tools/bootserver/cmd/main.go - fuchsia - Git at Google

 // Copyright 2019 The Fuchsia Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.

 package main

 import (
 	"context"
 	"errors"
 	"flag"
 	"fmt"
 	"io"
 	"io/ioutil"
 	"net"
 	"os"
 	"strings"
 	"time"

 	"go.fuchsia.dev/fuchsia/tools/bootserver"
 	"go.fuchsia.dev/fuchsia/tools/lib/logger"
 	"go.fuchsia.dev/fuchsia/tools/net/netboot"
 	"go.fuchsia.dev/fuchsia/tools/net/netutil"
 	"go.fuchsia.dev/fuchsia/tools/net/tftp"
 )

 const (
 	bootloaderVersion             = "0.7.22"
 	defaultMicrosecBetweenPackets = 20
 	nodenameEnvKey                = "ZIRCON_NODENAME"
 	retryDelay                    = time.Second
 )

 // Firmware arguments have variable names based on their type e.g.:
 //   --firmware=<file>
 //   --firmware-foo=<file>
 // The flag package doesn't support anything like this, so we have to do a  bit
 // of extra work to find any of these args and add them to the list.
 type firmwareArg struct {
 	name   string
 	value  string
 	fwType string
 	help   string
 }

 var (
 	bootOnce                       bool
 	bootIpv6                       string
 	tftpBlockSize                  int
 	packetInterval                 int
 	nodename                       string
 	windowSize                     int
 	boardName                      string
 	bootKernel                     string
 	fvm                            string
 	bootloader                     string
 	firmware                       []firmwareArg
 	zircona                        string
 	zirconb                        string
 	zirconr                        string
 	vbmetaa                        string
 	vbmetab                        string
 	vbmetar                        string
 	authorizedKeysFile             string
 	failFast                       bool
 	useNetboot                     bool
 	useTftp                        bool
 	nocolor                        bool
 	allowZedbootVersionMismatch    bool
 	failFastZedbootVersionMismatch bool
 	imageManifest                  string
 	mode                           bootserver.Mode
 	// TODO(ihuh): Remove when no longer used. This is not actually used
 	// anywhere. It is just here to hold the value of the --no-bind flag.
 	noBind bool

 	// errIncompleteTransfer represents a failure to transfer pave images
 	// to the device.
 	errIncompleteTransfer = errors.New("transfer incomplete")
 )

 func init() {
 	// Support classic cmd line interface.
 	flag.StringVar(&nodename, "n", "", "only boot device with this nodename")
 	flag.StringVar(&bootKernel, "boot", "", "use the supplied file as a kernel")
 	flag.StringVar(&fvm, "fvm", "", "use the supplied file as a sparse FVM image (up to 4 times)")
 	flag.StringVar(&bootloader, "bootloader", "", "use the supplied file as a bootloader image")
 	flag.StringVar(&zircona, "zircona", "", "use the supplied file as a zircon-a zbi")
 	flag.StringVar(&zirconb, "zirconb", "", "use the supplied file as a zircon-b zbi")
 	flag.StringVar(&zirconr, "zirconr", "", "use the supplied file as a zircon-r zbi")
 	flag.StringVar(&vbmetaa, "vbmetaa", "", "use the supplied file as a avb vbmeta_a image")
 	flag.StringVar(&vbmetab, "vbmetab", "", "use the supplied file as a avb vbmeta_b image")
 	flag.StringVar(&vbmetar, "vbmetar", "", "use the supplied file as a avb vbmeta_r image")

 	// Support firmware arguments.
 	firmware = getFirmwareArgs(os.Args)
 	for i := range firmware {
 		flag.StringVar(&firmware[i].value, firmware[i].name, "", firmware[i].help)
 	}

