snmp_traps.c

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/*
 * Copyright (c) 2001-2004 Swedish Institute of Computer Science.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without modification,
 * are permitted provided that the following conditions are met:
 *
 * 1. Redistributions of source code must retain the above copyright notice,
 *    this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright notice,
 *    this list of conditions and the following disclaimer in the documentation
 *    and/or other materials provided with the distribution.
 * 3. The name of the author may not be used to endorse or promote products
 *    derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
 * SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
 * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
 * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
 * OF SUCH DAMAGE.
 *
 * This file is part of the lwIP TCP/IP stack.
 *
 * Author: Martin Hentschel
 *         Christiaan Simons <christiaan.simons@axon.tv>
 *
 */

#include "lwip/apps/snmp_opts.h"

#if LWIP_SNMP /* don't build if not configured for use in lwipopts.h */

#include "lwip/snmp.h"
#include "lwip/sys.h"
#include "lwip/apps/snmp.h"
#include "lwip/apps/snmp_core.h"
#include "snmp_msg.h"
#include "snmp_asn1.h"

#include <string.h>

struct snmp_msg_trap
{
  /* source enterprise ID (sysObjectID) */
  const struct snmp_obj_id *enterprise;
  /* source IP address, raw network order format */
  ip_addr_t sip;
  /* generic trap code */
  u32_t gen_trap;
  /* specific trap code */
  u32_t spc_trap;
  /* timestamp */
  u32_t ts;
  /* snmp_version */
  u32_t snmp_version;

  /* output trap lengths used in ASN encoding */
  /* encoding pdu length */
  u16_t pdulen;
  /* encoding community length */
  u16_t comlen;
  /* encoding sequence length */
  u16_t seqlen;
};

static u16_t snmp_trap_header_sum(struct snmp_msg_trap *trap);
static void snmp_trap_header_enc(struct snmp_msg_trap *trap, struct snmp_pbuf_stream *pbuf_stream);

extern const char *snmp_community_trap;

void* snmp_traps_handle;

struct snmp_trap_dst
{
  /* destination IP address in network order */
  ip_addr_t dip;
  /* set to 0 when disabled, >0 when enabled */
  u8_t enable;
};
static struct snmp_trap_dst trap_dst[SNMP_TRAP_DESTINATIONS];

static u8_t snmp_auth_traps_enabled = 0;

void
snmp_trap_dst_enable(u8_t dst_idx, u8_t enable)
{
  if (dst_idx < SNMP_TRAP_DESTINATIONS) {
    trap_dst[dst_idx].enable = enable;
  }
}

void
snmp_trap_dst_ip_set(u8_t dst_idx, const ip_addr_t *dst)
{
  if (dst_idx < SNMP_TRAP_DESTINATIONS) {
    ip_addr_set(&trap_dst[dst_idx].dip, dst);
  }
}

void
snmp_set_auth_traps_enabled(u8_t enable)
{
  snmp_auth_traps_enabled = enable;
}

u8_t
snmp_get_auth_traps_enabled(void)
{
  return snmp_auth_traps_enabled;
}


static err_t
snmp_send_trap(const struct snmp_obj_id *device_enterprise_oid, s32_t generic_trap, s32_t specific_trap)
{
  struct snmp_msg_trap trap_msg;
  struct snmp_trap_dst *td;
  struct pbuf *p;
  u16_t i, tot_len;
  err_t err = ERR_OK;

  trap_msg.snmp_version = 0;

  for (i = 0, td = &trap_dst[0]; i < SNMP_TRAP_DESTINATIONS; i++, td++) {
    if ((td->enable != 0) && !ip_addr_isany(&td->dip)) {
      /* lookup current source address for this dst */
      if (snmp_get_local_ip_for_dst(snmp_traps_handle, &td->dip, &trap_msg.sip)) {
        if (device_enterprise_oid == NULL) {
          trap_msg.enterprise = snmp_get_device_enterprise_oid();
        } else {
          trap_msg.enterprise = device_enterprise_oid;
        }

        trap_msg.gen_trap = generic_trap;
        if (generic_trap == SNMP_GENTRAP_ENTERPRISE_SPECIFIC) {
          trap_msg.spc_trap = specific_trap;
        } else {
          trap_msg.spc_trap = 0;
        }

