mirror of
https://github.com/lwip-tcpip/lwip.git
synced 2024-07-07 13:29:19 +00:00
Improved message parse robustness. Rejecting 'error requests'. Removed invalid genError return on varbindlist parse error, changed badValue into noSuchName error for non-writeable objects.
This commit is contained in:
christiaans
parent
25ed4e9d16
commit
f7881e58bb
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@ -550,19 +550,27 @@ snmp_msg_set_event(u8_t request_id, struct snmp_msg_pstat *msg_ps)
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en = msg_ps->ext_mib_node;
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np = msg_ps->ext_name_ptr;
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if ((msg_ps->ext_object_def.access == MIB_OBJECT_READ_WRITE) &&
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(msg_ps->ext_object_def.asn_type == msg_ps->vb_ptr->value_type) &&
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(en->set_test_a(request_id,&msg_ps->ext_object_def,
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msg_ps->vb_ptr->value_len,msg_ps->vb_ptr->value) != 0))
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if (msg_ps->ext_object_def.access == MIB_OBJECT_READ_WRITE)
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{
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msg_ps->state = SNMP_MSG_SEARCH_OBJ;
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msg_ps->vb_idx += 1;
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if ((msg_ps->ext_object_def.asn_type == msg_ps->vb_ptr->value_type) &&
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(en->set_test_a(request_id,&msg_ps->ext_object_def,
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msg_ps->vb_ptr->value_len,msg_ps->vb_ptr->value) != 0))
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{
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msg_ps->state = SNMP_MSG_SEARCH_OBJ;
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msg_ps->vb_idx += 1;
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}
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else
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{
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en->set_test_pc(request_id,&msg_ps->ext_object_def);
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/* bad value */
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snmp_error_response(msg_ps,SNMP_ES_BADVALUE);
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}
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}
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else
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{
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en->set_test_pc(request_id,&msg_ps->ext_object_def);
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/* bad value */
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snmp_error_response(msg_ps,SNMP_ES_BADVALUE);
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/* object not available for set */
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snmp_error_response(msg_ps,SNMP_ES_NOSUCHNAME);
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}
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}
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else if (msg_ps->state == SNMP_MSG_EXTERNAL_GET_OBJDEF_S)
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@ -661,17 +669,24 @@ snmp_msg_set_event(u8_t request_id, struct snmp_msg_pstat *msg_ps)
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{
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msg_ps->state = SNMP_MSG_INTERNAL_SET_TEST;
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if ((object_def.access == MIB_OBJECT_READ_WRITE) &&
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(object_def.asn_type == msg_ps->vb_ptr->value_type) &&
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(mn->set_test(&object_def,msg_ps->vb_ptr->value_len,msg_ps->vb_ptr->value) != 0))
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if (object_def.access == MIB_OBJECT_READ_WRITE)
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{
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msg_ps->state = SNMP_MSG_SEARCH_OBJ;
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msg_ps->vb_idx += 1;
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if ((object_def.asn_type == msg_ps->vb_ptr->value_type) &&
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(mn->set_test(&object_def,msg_ps->vb_ptr->value_len,msg_ps->vb_ptr->value) != 0))
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{
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msg_ps->state = SNMP_MSG_SEARCH_OBJ;
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msg_ps->vb_idx += 1;
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}
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else
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{
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/* bad value */
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snmp_error_response(msg_ps,SNMP_ES_BADVALUE);
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}
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}
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else
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{
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/* bad value */
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snmp_error_response(msg_ps,SNMP_ES_BADVALUE);
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/* object not available for set */
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snmp_error_response(msg_ps,SNMP_ES_NOSUCHNAME);
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}
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}
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}
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@ -831,16 +846,18 @@ snmp_recv(void *arg, struct udp_pcb *pcb, struct pbuf *p, struct ip_addr *addr,
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/* check total length, version, community, pdu type */
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err_ret = snmp_pdu_header_check(p, payload_ofs, payload_len, &varbind_ofs, msg_ps);
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if ((msg_ps->rt == SNMP_ASN1_PDU_GET_REQ) ||
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(msg_ps->rt == SNMP_ASN1_PDU_GET_NEXT_REQ) ||
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(msg_ps->rt == SNMP_ASN1_PDU_SET_REQ))
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if (((msg_ps->rt == SNMP_ASN1_PDU_GET_REQ) ||
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(msg_ps->rt == SNMP_ASN1_PDU_GET_NEXT_REQ) ||
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(msg_ps->rt == SNMP_ASN1_PDU_SET_REQ)) &&
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((msg_ps->error_status == SNMP_ES_NOERROR) &&
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(msg_ps->error_index == 0)) )
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{
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/* Only accept requests. (be robust) */
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/* Only accept requests and requests without error (be robust) */
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err_ret = err_ret;
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}
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else
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{
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/* Reject response and trap headers as input! */
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/* Reject response and trap headers or error requests as input! */
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err_ret = ERR_ARG;
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}
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if (err_ret == ERR_OK)
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@ -869,22 +886,17 @@ snmp_recv(void *arg, struct udp_pcb *pcb, struct pbuf *p, struct ip_addr *addr,
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}
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else
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{
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/* varbind-list decode failed, or varbind list empty (silly cmd for agent) */
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/* varbind-list decode failed, or varbind list empty.
