Add a dedicated dissector for Zoom (#2265)

Move it from the RTP code and extend it

4 files changed, 186 insertions, 106 deletions

diff --git a/src/include/ndpi_private.h b/src/include/ndpi_private.h
index 7a56d1c4a..21fb11c38 100644
--- a/src/include/ndpi_private.h
+++ b/src/include/ndpi_private.h
@@ -723,6 +723,7 @@ void init_roughtime_dissector(struct ndpi_detection_module_struct *ndpi_struct,
 void init_kcp_dissector(struct ndpi_detection_module_struct *ndpi_struct, u_int32_t *id);
 void init_valve_sdr_dissector(struct ndpi_detection_module_struct *ndpi_struct, u_int32_t *id);
 void init_mumble_dissector(struct ndpi_detection_module_struct *ndpi_struct, u_int32_t *id);
+void init_zoom_dissector(struct ndpi_detection_module_struct *ndpi_struct, u_int32_t *id);
 
 #endif
 
diff --git a/src/lib/ndpi_main.c b/src/lib/ndpi_main.c
index 2d3eaf261..93060a2e5 100644
--- a/src/lib/ndpi_main.c
+++ b/src/lib/ndpi_main.c
@@ -5872,6 +5872,9 @@ static int ndpi_callback_init(struct ndpi_detection_module_struct *ndpi_str) {
   /* Mumble */
   init_mumble_dissector(ndpi_str, &a);
 
+  /* Zoom */
+  init_zoom_dissector(ndpi_str, &a);
+
 #ifdef CUSTOM_NDPI_PROTOCOLS
 #include "../../../nDPI-custom/custom_ndpi_main_init.c"
 #endif
diff --git a/src/lib/protocols/rtp.c b/src/lib/protocols/rtp.c
index 7977f79a8..b88c6afcd 100644
--- a/src/lib/protocols/rtp.c
+++ b/src/lib/protocols/rtp.c
@@ -84,90 +84,6 @@ static int is_valid_rtcp_payload_type(uint8_t type)
   return (type >= 192 && type <= 213);
 }
 
-/* *************************************************************** */
-
-/*
-  https://github.com/Princeton-Cabernet/zoom-analysis
-  https://citizenlab.ca/2020/04/move-fast-roll-your-own-crypto-a-quick-look-at-the-confidentiality-of-zoom-meetings/
-  https://github.com/marty90/rtc_pcap_cleaners
- */
-
-PACK_ON struct zoom_sfu_encapsulation {
-  u_int8_t  sfu_type; /* 3/4 = Zoom_0, 5 = RTCP/RTP */
-  u_int16_t sequence_num;
-  u_int32_t unknown;
-  u_int8_t  direction; /* 0 = -> Zoom, 4 = <- Zoom */
-} PACK_OFF;
-
-PACK_ON struct zoom_media_encapsulation {
-  u_int8_t  enc_type; /* 13/30 = Screen Share, 15 = Audio, 16 = Video, 33/34/35 = RTCP  */
-  u_int32_t unknown_1, unknown_2;
-  u_int16_t sequence_num;
-  u_int32_t timestamp;
-} PACK_OFF;
-
-#define ZOOM_PORT 8801
-
-static u_int8_t isZoom(struct ndpi_flow_struct *flow,
-		       u_int16_t sport, u_int16_t dport,
-		       const u_int8_t *payload, const u_int16_t payloadLen,
-		       u_int8_t *is_rtp, u_int8_t *zoom_stream_type,
-		       u_int16_t *payload_offset) {
-  u_int16_t header_offset = sizeof(struct zoom_sfu_encapsulation) + sizeof(struct zoom_media_encapsulation);
-
-  *payload_offset = 0;
-  if(payloadLen < header_offset)
-    return(0);
-
-  if((sport == ZOOM_PORT) || (dport == ZOOM_PORT)) {
-    struct zoom_sfu_encapsulation *enc = (struct zoom_sfu_encapsulation*)payload;
-
-    /* printf("==> %u <-> %u [type: %u]\n", sport, dport, enc->sfu_type); */
-
-    if((enc->sfu_type >= 3) && (enc->sfu_type <= 5)) {
-      struct zoom_media_encapsulation *enc = (struct zoom_media_encapsulation*)(&payload[sizeof(struct zoom_sfu_encapsulation)]);
-
-      *zoom_stream_type = enc->enc_type;
-      
-      switch(enc->enc_type) {
-      case 13: /* Screen Share */
-      case 30: /* Screen Share */
-	*is_rtp = 0;
-	*payload_offset = 27;
-	flow->flow_multimedia_type = ndpi_multimedia_screen_sharing_flow;
-	break;
-	
-      case 15: /* Audio */
-	*is_rtp = 1;
-	*payload_offset = 27;
-	flow->flow_multimedia_type = ndpi_multimedia_audio_flow;
-	break;
-	
-      case 16: /* Video */
-	*is_rtp = 1;
-	*payload_offset = 32;
-	flow->flow_multimedia_type = ndpi_multimedia_video_flow;
-	break;
-
-      case 33: /* RTCP */
-      case 34: /* RTCP */
-      case 35: /* RTCP */
-	*is_rtp = 1;
-	*payload_offset = 36;
-	break;
-
-      default:
-	*is_rtp = 0;
-	break;
-      }
-      
-      return(1);
-    }
-  }
-
-  return(0);
-}
-
 int is_rtp_or_rtcp(struct ndpi_detection_module_struct *ndpi_struct,
 		   struct ndpi_flow_struct *flow)
 {
@@ -230,11 +146,10 @@ int is_rtp_or_rtcp(struct ndpi_detection_module_struct *ndpi_struct,
 