 	// Support reading in images.json and paving zedboot.
 	flag.StringVar(&imageManifest, "images", "", "use an image manifest to pave")
 	flag.Var(&mode, "mode", "bootserver modes: either pave, netboot, or pave-zedboot")

 	flag.StringVar(&bootIpv6, "a", "", "only boot device with this IPv6 address")
 	flag.BoolVar(&allowZedbootVersionMismatch, "allow-zedboot-version-mismatch", false, "warn on zedboot version mismatch rather than fail")
 	flag.StringVar(&authorizedKeysFile, "authorized-keys", "", "use the supplied file as an authorized_keys file")
 	flag.IntVar(&tftpBlockSize, "b", 0, "tftp block size")
 	flag.StringVar(&boardName, "board_name", "", "name of the board files are meant for")
 	flag.BoolVar(&bootOnce, "1", true, "only boot once, then exit")
 	flag.BoolVar(&failFast, "fail-fast", false, "exit on first error")
 	flag.BoolVar(&failFastZedbootVersionMismatch, "fail-fast-if-version-mismatch", false, "error if zedboot version does not match")
 	// TODO(ihuh): Remove once all uses of this flag are removed. This is already true by default if -a or -n are provided.
 	flag.BoolVar(&noBind, "no-bind", false, "do not bind to bootserver port. Should be used with -a <IPV6>")
 	flag.IntVar(&windowSize, "w", 0, "tftp window size, ignored with --netboot")

 	//  TODO(fxbug.dev/38517): Implement the following unsupported flags.
 	flag.IntVar(&packetInterval, "i", defaultMicrosecBetweenPackets, "number of microseconds between packets; ignored with --tftp")
 	// We currently always default to tftp
 	flag.BoolVar(&useNetboot, "netboot", false, "use the netboot protocol")
 	flag.BoolVar(&useTftp, "tftp", true, "use the tftp protocol (default)")
 	flag.BoolVar(&nocolor, "nocolor", false, "disable ANSI color (false)")
 }

 // Creates a slice of FirmwareArgs from |args|.
 func getFirmwareArgs(args []string) []firmwareArg {
 	// Always include the default --firmware whether specified or not, to give
 	// a useful help message.
 	fwArgs := []firmwareArg{{
 		name:   "firmware",
 		value:  "",
 		fwType: "",
 		help:   "use the supplied file as the default firmware image; use --firmware-<type> for typed images",
 	}}

 	for _, arg := range args {
 		// Go supports one or two dash prefixes.
 		fwType := strings.TrimPrefix(arg, "-firmware")
 		fwType = strings.TrimPrefix(fwType, "--firmware")
 		if fwType == arg {
 			// Didn't find a prefix match, on to the next arg.
 			continue
 		}

 		// If the caller used "arg=value", peel off the "=value" part as we're
 		// not actually parsing, but just finding all the necessary arg names.
 		fwType = strings.SplitN(fwType, "=", 2)[0]

 		if fwType == "" {
 			// We already added the default untyped "--firmware" arg.
 		} else if fwType[0] == '-' {
 			fwType = fwType[1:]
 			fwArgs = append(fwArgs, firmwareArg{
 				name:   fmt.Sprintf("firmware-%s", fwType),
 				value:  "",
 				fwType: fwType,
 				help:   fmt.Sprintf("use the supplied file as the %q firmware image", fwType),
 			})
 		}

 		// If we got here it wasn't a firmware arg, just ignore it.
 	}

 	return fwArgs
 }

 func overrideImage(ctx context.Context, imgMap map[string]bootserver.Image, img bootserver.Image) map[string]bootserver.Image {
 	if existing, ok := imgMap[img.Name]; ok {
 		if existing.Reader != nil {
 			if closer, ok := existing.Reader.(io.Closer); ok {
 				if err := closer.Close(); err != nil {
 					logger.Warningf(ctx, "failed to close image %s: %v", existing.Name, err)
 				}
 			}
 		}
 	}
 	imgMap[img.Name] = img
 	return imgMap
 }

