socktap: bind UDP multicasts to network device

tools/socktap/ethernet_device.cpp

@@ -16,18 +16,19 @@ static void initialize(ifreq& request, const char* interface_name)
 }
 
 EthernetDevice::EthernetDevice(const char* devname) :
-    local_socket_(::socket(AF_LOCAL, SOCK_DGRAM, 0)),
+    inet_socket_(::socket(AF_INET, SOCK_DGRAM, 0)),
     interface_name_(devname)
 {
-    if (!local_socket_) {
+    if (!inet_socket_) {
         throw std::system_error(errno, std::system_category());
     }
 }
 
 EthernetDevice::~EthernetDevice()
 {
-    if (local_socket_ >= 0)
-        ::close(local_socket_);
+    if (inet_socket_ >= 0)
+        ::close(inet_socket_);
+
 }
 
 EthernetDevice::protocol::endpoint EthernetDevice::endpoint(int family) const
@@ -43,42 +44,29 @@ int EthernetDevice::index() const
 {
     ifreq data;
     initialize(data, interface_name_.c_str());
-    ::ioctl(local_socket_, SIOCGIFINDEX, &data);
+    ::ioctl(inet_socket_, SIOCGIFINDEX, &data);
     return data.ifr_ifindex;
 }
 
 vanetza::MacAddress EthernetDevice::address() const
 {
     ifreq data;
     initialize(data, interface_name_.c_str());
-    ::ioctl(local_socket_, SIOCGIFHWADDR, &data);
+    ::ioctl(inet_socket_, SIOCGIFHWADDR, &data);
 
     vanetza::MacAddress addr;
     std::copy_n(data.ifr_hwaddr.sa_data, addr.octets.size(), addr.octets.data());
     return addr;
 }
 
-std::string EthernetDevice::ip() const
+boost::asio::ip::address_v4 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;
+    ifreq data;
+    initialize(data, interface_name_.c_str());
+    ::ioctl(inet_socket_, SIOCGIFADDR, &data);
 
-            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;
+    char host[NI_MAXHOST] = { 0 };
+    ::getnameinfo(&data.ifr_addr, sizeof(sockaddr), host, NI_MAXHOST, nullptr, 0, NI_NUMERICHOST);
+
+    return boost::asio::ip::address_v4::from_string(host);
 }

tools/socktap/ethernet_device.hpp

@@ -3,6 +3,7 @@
 
 #include <vanetza/net/mac_address.hpp>
 #include <boost/asio/generic/raw_protocol.hpp>
+#include <boost/asio/ip/address_v4.hpp>
 #include <string>
 
 class EthernetDevice
@@ -17,12 +18,12 @@ class EthernetDevice
 
     protocol::endpoint endpoint(int family) const;
     vanetza::MacAddress address() const;
-    std::string ip() const;
+    boost::asio::ip::address_v4 ip() const;
 
 private:
     int index() const;
 
-    int local_socket_;
+    int inet_socket_;
     std::string interface_name_;
 };
 

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, device.ip() });
+        link_layer.reset(new UdpLink { io_service, multicast, device });
     } else if (name == "tcp") {
         namespace ip = boost::asio::ip;
 

tools/socktap/udp_link.cpp

@@ -7,26 +7,26 @@
 namespace ip = boost::asio::ip;
 using namespace vanetza;
 
-UdpLink::UdpLink(boost::asio::io_service& io_service, const ip::udp::endpoint& endpoint, const std::string& ip) :
+UdpLink::UdpLink(boost::asio::io_service& io_service, const ip::udp::endpoint& endpoint, const EthernetDevice& device) :
     multicast_endpoint_(endpoint),
     tx_socket_(io_service), rx_socket_(io_service),
     rx_buffer_(2560, 0x00)
 {
-    tx_socket_.open(multicast_endpoint_.protocol());
+    auto ip = device.ip();
 
-    if(ip.size() != 0){
-        boost::asio::ip::multicast::outbound_interface option(boost::asio::ip::address_v4::from_string(ip));
+    tx_socket_.open(multicast_endpoint_.protocol());
+    if (!ip.is_unspecified()) {
+        boost::asio::ip::multicast::outbound_interface option(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));
-
-    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{
+    if(!ip.is_unspecified() && multicast_endpoint_.address().is_v4()) {
+        rx_socket_.set_option(ip::multicast::join_group(multicast_endpoint_.address().to_v4(), ip));
+    } else {
         rx_socket_.set_option(ip::multicast::join_group(multicast_endpoint_.address()));
     }
 

tools/socktap/udp_link.hpp

@@ -6,10 +6,13 @@
 #include <boost/asio/ip/udp.hpp>
 #include <array>
 
+// forward declaration
+class EthernetDevice;
+
 class UdpLink : public LinkLayer
 {
 public:
-    UdpLink(boost::asio::io_service&, const boost::asio::ip::udp::endpoint&, const std::string&);
+    UdpLink(boost::asio::io_service&, const boost::asio::ip::udp::endpoint&, const EthernetDevice&);
 
     void indicate(IndicationCallback) override;
     void request(const vanetza::access::DataRequest&, std::unique_ptr<vanetza::ChunkPacket>) override;