udp multicast ip

tools/socktap/ethernet_device.cpp

@@ -6,6 +6,7 @@
 #include <linux/if_packet.h>
 #include <net/if.h>
 #include <sys/ioctl.h>
+#include <ifaddrs.h>
 
 static void initialize(ifreq& request, const char* interface_name)
 {
@@ -56,3 +57,28 @@ vanetza::MacAddress EthernetDevice::address() const
     std::copy_n(data.ifr_hwaddr.sa_data, addr.octets.size(), addr.octets.data());
     return addr;
 }
+
+std::string EthernetDevice::ip() const
+{
+    //@todo maybe there's a better way to obtain IP from device name...
+    std::string ip;
+    char host[NI_MAXHOST];
+    struct ifaddrs *interfaces = nullptr;
+    // get all network interfaces
+    if(getifaddrs(&interfaces) == 0){
+        // search for local interface and copy IP
+        for(struct ifaddrs *ifa = interfaces; ifa != NULL; ifa = ifa->ifa_next) {
+            if(ifa->ifa_addr == NULL)
+                continue;
+
+            if(ifa->ifa_addr->sa_family == AF_INET && std::string(ifa->ifa_name) == interface_name_){
+                if(getnameinfo(ifa->ifa_addr, sizeof(struct sockaddr_in), host, NI_MAXHOST, NULL, 0, NI_NUMERICHOST) == 0) {
+                    ip = std::string(host);
+                    break;
+                }
+            }
+        }
+        freeifaddrs(interfaces);
+    }
+    return ip;
+}

tools/socktap/ethernet_device.hpp

@@ -17,6 +17,7 @@ class EthernetDevice
 
     protocol::endpoint endpoint(int family) const;
     vanetza::MacAddress address() const;
+    std::string ip() const;
 
 private:
     int index() const;

tools/socktap/link_layer.cpp

@@ -64,7 +64,7 @@ create_link_layer(boost::asio::io_service& io_service, const EthernetDevice& dev
     } else if (name == "udp") {
         namespace ip = boost::asio::ip;
         ip::udp::endpoint multicast(ip::address::from_string("239.118.122.97"), 8947);
-        link_layer.reset(new UdpLink { io_service, multicast });
+        link_layer.reset(new UdpLink { io_service, multicast, device.ip() });
     } else if (name == "tcp") {
         namespace ip = boost::asio::ip;
 

tools/socktap/udp_link.cpp

@@ -7,18 +7,28 @@
 namespace ip = boost::asio::ip;
 using namespace vanetza;
 
-UdpLink::UdpLink(boost::asio::io_service& io_service, const ip::udp::endpoint& endpoint) :
+UdpLink::UdpLink(boost::asio::io_service& io_service, const ip::udp::endpoint& endpoint, const std::string& ip) :
     multicast_endpoint_(endpoint),
     tx_socket_(io_service), rx_socket_(io_service),
     rx_buffer_(2560, 0x00)
 {
     tx_socket_.open(multicast_endpoint_.protocol());
 
+    if(ip.size() != 0){
+        boost::asio::ip::multicast::outbound_interface option(boost::asio::ip::address_v4::from_string(ip));
+        tx_socket_.set_option(option);
+    }
+
     rx_socket_.open(multicast_endpoint_.protocol());
     rx_socket_.set_option(ip::udp::socket::reuse_address(true));
     rx_socket_.bind(multicast_endpoint_);
     rx_socket_.set_option(ip::multicast::enable_loopback(false));
-    rx_socket_.set_option(ip::multicast::join_group(multicast_endpoint_.address()));
+
+    if(ip.size() != 0){
+        rx_socket_.set_option(ip::multicast::join_group(multicast_endpoint_.address().to_v4(), boost::asio::ip::address_v4::from_string(ip)));
+    }else{
+        rx_socket_.set_option(ip::multicast::join_group(multicast_endpoint_.address()));
+    }
 
     do_receive();
 }

tools/socktap/udp_link.hpp

@@ -9,7 +9,7 @@
 class UdpLink : public LinkLayer
 {
 public:
-    UdpLink(boost::asio::io_service&, const boost::asio::ip::udp::endpoint&);
+    UdpLink(boost::asio::io_service&, const boost::asio::ip::udp::endpoint&, const std::string&);
 
     void indicate(IndicationCallback) override;
     void request(const vanetza::access::DataRequest&, std::unique_ptr<vanetza::ChunkPacket>) override;