mac_table.h

/*
 * Copyright (C) 2016-2017, 2020, 2022-2024 Kernkonzept GmbH.
 * Author(s): Jean Wolter <jean.wolter@kernkonzept.com>
 *
 * License: see LICENSE.spdx (in this directory or the directories above)
 */
#pragma once
 
#include "mac_addr.h"
#include "port.h"
 
#include <array>
#include <map>
#include <algorithm>
template<std::size_t Size = 1024U>
class Mac_table
{
public:
  Mac_table()
  : _mac_table(),
    _entries(),
    _rr_index(0U)
  {}
 
  Virtio_port *lookup(Mac_addr dst) const
  {
    auto entry = _mac_table.find(dst);
    return (entry != _mac_table.end()) ? entry->second->port : nullptr;
  }
 
  void learn(Mac_addr src, Virtio_port *port)
  {
    Dbg info(Dbg::Port, Dbg::Info);
 
    if (L4_UNLIKELY(info.is_active()))
      {
        // check whether we already know about src mac
        auto *p = lookup(src);
        if (!p || p != port)
          {
            info.printf("%s %-20s -> ", !p ? "learned " : "replaced",
                        port->get_name());
            src.print(info);
            info.cprintf("\n");
          }
      }
 
    auto status = _mac_table.emplace(src, &_entries[_rr_index]);
    if (L4_UNLIKELY(status.second))
      {
        if (_entries[_rr_index].port)
          {
            // remove old entry
            _mac_table.erase(_entries[_rr_index].addr);
          }
        // Set/Replace port and mac address
        _entries[_rr_index].port = port;
        _entries[_rr_index].addr = src;
        _rr_index = (_rr_index + 1U) % Size;
      }
    else
      {
        // Update port to allow for movement of client between ports
        status.first->second->port = port;
      }
  }
 
  void flush(Virtio_port *port)
  {
    typedef std::pair<const Mac_addr, Entry*> TableEntry;
 
    auto iter = _mac_table.begin();
    while ((iter = std::find_if(iter, _mac_table.end(),
                                [port](TableEntry const &p)
                                { return p.second->port == port; }))
           != _mac_table.end())
      {
        iter->second->port = nullptr;
        iter->second->addr = Mac_addr::Addr_unknown;
        iter = _mac_table.erase(iter);
      }
 
    assert(std::find_if(_mac_table.begin(), _mac_table.end(),
                        [port](TableEntry const &p)
                        { return p.second->port == port; }) == _mac_table.end());
  }
 
private:
  struct Entry {
    Virtio_port *port;
    Mac_addr addr;
 
    Entry()
    : port(nullptr),
      addr(Mac_addr::Addr_unknown)
    {}
  };
 
  std::map<Mac_addr, Entry*> _mac_table;
  std::array<Entry, Size> _entries;
  size_t _rr_index;
};