Method DoProcessBatch

core/modules/static_nat.cc:147–177

template <StaticNAT::Direction dir>
inline void StaticNAT::DoProcessBatch(Context *ctx, bess::PacketBatch *batch) {
  gate_idx_t ogate_idx = static_cast<gate_idx_t>(dir);
  int cnt = batch->cnt();

  for (int i = 0; i < cnt; i++) {
    bess::Packet *pkt = batch->pkts()[i];
    auto *eth = pkt->head_data<bess::utils::Ethernet *>();
    auto *ip = reinterpret_cast<bess::utils::Ipv4 *>(eth + 1);

    be32_t &addr_be = (dir == kForward) ? ip->src : ip->dst;
    uint32_t addr = addr_be.value();

    for (const auto &pair : pairs_) {
      uint32_t start_addr = (dir == kForward) ? pair.int_addr : pair.ext_addr;
      if (start_addr <= addr && addr < start_addr + pair.size) {
        uint32_t diff = (dir == kForward) ? (pair.ext_addr - pair.int_addr)
                                          : (pair.int_addr - pair.ext_addr);
        be32_t new_addr_be = be32_t(addr + diff);
        UpdateChecksum(ip, bess::utils::ChecksumIncrement32(
                               addr_be.raw_value(), new_addr_be.raw_value()));
        addr_be = new_addr_be;
        break;
      }
    }

    // If there is no matching address pair, forward without NAT.
    // TODO: add an option to redirect unmatched traffic to a specified ogate

    EmitPacket(ctx, pkt, ogate_idx);
  }
}

void StaticNAT::ProcessBatch(Context *ctx, bess::PacketBatch *batch) {
  gate_idx_t incoming_gate = ctx->current_igate;