Initial import from SVN

1 files changed, 122 insertions, 0 deletions

diff --git a/src/lib/protocols/skype.c b/src/lib/protocols/skype.c
new file mode 100644
index 000000000..8d2a3a72b
--- /dev/null
+++ b/src/lib/protocols/skype.c
@@ -0,0 +1,122 @@
+/*
+ * skype.c
+ *
+ * Copyright (C) 2011-15 - 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_api.h"
+
+#ifdef NDPI_PROTOCOL_SKYPE
+
+
+static u_int8_t is_skype_host(struct ndpi_detection_module_struct *ndpi_struct, u_int32_t host) {
+  struct in_addr pin;
+  
+  pin.s_addr = host;
+  
+  return((ndpi_network_ptree_match(ndpi_struct, &pin) == NDPI_PROTOCOL_SKYPE) ? 1 : 0);
+}
+
+u_int8_t is_skype_flow(struct ndpi_detection_module_struct *ndpi_struct,
+		       struct ndpi_flow_struct *flow) {
+  struct ndpi_packet_struct *packet = &flow->packet;
+	
+  if(packet->iph) {
+    /*
+      Skype connections are identified by some SSL-like communications
+      without SSL certificate being exchanged
+    */	
+    if(is_skype_host(ndpi_struct, ntohl(packet->iph->saddr))
+       || is_skype_host(ndpi_struct, ntohl(packet->iph->daddr))) {
+      return(1);
+    }
+  }
+
+  return(0);
+}
+
+static void ndpi_check_skype(struct ndpi_detection_module_struct *ndpi_struct, struct ndpi_flow_struct *flow)
+{
+  struct ndpi_packet_struct *packet = &flow->packet;
+  // const u_int8_t *packet_payload = packet->payload;
+  u_int32_t payload_len = packet->payload_packet_len;
+
+  /*
+    Skype AS8220
+    212.161.8.0/24
+  */
+  if(is_skype_flow(ndpi_struct, flow)) {
+    ndpi_int_add_connection(ndpi_struct, flow, NDPI_PROTOCOL_SKYPE, NDPI_REAL_PROTOCOL);
+    return;
+  }
+
+  if(packet->udp != NULL) {
+    flow->l4.udp.skype_packet_id++;
+
+    if(flow->l4.udp.skype_packet_id < 5) {
+      /* skype-to-skype */
+      if(((payload_len == 3) && ((packet->payload[2] & 0x0F)== 0x0d))
+	 || ((payload_len >= 16)
+	     && (packet->payload[0] != 0x30) /* Avoid invalid SNMP detection */
+	     && (packet->payload[2] == 0x02))) {
+	NDPI_LOG(NDPI_PROTOCOL_SKYPE, ndpi_struct, NDPI_LOG_DEBUG, "Found skype.\n");
+	ndpi_int_add_connection(ndpi_struct, flow, NDPI_PROTOCOL_SKYPE, NDPI_REAL_PROTOCOL);
+      }
+
+      return;
+    }
+
+    NDPI_ADD_PROTOCOL_TO_BITMASK(flow->excluded_protocol_bitmask, NDPI_PROTOCOL_SKYPE);
+    return;
+  } else if(packet->tcp != NULL) {
+    flow->l4.tcp.skype_packet_id++;
+
+    if(flow->l4.tcp.skype_packet_id < 3) {
+      ; /* Too early */
+    } else if((flow->l4.tcp.skype_packet_id == 3)
+	      /* We have seen the 3-way handshake */
+	      && flow->l4.tcp.seen_syn
+	      && flow->l4.tcp.seen_syn_ack
+	      && flow->l4.tcp.seen_ack) {
+      if((payload_len == 8) || (payload_len == 3)) {
+	//printf("[SKYPE] %u/%u\n", ntohs(packet->tcp->source), ntohs(packet->tcp->dest));
+
+	NDPI_LOG(NDPI_PROTOCOL_SKYPE, ndpi_struct, NDPI_LOG_DEBUG, "Found skype.\n");
+	ndpi_int_add_connection(ndpi_struct, flow, NDPI_PROTOCOL_SKYPE, NDPI_REAL_PROTOCOL);
+      }
+
+      /* printf("[SKYPE] [id: %u][len: %d]\n", flow->l4.tcp.skype_packet_id, payload_len);  */
+    } else
+      NDPI_ADD_PROTOCOL_TO_BITMASK(flow->excluded_protocol_bitmask, NDPI_PROTOCOL_SKYPE);
+
+    return;
+  }
+}
+
+void ndpi_search_skype(struct ndpi_detection_module_struct *ndpi_struct, struct ndpi_flow_struct *flow)
+{
+  struct ndpi_packet_struct *packet = &flow->packet;
+
+  NDPI_LOG(NDPI_PROTOCOL_SKYPE, ndpi_struct, NDPI_LOG_DEBUG, "skype detection...\n");
+
+  /* skip marked packets */
+  if(packet->detected_protocol_stack[0] != NDPI_PROTOCOL_SKYPE)
+    ndpi_check_skype(ndpi_struct, flow);
+}
+
+#endif