 static void ndpi_rtp_search(struct ndpi_detection_module_struct *ndpi_struct,
 			    struct ndpi_flow_struct *flow) {
-  u_int8_t is_rtp, zoom_stream_type;
-  u_int16_t s_port = ntohs(ndpi_struct->packet.udp->source), d_port = ntohs(ndpi_struct->packet.udp->dest), payload_offset;
+  u_int8_t is_rtp;
+  u_int16_t d_port = ntohs(ndpi_struct->packet.udp->dest);
   struct ndpi_packet_struct *packet = &ndpi_struct->packet;
   const u_int8_t *payload = packet->payload;
-  const u_int16_t payload_len = packet->payload_packet_len;
 
   NDPI_LOG_DBG(ndpi_struct, "search RTP\n");
 
@@ -245,25 +160,6 @@ static void ndpi_rtp_search(struct ndpi_detection_module_struct *ndpi_struct,
     return;
   }
 
-  /* TODO: should we move zoom stuff in a new, separated dissector? */
-  if(isZoom(flow, s_port, d_port, payload, payload_len,
-	    &is_rtp, &zoom_stream_type, &payload_offset)) {
-    if(payload_offset < payload_len) {
-      /*
-	payload_len -= payload_offset;
-	payload = &payload[payload_offset];
-      */
-
-      /* printf("->>> %u\n", zoom_stream_type); */
-      
-      ndpi_set_detected_protocol(ndpi_struct, flow, 
-				 NDPI_PROTOCOL_ZOOM,
-				 NDPI_PROTOCOL_SRTP,
-				 NDPI_CONFIDENCE_DPI);
-      return;
-    }
-  }
-
   /* * Let some "unknown" packets at the beginning
      * search for 3 consecutive RTP/RTCP packets
    */
diff --git a/src/lib/protocols/zoom.c b/src/lib/protocols/zoom.c
new file mode 100644
index 000000000..630068d08
--- /dev/null
+++ b/src/lib/protocols/zoom.c
@@ -0,0 +1,180 @@
+/*
+ * zoom.c
+ *
+ * Copyright (C) 2024 - 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_ZOOM
+
+#include "ndpi_api.h"
+#include "ndpi_private.h"
+
+/*
+  https://github.com/Princeton-Cabernet/zoom-analysis
+  https://citizenlab.ca/2020/04/move-fast-roll-your-own-crypto-a-quick-look-at-the-confidentiality-of-zoom-meetings/
+  https://github.com/marty90/rtc_pcap_cleaners
+ */
+
+PACK_ON struct zoom_sfu_enc { /* Zoom SFU encapsulation */
+  u_int8_t  sfu_type; /* 3/4 = Zoom_0, 5 = RTCP/RTP */
+  u_int16_t sequence_num;
+  u_int32_t unknown;
+  u_int8_t  direction; /* 0 = -> Zoom, 4 = <- Zoom */
+} PACK_OFF;
+
+PACK_ON struct zoom_media_enc { /* Zoom media encapsulation */
+  u_int8_t  enc_type; /* 13/30 = Screen Share, 15 = Audio, 16 = Video, 33/34/35 = RTCP  */
+  u_int32_t unknown_1, unknown_2;
+  u_int16_t sequence_num;
+  u_int32_t timestamp;
+} PACK_OFF;
+
+static int zoom_search_again(struct ndpi_detection_module_struct *ndpi_struct,
+                             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) {
+  NDPI_LOG_INFO(ndpi_struct, "found Zoom\n");
+  ndpi_set_detected_protocol(ndpi_struct, flow, NDPI_PROTOCOL_ZOOM, master, NDPI_CONFIDENCE_DPI);
+
+  /* Keep looking for RTP if we are at the beginning of the flow (SFU 1 or 2).
+   * It is similar to the STUN logic... */
+  if(master == NDPI_PROTOCOL_UNKNOWN) {
+    flow->max_extra_packets_to_check = 4;
+    flow->extra_packets_func = zoom_search_again;
+  }
+}
+
+static int is_zoom_port(struct ndpi_flow_struct *flow)
+{
+  /* https://support.zoom.com/hc/en/article?id=zm_kb&sysparm_article=KB0060548 */
+  if((ntohs(flow->c_port) >= 8801 && ntohs(flow->c_port) <= 8810) ||
+     (ntohs(flow->s_port) >= 8801 && ntohs(flow->s_port) <= 8810))
+    return 1;
+  return 0;
+}
+
+static int is_sfu_5(struct ndpi_detection_module_struct *ndpi_struct,