        MIB2_COPY_SYSUPTIME_TO(&trap_msg.ts);

        /* pass 0, calculate length fields */
        tot_len = snmp_trap_header_sum(&trap_msg);

        /* allocate pbuf(s) */
        p = pbuf_alloc(PBUF_TRANSPORT, tot_len, PBUF_RAM);
        if (p != NULL) {
          struct snmp_pbuf_stream pbuf_stream;
          snmp_pbuf_stream_init(&pbuf_stream, p, 0, tot_len);

          /* pass 1, encode packet ino the pbuf(s) */
          snmp_trap_header_enc(&trap_msg, &pbuf_stream);

          snmp_stats.outtraps++;
          snmp_stats.outpkts++;

          snmp_sendto(snmp_traps_handle, p, &td->dip, SNMP_TRAP_PORT);
        } else {
          err = ERR_MEM;
        }
      } else {
        /* routing error */
        err = ERR_RTE;
      }
    }
  }
  return err;
}

err_t 
snmp_send_trap_generic(s32_t generic_trap)
{
  return snmp_send_trap(NULL, generic_trap, 0);
}

err_t
snmp_send_trap_specific(s32_t specific_trap)
{
  return snmp_send_trap(NULL, SNMP_GENTRAP_ENTERPRISE_SPECIFIC, specific_trap);
}

void
snmp_coldstart_trap(void)
{
  snmp_send_trap_generic(SNMP_GENTRAP_COLDSTART);
}

void
snmp_authfail_trap(void)
{
  if (snmp_auth_traps_enabled != 0) {
    snmp_send_trap_generic(SNMP_GENTRAP_AUTH_FAILURE);
  }
}

static u16_t
snmp_trap_header_sum(struct snmp_msg_trap *trap)
{
  u16_t tot_len;
  u16_t len;
  u8_t lenlen;

  tot_len = 0;

  snmp_asn1_enc_u32t_cnt(trap->ts, &len);
  snmp_asn1_enc_length_cnt(len, &lenlen);
  tot_len += 1 + len + lenlen;

  snmp_asn1_enc_s32t_cnt(trap->spc_trap, &len);
  snmp_asn1_enc_length_cnt(len, &lenlen);
  tot_len += 1 + len + lenlen;

  snmp_asn1_enc_s32t_cnt(trap->gen_trap, &len);
  snmp_asn1_enc_length_cnt(len, &lenlen);
  tot_len += 1 + len + lenlen;

  if(IP_IS_V6_VAL(trap->sip)) {
#if LWIP_IPV6
    len = sizeof(ip_2_ip6(&trap->sip)->addr);
#endif
  } else {
#if LWIP_IPV4
    len = sizeof(ip_2_ip4(&trap->sip)->addr);
#endif
  }
  snmp_asn1_enc_length_cnt(len, &lenlen);
  tot_len += 1 + len + lenlen;

  snmp_asn1_enc_oid_cnt(trap->enterprise->id, trap->enterprise->len, &len);
  snmp_asn1_enc_length_cnt(len, &lenlen);
  tot_len += 1 + len + lenlen;

  trap->pdulen = tot_len;
  snmp_asn1_enc_length_cnt(trap->pdulen, &lenlen);
  tot_len += 1 + lenlen;

  trap->comlen = (u16_t)strlen(snmp_community_trap);
  snmp_asn1_enc_length_cnt(trap->comlen, &lenlen);
  tot_len += 1 + lenlen + trap->comlen;

  snmp_asn1_enc_s32t_cnt(trap->snmp_version, &len);
  snmp_asn1_enc_length_cnt(len, &lenlen);
  tot_len += 1 + len + lenlen;

  trap->seqlen = tot_len;
  snmp_asn1_enc_length_cnt(trap->seqlen, &lenlen);
  tot_len += 1 + lenlen;

  return tot_len;
}

static void
snmp_trap_header_enc(struct snmp_msg_trap *trap, struct snmp_pbuf_stream *pbuf_stream)
{
  struct snmp_asn1_tlv tlv;

  /* 'Message' sequence */
  SNMP_ASN1_SET_TLV_PARAMS(tlv, SNMP_ASN1_TYPE_SEQUENCE, 0, trap->seqlen);
  snmp_ans1_enc_tlv(pbuf_stream, &tlv);

