lwip_snmp_traps.c

00001 /**
00002  * @file
00003  * SNMPv1 traps implementation.
00004  */
00005 
00006 /*
00007  * Copyright (c) 2001-2004 Swedish Institute of Computer Science.
00008  * All rights reserved.
00009  *
00010  * Redistribution and use in source and binary forms, with or without modification,
00011  * are permitted provided that the following conditions are met:
00012  *
00013  * 1. Redistributions of source code must retain the above copyright notice,
00014  *    this list of conditions and the following disclaimer.
00015  * 2. Redistributions in binary form must reproduce the above copyright notice,
00016  *    this list of conditions and the following disclaimer in the documentation
00017  *    and/or other materials provided with the distribution.
00018  * 3. The name of the author may not be used to endorse or promote products
00019  *    derived from this software without specific prior written permission.
00020  *
00021  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
00022  * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
00023  * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
00024  * SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
00025  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
00026  * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
00027  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
00028  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
00029  * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
00030  * OF SUCH DAMAGE.
00031  *
00032  * This file is part of the lwIP TCP/IP stack.
00033  *
00034  * Author: Martin Hentschel
00035  *         Christiaan Simons <christiaan.simons@axon.tv>
00036  *
00037  */
00038 
00039 #include "lwip/apps/snmp_opts.h"
00040 
00041 #if LWIP_SNMP /* don't build if not configured for use in lwipopts.h */
00042 
00043 #include <string.h>
00044 
00045 #include "lwip/snmp.h"
00046 #include "lwip/sys.h"
00047 #include "lwip/apps/snmp.h"
00048 #include "lwip/apps/snmp_core.h"
00049 #include "lwip/prot/iana.h"
00050 #include "snmp_msg.h"
00051 #include "snmp_asn1.h"
00052 #include "snmp_core_priv.h"
00053 
00054 struct snmp_msg_trap {
00055   /* source enterprise ID (sysObjectID) */
00056   const struct snmp_obj_id *enterprise;
00057   /* source IP address, raw network order format */
00058   ip_addr_t sip;
00059   /* generic trap code */
00060   u32_t gen_trap;
00061   /* specific trap code */
00062   u32_t spc_trap;
00063   /* timestamp */
00064   u32_t ts;
00065   /* snmp_version */
00066   u32_t snmp_version;
00067 
00068   /* output trap lengths used in ASN encoding */
00069   /* encoding pdu length */
00070   u16_t pdulen;
00071   /* encoding community length */
00072   u16_t comlen;
00073   /* encoding sequence length */
00074   u16_t seqlen;
00075   /* encoding varbinds sequence length */
00076   u16_t vbseqlen;
00077 };
00078 
00079 static u16_t snmp_trap_varbind_sum(struct snmp_msg_trap *trap, struct snmp_varbind *varbinds);
00080 static u16_t snmp_trap_header_sum(struct snmp_msg_trap *trap, u16_t vb_len);
00081 static err_t snmp_trap_header_enc(struct snmp_msg_trap *trap, struct snmp_pbuf_stream *pbuf_stream);
00082 static err_t snmp_trap_varbind_enc(struct snmp_msg_trap *trap, struct snmp_pbuf_stream *pbuf_stream, struct snmp_varbind *varbinds);
00083 
00084 #define BUILD_EXEC(code) \
00085   if ((code) != ERR_OK) { \
00086     LWIP_DEBUGF(SNMP_DEBUG, ("SNMP error during creation of outbound trap frame!")); \
00087     return ERR_ARG; \
00088   }
00089 
00090 /** Agent community string for sending traps */
00091 extern const char *snmp_community_trap;
00092 
00093 void *snmp_traps_handle;
00094 
00095 struct snmp_trap_dst {
00096   /* destination IP address in network order */
00097   ip_addr_t dip;
00098   /* set to 0 when disabled, >0 when enabled */
00099   u8_t enable;
00100 };
00101 static struct snmp_trap_dst trap_dst[SNMP_TRAP_DESTINATIONS];
00102 
00103 static u8_t snmp_auth_traps_enabled = 0;
00104 
00105 /**
00106  * @ingroup snmp_traps
00107  * Sets enable switch for this trap destination.
00108  * @param dst_idx index in 0 .. SNMP_TRAP_DESTINATIONS-1
00109  * @param enable switch if 0 destination is disabled >0 enabled.
