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
  36 static int agentx_enabled = 0;
  37
  38 static struct thread_master *agentx_tm;
  39 static struct thread *timeout_thr = NULL;
  40 static struct list *events = NULL;
  41
  42 static void agentx_events_update(void);
  43
  44 static int agentx_timeout(struct thread *t)
  45 {
  46         timeout_thr = NULL;
  47
  48         snmp_timeout();
  49         run_alarms();
  50         netsnmp_check_outstanding_agent_requests();
  51         agentx_events_update();
  52         return 0;
  53 }
  54
  55 static int agentx_read(struct thread *t)
  56 {
  57         fd_set fds;
  58         struct listnode *ln = THREAD_ARG(t);
  59         list_delete_node(events, ln);
  60
  61         FD_ZERO(&fds);
  62         FD_SET(THREAD_FD(t), &fds);
  63         snmp_read(&fds);
  64
  65         netsnmp_check_outstanding_agent_requests();
  66         agentx_events_update();
  67         return 0;
  68 }
  69
  70 static void agentx_events_update(void)
  71 {
  72         int maxfd = 0;
  73         int block = 1;
  74         struct timeval timeout = {.tv_sec = 0, .tv_usec = 0};
  75         fd_set fds;
  76         struct listnode *ln;
  77         struct thread *thr;
  78         int fd, thr_fd;
  79
  80         THREAD_OFF(timeout_thr);
  81
  82         FD_ZERO(&fds);
  83         snmp_select_info(&maxfd, &fds, &timeout, &block);
  84
  85         if (!block) {
  86                 timeout_thr = NULL;
  87                 thread_add_timer_tv(agentx_tm, agentx_timeout, NULL, &timeout,
  88                                     &timeout_thr);
  89         }
  90
  91         ln = listhead(events);
  92         thr = ln ? listgetdata(ln) : NULL;
  93         thr_fd = thr ? THREAD_FD(thr) : -1;
  94
  95         /* "two-pointer" / two-list simultaneous iteration
  96          * ln/thr/thr_fd point to the next existing event listener to hit while
  97          * fd counts to catch up */
  98         for (fd = 0; fd < maxfd; fd++) {
  99                 /* caught up */
 100                 if (thr_fd == fd) {
 101                         struct listnode *nextln = listnextnode(ln);
 102                         if (!FD_ISSET(fd, &fds)) {
 103                                 thread_cancel(thr);
 104                                 list_delete_node(events, ln);
 105                         }
 106                         ln = nextln;
 107                         thr = ln ? listgetdata(ln) : NULL;
 108                         thr_fd = thr ? THREAD_FD(thr) : -1;
 109                 }
 110                 /* need listener, but haven't hit one where it would be */
 111                 else if (FD_ISSET(fd, &fds)) {
 112                         struct listnode *newln;
 113                         thr = NULL;
 114                         thread_add_read(agentx_tm, agentx_read, NULL, fd, &thr);
 115                         newln = listnode_add_before(events, ln, thr);
 116                         thr->arg = newln;
 117                 }
 118         }
 119
 120         /* leftover event listeners at this point have fd > maxfd, delete them
 121          */
 122         while (ln) {
 123                 struct listnode *nextln = listnextnode(ln);
 124                 thread_cancel(listgetdata(ln));
 125                 list_delete_node(events, ln);
 126                 ln = nextln;
 127         }
 128 }
 129
 130 /* AgentX node. */
 131 static struct cmd_node agentx_node = {SMUX_NODE,
 132                                       "", /* AgentX has no interface. */
 133                                       1};
 134
 135 /* Logging NetSNMP messages */
 136 static int agentx_log_callback(int major, int minor, void *serverarg,
 137                                void *clientarg)
 138 {
 139         struct snmp_log_message *slm = (struct snmp_log_message *)serverarg;
 140         char *msg = XSTRDUP(MTYPE_TMP, slm->msg);
 141         if (msg)
 142                 msg[strlen(msg) - 1] = '\0';
 143         switch (slm->priority) {
 144         case LOG_EMERG:
 145                 flog_err(LIB_ERR_SNMP,
 146                           "snmp[emerg]: %s", msg ? msg : slm->msg);
 147                 break;
 148         case LOG_ALERT:
 149                 flog_err(LIB_ERR_SNMP,
 150                           "snmp[alert]: %s", msg ? msg : slm->msg);
 151                 break;
 152         case LOG_CRIT:
 153                 flog_err(LIB_ERR_SNMP,
 154                           "snmp[crit]: %s", msg ? msg : slm->msg);
 155                 break;
 156         case LOG_ERR:
 157                 flog_err(LIB_ERR_SNMP,
 158                           "snmp[err]: %s", msg ? msg : slm->msg);
 159                 break;
 160         case LOG_WARNING:
 161                 flog_warn(LIB_WARN_SNMP, "snmp[warning]: %s",
 162                           msg ? msg : slm->msg);
 163                 break;
 164         case LOG_NOTICE:
 165                 zlog_notice("snmp[notice]: %s", msg ? msg : slm->msg);
 166                 break;
 167         case LOG_INFO:
 168                 zlog_info("snmp[info]: %s", msg ? msg : slm->msg);
 169                 break;
 170         case LOG_DEBUG:
 171                 zlog_debug("snmp[debug]: %s", msg ? msg : slm->msg);
 172                 break;
 173         }
 174         XFREE(MTYPE_TMP, msg);
 175         return SNMP_ERR_NOERROR;
 176 }
 177
 178 static int config_write_agentx(struct vty *vty)
 179 {
 180         if (agentx_enabled)
 181                 vty_out(vty, "agentx\n");
 182         return 1;
 183 }
 184
 185 DEFUN (agentx_enable,
 186        agentx_enable_cmd,
 187        "agentx",
 188        "SNMP AgentX protocol settings\n")
 189 {
 190         if (!agentx_enabled) {