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drop request silently, do not return error!
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(errors are only returned for a specific varbind failure) */
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pbuf_free(p);
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LWIP_DEBUGF(SNMP_MSG_DEBUG, ("snmp_pdu_dec_varbindlist() failed\n"));
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msg_ps->error_status = SNMP_ES_GENERROR;
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msg_ps->error_index = 0;
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msg_ps->outvb.head = NULL;
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msg_ps->outvb.tail = NULL;
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msg_ps->outvb.count = 0;
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msg_ps->outvb.seqlen = 0;
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msg_ps->outvb.seqlenlen = 1;
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snmp_send_response(msg_ps);
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}
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}
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else
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{
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/* header check failed! */
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/* header check failed
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drop request silently, do not return error! */
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pbuf_free(p);
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LWIP_DEBUGF(SNMP_MSG_DEBUG, ("snmp_pdu_header_check() failed\n"));
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}
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@ -918,11 +930,12 @@ static err_t
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snmp_pdu_header_check(struct pbuf *p, u16_t ofs, u16_t pdu_len, u16_t *ofs_ret, struct snmp_msg_pstat *m_stat)
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{
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err_t derr;
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u16_t len;
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u16_t len, ofs_base;
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u8_t len_octets;
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u8_t type;
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s32_t version;
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ofs_base = ofs;
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snmp_asn1_dec_type(p, ofs, &type);
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derr = snmp_asn1_dec_length(p, ofs+1, &len_octets, &len);
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if ((derr != ERR_OK) ||
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@ -1022,11 +1035,17 @@ snmp_pdu_header_check(struct pbuf *p, u16_t ofs, u16_t pdu_len, u16_t *ofs_ret,
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}
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if (derr != ERR_OK)
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{
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/* unsupported input PDU for this agent */
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/* unsupported input PDU for this agent (no parse error) */
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return ERR_ARG;
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}
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m_stat->rt = type & 0x1F;
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ofs += (1 + len_octets);
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if (len != (pdu_len - (ofs - ofs_base)))
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{
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/* decoded PDU length does not equal actual payload length */
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snmp_inc_snmpinasnparseerrs();
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return ERR_ARG;
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}
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snmp_asn1_dec_type(p, ofs, &type);
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derr = snmp_asn1_dec_length(p, ofs+1, &len_octets, &len);
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if ((derr != ERR_OK) || (type != (SNMP_ASN1_UNIV | SNMP_ASN1_PRIMIT | SNMP_ASN1_INTEG)))
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@ -1051,8 +1070,8 @@ snmp_pdu_header_check(struct pbuf *p, u16_t ofs, u16_t pdu_len, u16_t *ofs_ret,
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snmp_inc_snmpinasnparseerrs();
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return ERR_ARG;
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}
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/* usually noError (0) for incoming messages but log errors
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for mib-2 completeness and for debug purposes */
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/* must be noError (0) for incoming requests.
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log errors for mib-2 completeness and for debug purposes */
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derr = snmp_asn1_dec_s32t(p, ofs + 1 + len_octets, len, &m_stat->error_status);
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if (derr != ERR_OK)
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{
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@ -1087,7 +1106,15 @@ snmp_pdu_header_check(struct pbuf *p, u16_t ofs, u16_t pdu_len, u16_t *ofs_ret,
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snmp_inc_snmpinasnparseerrs();
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return ERR_ARG;
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}
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/* skip 'error-index', usually 0 for incoming requests */
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/* must be 0 for incoming requests.
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decode anyway to catch bad integers (and dirty tricks) */
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derr = snmp_asn1_dec_s32t(p, ofs + 1 + len_octets, len, &m_stat->error_index);
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if (derr != ERR_OK)
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{
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/* can't decode */
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snmp_inc_snmpinasnparseerrs();
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return ERR_ARG;
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}
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ofs += (1 + len_octets + len);
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*ofs_ret = ofs;
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return ERR_OK;
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@ -1125,7 +1152,8 @@ snmp_pdu_dec_varbindlist(struct pbuf *p, u16_t ofs, u16_t *ofs_ret, struct snmp_
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snmp_asn1_dec_type(p, ofs, &type);
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derr = snmp_asn1_dec_length(p, ofs+1, &len_octets, &len);
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if ((derr != ERR_OK) ||
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(type != (SNMP_ASN1_UNIV | SNMP_ASN1_CONSTR | SNMP_ASN1_SEQ)))
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(type != (SNMP_ASN1_UNIV | SNMP_ASN1_CONSTR | SNMP_ASN1_SEQ)) ||
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(len <= 0) || (len > vb_len))
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{
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snmp_inc_snmpinasnparseerrs();
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/* free varbinds (if available) */
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