 func getImages(ctx context.Context) ([]bootserver.Image, func() error, error) {
 	imgMap := make(map[string]bootserver.Image)
 	// If an image manifest is provided, we use that.
 	if imageManifest != "" {
 		imgs, closeFunc, err := bootserver.GetImages(ctx, imageManifest, mode)
 		if err != nil {
 			return imgs, closeFunc, err
 		}
 		for _, img := range imgs {
 			imgMap[img.Name] = img
 		}
 	}
 	// If cmdline args are provided, append them to the image list, overriding any
 	// images from the manifest.
 	if bootKernel != "" {
 		imgMap = overrideImage(ctx, imgMap, bootserver.Image{
 			Name: "zbi_netboot",
 			Path: bootKernel,
 			Args: []string{"--boot"},
 		})
 	}
 	if bootloader != "" {
 		imgMap = overrideImage(ctx, imgMap, bootserver.Image{
 			Name: "blk_efi",
 			Path: bootloader,
 			Args: []string{"--bootloader"},
 		})
 	}
 	for _, fw := range firmware {
 		imgMap = overrideImage(ctx, imgMap, bootserver.Image{
 			// Trailing delimiter is OK for untyped images.
 			Name: "img_firmware_" + fw.fwType,
 			Path: fw.value,
 			Args: []string{"--firmware-" + fw.fwType},
 		})
 	}
 	if fvm != "" {
 		imgMap = overrideImage(ctx, imgMap, bootserver.Image{
 			Name: "blk_storage-sparse",
 			Path: fvm,
 			Args: []string{"--fvm"},
 		})
 	}
 	if zircona != "" {
 		imgMap = overrideImage(ctx, imgMap, bootserver.Image{
 			Name: "zbi_zircon-a",
 			Path: zircona,
 			Args: []string{"--zircona"},
 		})
 	}
 	if zirconb != "" {
 		imgMap = overrideImage(ctx, imgMap, bootserver.Image{
 			Name: "zbi_zircon-b",
 			Path: zirconb,
 			Args: []string{"--zirconb"},
 		})
 	}
 	if zirconr != "" {
 		imgMap = overrideImage(ctx, imgMap, bootserver.Image{
 			Name: "zbi_zircon-r",
 			Path: zirconr,
 			Args: []string{"--zirconr"},
 		})
 	}
 	if vbmetaa != "" {
 		imgMap = overrideImage(ctx, imgMap, bootserver.Image{
 			Name: "vbmeta_zircon-a",
 			Path: vbmetaa,
 			Args: []string{"--vbmetaa"},
 		})
 	}
 	if vbmetab != "" {
 		imgMap = overrideImage(ctx, imgMap, bootserver.Image{
 			Name: "vbmeta_zircon-b",
 			Path: vbmetab,
 			Args: []string{"--vbmetab"},
 		})
 	}
 	if vbmetar != "" {
 		imgMap = overrideImage(ctx, imgMap, bootserver.Image{
 			Name: "vbmeta_zircon-r",
 			Path: vbmetar,
 			Args: []string{"--vbmetar"},
 		})
 	}
 	imgs := []bootserver.Image{}
 	for _, img := range imgMap {
 		imgs = append(imgs, img)
 	}
 	closeFunc, err := populateReaders(imgs)
 	return imgs, closeFunc, err
 }

 func populateReaders(imgs []bootserver.Image) (func() error, error) {
 	closeFunc := func() error {
 		var errs []error
 		for _, img := range imgs {
 			if img.Reader != nil {
 				if closer, ok := img.Reader.(io.Closer); ok {
 					if err := closer.Close(); err != nil {
 						errs = append(errs, err)
 					}
 				}
 			}
 		}
 		if len(errs) > 0 {
 			return fmt.Errorf("failed to close images: %v", errs)
 		}
 		return nil
 	}
 	for i := range imgs {
 		if imgs[i].Reader != nil {
 			continue
 		}
 		r, err := os.Open(imgs[i].Path)
 		if err != nil {
 			// Close already opened readers.
 			closeFunc()
 			return closeFunc, fmt.Errorf("failed to open %s: %w", imgs[i].Path, err)
 		}
 		fi, err := r.Stat()
 		if err != nil {
 			closeFunc()
 			return closeFunc, fmt.Errorf("failed to get file info for %s: %w", imgs[i].Path, err)
 		}
 		imgs[i].Reader = r
 		imgs[i].Size = fi.Size()
 	}
 	return closeFunc, nil
 }

