137 lines
3.3 KiB
Go
137 lines
3.3 KiB
Go
package qemu
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import (
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"bufio"
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"context"
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"fmt"
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"log"
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"os"
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"strconv"
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"strings"
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"time"
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"github.com/hashicorp/packer/packer"
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"github.com/hashicorp/packer/packer-plugin-sdk/multistep"
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"github.com/digitalocean/go-qemu/qmp"
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)
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// This step waits for the guest address to become available in the network
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// bridge, then it sets the guestAddress state property.
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type stepWaitGuestAddress struct {
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CommunicatorType string
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NetBridge string
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timeout time.Duration
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}
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func (s *stepWaitGuestAddress) Run(ctx context.Context, state multistep.StateBag) multistep.StepAction {
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ui := state.Get("ui").(packer.Ui)
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if s.CommunicatorType == "none" {
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ui.Message("No communicator is configured -- skipping StepWaitGuestAddress")
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return multistep.ActionContinue
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}
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if s.NetBridge == "" {
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ui.Message("Not using a NetBridge -- skipping StepWaitGuestAddress")
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return multistep.ActionContinue
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}
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qmpMonitor := state.Get("qmp_monitor").(*qmp.SocketMonitor)
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ctx, cancel := context.WithTimeout(ctx, s.timeout)
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defer cancel()
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ui.Say(fmt.Sprintf("Waiting for the guest address to become available in the %s network bridge...", s.NetBridge))
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for {
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guestAddress := getGuestAddress(qmpMonitor, s.NetBridge, "user.0")
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if guestAddress != "" {
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log.Printf("Found guest address %s", guestAddress)
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state.Put("guestAddress", guestAddress)
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return multistep.ActionContinue
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}
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select {
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case <-time.After(10 * time.Second):
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continue
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case <-ctx.Done():
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return multistep.ActionHalt
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}
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}
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}
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func (s *stepWaitGuestAddress) Cleanup(state multistep.StateBag) {
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}
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func getGuestAddress(qmpMonitor *qmp.SocketMonitor, bridgeName string, deviceName string) string {
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devices, err := getNetDevices(qmpMonitor)
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if err != nil {
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log.Printf("Could not retrieve QEMU QMP network device list: %v", err)
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return ""
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}
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for _, device := range devices {
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if device.Name == deviceName {
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ipAddress, _ := getDeviceIPAddress(bridgeName, device.MacAddress)
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return ipAddress
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}
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}
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log.Printf("QEMU QMP network device %s was not found", deviceName)
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return ""
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}
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func getDeviceIPAddress(device string, macAddress string) (string, error) {
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// this parses /proc/net/arp to retrieve the given device IP address.
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//
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// /proc/net/arp is normally someting alike:
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//
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// IP address HW type Flags HW address Mask Device
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// 192.168.121.111 0x1 0x2 52:54:00:12:34:56 * virbr0
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//
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const (
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IPAddressIndex int = iota
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HWTypeIndex
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FlagsIndex
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HWAddressIndex
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MaskIndex
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DeviceIndex
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)
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// see ARP flags at https://github.com/torvalds/linux/blob/v5.4/include/uapi/linux/if_arp.h#L132
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const (
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AtfCom int = 0x02 // ATF_COM (complete)
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)
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f, err := os.Open("/proc/net/arp")
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if err != nil {
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return "", fmt.Errorf("failed to open /proc/net/arp: %w", err)
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}
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defer f.Close()
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s := bufio.NewScanner(f)
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s.Scan()
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for s.Scan() {
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fields := strings.Fields(s.Text())
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if device != "" && fields[DeviceIndex] != device {
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continue
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}
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if fields[HWAddressIndex] != macAddress {
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continue
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}
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flags, err := strconv.ParseInt(fields[FlagsIndex], 0, 32)
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if err != nil {
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return "", fmt.Errorf("failed to parse /proc/net/arp flags field %s: %w", fields[FlagsIndex], err)
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}
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if int(flags)&AtfCom == AtfCom {
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return fields[IPAddressIndex], nil
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}
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}
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return "", fmt.Errorf("could not find %s", macAddress)
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}
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