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