 func connectAndBoot(ctx context.Context, nodename string, imgs []bootserver.Image, cmdlineArgs []string, authorizedKeys []byte) error {
 	var addr *net.UDPAddr
 	if bootIpv6 != "" {
 		ipAddr, err := net.ResolveIPAddr("ip6", bootIpv6)
 		if err != nil {
 			return fmt.Errorf("%s: invalid ipv6 address specified", bootIpv6)
 		}
 		addr = &net.UDPAddr{IP: ipAddr.IP, Zone: ipAddr.Zone}
 	}
 	addr, msg, cleanup, err := netutil.GetAdvertisement(ctx, nodename, addr)
 	if err != nil {
 		return fmt.Errorf("%w: %v", errIncompleteTransfer, err)
 	}
 	defer cleanup()
 	if msg.BootloaderVersion != bootloaderVersion {
 		mismatchErrMsg := fmt.Sprintf("WARNING: Bootserver version '%s' != remote Zedboot version '%s'", bootloaderVersion, msg.BootloaderVersion)
 		if allowZedbootVersionMismatch {
 			logger.Warningf(ctx, "%s. Paving may fail.", mismatchErrMsg)
 		} else {
 			if failFastZedbootVersionMismatch {
 				failFast = true
 			}
 			return fmt.Errorf("%w: %s. Device will not be serviced. Please upgrade Zedboot.", errIncompleteTransfer, mismatchErrMsg)
 		}
 	}
 	udpAddr := &net.UDPAddr{
 		IP:   addr.IP,
 		Port: tftp.ClientPort,
 		Zone: addr.Zone,
 	}
 	client, err := tftp.NewClient(udpAddr, uint16(tftpBlockSize), uint16(windowSize))
 	if err != nil {
 		return fmt.Errorf("%w: %v", errIncompleteTransfer, err)
 	}

 	if boardName != "" {
 		if err := bootserver.ValidateBoard(ctx, client, boardName); err != nil {
 			return err
 		}
 	}

 	logger.Infof(ctx, "Proceeding with nodename %s", msg.Nodename)

 	if err := bootserver.Boot(ctx, client, imgs, cmdlineArgs, authorizedKeys); err != nil {
 		return fmt.Errorf("%w: %v", errIncompleteTransfer, err)
 	}
 	return nil
 }

 func resolveNodename() (string, error) {
 	if nodename == "" {
 		envNodename, ok := os.LookupEnv(nodenameEnvKey)
 		if ok && envNodename != "" {
 			return envNodename, nil
 		} else {
 			// Return the NodenameWildcard to discover any device.
 			return netboot.NodenameWildcard, nil
 		}
 	}
 	return nodename, nil
 }

 func execute(ctx context.Context, cmdlineArgs []string) error {
 	// Do some secondary cmdline arg validation.
 	if imageManifest != "" && mode == bootserver.ModeNull {
 		return fmt.Errorf("must specify a bootserver mode [--mode] when using an image manifest")
 	} else if imageManifest == "" && mode != bootserver.ModeNull {
 		return fmt.Errorf("cannot specify a bootserver mode without an image manifest [--images]")
 	}

 	// Remove the default firmware if the caller didn't actually use it.
 	if firmware[0].value == "" {
 		firmware = firmware[1:]
 	}

 	if boardName != "" {
 		logger.Infof(ctx, "Board name set to [%s]", boardName)
 	}

 	imgs, closeFunc, err := getImages(ctx)
 	if err != nil {
 		return err
 	}
 	if len(imgs) == 0 {
 		return fmt.Errorf("no images provided!")
 	}
 	defer closeFunc()

 	n, err := resolveNodename()
 	if err != nil {
 		return err
 	}

 	if allowZedbootVersionMismatch && failFastZedbootVersionMismatch {
 		return fmt.Errorf("only one of allow-zedboot-version-mismatch and fail-fast-if-version-mismatch can be true")
 	}

 	var authorizedKeys []byte
 	if authorizedKeysFile != "" {
 		authorizedKeys, err = ioutil.ReadFile(authorizedKeysFile)
 		if err != nil {
 			return fmt.Errorf("could not read SSH key file %q: %v", authorizedKeysFile, err)
 		}
 	}

