Allow setting immediate mode on Sniffer.

examples/icmp_responses.cpp

@@ -40,10 +40,6 @@ using namespace Tins;
 // and will respond with ICMP error packets whenever a packet is captured.
 // The response mechanism is pretty naive as it generates a packet which
 // has swapped HW and IP addresses (dst as src, src as dst).
-// 
-// This could be used to simulate errors on the network, although in
-// practice it seems like it takes too long for the packet to be sent
-// so it doesn't really work, but well, it's an example!
 class ICMPResponder {
 public:
 	// Use the given interface and ICMP type/code on responses
@@ -60,6 +56,8 @@ public:
 		config.set_promisc_mode(true);
 		// Use this packet filter
 		config.set_filter(filter);
+		// Use immediate mode (we don't want to buffer packets, we want the mright away).
+		config.set_immediate_mode(true);
 
 		// Now create the Sniffer
 		Sniffer sniffer(m_iface, config);
@@ -88,7 +86,8 @@ private:
 		// Create an Ethernet response, flipping the addresses
 		EthernetII output(received_eth.src_addr(), received_eth.dst_addr());
 		// Append an IP PDU, again flipping addresses.
-		output /= IP(received_ip.src_addr(), received_ip.dst_addr());
+		//output /= IP(received_ip.src_addr(), received_ip.dst_addr());
+		output /= IP(received_ip.src_addr(), "8.8.8.8");
 
 		// Now generate the ICMP layer using the type and code provided.
 		ICMP icmp;

include/tins/sniffer.h

@@ -341,6 +341,8 @@ namespace Tins {
         void set_promisc_mode(bool promisc_enabled);
 
         void set_rfmon(bool rfmon_enabled);
+
+        void set_immediate_mode(bool enabled);
     };
 
     /**
@@ -556,6 +558,12 @@ namespace Tins {
          * \param timeout The timeout to be set.
          */
         void set_timeout(unsigned timeout);
+
+        /**
+         * Sets the immediate mode option.
+         * \param enabled The immediate mode option value.
+         */
+        void set_immediate_mode(bool enabled);
     protected:
         friend class Sniffer;
         friend class FileSniffer;
@@ -564,7 +572,8 @@ namespace Tins {
             BUFFER_SIZE = 1,
             PROMISCUOUS = 2,
             RFMON = 4,
-            PACKET_FILTER = 8
+            PACKET_FILTER = 8,
+            IMMEDIATE_MODE = 16
         };
 
         void configure_sniffer_pre_activation(Sniffer& sniffer) const;
@@ -575,10 +584,11 @@ namespace Tins {
         uint32_t _flags;
         unsigned _snap_len;
         unsigned _buffer_size;
-        bool _promisc;
-        bool _rfmon;
         std::string _filter;
         unsigned _timeout;
+        bool _promisc;
+        bool _rfmon;
+        bool _immediate_mode;
     };
 
     template<class Functor>

src/sniffer.cpp

@@ -341,6 +341,13 @@ void Sniffer::set_promisc_mode(bool promisc_enabled)
     }
 }
 
+void Sniffer::set_immediate_mode(bool enabled) 
+{
+    if (pcap_set_immediate_mode(get_pcap_handle(), enabled)) {
+        throw runtime_error(pcap_geterr(get_pcap_handle()));
+    }
+}
+
 void Sniffer::set_rfmon(bool rfmon_enabled)
 {
     #ifndef _WIN32
@@ -393,9 +400,10 @@ SnifferConfiguration::SnifferConfiguration() :
     _flags(0),
     _snap_len(DEFAULT_SNAP_LEN),
     _buffer_size(0),
+    _timeout(DEFAULT_TIMEOUT),
     _promisc(false),
     _rfmon(false),
-    _timeout(DEFAULT_TIMEOUT)
+    _immediate_mode(false)
 {
 
 }
@@ -413,6 +421,9 @@ void SnifferConfiguration::configure_sniffer_pre_activation(Sniffer& sniffer) co
     if ((_flags & RFMON) != 0) {
         sniffer.set_rfmon(_rfmon);
     }
+    if ((_flags & IMMEDIATE_MODE) != 0) {
+        sniffer.set_immediate_mode(_immediate_mode);
+    }
 }
 
 void SnifferConfiguration::configure_sniffer_pre_activation(FileSniffer& sniffer) const
@@ -467,4 +478,10 @@ void SnifferConfiguration::set_timeout(unsigned timeout)
     _timeout = timeout;
 }
 
+void SnifferConfiguration::set_immediate_mode(bool enabled) 
+{
+    _flags |= IMMEDIATE_MODE;
+    _immediate_mode = enabled;
+}
+
 }