  /* version */
  SNMP_ASN1_SET_TLV_PARAMS(tlv, SNMP_ASN1_TYPE_INTEGER, 0, 0);
  snmp_asn1_enc_s32t_cnt(trap->snmp_version, &tlv.value_len);
  snmp_ans1_enc_tlv(pbuf_stream, &tlv);
  snmp_asn1_enc_s32t(pbuf_stream, tlv.value_len, trap->snmp_version);

  /* community */
  SNMP_ASN1_SET_TLV_PARAMS(tlv, SNMP_ASN1_TYPE_OCTET_STRING, 0, trap->comlen);
  snmp_ans1_enc_tlv(pbuf_stream, &tlv);
  snmp_asn1_enc_raw(pbuf_stream,  (const u8_t *)snmp_community_trap, trap->comlen);

  /* 'PDU' sequence */
  SNMP_ASN1_SET_TLV_PARAMS(tlv, (SNMP_ASN1_CLASS_CONTEXT | SNMP_ASN1_CONTENTTYPE_CONSTRUCTED | SNMP_ASN1_CONTEXT_PDU_TRAP), 0, trap->pdulen);
  snmp_ans1_enc_tlv(pbuf_stream, &tlv);

  /* object ID */
  SNMP_ASN1_SET_TLV_PARAMS(tlv, SNMP_ASN1_TYPE_OBJECT_ID, 0, 0);
  snmp_asn1_enc_oid_cnt(trap->enterprise->id, trap->enterprise->len, &tlv.value_len);
  snmp_ans1_enc_tlv(pbuf_stream, &tlv);
  snmp_asn1_enc_oid(pbuf_stream, trap->enterprise->id, trap->enterprise->len);

  /* IP addr */
  if(IP_IS_V6_VAL(trap->sip)) {
#if LWIP_IPV6
    SNMP_ASN1_SET_TLV_PARAMS(tlv, SNMP_ASN1_TYPE_IPADDR, 0, sizeof(ip_2_ip6(&trap->sip)->addr));
    snmp_ans1_enc_tlv(pbuf_stream, &tlv);
    snmp_asn1_enc_raw(pbuf_stream, (const u8_t *)&ip_2_ip6(&trap->sip)->addr, sizeof(ip_2_ip6(&trap->sip)->addr));
#endif
  } else {
#if LWIP_IPV4
    SNMP_ASN1_SET_TLV_PARAMS(tlv, SNMP_ASN1_TYPE_IPADDR, 0, sizeof(ip_2_ip4(&trap->sip)->addr));
    snmp_ans1_enc_tlv(pbuf_stream, &tlv);
    snmp_asn1_enc_raw(pbuf_stream, (const u8_t *)&ip_2_ip4(&trap->sip)->addr, sizeof(ip_2_ip4(&trap->sip)->addr));
#endif
  }

  /* trap length */
  SNMP_ASN1_SET_TLV_PARAMS(tlv, SNMP_ASN1_TYPE_INTEGER, 0, 0);
  snmp_asn1_enc_s32t_cnt(trap->gen_trap, &tlv.value_len);
  snmp_ans1_enc_tlv(pbuf_stream, &tlv);
  snmp_asn1_enc_s32t(pbuf_stream, tlv.value_len, trap->gen_trap);

  /* specific trap */
  SNMP_ASN1_SET_TLV_PARAMS(tlv, SNMP_ASN1_TYPE_INTEGER, 0, 0);
  snmp_asn1_enc_s32t_cnt(trap->spc_trap, &tlv.value_len);
  snmp_ans1_enc_tlv(pbuf_stream, &tlv);
  snmp_asn1_enc_s32t(pbuf_stream, tlv.value_len, trap->spc_trap);

  /* timestamp */
  SNMP_ASN1_SET_TLV_PARAMS(tlv, SNMP_ASN1_TYPE_TIMETICKS, 0, 0);
  snmp_asn1_enc_s32t_cnt(trap->ts, &tlv.value_len);
  snmp_ans1_enc_tlv(pbuf_stream, &tlv);
  snmp_asn1_enc_s32t(pbuf_stream, tlv.value_len, trap->ts);
}

#endif /* LWIP_SNMP */