 	// Keep discovering and booting devices.
 	for {
 		err = connectAndBoot(ctx, n, imgs, cmdlineArgs, authorizedKeys)
 		if !(err == nil || errors.Is(err, errIncompleteTransfer)) {
 			// Exit early for any error other than an errIncompleteTransfer.
 			return err
 		} else if bootOnce || (failFast && err != nil) {
 			// Exit after booting first device or if boot failed.
 			return err
 		} else if err != nil {
 			// Error is an errIncompleteTransfer. Retry after some delay.
 			logger.Errorf(ctx, "%v", err)
 			time.Sleep(retryDelay)
 		}
 	}
 }

 func main() {
 	flag.Parse()

 	ctx := context.Background()
 	if err := execute(ctx, flag.Args()); err != nil {
 		logger.Fatalf(ctx, "%v", err)
 	}
 }
	// Copyright 2019 The Fuchsia Authors. All rights reserved.
	// Use of this source code is governed by a BSD-style license that can be
	// found in the LICENSE file.

	package main

	import (
	"context"
	"errors"
	"flag"
	"fmt"
	"io"
	"io/ioutil"
	"net"
	"os"
	"strings"
	"time"

	"go.fuchsia.dev/fuchsia/tools/bootserver"
	"go.fuchsia.dev/fuchsia/tools/lib/logger"
	"go.fuchsia.dev/fuchsia/tools/net/netboot"
	"go.fuchsia.dev/fuchsia/tools/net/netutil"
	"go.fuchsia.dev/fuchsia/tools/net/tftp"
	)

	const (
	bootloaderVersion = "0.7.22"
	defaultMicrosecBetweenPackets = 20
	nodenameEnvKey = "ZIRCON_NODENAME"
	retryDelay = time.Second
	)

	// Firmware arguments have variable names based on their type e.g.:
	// --firmware=<file>
	// --firmware-foo=<file>
	// The flag package doesn't support anything like this, so we have to do a bit
	// of extra work to find any of these args and add them to the list.
	type firmwareArg struct {
	name string
	value string
	fwType string
	help string
	}

	var (
	bootOnce bool
	bootIpv6 string
	tftpBlockSize int
	packetInterval int
	nodename string
	windowSize int
	boardName string
	bootKernel string
	fvm string
	bootloader string
	firmware []firmwareArg
	zircona string
	zirconb string
	zirconr string
	vbmetaa string
	vbmetab string
	vbmetar string
	authorizedKeysFile string
	failFast bool
	useNetboot bool
	useTftp bool
	nocolor bool
	allowZedbootVersionMismatch bool
	failFastZedbootVersionMismatch bool
	imageManifest string
	mode bootserver.Mode
	// TODO(ihuh): Remove when no longer used. This is not actually used
	// anywhere. It is just here to hold the value of the --no-bind flag.
	noBind bool

	// errIncompleteTransfer represents a failure to transfer pave images
	// to the device.
	errIncompleteTransfer = errors.New("transfer incomplete")
	)

	func init() {
	// Support classic cmd line interface.
	flag.StringVar(&nodename, "n", "", "only boot device with this nodename")
	flag.StringVar(&bootKernel, "boot", "", "use the supplied file as a kernel")
	flag.StringVar(&fvm, "fvm", "", "use the supplied file as a sparse FVM image (up to 4 times)")
	flag.StringVar(&bootloader, "bootloader", "", "use the supplied file as a bootloader image")
	flag.StringVar(&zircona, "zircona", "", "use the supplied file as a zircon-a zbi")
	flag.StringVar(&zirconb, "zirconb", "", "use the supplied file as a zircon-b zbi")
	flag.StringVar(&zirconr, "zirconr", "", "use the supplied file as a zircon-r zbi")
	flag.StringVar(&vbmetaa, "vbmetaa", "", "use the supplied file as a avb vbmeta_a image")
	flag.StringVar(&vbmetab, "vbmetab", "", "use the supplied file as a avb vbmeta_b image")
	flag.StringVar(&vbmetar, "vbmetar", "", "use the supplied file as a avb vbmeta_r image")

	// Support firmware arguments.
	firmware = getFirmwareArgs(os.Args)
	for i := range firmware {
	flag.StringVar(&firmware[i].value, firmware[i].name, "", firmware[i].help)
	}

