Added Sniffer class. Added a constructor to eery PDU subclass which creates an instance of the PDU from a byte array.

src/sniffer.cpp

@@ -0,0 +1,64 @@
+#include <stdexcept>
+#include "sniffer.h"
+#include "ethernetII.h"
+
+
+using namespace std;
+
+Tins::Sniffer::Sniffer(const string &device, unsigned max_packet_size) {
+    char error[PCAP_ERRBUF_SIZE];
+    if (pcap_lookupnet(device.c_str(), &ip, &mask, error) == -1)
+        throw runtime_error(error);
+    handle = pcap_open_live(device.c_str(), max_packet_size, 0, 0, error);
+    if(!handle)
+        throw runtime_error(error);
+}
+
+Tins::Sniffer::~Sniffer() {
+    if(handle)
+        pcap_close(handle);
+}
+
+bool Tins::Sniffer::compile_set_filter(const string &filter, bpf_program &prog) {
+    return (pcap_compile(handle, &prog, filter.c_str(), 0, ip) != -1 && pcap_setfilter(handle, &prog) != -1);
+}
+
+Tins::PDU *Tins::Sniffer::next_pdu(const string &filter) {
+    bpf_program prog;
+    if(!compile_set_filter(filter, prog))
+        return 0;
+    pcap_pkthdr header;
+    PDU *ret = 0;
+    while(!ret) {
+        const u_char *content = pcap_next(handle, &header);
+        try {
+            ret = new EthernetII((const uint8_t*)content, header.caplen);
+        }
+        catch(...) {
+            ret = 0;
+        }
+    }
+    pcap_freecode(&prog);
+    return ret;
+}
+
+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)) {
+        pcap_loop(handle, max_packets, Sniffer::callback_handler, (u_char*)cback_handler);
+        pcap_freecode(&prog);
+    }
+}
+
+// Static
+void Tins::Sniffer::callback_handler(u_char *args, const struct pcap_pkthdr *header, const u_char *packet) {
+    try {
+        PDU *pdu = new EthernetII((const uint8_t*)packet, header->caplen);
+        reinterpret_cast<AbstractSnifferHandler*>(args)->handle(pdu);
+        delete pdu;
+    }
+    catch(...) {
+        
+    }
+}
+