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(EC_LIB_SNMP, "snmp[emerg]: %s", msg ? msg : slm->msg);
 146                 break;
 147         case LOG_ALERT:
 148                 flog_err(EC_LIB_SNMP, "snmp[alert]: %s", msg ? msg : slm->msg);
 149                 break;
 150         case LOG_CRIT:
 151                 flog_err(EC_LIB_SNMP, "snmp[crit]: %s", msg ? msg : slm->msg);
 152                 break;
 153         case LOG_ERR:
 154                 flog_err(EC_LIB_SNMP, "snmp[err]: %s", msg ? msg : slm->msg);
 155                 break;
 156         case LOG_WARNING:
 157                 flog_warn(EC_LIB_SNMP, "snmp[warning]: %s",
 158                           msg ? msg : slm->msg);
 159                 break;
 160         case LOG_NOTICE:
 161                 zlog_notice("snmp[notice]: %s", msg ? msg : slm->msg);
 162                 break;
 163         case LOG_INFO:
 164                 zlog_info("snmp[info]: %s", msg ? msg : slm->msg);
 165                 break;
 166         case LOG_DEBUG:
 167                 zlog_debug("snmp[debug]: %s", msg ? msg : slm->msg);
 168                 break;
 169         }
 170         XFREE(MTYPE_TMP, msg);
 171         return SNMP_ERR_NOERROR;
 172 }
 173
 174 static int config_write_agentx(struct vty *vty)
 175 {
 176         if (agentx_enabled)
 177                 vty_out(vty, "agentx\n");
 178         return 1;
 179 }
 180
 181 DEFUN (agentx_enable,
 182        agentx_enable_cmd,
 183        "agentx",
 184        "SNMP AgentX protocol settings\n")
 185 {
 186         if (!agentx_enabled) {
 187                 init_snmp(FRR_SMUX_NAME);
 188                 events = list_new();
 189                 agentx_events_update();
 190                 agentx_enabled = 1;
 191         }
 192
 193         return CMD_SUCCESS;
 194 }
 195
 196 DEFUN (no_agentx,
 197        no_agentx_cmd,
 198        "no agentx",
 199        NO_STR
 200        "SNMP AgentX protocol settings\n")
 201 {
 202         if (!agentx_enabled)
 203                 return CMD_SUCCESS;
 204         vty_out(vty, "SNMP AgentX support cannot be disabled once enabled\n");
 205         return CMD_WARNING_CONFIG_FAILED;
 206 }
 207
 208 void smux_init(struct thread_master *tm)
 209 {
 210         agentx_tm = tm;
 211
 212         netsnmp_enable_subagent();
 213         snmp_disable_log();
 214         snmp_enable_calllog();
 215         snmp_register_callback(SNMP_CALLBACK_LIBRARY, SNMP_CALLBACK_LOGGING,
 216                                agentx_log_callback, NULL);
 217         init_agent(FRR_SMUX_NAME);
 218
 219         install_node(&agentx_node, config_write_agentx);
 220         install_element(CONFIG_NODE, &agentx_enable_cmd);
 221         install_element(CONFIG_NODE, &no_agentx_cmd);
 222 }
 223
 224 void smux_register_mib(const char *descr, struct variable *var, size_t width,
 225                        int num, oid name[], size_t namelen)
 226 {
 227         register_mib(descr, var, width, num, name, namelen);
 228 }
 229
 230 int smux_trap(struct variable *vp, size_t vp_len, const oid *ename,
 231               size_t enamelen, const oid *name, size_t namelen,
 232               const oid *iname, size_t inamelen,
 233               const struct trap_object *trapobj, size_t trapobjlen,
 234               uint8_t sptrap)
 235 {
 236         oid objid_snmptrap[] = {1, 3, 6, 1, 6, 3, 1, 1, 4, 1, 0};
 237         size_t objid_snmptrap_len = sizeof objid_snmptrap / sizeof(oid);
 238         oid notification_oid[MAX_OID_LEN];
 239         size_t notification_oid_len;
 240         unsigned int i;
 241
 242         netsnmp_variable_list *notification_vars = NULL;
 243         if (!agentx_enabled)
 244                 return 0;
 245
 246         /* snmpTrapOID */
 247         oid_copy(notification_oid, ename, enamelen);
 248         notification_oid[enamelen] = sptrap;
 249         notification_oid_len = enamelen + 1;
 250         snmp_varlist_add_variable(&notification_vars, objid_snmptrap,
 251                                   objid_snmptrap_len, ASN_OBJECT_ID,
 252                                   (uint8_t *)notification_oid,
 253                                   notification_oid_len * sizeof(oid));
 254
 255         /* Provided bindings */
 256         for (i = 0; i < trapobjlen; i++) {
 257                 unsigned int j;
 258                 oid oid[MAX_OID_LEN];
 259                 size_t oid_len, onamelen;
 260                 uint8_t *val;
 261                 size_t val_len;
 262                 WriteMethod *wm = NULL;
 263                 struct variable cvp;
 264
 265                 /* Make OID. */
 266                 if (trapobj[i].namelen > 0) {
 267                         /* Columnar object */
 268                         onamelen = trapobj[i].namelen;
 269                         oid_copy(oid, name, namelen);
 270                         oid_copy(oid + namelen, trapobj[i].name, onamelen);
 271                         oid_copy(oid + namelen + onamelen, iname, inamelen);
 272                         oid_len = namelen + onamelen + inamelen;
 273                 } else {
 274                         /* Scalar object */
 275                         onamelen = trapobj[i].namelen * (-1);
 276                         oid_copy(oid, name, namelen);
 277                         oid_copy(oid + namelen, trapobj[i].name, onamelen);
 278                         oid[onamelen + namelen] = 0;
 279                         oid_len = namelen + onamelen + 1;
 280                 }
 281
 282                 /* Locate the appropriate function and type in the MIB registry.
 283                  */
 284                 for (j = 0; j < vp_len; j++) {
 285                         if (oid_compare(trapobj[i].name, onamelen, vp[j].name,
 286                                         vp[j].namelen)
 287                             != 0)
 288                                 continue;
 289                         /* We found the appropriate variable in the MIB
 290                          * registry. */
 291                         oid_copy(cvp.name, name, namelen);
 292                         oid_copy(cvp.name + namelen, vp[j].name, vp[j].namelen);
 293                         cvp.namelen = namelen + vp[j].namelen;
 294                         cvp.type = vp[j].type;
 295                         cvp.magic = vp[j].magic;
 296                         cvp.acl = vp[j].acl;
 297                         cvp.findVar = vp[j].findVar;
 298                         /* Grab the result. */
 299                         val = cvp.findVar(&cvp, oid, &oid_len, 1, &val_len,
 300                                           &wm);
 301                         if (!val)
 302                                 break;
 303                         snmp_varlist_add_variable(&notification_vars, oid,
 304                                                   oid_len, vp[j].type, val,
 305                                                   val_len);
 306                         break;
 307                 }
 308         }
 309
 310
 311         send_v2trap(notification_vars);
 312         snmp_free_varbind(notification_vars);
 313         agentx_events_update();
 314         return 1;
 315 }
 316
 317 #endif /* SNMP_AGENTX */