00110  */
00111 void
00112 snmp_trap_dst_enable(u8_t dst_idx, u8_t enable)
00113 {
00114   LWIP_ASSERT_CORE_LOCKED();
00115   if (dst_idx < SNMP_TRAP_DESTINATIONS) {
00116     trap_dst[dst_idx].enable = enable;
00117   }
00118 }
00119 
00120 /**
00121  * @ingroup snmp_traps
00122  * Sets IPv4 address for this trap destination.
00123  * @param dst_idx index in 0 .. SNMP_TRAP_DESTINATIONS-1
00124  * @param dst IPv4 address in host order.
00125  */
00126 void
00127 snmp_trap_dst_ip_set(u8_t dst_idx, const ip_addr_t *dst)
00128 {
00129   LWIP_ASSERT_CORE_LOCKED();
00130   if (dst_idx < SNMP_TRAP_DESTINATIONS) {
00131     ip_addr_set(&trap_dst[dst_idx].dip, dst);
00132   }
00133 }
00134 
00135 /**
00136  * @ingroup snmp_traps
00137  * Enable/disable authentication traps
00138  */
00139 void
00140 snmp_set_auth_traps_enabled(u8_t enable)
00141 {
00142   snmp_auth_traps_enabled = enable;
00143 }
00144 
00145 /**
00146  * @ingroup snmp_traps
00147  * Get authentication traps enabled state
00148  */
00149 u8_t
00150 snmp_get_auth_traps_enabled(void)
00151 {
00152   return snmp_auth_traps_enabled;
00153 }
00154 
00155 
00156 /**
00157  * @ingroup snmp_traps
00158  * Sends a generic or enterprise specific trap message.
00159  *
00160  * @param eoid points to enterprise object identifier
00161  * @param generic_trap is the trap code
00162  * @param specific_trap used for enterprise traps when generic_trap == 6
00163  * @param varbinds linked list of varbinds to be sent
00164  * @return ERR_OK when success, ERR_MEM if we're out of memory
00165  *
00166  * @note the use of the enterprise identifier field
00167  * is per RFC1215.
00168  * Use .iso.org.dod.internet.mgmt.mib-2.snmp for generic traps
00169  * and .iso.org.dod.internet.private.enterprises.yourenterprise
00170  * (sysObjectID) for specific traps.
00171  */
00172 err_t
00173 snmp_send_trap(const struct snmp_obj_id *eoid, s32_t generic_trap, s32_t specific_trap, struct snmp_varbind *varbinds)
00174 {
00175   struct snmp_msg_trap trap_msg;
00176   struct snmp_trap_dst *td;
00177   struct pbuf *p;
00178   u16_t i, tot_len;
00179   err_t err = ERR_OK;
00180 
00181   LWIP_ASSERT_CORE_LOCKED();
00182 
00183   trap_msg.snmp_version = 0;
00184 
00185   for (i = 0, td = &trap_dst[0]; i < SNMP_TRAP_DESTINATIONS; i++, td++) {
00186     if ((td->enable != 0) && !ip_addr_isany(&td->dip)) {
00187       /* lookup current source address for this dst */
00188       if (snmp_get_local_ip_for_dst(snmp_traps_handle, &td->dip, &trap_msg.sip)) {
00189         if (eoid == NULL) {
00190           trap_msg.enterprise = snmp_get_device_enterprise_oid();
00191         } else {
00192           trap_msg.enterprise = eoid;
00193         }
00194 
00195         trap_msg.gen_trap = generic_trap;
00196         if (generic_trap == SNMP_GENTRAP_ENTERPRISE_SPECIFIC) {
00197           trap_msg.spc_trap = specific_trap;
00198         } else {
00199           trap_msg.spc_trap = 0;
00200         }
00201 
00202         MIB2_COPY_SYSUPTIME_TO(&trap_msg.ts);
00203 
00204         /* pass 0, calculate length fields */