	// Support reading in images.json and paving zedboot.
	flag.StringVar(&imageManifest, "images", "", "use an image manifest to pave")
	flag.Var(&mode, "mode", "bootserver modes: either pave, netboot, or pave-zedboot")

	flag.StringVar(&bootIpv6, "a", "", "only boot device with this IPv6 address")
	flag.BoolVar(&allowZedbootVersionMismatch, "allow-zedboot-version-mismatch", false, "warn on zedboot version mismatch rather than fail")
	flag.StringVar(&authorizedKeysFile, "authorized-keys", "", "use the supplied file as an authorized_keys file")
	flag.IntVar(&tftpBlockSize, "b", 0, "tftp block size")
	flag.StringVar(&boardName, "board_name", "", "name of the board files are meant for")
	flag.BoolVar(&bootOnce, "1", true, "only boot once, then exit")
	flag.BoolVar(&failFast, "fail-fast", false, "exit on first error")
	flag.BoolVar(&failFastZedbootVersionMismatch, "fail-fast-if-version-mismatch", false, "error if zedboot version does not match")
	// TODO(ihuh): Remove once all uses of this flag are removed. This is already true by default if -a or -n are provided.
	flag.BoolVar(&noBind, "no-bind", false, "do not bind to bootserver port. Should be used with -a <IPV6>")
	flag.IntVar(&windowSize, "w", 0, "tftp window size, ignored with --netboot")

	// TODO(fxbug.dev/38517): Implement the following unsupported flags.
	flag.IntVar(&packetInterval, "i", defaultMicrosecBetweenPackets, "number of microseconds between packets; ignored with --tftp")
	// We currently always default to tftp
	flag.BoolVar(&useNetboot, "netboot", false, "use the netboot protocol")
	flag.BoolVar(&useTftp, "tftp", true, "use the tftp protocol (default)")
	flag.BoolVar(&nocolor, "nocolor", false, "disable ANSI color (false)")
	}

	// Creates a slice of FirmwareArgs from \|args\|.
	func getFirmwareArgs(args []string) []firmwareArg {
	// Always include the default --firmware whether specified or not, to give
	// a useful help message.
	fwArgs := []firmwareArg{{
	name: "firmware",
	value: "",
	fwType: "",
	help: "use the supplied file as the default firmware image; use --firmware-<type> for typed images",
	}}

	for _, arg := range args {
	// Go supports one or two dash prefixes.
	fwType := strings.TrimPrefix(arg, "-firmware")
	fwType = strings.TrimPrefix(fwType, "--firmware")
	if fwType == arg {
	// Didn't find a prefix match, on to the next arg.
	continue
	}

	// If the caller used "arg=value", peel off the "=value" part as we're
	// not actually parsing, but just finding all the necessary arg names.
	fwType = strings.SplitN(fwType, "=", 2)[0]

	if fwType == "" {
	// We already added the default untyped "--firmware" arg.
	} else if fwType[0] == '-' {
	fwType = fwType[1:]
	fwArgs = append(fwArgs, firmwareArg{
	name: fmt.Sprintf("firmware-%s", fwType),
	value: "",
	fwType: fwType,
	help: fmt.Sprintf("use the supplied file as the %q firmware image", fwType),
	})
	}

	// If we got here it wasn't a firmware arg, just ignore it.
	}

	return fwArgs
	}

	func overrideImage(ctx context.Context, imgMap map[string]bootserver.Image, img bootserver.Image) map[string]bootserver.Image {
	if existing, ok := imgMap[img.Name]; ok {
	if existing.Reader != nil {
	if closer, ok := existing.Reader.(io.Closer); ok {
	if err := closer.Close(); err != nil {
	logger.Warningf(ctx, "failed to close image %s: %v", existing.Name, err)
	}
	}
	}
	}
	imgMap[img.Name] = img
	return imgMap
	}

