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         int flags;
  59         int nonblock = false;
  60         struct listnode *ln = THREAD_ARG(t);
  61         list_delete_node(events, ln);
  62
  63         /* fix for non blocking socket */
  64         flags = fcntl(THREAD_FD(t), F_GETFL, 0);
  65         if (-1 == flags)
  66                 return -1;
  67
  68         if (flags & O_NONBLOCK)
  69                 nonblock = true;
  70         else
  71                 fcntl(THREAD_FD(t), F_SETFL, flags | O_NONBLOCK);
  72
  73         FD_ZERO(&fds);
  74         FD_SET(THREAD_FD(t), &fds);
  75         snmp_read(&fds);
  76
  77         /* Reset the flag */
  78         if (!nonblock)
  79                 fcntl(THREAD_FD(t), F_SETFL, flags);
  80
  81         netsnmp_check_outstanding_agent_requests();
  82         agentx_events_update();
  83         return 0;
  84 }
  85
  86 static void agentx_events_update(void)
  87 {
  88         int maxfd = 0;
  89         int block = 1;
  90         struct timeval timeout = {.tv_sec = 0, .tv_usec = 0};
  91         fd_set fds;
  92         struct listnode *ln;
  93         struct thread *thr;
  94         int fd, thr_fd;
  95
  96         THREAD_OFF(timeout_thr);
  97
  98         FD_ZERO(&fds);
  99         snmp_select_info(&maxfd, &fds, &timeout, &block);
 100
 101         if (!block) {
 102                 timeout_thr = NULL;
 103                 thread_add_timer_tv(agentx_tm, agentx_timeout, NULL, &timeout,
 104                                     &timeout_thr);
 105         }
 106
 107         ln = listhead(events);
 108         thr = ln ? listgetdata(ln) : NULL;
 109         thr_fd = thr ? THREAD_FD(thr) : -1;
 110
 111         /* "two-pointer" / two-list simultaneous iteration
 112          * ln/thr/thr_fd point to the next existing event listener to hit while
 113          * fd counts to catch up */
 114         for (fd = 0; fd < maxfd; fd++) {
 115                 /* caught up */
 116                 if (thr_fd == fd) {
 117                         struct listnode *nextln = listnextnode(ln);
 118                         if (!FD_ISSET(fd, &fds)) {
 119                                 thread_cancel(thr);
 120                                 list_delete_node(events, ln);
 121                         }
 122                         ln = nextln;
 123                         thr = ln ? listgetdata(ln) : NULL;
 124                         thr_fd = thr ? THREAD_FD(thr) : -1;
 125                 }
 126                 /* need listener, but haven't hit one where it would be */
 127                 else if (FD_ISSET(fd, &fds)) {
 128                         struct listnode *newln;
 129                         thr = NULL;
 130                         thread_add_read(agentx_tm, agentx_read, NULL, fd, &thr);
 131                         newln = listnode_add_before(events, ln, thr);
 132                         thr->arg = newln;
 133                 }
 134         }
 135
 136         /* leftover event listeners at this point have fd > maxfd, delete them
 137          */
 138         while (ln) {
 139                 struct listnode *nextln = listnextnode(ln);
 140                 thread_cancel(listgetdata(ln));
 141                 list_delete_node(events, ln);
 142                 ln = nextln;
 143         }
 144 }
 145
 146 /* AgentX node. */
 147 static struct cmd_node agentx_node = {SMUX_NODE,
 148                                       "", /* AgentX has no interface. */
 149                                       1};
 150
 151 /* Logging NetSNMP messages */
 152 static int agentx_log_callback(int major, int minor, void *serverarg,
 153                                void *clientarg)
 154 {
 155         struct snmp_log_message *slm = (struct snmp_log_message *)serverarg;
 156         char *msg = XSTRDUP(MTYPE_TMP, slm->msg);
 157         if (msg)
 158                 msg[strlen(msg) - 1] = '\0';
 159         switch (slm->priority) {
 160         case LOG_EMERG:
 161                 flog_err(EC_LIB_SNMP, "snmp[emerg]: %s", msg ? msg : slm->msg);
 162                 break;
 163         case LOG_ALERT:
 164                 flog_err(EC_LIB_SNMP, "snmp[alert]: %s", msg ? msg : slm->msg);
 165                 break;
 166         case LOG_CRIT:
 167                 flog_err(EC_LIB_SNMP, "snmp[crit]: %s", msg ? msg : slm->msg);
 168                 break;
 169         case LOG_ERR:
 170                 flog_err(EC_LIB_SNMP, "snmp[err]: %s", msg ? msg : slm->msg);
 171                 break;
 172         case LOG_WARNING:
 173                 flog_warn(EC_LIB_SNMP, "snmp[warning]: %s",
 174                           msg ? msg : slm->msg);
 175                 break;
 176         case LOG_NOTICE:
 177                 zlog_notice("snmp[notice]: %s", msg ? msg : slm->msg);
 178                 break;
 179         case LOG_INFO:
 180                 zlog_info("snmp[info]: %s", msg ? msg : slm->msg);
 181                 break;
 182         case LOG_DEBUG:
 183                 zlog_debug("snmp[debug]: %s", msg ? msg : slm->msg);
 184                 break;
 185         }
 186         XFREE(MTYPE_TMP, msg);
 187         return SNMP_ERR_NOERROR;
 188 }
 189
 190 static int config_write_agentx(struct vty *vty)
 191 {
 192         if (agentx_enabled)
 193                 vty_out(vty, "agentx\n");
 194         return 1;
 195 }
 196
 197 DEFUN (agentx_enable,
 198        agentx_enable_cmd,
 199        "agentx",
 200        "SNMP AgentX protocol settings\n")
 201 {
 202         if (!agentx_enabled) {
 203                 init_snmp(FRR_SMUX_NAME);