00205         tot_len = snmp_trap_varbind_sum(&trap_msg, varbinds);
00206         tot_len = snmp_trap_header_sum(&trap_msg, tot_len);
00207 
00208         /* allocate pbuf(s) */
00209         p = pbuf_alloc(PBUF_TRANSPORT, tot_len, PBUF_RAM);
00210         if (p != NULL) {
00211           struct snmp_pbuf_stream pbuf_stream;
00212           snmp_pbuf_stream_init(&pbuf_stream, p, 0, tot_len);
00213 
00214           /* pass 1, encode packet into the pbuf(s) */
00215           snmp_trap_header_enc(&trap_msg, &pbuf_stream);
00216           snmp_trap_varbind_enc(&trap_msg, &pbuf_stream, varbinds);
00217 
00218           snmp_stats.outtraps++;
00219           snmp_stats.outpkts++;
00220 
00221           /** send to the TRAP destination */
00222           snmp_sendto(snmp_traps_handle, p, &td->dip, LWIP_IANA_PORT_SNMP_TRAP);
00223           pbuf_free(p);
00224         } else {
00225           err = ERR_MEM;
00226         }
00227       } else {
00228         /* routing error */
00229         err = ERR_RTE;
00230       }
00231     }
00232   }
00233   return err;
00234 }
00235 
00236 /**
00237  * @ingroup snmp_traps
00238  * Send generic SNMP trap
00239  */
00240 err_t
00241 snmp_send_trap_generic(s32_t generic_trap)
00242 {
00243   static const struct snmp_obj_id oid = { 7, { 1, 3, 6, 1, 2, 1, 11 } };
00244   return snmp_send_trap(&oid, generic_trap, 0, NULL);
00245 }
00246 
00247 /**
00248  * @ingroup snmp_traps
00249  * Send specific SNMP trap with variable bindings
00250  */
00251 err_t
00252 snmp_send_trap_specific(s32_t specific_trap, struct snmp_varbind *varbinds)
00253 {
00254   return snmp_send_trap(NULL, SNMP_GENTRAP_ENTERPRISE_SPECIFIC, specific_trap, varbinds);
00255 }
00256 
00257 /**
00258  * @ingroup snmp_traps
00259  * Send coldstart trap
00260  */
00261 void
00262 snmp_coldstart_trap(void)
00263 {
00264   snmp_send_trap_generic(SNMP_GENTRAP_COLDSTART);
00265 }
00266 
00267 /**
00268  * @ingroup snmp_traps
00269  * Send authentication failure trap (used internally by agent)
00270  */
00271 void
00272 snmp_authfail_trap(void)
00273 {
00274   if (snmp_auth_traps_enabled != 0) {
00275     snmp_send_trap_generic(SNMP_GENTRAP_AUTH_FAILURE);
00276   }
00277 }
00278 
00279 static u16_t
00280 snmp_trap_varbind_sum(struct snmp_msg_trap *trap, struct snmp_varbind *varbinds)
00281 {
00282   struct snmp_varbind *varbind;
00283   u16_t tot_len;
00284   u8_t tot_len_len;
00285 
00286   tot_len = 0;
00287   varbind = varbinds;
00288   while (varbind != NULL) {
00289     struct snmp_varbind_len len;
00290 
00291     if (snmp_varbind_length(varbind, &len) == ERR_OK) {
00292       tot_len += 1 + len.vb_len_len + len.vb_value_len;
00293     }
00294 
00295     varbind = varbind->next;
00296   }
00297 
00298   trap->vbseqlen = tot_len;
00299   snmp_asn1_enc_length_cnt(trap->vbseqlen, &tot_len_len);
00300   tot_len += 1 + tot_len_len;
00301 
00302   return tot_len;
00303 }
00304 
00305 /**
00306  * Sums trap header field lengths from tail to head and
00307  * returns trap_header_lengths for second encoding pass.
