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snmp_recv: don't peek the UDP header, p->tot_len does the same; no need for the extra checks at the beginning; don't use so many if/else but if/return instead to make the code more readable
This commit is contained in:
goldsimon
parent
0644c4c08e
commit
853e33bdb4
@ -808,121 +808,83 @@ snmp_msg_event(u8_t request_id)
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static void
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static void
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snmp_recv(void *arg, struct udp_pcb *pcb, struct pbuf *p, struct ip_addr *addr, u16_t port)
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snmp_recv(void *arg, struct udp_pcb *pcb, struct pbuf *p, struct ip_addr *addr, u16_t port)
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{
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{
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struct udp_hdr *udphdr;
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struct snmp_msg_pstat *msg_ps;
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u8_t req_idx;
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err_t err_ret;
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u16_t payload_len = p->tot_len;
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u16_t payload_ofs = 0;
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u16_t varbind_ofs = 0;
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/* suppress unused argument warning */
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/* suppress unused argument warning */
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LWIP_UNUSED_ARG(arg);
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LWIP_UNUSED_ARG(arg);
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/* peek in the UDP header (goto IP payload) */
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if(pbuf_header(p, UDP_HLEN)){
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/* traverse input message process list, look for SNMP_MSG_EMPTY */
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LWIP_ASSERT("Can't move to UDP header", 0);
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msg_ps = &msg_input_list[0];
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req_idx = 0;
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while ((req_idx < SNMP_CONCURRENT_REQUESTS) && (msg_ps->state != SNMP_MSG_EMPTY))
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{
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req_idx++;
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msg_ps++;
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}
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if (req_idx == SNMP_CONCURRENT_REQUESTS)
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{
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/* exceeding number of concurrent requests */
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pbuf_free(p);
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pbuf_free(p);
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return;
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return;
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}
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}
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udphdr = p->payload;
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/* check if datagram is really directed at us (including broadcast requests) */
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/* accepting request */
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if ((pcb == snmp1_pcb) && (ntohs(udphdr->dest) == SNMP_IN_PORT))
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snmp_inc_snmpinpkts();
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/* record used 'protocol control block' */
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msg_ps->pcb = pcb;
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/* source address (network order) */
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msg_ps->sip = *addr;
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/* source port (host order (lwIP oddity)) */
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msg_ps->sp = port;
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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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/* Only accept requests and requests without error (be robust) */
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/* Reject response and trap headers or error requests as input! */
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if ((err_ret != ERR_OK) ||
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((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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{
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struct snmp_msg_pstat *msg_ps;
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/* header check failed drop request silently, do not return error! */
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u8_t req_idx;
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/* traverse input message process list, look for SNMP_MSG_EMPTY */
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msg_ps = &msg_input_list[0];
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req_idx = 0;
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while ((req_idx<SNMP_CONCURRENT_REQUESTS) && (msg_ps->state != SNMP_MSG_EMPTY))
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{
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req_idx++;
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msg_ps++;
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}
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if (req_idx != SNMP_CONCURRENT_REQUESTS)
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{
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err_t err_ret;
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u16_t payload_len;
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u16_t payload_ofs;
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u16_t varbind_ofs = 0;
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/* accepting request */
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snmp_inc_snmpinpkts();
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/* record used 'protocol control block' */
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msg_ps->pcb = pcb;
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/* source address (network order) */
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msg_ps->sip = *addr;
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/* source port (host order (lwIP oddity)) */
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msg_ps->sp = port;
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/* read UDP payload length from UDP header */
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payload_len = ntohs(udphdr->len) - UDP_HLEN;
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/* adjust to UDP payload */
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payload_ofs = UDP_HLEN;
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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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((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 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 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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{
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LWIP_DEBUGF(SNMP_MSG_DEBUG, ("snmp_recv ok, community %s\n", msg_ps->community));
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/* Builds a list of variable bindings. Copy the varbinds from the pbuf
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chain to glue them when these are divided over two or more pbuf's. */
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err_ret = snmp_pdu_dec_varbindlist(p, varbind_ofs, &varbind_ofs, msg_ps);
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if ((err_ret == ERR_OK) && (msg_ps->invb.count > 0))
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{
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/* we've decoded the incoming message, release input msg now */
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pbuf_free(p);
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msg_ps->error_status = SNMP_ES_NOERROR;
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msg_ps->error_index = 0;
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/* find object for each variable binding */
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msg_ps->state = SNMP_MSG_SEARCH_OBJ;
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/* first variable binding from list to inspect */
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msg_ps->vb_idx = 0;
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LWIP_DEBUGF(SNMP_MSG_DEBUG, ("snmp_recv varbind cnt=%"U16_F"\n",(u16_t)msg_ps->invb.count));
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/* handle input event and as much objects as possible in one go */
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snmp_msg_event(req_idx);
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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.
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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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}
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}
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else
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{
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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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}
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else
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{
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/* exceeding number of concurrent requests */
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pbuf_free(p);
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}
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}
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else
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{
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/* datagram not for us */
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pbuf_free(p);
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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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return;
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}
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}
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LWIP_DEBUGF(SNMP_MSG_DEBUG, ("snmp_recv ok, community %s\n", msg_ps->community));
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/* Builds a list of variable bindings. Copy the varbinds from the pbuf
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chain to glue them when these are divided over two or more pbuf's. */
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err_ret = snmp_pdu_dec_varbindlist(p, varbind_ofs, &varbind_ofs, msg_ps);
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/* we've decoded the incoming message, release input msg now */
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pbuf_free(p);
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if ((err_ret != ERR_OK) || (msg_ps->invb.count == 0))
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{
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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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LWIP_DEBUGF(SNMP_MSG_DEBUG, ("snmp_pdu_dec_varbindlist() failed\n"));
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return;
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}
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msg_ps->error_status = SNMP_ES_NOERROR;
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msg_ps->error_index = 0;
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/* find object for each variable binding */
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msg_ps->state = SNMP_MSG_SEARCH_OBJ;
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/* first variable binding from list to inspect */
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msg_ps->vb_idx = 0;
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LWIP_DEBUGF(SNMP_MSG_DEBUG, ("snmp_recv varbind cnt=%"U16_F"\n",(u16_t)msg_ps->invb.count));
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/* handle input event and as much objects as possible in one go */
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snmp_msg_event(req_idx);
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}
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}
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/**
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/**
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