Improved dnscrypt v1/v2 protocol detection.

Signed-off-by: Toni Uhlig <matzeton@googlemail.com>

4 files changed, 74 insertions, 1 deletions

diff --git a/src/include/ndpi_protocol_ids.h b/src/include/ndpi_protocol_ids.h
index 07f444e8e..317c36b44 100644
--- a/src/include/ndpi_protocol_ids.h
+++ b/src/include/ndpi_protocol_ids.h
@@ -237,7 +237,7 @@ typedef enum {
   NDPI_PROTOCOL_FREE_205              = 205,
   NDPI_PROTOCOL_WIREGUARD             = 206,
   NDPI_PROTOCOL_SMPP                  = 207, /* Damir Franusic <df@release14.org> */
-  NDPI_PROTOCOL_DNSCRYPT              = 208,
+  NDPI_PROTOCOL_DNSCRYPT              = 208, /* Toni Uhlig <matzeton@googlemail.com> */
   NDPI_PROTOCOL_TINC                  = 209, /* William Guglielmo <william@deselmo.com> */
   NDPI_PROTOCOL_DEEZER                = 210,
   NDPI_PROTOCOL_INSTAGRAM             = 211, /* Andrea Buscarinu <andrea.buscarinu@gmail.com> */
diff --git a/src/include/ndpi_protocols.h b/src/include/ndpi_protocols.h
index 392abf9e1..e0ea5a906 100644
--- a/src/include/ndpi_protocols.h
+++ b/src/include/ndpi_protocols.h
@@ -214,5 +214,6 @@ void init_104_dissector(struct ndpi_detection_module_struct *ndpi_struct, u_int3
 void init_s7comm_dissector(struct ndpi_detection_module_struct *ndpi_struct,u_int32_t *id, NDPI_PROTOCOL_BITMASK *detection_bitmask);
 void init_websocket_dissector(struct ndpi_detection_module_struct *ndpi_struct, u_int32_t *id, NDPI_PROTOCOL_BITMASK *detection_bitmask);
 void init_soap_dissector(struct ndpi_detection_module_struct *ndpi_struct, u_int32_t *id, NDPI_PROTOCOL_BITMASK *detection_bitmask);
+void init_dnscrypt_dissector(struct ndpi_detection_module_struct *ndpi_struct, u_int32_t *id, NDPI_PROTOCOL_BITMASK *detection_bitmask);
 
 #endif /* __NDPI_PROTOCOLS_H__ */
diff --git a/src/lib/ndpi_main.c b/src/lib/ndpi_main.c
index efd8a18a5..564f8978d 100644
--- a/src/lib/ndpi_main.c
+++ b/src/lib/ndpi_main.c
@@ -3358,6 +3358,9 @@ void ndpi_set_protocol_detection_bitmask2(struct ndpi_detection_module_struct *n
   /* SOAP */
   init_soap_dissector(ndpi_str, &a, detection_bitmask);
 
+  /* DNScrypt */
+  init_dnscrypt_dissector(ndpi_str, &a, detection_bitmask);
+
 #ifdef CUSTOM_NDPI_PROTOCOLS
 #include "../../../nDPI-custom/custom_ndpi_main_init.c"
 #endif
diff --git a/src/lib/protocols/dnscrypt.c b/src/lib/protocols/dnscrypt.c
new file mode 100644
index 000000000..6c89466f1
--- /dev/null
+++ b/src/lib/protocols/dnscrypt.c
@@ -0,0 +1,69 @@
+/*
+ * dnscrypt.c
+ *
+ * Copyright (C) 2020 - 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_DNSCRYPT
+
+#include "ndpi_api.h"
+
+static void ndpi_int_dnscrypt_add_connection(struct ndpi_detection_module_struct *ndpi_struct,
+                                             struct ndpi_flow_struct *flow)
+{
+  ndpi_set_detected_protocol(ndpi_struct, flow, NDPI_PROTOCOL_DNSCRYPT, NDPI_PROTOCOL_UNKNOWN);
+}
+
+void ndpi_search_dnscrypt(struct ndpi_detection_module_struct *ndpi_struct,
+                          struct ndpi_flow_struct *flow)
+{
+  struct ndpi_packet_struct *packet = &flow->packet;
+  static char const * const dnscrypt_initial = "2\rdnscrypt";
+
+  NDPI_LOG_DBG(ndpi_struct, "search dnscrypt\n");
+
+  if (flow->packet_counter > 2)
+  {
+    NDPI_EXCLUDE_PROTO(ndpi_struct, flow);
+  }
+
+  /* dnscrypt protocol version 1: check magic */
+  if (packet->payload_packet_len >= 64 &&
+      strncmp((char*)packet->payload, "r6fnvWj8", strlen("r6fnvWj8")) == 0)
+  {
+    ndpi_int_dnscrypt_add_connection(ndpi_struct, flow);
+  }
+  /* dnscrypt protocol version 1 and 2: resolver ping */
+  if (packet->payload_packet_len > 13 + strlen(dnscrypt_initial) &&
+      strncasecmp((char*)packet->payload + 13, dnscrypt_initial, strlen(dnscrypt_initial)) == 0)
+  {
+    ndpi_int_dnscrypt_add_connection(ndpi_struct, flow);
+  }
+}
+
+void init_dnscrypt_dissector(struct ndpi_detection_module_struct *ndpi_struct, u_int32_t *id,
+                             NDPI_PROTOCOL_BITMASK *detection_bitmask)
+{
+  ndpi_set_bitmask_protocol_detection(
+    "DNScrypt", ndpi_struct, detection_bitmask, *id,
+    NDPI_PROTOCOL_DNSCRYPT, ndpi_search_dnscrypt, NDPI_SELECTION_BITMASK_PROTOCOL_V4_V6_TCP_OR_UDP_WITH_PAYLOAD,
+    SAVE_DETECTION_BITMASK_AS_UNKNOWN, ADD_TO_DETECTION_BITMASK);
+  *id += 1;
+}
+