00308  *
00309  * @param trap Trap message
00310  * @param vb_len varbind-list length
00311  * @return the required length for encoding the trap header
00312  */
00313 static u16_t
00314 snmp_trap_header_sum(struct snmp_msg_trap *trap, u16_t vb_len)
00315 {
00316   u16_t tot_len;
00317   u16_t len;
00318   u8_t lenlen;
00319 
00320   tot_len = vb_len;
00321 
00322   snmp_asn1_enc_u32t_cnt(trap->ts, &len);
00323   snmp_asn1_enc_length_cnt(len, &lenlen);
00324   tot_len += 1 + len + lenlen;
00325 
00326   snmp_asn1_enc_s32t_cnt(trap->spc_trap, &len);
00327   snmp_asn1_enc_length_cnt(len, &lenlen);
00328   tot_len += 1 + len + lenlen;
00329 
00330   snmp_asn1_enc_s32t_cnt(trap->gen_trap, &len);
00331   snmp_asn1_enc_length_cnt(len, &lenlen);
00332   tot_len += 1 + len + lenlen;
00333 
00334   if (IP_IS_V6_VAL(trap->sip)) {
00335 #if LWIP_IPV6
00336     len = sizeof(ip_2_ip6(&trap->sip)->addr);
00337 #endif
00338   } else {
00339 #if LWIP_IPV4
00340     len = sizeof(ip_2_ip4(&trap->sip)->addr);
00341 #endif
00342   }
00343   snmp_asn1_enc_length_cnt(len, &lenlen);
00344   tot_len += 1 + len + lenlen;
00345 
00346   snmp_asn1_enc_oid_cnt(trap->enterprise->id, trap->enterprise->len, &len);
00347   snmp_asn1_enc_length_cnt(len, &lenlen);
00348   tot_len += 1 + len + lenlen;
00349 
00350   trap->pdulen = tot_len;
00351   snmp_asn1_enc_length_cnt(trap->pdulen, &lenlen);
00352   tot_len += 1 + lenlen;
00353 
00354   trap->comlen = (u16_t)LWIP_MIN(strlen(snmp_community_trap), 0xFFFF);
00355   snmp_asn1_enc_length_cnt(trap->comlen, &lenlen);
00356   tot_len += 1 + lenlen + trap->comlen;
00357 
00358   snmp_asn1_enc_s32t_cnt(trap->snmp_version, &len);
00359   snmp_asn1_enc_length_cnt(len, &lenlen);
00360   tot_len += 1 + len + lenlen;
00361 
00362   trap->seqlen = tot_len;
00363   snmp_asn1_enc_length_cnt(trap->seqlen, &lenlen);
00364   tot_len += 1 + lenlen;
00365 
00366   return tot_len;
00367 }
00368 
00369 static err_t
00370 snmp_trap_varbind_enc(struct snmp_msg_trap *trap, struct snmp_pbuf_stream *pbuf_stream, struct snmp_varbind *varbinds)
00371 {
00372   struct snmp_asn1_tlv tlv;
00373   struct snmp_varbind *varbind;
00374 
00375   varbind = varbinds;
00376 
00377   SNMP_ASN1_SET_TLV_PARAMS(tlv, SNMP_ASN1_TYPE_SEQUENCE, 0, trap->vbseqlen);
00378   BUILD_EXEC( snmp_ans1_enc_tlv(pbuf_stream, &tlv) );
00379 
00380   while (varbind != NULL) {
00381     BUILD_EXEC( snmp_append_outbound_varbind(pbuf_stream, varbind) );
00382 
00383     varbind = varbind->next;
00384   }
00385 
00386   return ERR_OK;
00387 }
00388 
00389 /**
00390  * Encodes trap header from head to tail.
00391  */
00392 static err_t
00393 snmp_trap_header_enc(struct snmp_msg_trap *trap, struct snmp_pbuf_stream *pbuf_stream)
00394 {
00395   struct snmp_asn1_tlv tlv;
00396 
00397   /* 'Message' sequence */
00398   SNMP_ASN1_SET_TLV_PARAMS(tlv, SNMP_ASN1_TYPE_SEQUENCE, 0, trap->seqlen);
00399   BUILD_EXEC( snmp_ans1_enc_tlv(pbuf_stream, &tlv) );
