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Merge pull request #4 from rancher-sandbox/add-vm-switch
Add vm-switch core logic
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,4 @@ | ||
| /bin/ | ||
| capture.pcap | ||
| tmp/ | ||
| *.exe |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,275 @@ | ||
| /* | ||
| Copyright © 2023 SUSE LLC | ||
| Licensed under the Apache License, Version 2.0 (the "License"); | ||
| you may not use this file except in compliance with the License. | ||
| You may obtain a copy of the License at | ||
| http://www.apache.org/licenses/LICENSE-2.0 | ||
| Unless required by applicable law or agreed to in writing, software | ||
| distributed under the License is distributed on an "AS IS" BASIS, | ||
| WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. | ||
| See the License for the specific language governing permissions and | ||
| limitations under the License. | ||
| */ | ||
|
|
||
| package main | ||
|
|
||
| import ( | ||
| "context" | ||
| "encoding/binary" | ||
| "flag" | ||
| "fmt" | ||
| "io" | ||
| "net" | ||
| "os" | ||
| "os/exec" | ||
| "os/signal" | ||
| "syscall" | ||
| "time" | ||
|
|
||
| "github.com/google/gopacket" | ||
| "github.com/google/gopacket/layers" | ||
| "github.com/sirupsen/logrus" | ||
| "github.com/songgao/packets/ethernet" | ||
| "github.com/songgao/water" | ||
| "github.com/vishvananda/netlink" | ||
| "gvisor.dev/gvisor/pkg/tcpip/header" | ||
| ) | ||
|
|
||
| var ( | ||
| debug bool | ||
| tapIface string | ||
| ) | ||
|
|
||
| const ( | ||
| defaultTapDevice = "eth0" | ||
| defaultMacAddr = "5a:94:ef:e4:0c:ee" | ||
| maxMTU = 4000 | ||
| ) | ||
|
|
||
| func main() { | ||
| flag.BoolVar(&debug, "debug", true, "enable debug flag") | ||
| flag.StringVar(&tapIface, "tap-interface", defaultTapDevice, "tap interface name, eg. eth0, eth1") | ||
| flag.Parse() | ||
|
|
||
| if debug { | ||
| logrus.SetLevel(logrus.DebugLevel) | ||
| } | ||
|
|
||
| // the FD is passed-in as an extra arg from exec.Command | ||
| // of the parent process. This is for the AF_VSOCK connection that | ||
| // is handed over from the default namespace to Rancher Desktop's | ||
| // network namespace, the logic behind this approach is because | ||
| // AF_VSOCK is affected by network namespaces, therefore we need | ||
| // to open it before entering a new namespace (via unshare/nsenter) | ||
| connFile := os.NewFile(uintptr(3), "vsock connection") | ||
| connFile.Close() | ||
|
|
||
| logrus.Debugf("using a AF_VSOCK connection file from default namespace: %v", connFile) | ||
|
|
||
| // this should never happen | ||
| if err := checkForExistingIface(tapIface); err != nil { | ||
| logrus.Fatal(err) | ||
| } | ||
|
|
||
| // catch user issued signals | ||
| sigChan := make(chan os.Signal, 1) | ||
| signal.Notify(sigChan, os.Interrupt, syscall.SIGTERM, syscall.SIGINT) | ||
|
|
||
| // try every second until we get DHCP | ||
| retryTicker := time.NewTicker(time.Second) | ||
| for { | ||
| ctx, cancel := context.WithCancel(context.Background()) | ||
| select { | ||
| case s := <-sigChan: | ||
| logrus.Errorf("signal caught: %v", s) | ||
| cancel() | ||
| os.Exit(1) | ||
| case <-retryTicker.C: | ||
| if err := run(ctx, cancel, connFile); err != nil { | ||
| logrus.Error(err) | ||
| } | ||
| } | ||
| } | ||
| } | ||
|
|
||
| func run(ctx context.Context, cancel context.CancelFunc, connFile io.ReadWriteCloser) error { | ||
| tap, err := water.New(water.Config{ | ||
| DeviceType: water.TAP, | ||
| PlatformSpecificParams: water.PlatformSpecificParams{ | ||
| Name: tapIface, | ||
| }, | ||
| }) | ||
| if err != nil { | ||
| logrus.Fatalf("creating tap device %v failed: %s", tapIface, err) | ||
| } | ||
| logrus.Debugf("created tap device %s: %v", tapIface, tap) | ||
|
|
||
| defer func() { | ||
| connFile.Close() | ||
| tap.Close() | ||
| logrus.Debugf("closed tap device: %s", tapIface) | ||
| }() | ||
|
|
||
| if err := linkUp(tapIface, defaultMacAddr); err != nil { | ||
| logrus.Fatalf("setting mac address [%s] for %s tap device failed: %s", defaultMacAddr, tapIface, err) | ||
| } | ||
| if err := loopbackUp(); err != nil { | ||
| logrus.Fatalf("enabling loop back device failed: %s", err) | ||
| } | ||
|
|
||
| logrus.Debugf("setup complete for tap interface %s(%s) + loopback", tapIface, defaultMacAddr) | ||
|
|
||
| errCh := make(chan error, 1) | ||
| go tx(ctx, connFile, tap, errCh, maxMTU) | ||
| go rx(ctx, connFile, tap, errCh, maxMTU) | ||
