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tapManager.go
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tapManager.go
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// MIT License
//
// Copyright (c) 2020 Plamen Petrov and EASE lab
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in all
// copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
// SOFTWARE.
package taps
import (
"errors"
"fmt"
"sync/atomic"
log "github.com/sirupsen/logrus"
"net"
"github.com/vishvananda/netlink"
)
// getGatewayAddr Creates the gateway address (first address in pool)
func getGatewayAddr(bridgeID int) string {
return fmt.Sprintf("19%d.128.0.1", bridgeID)
}
// getBridgeName Create bridge name
func getBridgeName(id int) string {
return fmt.Sprintf("br%d", id)
}
// getPrimaryAddress Creates the primary address for a tap
func getPrimaryAddress(curTaps, bridgeID int) string {
return fmt.Sprintf("19%d.128.%d.%d", bridgeID, (curTaps+2)/256, (curTaps+2)%256)
}
// NewTapManager Creates a new tap manager
func NewTapManager() *TapManager {
tm := new(TapManager)
tm.numBridges = NumBridges
tm.TapCountsPerBridge = make([]int64, NumBridges)
tm.createdTaps = make(map[string]*NetworkInterface)
log.Info("Registering bridges for tap manager")
for i := 0; i < NumBridges; i++ {
brName := getBridgeName(i)
gatewayAddr := getGatewayAddr(i)
createBridge(brName, gatewayAddr)
}
return tm
}
// Creates the bridge, add a gateway to it, and enables it
func createBridge(bridgeName, gatewayAddr string) {
logger := log.WithFields(log.Fields{"bridge": bridgeName})
logger.Debug("Creating bridge")
la := netlink.NewLinkAttrs()
la.Name = bridgeName
br := &netlink.Bridge{LinkAttrs: la}
if err := netlink.LinkAdd(br); err != nil {
logger.Panic("Bridge could not be created")
}
if err := netlink.LinkSetUp(br); err != nil {
logger.Panic("Bridge could not be enabled")
}
bridgeAddress := gatewayAddr + Subnet
addr, err := netlink.ParseAddr(bridgeAddress)
if err != nil {
log.Panic(fmt.Sprintf("could not parse bridge address %s", bridgeAddress))
}
if err := netlink.AddrAdd(br, addr); err != nil {
logger.Panic(fmt.Sprintf("could not add %s to bridge", bridgeAddress))
}
}
// AddTap Creates a new tap and returns the corresponding network interface
func (tm *TapManager) AddTap(tapName string) (*NetworkInterface, error) {
tm.Lock()
if ni, ok := tm.createdTaps[tapName]; ok {
tm.Unlock()
return ni, tm.reconnectTap(tapName, ni)
}
tm.Unlock()
for i := 0; i < tm.numBridges; i++ {
tapsInBridge := atomic.AddInt64(&tm.TapCountsPerBridge[i], 1)
if tapsInBridge-1 < TapsPerBridge {
// Create a tap with this bridge
ni, err := tm.addTap(tapName, i, int(tapsInBridge-1))
if err == nil {
tm.Lock()
tm.createdTaps[tapName] = ni
tm.Unlock()
}
return ni, err
}
}
log.Error("No space for creating taps")
return nil, errors.New("No space for creating taps")
}
// Reconnects a single tap with the same network interface that it was
// create with previously
func (tm *TapManager) reconnectTap(tapName string, ni *NetworkInterface) error {
logger := log.WithFields(log.Fields{"tap": tapName, "bridge": ni.BridgeName})
la := netlink.NewLinkAttrs()
la.Name = tapName
logger.Debug("Reconnecting tap")
tap := &netlink.Tuntap{LinkAttrs: la, Mode: netlink.TUNTAP_MODE_TAP}
if err := netlink.LinkAdd(tap); err != nil {
logger.Error("Tap could not be reconnected")
return err
}
br, err := netlink.LinkByName(ni.BridgeName)
if err != nil {
logger.Error("Could not reconnect tap, because corresponding bridge does not exist")
return err
}
hwAddr, err := net.ParseMAC(ni.MacAddress)
if err != nil {
logger.Error("Could not parse MAC")
return err
}
if err := netlink.LinkSetHardwareAddr(tap, hwAddr); err != nil {
logger.Error("Could not set MAC address")
return err
}
if err := netlink.LinkSetMaster(tap, br); err != nil {
logger.Error("Master could not be set")
return err
}
if err := netlink.LinkSetUp(tap); err != nil {
logger.Error("Tap could not be enabled")
return err
}
return nil
}
// Creates a single tap and connects it to the corresponding bridge
func (tm *TapManager) addTap(tapName string, bridgeID, currentNumTaps int) (*NetworkInterface, error) {
bridgeName := getBridgeName(bridgeID)
logger := log.WithFields(log.Fields{"tap": tapName, "bridge": bridgeName})
la := netlink.NewLinkAttrs()
la.Name = tapName
logger.Debug("Creating tap")
tap := &netlink.Tuntap{LinkAttrs: la, Mode: netlink.TUNTAP_MODE_TAP}
if err := netlink.LinkAdd(tap); err != nil {
logger.Error("Tap could not be created")
return nil, err
}
br, err := netlink.LinkByName(bridgeName)
if err != nil {
logger.Error("Could not create tap, because corresponding bridge does not exist")
return nil, err
}
if err := netlink.LinkSetMaster(tap, br); err != nil {
logger.Error("Master could not be set")
return nil, err
}
macIndex := bridgeID*TapsPerBridge + currentNumTaps
macAddress := fmt.Sprintf("02:FC:00:00:%02X:%02X", macIndex/256, macIndex%256)
hwAddr, err := net.ParseMAC(macAddress)
if err != nil {
logger.Error("Could not parse MAC")
return nil, err
}
if err := netlink.LinkSetHardwareAddr(tap, hwAddr); err != nil {
logger.Error("Could not set MAC address")
return nil, err
}
if err := netlink.LinkSetUp(tap); err != nil {
logger.Error("Tap could not be enabled")
return nil, err
}
return &NetworkInterface{
BridgeName: bridgeName,
MacAddress: macAddress,
PrimaryAddress: getPrimaryAddress(currentNumTaps, bridgeID),
HostDevName: tapName,
Subnet: Subnet,
GatewayAddress: getGatewayAddr(bridgeID),
}, nil
}
// RemoveTap Removes the tap
func (tm *TapManager) RemoveTap(tapName string) error {
logger := log.WithFields(log.Fields{"tap": tapName})
logger.Debug("Removing tap")
tap, err := netlink.LinkByName(tapName)
if err != nil {
logger.Warn("Could not find tap")
return nil
}
if err := netlink.LinkDel(tap); err != nil {
logger.Error("Tap could not be removed")
return err
}
return nil
}
// RemoveBridges Removes the bridges created by the tap manager
func (tm *TapManager) RemoveBridges() {
log.Info("Removing bridges")
for i := 0; i < tm.numBridges; i++ {
bridgeName := getBridgeName(i)
logger := log.WithFields(log.Fields{"bridge": bridgeName})
br, err := netlink.LinkByName(bridgeName)
if err != nil {
logger.Warn("Could not find bridge")
continue
}
if err := netlink.LinkDel(br); err != nil {
logger.WithFields(log.Fields{"bridge": bridgeName}).Panic("Bridge could not be deleted")
}
}
}