1 files changed, 120 insertions, 0 deletions
diff --git a/src/lib/protocols/fins.c b/src/lib/protocols/fins.c
new file mode 100644
index 000000000..980697e33
--- /dev/null
+++ b/src/lib/protocols/fins.c
@@ -0,0 +1,120 @@
+/*
+ * fins.c
+ *
+ * Factory Interface Network Service
+ *
+ * Copyright (C) 2023 - ntop.org
+ * Copyright (C) V.G <jacendi@protonmail.com>
+ *
+ * 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_FINS
+
+#include "ndpi_api.h"
+#include "ndpi_private.h"
+
+struct fins_hdr {
+  u_int8_t icf; /* Information Control Field */
+  u_int8_t rsv; /* Reserved, must be set to 0 */
+  u_int8_t gct; /* Permissible number of gateways */
+  u_int8_t dna; /* Destination network address */
+  u_int8_t da1; /* Destination node address */
+  u_int8_t da2; /* Destination unit address */
+  u_int8_t sna; /* Source network address */
+  u_int8_t sa1; /* Source node address */
+  u_int8_t sa2; /* Source unit address */
+  u_int8_t sid; /* Service ID */
+};
+
+static void ndpi_int_fins_add_connection(struct ndpi_detection_module_struct * const ndpi_struct,
+                                         struct ndpi_flow_struct * const flow)
+{
+  ndpi_set_detected_protocol(ndpi_struct, flow,
+                             NDPI_PROTOCOL_FINS,
+                             NDPI_PROTOCOL_UNKNOWN,
+                             NDPI_CONFIDENCE_DPI);
+}
+
+static void ndpi_search_fins(struct ndpi_detection_module_struct *ndpi_struct,
+                             struct ndpi_flow_struct *flow)
+{
+  struct ndpi_packet_struct const * const packet = &ndpi_struct->packet;
+  
+  /* FINS/TCP header is 20 bytes long, but it's usually followed
+   * by 10 byte FINS header and command data
+   */
+  if (packet->tcp != NULL && packet->payload_packet_len >= 20) {
+    /* The FINS/TCP header always contains the
+     * 4 byte ASCII magic value 'FINS'
+     */
+    if (memcmp(packet->payload, "FINS", 4) == 0) {
+      NDPI_LOG_INFO(ndpi_struct, "found FINS over TCP\n");
+      ndpi_int_fins_add_connection(ndpi_struct, flow);
+      return;
+    }
+  } else if ((packet->udp != NULL) &&
+             (packet->payload_packet_len > sizeof(struct fins_hdr)))
+  {
+    struct fins_hdr const * const fins = (struct fins_hdr *)packet->payload;
+
+    /* 0x80 - command, response required
+     * 0xC0 - response, response not required
+     * 0xC1 - response, response required
+     */
+    if ((fins->icf != 0x80) && (fins->icf != 0xC0) && 
+        (fins->icf != 0xC1))
+    {
+      goto not_fins;
+    }
+    
+    if ((fins->dna > 0x7F) || (fins->sna > 0x7F)) {
+      goto not_fins;
+    }
+
+    if ((fins->da2 == 0x00) || (fins->da2 == 0xFE) ||
+        (fins->da2 == 0xE1) || ((fins->da2 >= 0x10) && 
+        (fins->da2 <= 0x1F)))
+    {
+      if ((fins->sa2 == 0x00) || (fins->sa2 == 0xFE) ||
+          (fins->sa2 == 0xE1) || ((fins->sa2 >= 0x10) && 
+          (fins->sa2 <= 0x1F)))
+      {
+        NDPI_LOG_INFO(ndpi_struct, "found FINS over UDP\n");
+        ndpi_int_fins_add_connection(ndpi_struct, flow);
+        return;
+      }
+    }
+  }
+
+not_fins:
+  NDPI_EXCLUDE_PROTO(ndpi_struct, flow);
+}
+
+void init_fins_dissector(struct ndpi_detection_module_struct *ndpi_struct,
+                                  u_int32_t *id)
+{
+  ndpi_set_bitmask_protocol_detection("FINS", ndpi_struct, *id,
+                                      NDPI_PROTOCOL_FINS,
+                                      ndpi_search_fins,
+                                      NDPI_SELECTION_BITMASK_PROTOCOL_V4_V6_TCP_OR_UDP_WITH_PAYLOAD_WITHOUT_RETRANSMISSION,
+                                      SAVE_DETECTION_BITMASK_AS_UNKNOWN,
+                                      ADD_TO_DETECTION_BITMASK
+                                     );
+
+  *id += 1;
+}