SONiC host VLAN fundamentals

VlanMgr::VlanMgr(DBConnector *cfgDb, DBConnector *appDb, DBConnector *stateDb, const vector<string> &tableNames) :
        Orch(cfgDb, tableNames),
        m_cfgVlanTable(cfgDb, CFG_VLAN_TABLE_NAME),
        m_cfgVlanMemberTable(cfgDb, CFG_VLAN_MEMBER_TABLE_NAME),
        m_statePortTable(stateDb, STATE_PORT_TABLE_NAME),
        m_stateLagTable(stateDb, STATE_LAG_TABLE_NAME),
        m_stateVlanTable(stateDb, STATE_VLAN_TABLE_NAME),
        m_stateVlanMemberTable(stateDb, STATE_VLAN_MEMBER_TABLE_NAME),
        m_appVlanTableProducer(appDb, APP_VLAN_TABLE_NAME),
        m_appVlanMemberTableProducer(appDb, APP_VLAN_MEMBER_TABLE_NAME),
        replayDone(false)
{
    ...
 
    const std::string cmds = std::string("")
      + BASH_CMD + " -c \""
      + IP_CMD + " link del " + DOT1Q_BRIDGE_NAME + " 2>/dev/null; "
      + IP_CMD + " link add " + DOT1Q_BRIDGE_NAME + " up type bridge && "
      + IP_CMD + " link set " + DOT1Q_BRIDGE_NAME + " mtu " + DEFAULT_MTU_STR + " && "
      + IP_CMD + " link set " + DOT1Q_BRIDGE_NAME + " address " + gMacAddress.to_string() + " && "
      + BRIDGE_CMD + " vlan del vid " + DEFAULT_VLAN_ID + " dev " + DOT1Q_BRIDGE_NAME + " self; "
      + IP_CMD + " link del dev dummy 2>/dev/null; "
      + IP_CMD + " link add dummy type dummy && "
      + IP_CMD + " link set dummy master " + DOT1Q_BRIDGE_NAME + "\"";

    std::string res;
    EXEC_WITH_ERROR_THROW(cmds, res);

    // The generated command is:
    // /bin/echo 1 > /sys/class/net/Bridge/bridge/vlan_filtering
    const std::string echo_cmd = std::string("")
      + ECHO_CMD + " 1 > /sys/class/net/" + DOT1Q_BRIDGE_NAME + "/bridge/vlan_filtering";

    int ret = swss::exec(echo_cmd, res);
    /* echo will fail in virtual switch since /sys directory is read-only.
     * need to use ip command to setup the vlan_filtering which is not available in debian 8.
     * Once we move sonic to debian 9, we can use IP command by default
     * ip command available in Debian 9 to create a bridge with a vlan filtering:
     * /sbin/ip link add Bridge up type bridge vlan_filtering 1 */
    if (ret != 0)
    {
        const std::string echo_cmd_backup = std::string("")
          + IP_CMD + " link set " + DOT1Q_BRIDGE_NAME + " type bridge vlan_filtering 1";

        EXEC_WITH_ERROR_THROW(echo_cmd_backup, res);
    }
}

bool VlanMgr::addHostVlan(int vlan_id)
{
    SWSS_LOG_ENTER();

    // The command should be generated as:
    // /bin/bash -c "/sbin/bridge vlan add vid  dev Bridge self &&
    //               /sbin/ip link add link Bridge up name Vlan address  type vlan id "
    const std::string cmds = std::string("")
      + BASH_CMD + " -c \""
      + BRIDGE_CMD + " vlan add vid " + std::to_string(vlan_id) + " dev " + DOT1Q_BRIDGE_NAME + " self && "
      + IP_CMD + " link add link " + DOT1Q_BRIDGE_NAME
               + " up"
               + " name " + VLAN_PREFIX + std::to_string(vlan_id)
               + " address " + gMacAddress.to_string()
               + " type vlan id " + std::to_string(vlan_id) + "\"";

    std::string res;
    EXEC_WITH_ERROR_THROW(cmds, res);

    return true;
}

bool VlanMgr::addHostVlanMember(int vlan_id, const string &port_alias, const string& tagging_mode)
{
    SWSS_LOG_ENTER();

    std::string tagging_cmd;
    if (tagging_mode == "untagged" || tagging_mode == "priority_tagged")
    {
        tagging_cmd = "pvid untagged";
    }

    // The command should be generated as:
    // /bin/bash -c "/sbin/ip link set  master Bridge &&
    //               /sbin/bridge vlan del vid 1 dev  &&
    //               /sbin/bridge vlan add vid  dev  "
    ostringstream cmds, inner;
    inner << IP_CMD " link set " << shellquote(port_alias) << " master " DOT1Q_BRIDGE_NAME " && "
      BRIDGE_CMD " vlan del vid " DEFAULT_VLAN_ID " dev " << shellquote(port_alias) << " && "
      BRIDGE_CMD " vlan add vid " + std::to_string(vlan_id) + " dev " << shellquote(port_alias) << " " + tagging_cmd;
    cmds << BASH_CMD " -c " << shellquote(inner.str());

    std::string res;
    EXEC_WITH_ERROR_THROW(cmds.str(), res);

    return true;
}