	func getImages(ctx context.Context) ([]bootserver.Image, func() error, error) {
	imgMap := make(map[string]bootserver.Image)
	// If an image manifest is provided, we use that.
	if imageManifest != "" {
	imgs, closeFunc, err := bootserver.GetImages(ctx, imageManifest, mode)
	if err != nil {
	return imgs, closeFunc, err
	}
	for _, img := range imgs {
	imgMap[img.Name] = img
	}
	}
	// If cmdline args are provided, append them to the image list, overriding any
	// images from the manifest.
	if bootKernel != "" {
	imgMap = overrideImage(ctx, imgMap, bootserver.Image{
	Name: "zbi_netboot",
	Path: bootKernel,
	Args: []string{"--boot"},
	})
	}
	if bootloader != "" {
	imgMap = overrideImage(ctx, imgMap, bootserver.Image{
	Name: "blk_efi",
	Path: bootloader,
	Args: []string{"--bootloader"},
	})
	}
	for _, fw := range firmware {
	imgMap = overrideImage(ctx, imgMap, bootserver.Image{
	// Trailing delimiter is OK for untyped images.
	Name: "img_firmware_" + fw.fwType,
	Path: fw.value,
	Args: []string{"--firmware-" + fw.fwType},
	})
	}
	if fvm != "" {
	imgMap = overrideImage(ctx, imgMap, bootserver.Image{
	Name: "blk_storage-sparse",
	Path: fvm,
	Args: []string{"--fvm"},
	})
	}
	if zircona != "" {
	imgMap = overrideImage(ctx, imgMap, bootserver.Image{
	Name: "zbi_zircon-a",
	Path: zircona,
	Args: []string{"--zircona"},
	})
	}
	if zirconb != "" {
	imgMap = overrideImage(ctx, imgMap, bootserver.Image{
	Name: "zbi_zircon-b",
	Path: zirconb,
	Args: []string{"--zirconb"},
	})
	}
	if zirconr != "" {
	imgMap = overrideImage(ctx, imgMap, bootserver.Image{
	Name: "zbi_zircon-r",
	Path: zirconr,
	Args: []string{"--zirconr"},
	})
	}
	if vbmetaa != "" {
	imgMap = overrideImage(ctx, imgMap, bootserver.Image{
	Name: "vbmeta_zircon-a",
	Path: vbmetaa,
	Args: []string{"--vbmetaa"},
	})
	}
	if vbmetab != "" {
	imgMap = overrideImage(ctx, imgMap, bootserver.Image{
	Name: "vbmeta_zircon-b",
	Path: vbmetab,
	Args: []string{"--vbmetab"},
	})
	}
	if vbmetar != "" {
	imgMap = overrideImage(ctx, imgMap, bootserver.Image{
	Name: "vbmeta_zircon-r",
	Path: vbmetar,
	Args: []string{"--vbmetar"},
	})
	}
	imgs := []bootserver.Image{}
	for _, img := range imgMap {
	imgs = append(imgs, img)
	}
	closeFunc, err := populateReaders(imgs)
	return imgs, closeFunc, err
	}

	func populateReaders(imgs []bootserver.Image) (func() error, error) {
	closeFunc := func() error {
	var errs []error
	for _, img := range imgs {
	if img.Reader != nil {
	if closer, ok := img.Reader.(io.Closer); ok {
	if err := closer.Close(); err != nil {
	errs = append(errs, err)
	}
	}
	}
	}
	if len(errs) > 0 {
	return fmt.Errorf("failed to close images: %v", errs)
	}
	return nil
	}
	for i := range imgs {
	if imgs[i].Reader != nil {
	continue
	}
	r, err := os.Open(imgs[i].Path)
	if err != nil {
	// Close already opened readers.
	closeFunc()
	return closeFunc, fmt.Errorf("failed to open %s: %w", imgs[i].Path, err)
	}
	fi, err := r.Stat()
	if err != nil {
	closeFunc()
	return closeFunc, fmt.Errorf("failed to get file info for %s: %w", imgs[i].Path, err)
	}
	imgs[i].Reader = r
	imgs[i].Size = fi.Size()
	}
	return closeFunc, nil
	}

