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Zoom: fix detection of screen sharing #2476

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Jun 17, 2024
Merged

Zoom: fix detection of screen sharing #2476

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38 changes: 26 additions & 12 deletions src/lib/protocols/zoom.c
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Original file line number Diff line number Diff line change
Expand Up @@ -50,8 +50,14 @@ static int zoom_search_again(struct ndpi_detection_module_struct *ndpi_struct,
static int keep_extra_dissection(struct ndpi_flow_struct *flow);

static void ndpi_int_zoom_add_connection(struct ndpi_detection_module_struct *ndpi_struct,
struct ndpi_flow_struct *flow,
u_int16_t master) {
struct ndpi_flow_struct *flow) {
u_int16_t master;

if(flow->flow_multimedia_type != ndpi_multimedia_unknown_flow)
master = NDPI_PROTOCOL_SRTP;
else
master = NDPI_PROTOCOL_UNKNOWN;

NDPI_LOG_INFO(ndpi_struct, "found Zoom\n");
ndpi_set_detected_protocol(ndpi_struct, flow, NDPI_PROTOCOL_ZOOM, master, NDPI_CONFIDENCE_DPI);

Expand Down Expand Up @@ -82,10 +88,18 @@ static int is_zme(struct ndpi_detection_module_struct *ndpi_struct,
struct zoom_media_enc *enc = (struct zoom_media_enc *)payload;

switch(enc->enc_type) {
case 13: /* Screen Share */
case 30: /* Screen Share */
if(payload_len > 27 &&
is_rtp_or_rtcp(ndpi_struct, payload + 27, payload_len - 27, NULL) == IS_RTP) {
case 13: /* Screen Share: RTP is not always there, expecially at the beginning of the flow */
if(payload_len > 27) {
if(is_rtp_or_rtcp(ndpi_struct, payload + 27, payload_len - 27, NULL) == IS_RTP) {
flow->flow_multimedia_type = ndpi_multimedia_screen_sharing_flow;
}
return 1;
}
break;

case 30: /* P2P Screen Share: it seems RTP is always present */
if(payload_len > 20 &&
is_rtp_or_rtcp(ndpi_struct, payload + 20, payload_len - 20, NULL) == IS_RTP) {
flow->flow_multimedia_type = ndpi_multimedia_screen_sharing_flow;
return 1;
}
Expand Down Expand Up @@ -150,11 +164,11 @@ static int zoom_search_again(struct ndpi_detection_module_struct *ndpi_struct,

if(!flow->l4.udp.zoom_p2p &&
is_sfu_5(ndpi_struct, flow)) {
ndpi_int_zoom_add_connection(ndpi_struct, flow, NDPI_PROTOCOL_SRTP);
ndpi_int_zoom_add_connection(ndpi_struct, flow);
}
if(flow->l4.udp.zoom_p2p &&
is_zme(ndpi_struct, flow, packet->payload, packet->payload_packet_len)) {
ndpi_int_zoom_add_connection(ndpi_struct, flow, NDPI_PROTOCOL_SRTP);
ndpi_int_zoom_add_connection(ndpi_struct, flow);
}

return keep_extra_dissection(flow);
Expand All @@ -178,20 +192,20 @@ static void ndpi_search_zoom(struct ndpi_detection_module_struct *ndpi_struct,
memcmp(packet->payload, tomatch_a, 3) == 0 ||
memcmp(packet->payload, tomatch2, 3) == 0 ||
memcmp(packet->payload, tomatch2_a, 3) == 0) {
ndpi_int_zoom_add_connection(ndpi_struct, flow, NDPI_PROTOCOL_UNKNOWN);
ndpi_int_zoom_add_connection(ndpi_struct, flow);
return;

/* SFU types 3 and 4. This check is quite weak: let give time to the other
dissectors to kick in */
} else if((packet->payload[0] == 0x03 || packet->payload[0] == 0x04)) {
if(flow->packet_counter < 4)
return;
ndpi_int_zoom_add_connection(ndpi_struct, flow, NDPI_PROTOCOL_UNKNOWN);
ndpi_int_zoom_add_connection(ndpi_struct, flow);
return;

/* SFU types 5 */
} else if(is_sfu_5(ndpi_struct, flow)) {
ndpi_int_zoom_add_connection(ndpi_struct, flow, NDPI_PROTOCOL_SRTP);
ndpi_int_zoom_add_connection(ndpi_struct, flow);
return;
}
} else if(packet->payload_packet_len > 36 &&
Expand Down Expand Up @@ -219,7 +233,7 @@ static void ndpi_search_zoom(struct ndpi_detection_module_struct *ndpi_struct,
if(packet->payload_packet_len == 24 + 4 + ip_len + 4 + uuid_len + 4) {
NDPI_LOG_DBG(ndpi_struct, "found P2P Zoom\n");
flow->l4.udp.zoom_p2p = 1;
ndpi_int_zoom_add_connection(ndpi_struct, flow, NDPI_PROTOCOL_UNKNOWN);
ndpi_int_zoom_add_connection(ndpi_struct, flow);
return;
}
}
Expand Down
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