Added a portscan example. It's kind of nasty, but works.

src/sniffer.cpp

@@ -1,3 +1,25 @@
+/*
+ * libtins is a net packet wrapper library for crafting and
+ * interpreting sniffed packets.
+ *
+ * Copyright (C) 2011 Nasel
+ *
+ * This library 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 2.1 of the License, or (at your option) any later version.
+ *
+ * This library 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 this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+ */
+
+
 #include <stdexcept>
 #include "sniffer.h"
 #include "ethernetII.h"
@@ -54,6 +76,10 @@ Tins::PDU *Tins::Sniffer::next_pdu(const string &filter) {
     return ret;
 }
 
+void Tins::Sniffer::stop_sniff() {
+    pcap_breakloop(handle);
+}
+
 void Tins::Sniffer::sniff_loop(const std::string &filter, AbstractSnifferHandler *cback_handler, uint32_t max_packets) {
     bpf_program prog;
     if(compile_set_filter(filter, prog)) {

src/utils.cpp

@@ -21,6 +21,7 @@
 
 #include <stdexcept>
 #include <sstream>
+#include <fstream>
 #include <stdexcept>
 #include <cassert>
 #include <cstring>
@@ -76,6 +77,29 @@ struct HWAddressCollector {
     }
 };
 
+bool from_hex(const string &str, uint32_t &result) {
+    unsigned i(0);
+    result = 0;
+    while(i < str.size()) {
+        uint8_t tmp;
+        if(str[i] >= 'A' && str[i] <= 'F')
+            tmp = (str[i] - 'A' + 10);
+        else if(str[i] >= '0' && str[i] <= '9')
+            tmp = (str[i] - '0');
+        else
+            return false;
+        result = (result << 4) | tmp;
+        i++;
+    }
+    return true;
+}
+
+void skip_line(istream &input) {
+    int c = 0;
+    while(c != '\n' && input)
+         c = input.get();
+}
+
 /** \endcond */
 
 uint32_t Tins::Utils::ip_to_int(const string &ip) {
@@ -179,6 +203,26 @@ bool Tins::Utils::resolve_hwaddr(const string &iface, uint32_t ip, uint8_t *buff
         return false;
 }
 
+string Tins::Utils::interface_from_ip(uint32_t ip) {
+    ifstream input("/proc/net/route");
+    bool match(false);
+    string iface;
+    string destination, mask;
+    uint32_t destination_int, mask_int;
+    skip_line(input);
+    while(!match) {
+        input >> iface >> destination;
+        for(unsigned i(0); i < 6; ++i)
+            input >> mask;
+        from_hex(destination, destination_int);
+        from_hex(mask, mask_int);
+        if((ip & mask_int) == destination_int)
+            return iface;
+        skip_line(input);
+    }
+    return "";
+}
+
 set<string> Tins::Utils::network_interfaces() {
     InterfaceCollector collector;
     generic_iface_loop(collector);