00400 
00401   /* version */
00402   SNMP_ASN1_SET_TLV_PARAMS(tlv, SNMP_ASN1_TYPE_INTEGER, 0, 0);
00403   snmp_asn1_enc_s32t_cnt(trap->snmp_version, &tlv.value_len);
00404   BUILD_EXEC( snmp_ans1_enc_tlv(pbuf_stream, &tlv) );
00405   BUILD_EXEC( snmp_asn1_enc_s32t(pbuf_stream, tlv.value_len, trap->snmp_version) );
00406 
00407   /* community */
00408   SNMP_ASN1_SET_TLV_PARAMS(tlv, SNMP_ASN1_TYPE_OCTET_STRING, 0, trap->comlen);
00409   BUILD_EXEC( snmp_ans1_enc_tlv(pbuf_stream, &tlv) );
00410   BUILD_EXEC( snmp_asn1_enc_raw(pbuf_stream,  (const u8_t *)snmp_community_trap, trap->comlen) );
00411 
00412   /* 'PDU' sequence */
00413   SNMP_ASN1_SET_TLV_PARAMS(tlv, (SNMP_ASN1_CLASS_CONTEXT | SNMP_ASN1_CONTENTTYPE_CONSTRUCTED | SNMP_ASN1_CONTEXT_PDU_TRAP), 0, trap->pdulen);
00414   BUILD_EXEC( snmp_ans1_enc_tlv(pbuf_stream, &tlv) );
00415 
00416   /* object ID */
00417   SNMP_ASN1_SET_TLV_PARAMS(tlv, SNMP_ASN1_TYPE_OBJECT_ID, 0, 0);
00418   snmp_asn1_enc_oid_cnt(trap->enterprise->id, trap->enterprise->len, &tlv.value_len);
00419   BUILD_EXEC( snmp_ans1_enc_tlv(pbuf_stream, &tlv) );
00420   BUILD_EXEC( snmp_asn1_enc_oid(pbuf_stream, trap->enterprise->id, trap->enterprise->len) );
00421 
00422   /* IP addr */
00423   if (IP_IS_V6_VAL(trap->sip)) {
00424 #if LWIP_IPV6
00425     SNMP_ASN1_SET_TLV_PARAMS(tlv, SNMP_ASN1_TYPE_IPADDR, 0, sizeof(ip_2_ip6(&trap->sip)->addr));
00426     BUILD_EXEC( snmp_ans1_enc_tlv(pbuf_stream, &tlv) );
00427     BUILD_EXEC( snmp_asn1_enc_raw(pbuf_stream, (const u8_t *)&ip_2_ip6(&trap->sip)->addr, sizeof(ip_2_ip6(&trap->sip)->addr)) );
00428 #endif
00429   } else {
00430 #if LWIP_IPV4
00431     SNMP_ASN1_SET_TLV_PARAMS(tlv, SNMP_ASN1_TYPE_IPADDR, 0, sizeof(ip_2_ip4(&trap->sip)->addr));
00432     BUILD_EXEC( snmp_ans1_enc_tlv(pbuf_stream, &tlv) );
00433     BUILD_EXEC( snmp_asn1_enc_raw(pbuf_stream, (const u8_t *)&ip_2_ip4(&trap->sip)->addr, sizeof(ip_2_ip4(&trap->sip)->addr)) );
00434 #endif
00435   }
00436 
00437   /* trap length */
00438   SNMP_ASN1_SET_TLV_PARAMS(tlv, SNMP_ASN1_TYPE_INTEGER, 0, 0);
00439   snmp_asn1_enc_s32t_cnt(trap->gen_trap, &tlv.value_len);
00440   BUILD_EXEC( snmp_ans1_enc_tlv(pbuf_stream, &tlv) );
00441   BUILD_EXEC( snmp_asn1_enc_s32t(pbuf_stream, tlv.value_len, trap->gen_trap) );
00442 
00443   /* specific trap */
00444   SNMP_ASN1_SET_TLV_PARAMS(tlv, SNMP_ASN1_TYPE_INTEGER, 0, 0);
00445   snmp_asn1_enc_s32t_cnt(trap->spc_trap, &tlv.value_len);
00446   BUILD_EXEC( snmp_ans1_enc_tlv(pbuf_stream, &tlv) );
00447   BUILD_EXEC( snmp_asn1_enc_s32t(pbuf_stream, tlv.value_len, trap->spc_trap) );
00448 
00449   /* timestamp */
00450   SNMP_ASN1_SET_TLV_PARAMS(tlv, SNMP_ASN1_TYPE_TIMETICKS, 0, 0);
00451   snmp_asn1_enc_s32t_cnt(trap->ts, &tlv.value_len);
00452   BUILD_EXEC( snmp_ans1_enc_tlv(pbuf_stream, &tlv) );
00453   BUILD_EXEC( snmp_asn1_enc_s32t(pbuf_stream, tlv.value_len, trap->ts) );
00454 
00455   return ERR_OK;
00456 }
00457 
00458 #endif /* LWIP_SNMP */