| go func() { | ||
| if err := dhcp(ctx, tapIface); err != nil { | ||
| errCh <- fmt.Errorf("dhcp error: %w", err) | ||
| cancel() | ||
| } | ||
| }() | ||
|
|
||
| return <-errCh | ||
| } | ||
|
|
||
| func loopbackUp() error { | ||
| lo, err := netlink.LinkByName("lo") | ||
| if err != nil { | ||
| return err | ||
| } | ||
|
|
||
| return netlink.LinkSetUp(lo) | ||
| } | ||
|
|
||
| func linkUp(iface, mac string) error { | ||
| link, err := netlink.LinkByName(iface) | ||
| if err != nil { | ||
| return err | ||
| } | ||
| if mac == "" { | ||
| return netlink.LinkSetUp(link) | ||
| } | ||
| hw, err := net.ParseMAC(mac) | ||
| if err != nil { | ||
| return err | ||
| } | ||
| if err := netlink.LinkSetHardwareAddr(link, hw); err != nil { | ||
| return err | ||
| } | ||
|
|
||
| logrus.Debugf("successful link setup %+v\n", link) | ||
| return netlink.LinkSetUp(link) | ||
| } | ||
|
|
||
| func dhcp(ctx context.Context, iface string) error { | ||
| if _, err := exec.LookPath("udhcpc"); err == nil { // busybox dhcp client | ||
| cmd := exec.CommandContext(ctx, "udhcpc", "-f", "-q", "-i", iface, "-v") | ||
| cmd.Stderr = os.Stderr | ||
| cmd.Stdout = os.Stdout | ||
| return cmd.Run() | ||
| } | ||
| cmd := exec.CommandContext(ctx, "dhclient", "-4", "-d", "-v", iface) | ||
| cmd.Stderr = os.Stderr | ||
| cmd.Stdout = os.Stdout | ||
| return cmd.Run() | ||
| } | ||
|
|
||
| func rx(ctx context.Context, conn io.Writer, tap *water.Interface, errCh chan error, mtu int) { | ||
| logrus.Info("waiting for packets...") | ||
| var frame ethernet.Frame | ||
| for { | ||
| select { | ||
| case <-ctx.Done(): | ||
| logrus.Info("exiting rx goroutine") | ||
| return | ||
| default: | ||
| frame.Resize(mtu) | ||
| n, err := tap.Read([]byte(frame)) | ||
| if err != nil { | ||
| errCh <- fmt.Errorf("reading packet from tap failed: %w", err) | ||
| return | ||
| } | ||
| frame = frame[:n] | ||
|
|
||
| size := make([]byte, 2) | ||
| binary.LittleEndian.PutUint16(size, uint16(n)) | ||
|
|
||
| if _, err := conn.Write(size); err != nil { | ||
| errCh <- fmt.Errorf("writing size to the socket failed: %w", err) | ||
| return | ||
| } | ||
| if _, err := conn.Write(frame); err != nil { | ||
| errCh <- fmt.Errorf("writing packet to the socket failed: %w", err) | ||
| return | ||
| } | ||
|
|
||
| if debug { | ||
| packet := gopacket.NewPacket(frame, layers.LayerTypeEthernet, gopacket.Default) | ||
| logrus.Infof("wrote packet (vm -> host %d): %s", size, packet.String()) | ||
| } | ||
| } | ||
| } | ||
| } | ||
|
|
||
| func tx(ctx context.Context, conn io.Reader, tap *water.Interface, errCh chan error, mtu int) { | ||
| sizeBuf := make([]byte, 2) | ||
| buf := make([]byte, mtu+header.EthernetMinimumSize) | ||
|
|
||
| for { | ||
| select { | ||
| case <-ctx.Done(): | ||
| logrus.Info("exiting tx goroutine") | ||
| return | ||
| default: | ||
| n, err := io.ReadFull(conn, sizeBuf) | ||
| if err != nil { | ||
| errCh <- fmt.Errorf("reading size from socket failed: %w", err) | ||
| return | ||
| } | ||
| if n != 2 { | ||
| errCh <- fmt.Errorf("unexpected size %d", n) | ||
| return | ||
| } | ||
| size := int(binary.LittleEndian.Uint16(sizeBuf[0:2])) | ||
|
|
||
| if cap(buf) < size { | ||
| buf = make([]byte, size) | ||
| } | ||
|
|
||
| n, err = io.ReadFull(conn, buf[:size]) | ||
| if err != nil { | ||
| errCh <- fmt.Errorf("reading payload from socket failed: %w", err) | ||
| return | ||
| } | ||
| if n == 0 || n != size { | ||
| errCh <- fmt.Errorf("unexpected size %d != %d", n, size) | ||
| return | ||
| } | ||
|
|
||
| if _, err := tap.Write(buf[:size]); err != nil { | ||
| errCh <- fmt.Errorf("writing packet to tap failed: %w", err) | ||
| return | ||
| } | ||
|
|
||
| if debug { | ||
| packet := gopacket.NewPacket(buf[:size], layers.LayerTypeEthernet, gopacket.Default) | ||
| logrus.Infof("read packet (host -> vm %d): %s", size, packet.String()) | ||
| } | ||
| } | ||
| } | ||
| } | ||
|
|
||
| func checkForExistingIface(ifName string) error { | ||
| // equivalent to: `ip link show` | ||
| links, err := netlink.LinkList() | ||
| if err != nil { | ||
| return fmt.Errorf("getting link devices failed: %w", err) | ||
| } | ||
|
|
||
| for _, link := range links { | ||
| if link.Attrs().Name == ifName { | ||
| return fmt.Errorf("%s interface already exist, exiting now", ifName) | ||
| } | ||
| } | ||
| return nil | ||
| } |
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