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/*
* capwap.c
*
* Copyright (C) 2019 - ntop.org
*
* nDPI is free software: you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* nDPI is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with nDPI. If not, see <http://www.gnu.org/licenses/>.
*
*/
#include "ndpi_protocol_ids.h"
#define NDPI_CURRENT_PROTO NDPI_PROTOCOL_CAPWAP
#include "ndpi_api.h"
#define NDPI_CAPWAP_CONTROL_PORT 5246
#define NDPI_CAPWAP_DATA_PORT 5247
static void ndpi_int_capwap_add_connection(struct ndpi_detection_module_struct *ndpi_struct,
struct ndpi_flow_struct *flow) {
ndpi_set_detected_protocol(ndpi_struct, flow, NDPI_PROTOCOL_CAPWAP, NDPI_PROTOCOL_UNKNOWN, NDPI_CONFIDENCE_DPI);
}
static int is_capwap_multicast(const struct ndpi_packet_struct *packet)
{
/* RFC 5115 Sec 3.3
"The WTP MUST send the Discovery Request
message to either the limited broadcast IP address (255.255.255.255),
the well-known CAPWAP multicast address (224.0.1.140), or to the
unicast IP address of the AC. For IPv6 networks, since broadcast
does not exist, the use of "All ACs multicast address" (FF0X:0:0:0:0:
0:0:18C) is used instead.
*/
if(packet->iph) {
if((packet->iph->daddr == 0xFFFFFFFF) ||
(ntohl(packet->iph->daddr) == 0XE000018C))
return 1;
} else if(packet->iphv6) {
if(((ntohl(packet->iphv6->ip6_dst.u6_addr.u6_addr32[0] & 0xFFF0FFFF) == 0xFF000000)) &&
(packet->iphv6->ip6_dst.u6_addr.u6_addr32[1] == 0) &&
(packet->iphv6->ip6_dst.u6_addr.u6_addr32[2] == 0) &&
(ntohl(packet->iphv6->ip6_dst.u6_addr.u6_addr32[3] == 0x0000018C)))
return 1;
}
return 0;
}
/* ************************************************** */
static void ndpi_search_setup_capwap(struct ndpi_detection_module_struct *ndpi_struct,
struct ndpi_flow_struct *flow) {
struct ndpi_packet_struct *packet = &ndpi_struct->packet;
u_int16_t sport, dport;
sport = ntohs(packet->udp->source), dport = ntohs(packet->udp->dest);
if((dport == NDPI_CAPWAP_CONTROL_PORT)
&& (is_capwap_multicast(packet))
&& (packet->payload_packet_len >= 16)
&& (packet->payload[0] == 0x0)
&& (packet->payload[8] == 6 /* Mac len */)
)
goto capwap_found;
if(((sport == NDPI_CAPWAP_CONTROL_PORT) || (dport == NDPI_CAPWAP_CONTROL_PORT))
&& ((packet->payload[0] == 0x0) || (packet->payload[0] == 0x1))
) {
u_int16_t msg_len, offset, to_add;
if(packet->payload[0] == 0x0)
offset = 13, to_add = 13;
else
offset = 15, to_add = 17;
if (packet->payload_packet_len >= offset + sizeof(u_int16_t)) {
msg_len = ntohs(*(u_int16_t*)&packet->payload[offset]);
if((msg_len+to_add) == packet->payload_packet_len)
goto capwap_found;
}
}
if(
(((dport == NDPI_CAPWAP_DATA_PORT) && (!is_capwap_multicast(packet))) || (sport == NDPI_CAPWAP_DATA_PORT))
&& (packet->payload_packet_len >= 16)
&& (packet->payload[0] == 0x0)
) {
u_int8_t is_80211_data = (packet->payload[9] & 0x0C) >> 2;
if((sport == NDPI_CAPWAP_DATA_PORT) && (is_80211_data == 2 /* IEEE 802.11 Data */))
goto capwap_found;
else if(dport == NDPI_CAPWAP_DATA_PORT) {
u_int16_t msg_len = ntohs(*(u_int16_t*)&packet->payload[13]);
if((packet->payload[8] == 1 /* Mac len */)
|| (packet->payload[8] == 6 /* Mac len */)
|| (packet->payload[8] == 4 /* Wireless len */)
|| ((msg_len+15) == packet->payload_packet_len))
goto capwap_found;
}
}
NDPI_EXCLUDE_PROTO(ndpi_struct, flow);
return;
capwap_found:
ndpi_int_capwap_add_connection(ndpi_struct, flow);
}
void ndpi_search_capwap(struct ndpi_detection_module_struct *ndpi_struct, struct ndpi_flow_struct *flow)
{
struct ndpi_packet_struct *packet = &ndpi_struct->packet;
if(packet->udp && (flow->detected_protocol_stack[0] == NDPI_PROTOCOL_UNKNOWN))
ndpi_search_setup_capwap(ndpi_struct, flow);
}
void init_capwap_dissector(struct ndpi_detection_module_struct *ndpi_struct,
u_int32_t *id, NDPI_PROTOCOL_BITMASK *detection_bitmask)
{
ndpi_set_bitmask_protocol_detection("CAPWAP", ndpi_struct, detection_bitmask, *id,
NDPI_PROTOCOL_CAPWAP,
ndpi_search_capwap,
NDPI_SELECTION_BITMASK_PROTOCOL_V4_V6_UDP_WITH_PAYLOAD,
SAVE_DETECTION_BITMASK_AS_UNKNOWN,
ADD_TO_DETECTION_BITMASK);
*id += 1;
}
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