 191                 init_snmp(FRR_SMUX_NAME);
 192                 events = list_new();
 193                 agentx_events_update();
 194                 agentx_enabled = 1;
 195                 return CMD_SUCCESS;
 196         }
 197         vty_out(vty, "SNMP AgentX already enabled\n");
 198         return CMD_SUCCESS;
 199 }
 200
 201 DEFUN (no_agentx,
 202        no_agentx_cmd,
 203        "no agentx",
 204        NO_STR
 205        "SNMP AgentX protocol settings\n")
 206 {
 207         if (!agentx_enabled)
 208                 return CMD_SUCCESS;
 209         vty_out(vty, "SNMP AgentX support cannot be disabled once enabled\n");
 210         return CMD_WARNING_CONFIG_FAILED;
 211 }
 212
 213 void smux_init(struct thread_master *tm)
 214 {
 215         agentx_tm = tm;
 216
 217         netsnmp_enable_subagent();
 218         snmp_disable_log();
 219         snmp_enable_calllog();
 220         snmp_register_callback(SNMP_CALLBACK_LIBRARY, SNMP_CALLBACK_LOGGING,
 221                                agentx_log_callback, NULL);
 222         init_agent(FRR_SMUX_NAME);
 223
 224         install_node(&agentx_node, config_write_agentx);
 225         install_element(CONFIG_NODE, &agentx_enable_cmd);
 226         install_element(CONFIG_NODE, &no_agentx_cmd);
 227 }
 228
 229 void smux_register_mib(const char *descr, struct variable *var, size_t width,
 230                        int num, oid name[], size_t namelen)
 231 {
 232         register_mib(descr, var, width, num, name, namelen);
 233 }
 234
 235 int smux_trap(struct variable *vp, size_t vp_len, const oid *ename,
 236               size_t enamelen, const oid *name, size_t namelen,
 237               const oid *iname, size_t inamelen,
 238               const struct trap_object *trapobj, size_t trapobjlen,
 239               uint8_t sptrap)
 240 {
 241         oid objid_snmptrap[] = {1, 3, 6, 1, 6, 3, 1, 1, 4, 1, 0};
 242         size_t objid_snmptrap_len = sizeof objid_snmptrap / sizeof(oid);
 243         oid notification_oid[MAX_OID_LEN];
 244         size_t notification_oid_len;
 245         unsigned int i;
 246
 247         netsnmp_variable_list *notification_vars = NULL;
 248         if (!agentx_enabled)
 249                 return 0;
 250
 251         /* snmpTrapOID */
 252         oid_copy(notification_oid, ename, enamelen);
 253         notification_oid[enamelen] = sptrap;
 254         notification_oid_len = enamelen + 1;
 255         snmp_varlist_add_variable(&notification_vars, objid_snmptrap,
 256                                   objid_snmptrap_len, ASN_OBJECT_ID,
 257                                   (uint8_t *)notification_oid,
 258                                   notification_oid_len * sizeof(oid));
 259
 260         /* Provided bindings */
 261         for (i = 0; i < trapobjlen; i++) {
 262                 unsigned int j;
 263                 oid oid[MAX_OID_LEN];
 264                 size_t oid_len, onamelen;
 265                 uint8_t *val;
 266                 size_t val_len;
 267                 WriteMethod *wm = NULL;
 268                 struct variable cvp;
 269
 270                 /* Make OID. */
 271                 if (trapobj[i].namelen > 0) {
 272                         /* Columnar object */
 273                         onamelen = trapobj[i].namelen;
 274                         oid_copy(oid, name, namelen);
 275                         oid_copy(oid + namelen, trapobj[i].name, onamelen);
 276                         oid_copy(oid + namelen + onamelen, iname, inamelen);
 277                         oid_len = namelen + onamelen + inamelen;
 278                 } else {
 279                         /* Scalar object */
 280                         onamelen = trapobj[i].namelen * (-1);
 281                         oid_copy(oid, name, namelen);
 282                         oid_copy(oid + namelen, trapobj[i].name, onamelen);
 283                         oid[onamelen + namelen] = 0;
 284                         oid_len = namelen + onamelen + 1;
 285                 }
 286
 287                 /* Locate the appropriate function and type in the MIB registry.
 288                  */
 289                 for (j = 0; j < vp_len; j++) {
 290                         if (oid_compare(trapobj[i].name, onamelen, vp[j].name,
 291                                         vp[j].namelen)
 292                             != 0)
 293                                 continue;
 294                         /* We found the appropriate variable in the MIB
 295                          * registry. */
 296                         oid_copy(cvp.name, name, namelen);
 297                         oid_copy(cvp.name + namelen, vp[j].name, vp[j].namelen);
 298                         cvp.namelen = namelen + vp[j].namelen;
 299                         cvp.type = vp[j].type;
 300                         cvp.magic = vp[j].magic;
 301                         cvp.acl = vp[j].acl;
 302                         cvp.findVar = vp[j].findVar;
 303                         /* Grab the result. */
 304                         val = cvp.findVar(&cvp, oid, &oid_len, 1, &val_len,
 305                                           &wm);
 306                         if (!val)
 307                                 break;
 308                         snmp_varlist_add_variable(&notification_vars, oid,
 309                                                   oid_len, vp[j].type, val,
 310                                                   val_len);
 311                         break;
 312                 }
 313         }
 314
 315
 316         send_v2trap(notification_vars);
 317         snmp_free_varbind(notification_vars);
 318         agentx_events_update();
 319         return 1;
 320 }
 321
 322 #endif /* SNMP_AGENTX */