tuntap_adapter.cc

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#include "tuntap_adapter.hh"
 
using namespace std;
 
TCPOverIPv4OverEthernetAdapter::TCPOverIPv4OverEthernetAdapter(TapFD &&tap,
                                                               const EthernetAddress &eth_address,
                                                               const Address &ip_address,
                                                               const Address &next_hop)
    : _tap(move(tap)), _interface(eth_address, ip_address), _next_hop(next_hop) {
    // Linux seems to ignore the first frame sent on a TAP device, so send a dummy frame to prime the pump :-(
    EthernetFrame dummy_frame;
    _tap.write(dummy_frame.serialize());
}
 
optional<TCPSegment> TCPOverIPv4OverEthernetAdapter::read() {
    // Read Ethernet frame from the raw device
    EthernetFrame frame;
    if (frame.parse(_tap.read()) != ParseResult::NoError) {
        return {};
    }
 
    // Give the frame to the NetworkInterface. Get back an Internet datagram if frame was carrying one.
    optional<InternetDatagram> ip_dgram = _interface.recv_frame(frame);
 
    // The incoming frame may have caused the NetworkInterface to send a frame.
    send_pending();
 
    // Try to interpret IPv4 datagram as TCP
    if (ip_dgram) {
        return unwrap_tcp_in_ip(ip_dgram.value());
    }
    return {};
}
 
void TCPOverIPv4OverEthernetAdapter::tick(const size_t ms_since_last_tick) {
    _interface.tick(ms_since_last_tick);
    send_pending();
}
 
void TCPOverIPv4OverEthernetAdapter::write(TCPSegment &seg) {
    _interface.send_datagram(wrap_tcp_in_ip(seg), _next_hop);
    send_pending();
}
 
void TCPOverIPv4OverEthernetAdapter::send_pending() {
    while (not _interface.frames_out().empty()) {
        _tap.write(_interface.frames_out().front().serialize());
        _interface.frames_out().pop();
    }
}
 
template class LossyFdAdapter<TCPOverIPv4OverTunFdAdapter>;