Add support for WireGuard VPN

1 files changed, 109 insertions, 0 deletions

diff --git a/src/lib/protocols/wireguard.c b/src/lib/protocols/wireguard.c
new file mode 100644
index 000000000..3c8b457fd
--- /dev/null
+++ b/src/lib/protocols/wireguard.c
@@ -0,0 +1,109 @@
+/*
+ * wireguard.c
+ *
+ * Copyright (C) 2019 - ntop.org
+ * Copyright (C) 2019 - Yağmur Oymak
+ *
+ * This file is part of nDPI, an open source deep packet inspection
+ * library based on the OpenDPI and PACE technology by ipoque GmbH
+ *
+ * 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_WIREGUARD
+
+#include "ndpi_api.h"
+
+/*
+ * TODO: Detection mechanism can be improved by taking the properties
+ * of specific message types into account. For example:
+ *  - Handshake messages have a fixed size.
+ *  - Counter field is an integer that is incremented with each packet.
+ *  - Receiver/sender index fields.
+ * etc. (https://lists.zx2c4.com/pipermail/wireguard/2016-July/000185.html)
+ * Exploiting these properties may reduce the probability of false positives;
+ * with the tradeoff of requiring the inspection of multiple packets.
+ *
+ * Current approach identifies the protocol with a single packet and
+ * does not yield false positives in any of the existing tests.
+ */
+
+/*
+ * See https://www.wireguard.com/protocol/ for protocol reference.
+ */
+void ndpi_search_wireguard(struct ndpi_detection_module_struct
+			   *ndpi_struct, struct ndpi_flow_struct *flow)
+{
+  struct ndpi_packet_struct *packet = &flow->packet;
+  const u_int8_t *payload = packet->payload;
+  /*
+   * The first byte of the payload is the message type.
+   */
+  u_int8_t message_type = payload[0];
+
+  NDPI_LOG_DBG(ndpi_struct, "search WireGuard\n");
+  /*
+   * A transport packet contains at minimum the following fields:
+   *  u8 message_type
+   *  u8 reserved_zero[3]
+   *  u32 receiver_index
+   *  u64 counter
+   *  u8 encrypted_encapsulated_packet[]
+   * In the case of a keepalive message, the encapsulated packet will have
+   * zero length, but will still have a 16 byte poly1305 authentication tag.
+   * Thus, packet->payload will be at least 32 bytes in size.
+   * Note that handshake packets have a slightly different structure, but they are larger.
+   */
+  if (packet->payload_packet_len < 32) {
+    NDPI_EXCLUDE_PROTO(ndpi_struct, flow);
+    return;
+  }
+  /*
+   * The next three bytes after the message type are reserved and set to zero.
+   */
+  if (payload[1] != 0 || payload[2] != 0 || payload[3] != 0) {
+    NDPI_EXCLUDE_PROTO(ndpi_struct, flow);
+    return;
+  }
+  /*
+   * Message type can have one of the following values:
+   * 1) Handshake Initiation
+   * 2) Handshake Response
+   * 3) Cookie Reply
+   * 4) Transport Data
+   */
+  if (message_type == 0 || message_type > 4) {
+    NDPI_EXCLUDE_PROTO(ndpi_struct, flow);
+    return;
+  }
+
+  ndpi_set_detected_protocol(ndpi_struct, flow, NDPI_PROTOCOL_WIREGUARD, NDPI_PROTOCOL_UNKNOWN);
+  return;
+}
+
+void init_wireguard_dissector(struct ndpi_detection_module_struct *ndpi_struct, u_int32_t *id, NDPI_PROTOCOL_BITMASK *detection_bitmask)
+{
+  ndpi_set_bitmask_protocol_detection("WireGuard", ndpi_struct, detection_bitmask, *id,
+				      NDPI_PROTOCOL_WIREGUARD,
+				      ndpi_search_wireguard,
+				      NDPI_SELECTION_BITMASK_PROTOCOL_V4_V6_UDP_WITH_PAYLOAD,
+				      SAVE_DETECTION_BITMASK_AS_UNKNOWN,
+				      ADD_TO_DETECTION_BITMASK);
+
+  *id += 1;
+}
+