Add defragmenter example

examples/CMakeLists.txt

@@ -37,13 +37,15 @@ ADD_CUSTOM_TARGET(
     beacon_display
     portscan
     route_table
+    defragmenter
 )
 
 # Make sure we first build libtins
 ADD_DEPENDENCIES(examples tins)
 
 ADD_EXECUTABLE(arpspoofing EXCLUDE_FROM_ALL arpspoofing.cpp)
 ADD_EXECUTABLE(route_table EXCLUDE_FROM_ALL route_table.cpp)
+ADD_EXECUTABLE(defragmenter EXCLUDE_FROM_ALL defragmenter.cpp)
 IF(TINS_HAVE_CXX11)
     ADD_EXECUTABLE(arpmonitor EXCLUDE_FROM_ALL arpmonitor.cpp)
     ADD_EXECUTABLE(dns_queries EXCLUDE_FROM_ALL dns_queries.cpp)

examples/defragmenter.cpp

@@ -0,0 +1,118 @@
+/*
+ * Copyright (c) 2016, Matias Fontanini
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ * * Redistributions of source code must retain the above copyright
+ *   notice, this list of conditions and the following disclaimer.
+ * * Redistributions in binary form must reproduce the above
+ *   copyright notice, this list of conditions and the following disclaimer
+ *   in the documentation and/or other materials provided with the
+ *   distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ */
+
+#include <iostream>
+#include <string>
+#include <stdexcept>
+#include "tins/ip.h"
+#include "tins/ip_reassembler.h"
+#include "tins/sniffer.h"
+#include "tins/packet_writer.h"
+
+using std::cout;
+using std::cerr;
+using std::endl;
+using std::string;
+using std::exception;
+
+using Tins::IPv4Reassembler;
+using Tins::IP;
+using Tins::Packet;
+using Tins::FileSniffer;
+using Tins::PacketWriter;
+using Tins::DataLinkType;
+
+// This example reads packets from a pcap file and writes them to a new file.
+// If any IPv4 fragmented packets are found in the input file, then they will
+// be reassembled before writing them, so instead of the individual fragments
+// it will write the whole packet.
+
+class Defragmenter {
+public:
+    // Construct the sniffer and the packet writer using the sniffer's
+    // data link type
+    Defragmenter(const string& input_file, const string& output_file)
+    : sniffer_(input_file),
+      writer_(output_file, (PacketWriter::LinkType)sniffer_.link_type()),
+      total_reassembled_(0) {
+
+    }
+
+    void run() {
+        Packet packet;
+        // Read packets and keep going until there's no more packets to read
+        while (packet = sniffer_.next_packet()) {
+            // Try to reassemble the packet
+            IPv4Reassembler::PacketStatus status = reassembler_.process(*packet.pdu());
+
+            // If we did reassemble it, increase this counter
+            if (status == IPv4Reassembler::REASSEMBLED) {
+                total_reassembled_++;
+            }
+
+            // Regardless, we'll write it into the output file unless it's fragmented
+            // (and not yet reassembled) 
+            if (status != IPv4Reassembler::FRAGMENTED) {
+                writer_.write(packet);
+            }
+        }
+    }
+
+    uint64_t total_packets_reassembled() const {
+        return total_reassembled_;
+    }
+private:
+    FileSniffer sniffer_;
+    IPv4Reassembler reassembler_;
+    PacketWriter writer_;
+    uint64_t total_reassembled_;
+};
+
+int main(int argc, char* argv[]) {
+    if (argc != 3) {
+        cout << "Usage: " << argv[0] << " <input-file> <output-file>" << endl;
+        return 1;
+    }
+    try {
+        // Build the defragmented
+        Defragmenter defragmenter(argv[1], argv[2]);
+        cout << "Processing " << argv[1] << endl;
+        cout << "Writing results to " << argv[2] << endl;
+
+        // Run!
+        defragmenter.run();
+        cout << "Done" << endl;
+        cout << "Reassembled: " << defragmenter.total_packets_reassembled() 
+             << " packet(s)" << endl;
+    }
+    catch (exception& ex) {
+        cerr << "Error: " << ex.what() << endl;
+    }
+}
+