+                    struct ndpi_flow_struct *flow)
+{
+  struct ndpi_packet_struct *packet = &ndpi_struct->packet;
+
+  /* SFU types 5 */
+  if(packet->payload[0] == 0x05 &&
+     packet->payload_packet_len > sizeof(struct zoom_sfu_enc) +
+                                  sizeof(struct zoom_media_enc)) {
+    struct zoom_media_enc *enc = (struct zoom_media_enc *)&packet->payload[sizeof(struct zoom_sfu_enc)];
+
+    switch(enc->enc_type) {
+    case 13: /* Screen Share */
+    case 30: /* Screen Share */
+      if(packet->payload_packet_len >= 27) {
+        flow->flow_multimedia_type = ndpi_multimedia_screen_sharing_flow;
+        return 1;
+      }
+      break;
+
+    case 15: /* RTP Audio */
+      if(packet->payload_packet_len >= 27) {
+        flow->flow_multimedia_type = ndpi_multimedia_audio_flow;
+        return 1;
+      }
+      break;
+
+    case 16: /* RTP Video */
+      if(packet->payload_packet_len >= 32) {
+        flow->flow_multimedia_type = ndpi_multimedia_video_flow;
+        return 1;
+      }
+      break;
+
+    case 33: /* RTCP */
+    case 34: /* RTCP */
+    case 35: /* RTCP */
+      if(packet->payload_packet_len >= 36) {
+        return 1;
+      }
+      break;
+
+    default:
+      return 1;
+    }
+  }
+  return 0;
+}
+
+static int zoom_search_again(struct ndpi_detection_module_struct *ndpi_struct,
+                             struct ndpi_flow_struct *flow)
+{
+  if(is_sfu_5(ndpi_struct, flow)) {
+    ndpi_int_zoom_add_connection(ndpi_struct, flow, NDPI_PROTOCOL_SRTP);
+    return 0; /* Stop */
+  }
+  return 1; /* Keep looking */
+}
+
+static void ndpi_search_zoom(struct ndpi_detection_module_struct *ndpi_struct,
+			     struct ndpi_flow_struct *flow) {
+  struct ndpi_packet_struct *packet = &ndpi_struct->packet;
+  u_int8_t tomatch[] = { 0x01, 0x00, 0x03 };  /* Usually first pkt from the client */
+  u_int8_t tomatch_a[] = { 0x01, 0x00, 0x02 };  /* Other first pkt from the client */
+  u_int8_t tomatch2[] = { 0x02, 0x00, 0x03 }; /* Usually first pkt from the server: useful with asymmetric traffic */
+  u_int8_t tomatch2_a[] = { 0x02, 0x00, 0x02 }; /* Other first pkt from the server */
+
+  NDPI_LOG_DBG(ndpi_struct, "search Zoom\n");
+
+  if(is_zoom_port(flow) &&
+     packet->payload_packet_len > sizeof(struct zoom_sfu_enc)) {
+    /* SFU types 1 and 2 */
+    if(memcmp(packet->payload, tomatch, 3) == 0 ||
+       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);
+      return;
+
+    /* SFU types 3 and 4. This check is quite weak but these packets are rare.
+       Wait for other kind of traffic */
+    } else if((packet->payload[0] == 0x03 || packet->payload[0] == 0x04) &&
+              flow->packet_counter < 3) {
+      return;
+
+    /* SFU types 5 */
+    } else if(is_sfu_5(ndpi_struct, flow)) {
+      ndpi_int_zoom_add_connection(ndpi_struct, flow, NDPI_PROTOCOL_SRTP);
+      return;
+    }
+  }
+
+  NDPI_EXCLUDE_PROTO(ndpi_struct, flow);
+}
+
+/* *************************************************** */
+
+void init_zoom_dissector(struct ndpi_detection_module_struct *ndpi_struct, u_int32_t *id) {
+  ndpi_set_bitmask_protocol_detection("Zoom", ndpi_struct, *id,
+				      NDPI_PROTOCOL_ZOOM,
+				      ndpi_search_zoom,
+				      NDPI_SELECTION_BITMASK_PROTOCOL_V4_V6_UDP_WITH_PAYLOAD,
+				      SAVE_DETECTION_BITMASK_AS_UNKNOWN,
+				      ADD_TO_DETECTION_BITMASK);
+
+  *id += 1;
+}