const oid *ename,
 289                size_t enamelen, const oid *name, size_t namelen,
 290                const oid *iname, size_t inamelen,
 291                const struct trap_object *trapobj, size_t trapobjlen,
 292                uint8_t sptrap)
 293 {
 294         struct index_oid trap_index[1];
 295
 296         /* copy the single index into the multi-index format */
 297         oid_copy(trap_index[0].indexname, iname, inamelen);
 298         trap_index[0].indexlen = inamelen;
 299
 300         smux_trap_multi_index(vp, vp_len, ename, enamelen, name, namelen,
 301                               trap_index, array_size(trap_index), trapobj,
 302                               trapobjlen, sptrap);
 303 }
 304
 305 int smux_trap_multi_index(struct variable *vp, size_t vp_len, const oid *ename,
 306                           size_t enamelen, const oid *name, size_t namelen,
 307                           struct index_oid *iname, size_t index_len,
 308                           const struct trap_object *trapobj, size_t trapobjlen,
 309                           uint8_t sptrap)
 310 {
 311         oid objid_snmptrap[] = {1, 3, 6, 1, 6, 3, 1, 1, 4, 1, 0};
 312         size_t objid_snmptrap_len = sizeof(objid_snmptrap) / sizeof(oid);
 313         oid notification_oid[MAX_OID_LEN];
 314         size_t notification_oid_len;
 315         unsigned int i;
 316
 317         netsnmp_variable_list *notification_vars = NULL;
 318         if (!agentx_enabled)
 319                 return 0;
 320
 321         /* snmpTrapOID */
 322         oid_copy(notification_oid, ename, enamelen);
 323         notification_oid[enamelen] = sptrap;
 324         notification_oid_len = enamelen + 1;
 325         snmp_varlist_add_variable(&notification_vars, objid_snmptrap,
 326                                   objid_snmptrap_len, ASN_OBJECT_ID,
 327                                   (uint8_t *)notification_oid,
 328                                   notification_oid_len * sizeof(oid));
 329
 330         /* Provided bindings */
 331         for (i = 0; i < trapobjlen; i++) {
 332                 unsigned int j;
 333                 oid oid[MAX_OID_LEN];
 334                 size_t oid_len, onamelen;
 335                 uint8_t *val;
 336                 size_t val_len;
 337                 WriteMethod *wm = NULL;
 338                 struct variable cvp;
 339                 unsigned int iindex;
 340                 /*
 341                  * this allows the behaviour of smux_trap with a singe index
 342                  * for all objects to be maintained whilst allowing traps which
 343                  * have different indices per object to be supported
 344                  */
 345                 iindex = (index_len == 1) ? 0 : i;
 346
 347                 /* Make OID. */
 348                 if (trapobj[i].namelen > 0) {
 349                         /* Columnar object */
 350                         onamelen = trapobj[i].namelen;
 351                         oid_copy(oid, name, namelen);
 352                         oid_copy(oid + namelen, trapobj[i].name, onamelen);
 353                         oid_copy(oid + namelen + onamelen,
 354                                  iname[iindex].indexname,
 355                                  iname[iindex].indexlen);
 356                         oid_len = namelen + onamelen + iname[iindex].indexlen;
 357                 } else {
 358                         /* Scalar object */
 359                         onamelen = trapobj[i].namelen * (-1);
 360                         oid_copy(oid, name, namelen);
 361                         oid_copy(oid + namelen, trapobj[i].name, onamelen);
 362                         oid[onamelen + namelen] = 0;
 363                         oid_len = namelen + onamelen + 1;
 364                 }
 365
 366                 /* Locate the appropriate function and type in the MIB registry.
 367                  */
 368                 for (j = 0; j < vp_len; j++) {
 369                         if (oid_compare(trapobj[i].name, onamelen, vp[j].name,
 370                                         vp[j].namelen)
 371                             != 0)
 372                                 continue;
 373                         /* We found the appropriate variable in the MIB
 374                          * registry. */
 375                         oid_copy(cvp.name, name, namelen);
 376                         oid_copy(cvp.name + namelen, vp[j].name, vp[j].namelen);
 377                         cvp.namelen = namelen + vp[j].namelen;
 378                         cvp.type = vp[j].type;
 379                         cvp.magic = vp[j].magic;
 380                         cvp.acl = vp[j].acl;
 381                         cvp.findVar = vp[j].findVar;
 382
 383                         /* Grab the result. */
 384                         val = cvp.findVar(&cvp, oid, &oid_len, 1, &val_len,
 385                                           &wm);
 386                         if (!val)
 387                                 break;
 388                         snmp_varlist_add_variable(&notification_vars, oid,
 389                                                   oid_len, vp[j].type, val,
 390                                                   val_len);
 391                         break;
 392                 }
 393         }
 394
 395
 396         send_v2trap(notification_vars);
 397         snmp_free_varbind(notification_vars);
 398         agentx_events_update();
 399         return 1;
 400 }
 401
 402 void smux_events_update(void)
 403 {
 404         agentx_events_update();
 405 }
 406
 407 #endif /* SNMP_AGENTX */