 204                 events = list_new();
 205                 agentx_events_update();
 206                 agentx_enabled = 1;
 207         }
 208
 209         return CMD_SUCCESS;
 210 }
 211
 212 DEFUN (no_agentx,
 213        no_agentx_cmd,
 214        "no agentx",
 215        NO_STR
 216        "SNMP AgentX protocol settings\n")
 217 {
 218         if (!agentx_enabled)
 219                 return CMD_SUCCESS;
 220         vty_out(vty, "SNMP AgentX support cannot be disabled once enabled\n");
 221         return CMD_WARNING_CONFIG_FAILED;
 222 }
 223
 224 void smux_init(struct thread_master *tm)
 225 {
 226         agentx_tm = tm;
 227
 228         netsnmp_enable_subagent();
 229         snmp_disable_log();
 230         snmp_enable_calllog();
 231         snmp_register_callback(SNMP_CALLBACK_LIBRARY, SNMP_CALLBACK_LOGGING,
 232                                agentx_log_callback, NULL);
 233         init_agent(FRR_SMUX_NAME);
 234
 235         install_node(&agentx_node, config_write_agentx);
 236         install_element(CONFIG_NODE, &agentx_enable_cmd);
 237         install_element(CONFIG_NODE, &no_agentx_cmd);
 238 }
 239
 240 void smux_register_mib(const char *descr, struct variable *var, size_t width,
 241                        int num, oid name[], size_t namelen)
 242 {
 243         register_mib(descr, var, width, num, name, namelen);
 244 }
 245
 246 int smux_trap(struct variable *vp, size_t vp_len, const oid *ename,
 247               size_t enamelen, const oid *name, size_t namelen,
 248               const oid *iname, size_t inamelen,
 249               const struct trap_object *trapobj, size_t trapobjlen,
 250               uint8_t sptrap)
 251 {
 252         oid objid_snmptrap[] = {1, 3, 6, 1, 6, 3, 1, 1, 4, 1, 0};
 253         size_t objid_snmptrap_len = sizeof objid_snmptrap / sizeof(oid);
 254         oid notification_oid[MAX_OID_LEN];
 255         size_t notification_oid_len;
 256         unsigned int i;
 257
 258         netsnmp_variable_list *notification_vars = NULL;
 259         if (!agentx_enabled)
 260                 return 0;
 261
 262         /* snmpTrapOID */
 263         oid_copy(notification_oid, ename, enamelen);
 264         notification_oid[enamelen] = sptrap;
 265         notification_oid_len = enamelen + 1;
 266         snmp_varlist_add_variable(&notification_vars, objid_snmptrap,
 267                                   objid_snmptrap_len, ASN_OBJECT_ID,
 268                                   (uint8_t *)notification_oid,
 269                                   notification_oid_len * sizeof(oid));
 270
 271         /* Provided bindings */
 272         for (i = 0; i < trapobjlen; i++) {
 273                 unsigned int j;
 274                 oid oid[MAX_OID_LEN];
 275                 size_t oid_len, onamelen;
 276                 uint8_t *val;
 277                 size_t val_len;
 278                 WriteMethod *wm = NULL;
 279                 struct variable cvp;
 280
 281                 /* Make OID. */
 282                 if (trapobj[i].namelen > 0) {
 283                         /* Columnar object */
 284                         onamelen = trapobj[i].namelen;
 285                         oid_copy(oid, name, namelen);
 286                         oid_copy(oid + namelen, trapobj[i].name, onamelen);
 287                         oid_copy(oid + namelen + onamelen, iname, inamelen);
 288                         oid_len = namelen + onamelen + inamelen;
 289                 } else {
 290                         /* Scalar object */
 291                         onamelen = trapobj[i].namelen * (-1);
 292                         oid_copy(oid, name, namelen);
 293                         oid_copy(oid + namelen, trapobj[i].name, onamelen);
 294                         oid[onamelen + namelen] = 0;
 295                         oid_len = namelen + onamelen + 1;
 296                 }
 297
 298                 /* Locate the appropriate function and type in the MIB registry.
 299                  */
 300                 for (j = 0; j < vp_len; j++) {
 301                         if (oid_compare(trapobj[i].name, onamelen, vp[j].name,
 302                                         vp[j].namelen)
 303                             != 0)
 304                                 continue;
 305                         /* We found the appropriate variable in the MIB
 306                          * registry. */
 307                         oid_copy(cvp.name, name, namelen);
 308                         oid_copy(cvp.name + namelen, vp[j].name, vp[j].namelen);
 309                         cvp.namelen = namelen + vp[j].namelen;
 310                         cvp.type = vp[j].type;
 311                         cvp.magic = vp[j].magic;
 312                         cvp.acl = vp[j].acl;
 313                         cvp.findVar = vp[j].findVar;
 314                         /* Grab the result. */
 315                         val = cvp.findVar(&cvp, oid, &oid_len, 1, &val_len,
 316                                           &wm);
 317                         if (!val)
 318                                 break;
 319                         snmp_varlist_add_variable(&notification_vars, oid,
 320                                                   oid_len, vp[j].type, val,
 321                                                   val_len);
 322                         break;
 323                 }
 324         }
 325
 326
 327         send_v2trap(notification_vars);
 328         snmp_free_varbind(notification_vars);
 329         agentx_events_update();
 330         return 1;
 331 }
 332
 333 #endif /* SNMP_AGENTX */