	func connectAndBoot(ctx context.Context, nodename string, imgs []bootserver.Image, cmdlineArgs []string, authorizedKeys []byte) error {
	var addr *net.UDPAddr
	if bootIpv6 != "" {
	ipAddr, err := net.ResolveIPAddr("ip6", bootIpv6)
	if err != nil {
	return fmt.Errorf("%s: invalid ipv6 address specified", bootIpv6)
	}
	addr = &net.UDPAddr{IP: ipAddr.IP, Zone: ipAddr.Zone}
	}
	addr, msg, cleanup, err := netutil.GetAdvertisement(ctx, nodename, addr)
	if err != nil {
	return fmt.Errorf("%w: %v", errIncompleteTransfer, err)
	}
	defer cleanup()
	if msg.BootloaderVersion != bootloaderVersion {
	mismatchErrMsg := fmt.Sprintf("WARNING: Bootserver version '%s' != remote Zedboot version '%s'", bootloaderVersion, msg.BootloaderVersion)
	if allowZedbootVersionMismatch {
	logger.Warningf(ctx, "%s. Paving may fail.", mismatchErrMsg)
	} else {
	if failFastZedbootVersionMismatch {
	failFast = true
	}
	return fmt.Errorf("%w: %s. Device will not be serviced. Please upgrade Zedboot.", errIncompleteTransfer, mismatchErrMsg)
	}
	}
	udpAddr := &net.UDPAddr{
	IP: addr.IP,
	Port: tftp.ClientPort,
	Zone: addr.Zone,
	}
	client, err := tftp.NewClient(udpAddr, uint16(tftpBlockSize), uint16(windowSize))
	if err != nil {
	return fmt.Errorf("%w: %v", errIncompleteTransfer, err)
	}

	if boardName != "" {
	if err := bootserver.ValidateBoard(ctx, client, boardName); err != nil {
	return err
	}
	}

	logger.Infof(ctx, "Proceeding with nodename %s", msg.Nodename)

	if err := bootserver.Boot(ctx, client, imgs, cmdlineArgs, authorizedKeys); err != nil {
	return fmt.Errorf("%w: %v", errIncompleteTransfer, err)
	}
	return nil
	}

	func resolveNodename() (string, error) {
	if nodename == "" {
	envNodename, ok := os.LookupEnv(nodenameEnvKey)
	if ok && envNodename != "" {
	return envNodename, nil
	} else {
	// Return the NodenameWildcard to discover any device.
	return netboot.NodenameWildcard, nil
	}
	}
	return nodename, nil
	}

	func execute(ctx context.Context, cmdlineArgs []string) error {
	// Do some secondary cmdline arg validation.
	if imageManifest != "" && mode == bootserver.ModeNull {
	return fmt.Errorf("must specify a bootserver mode [--mode] when using an image manifest")
	} else if imageManifest == "" && mode != bootserver.ModeNull {
	return fmt.Errorf("cannot specify a bootserver mode without an image manifest [--images]")
	}

	// Remove the default firmware if the caller didn't actually use it.
	if firmware[0].value == "" {
	firmware = firmware[1:]
	}

	if boardName != "" {
	logger.Infof(ctx, "Board name set to [%s]", boardName)
	}

	imgs, closeFunc, err := getImages(ctx)
	if err != nil {
	return err
	}
	if len(imgs) == 0 {
	return fmt.Errorf("no images provided!")
	}
	defer closeFunc()

	n, err := resolveNodename()
	if err != nil {
	return err
	}

	if allowZedbootVersionMismatch && failFastZedbootVersionMismatch {
	return fmt.Errorf("only one of allow-zedboot-version-mismatch and fail-fast-if-version-mismatch can be true")
	}

	var authorizedKeys []byte
	if authorizedKeysFile != "" {
	authorizedKeys, err = ioutil.ReadFile(authorizedKeysFile)
	if err != nil {
	return fmt.Errorf("could not read SSH key file %q: %v", authorizedKeysFile, err)
	}
	}

	// Keep discovering and booting devices.
	for {
	err = connectAndBoot(ctx, n, imgs, cmdlineArgs, authorizedKeys)
	if !(err == nil \|\| errors.Is(err, errIncompleteTransfer)) {
	// Exit early for any error other than an errIncompleteTransfer.
	return err
	} else if bootOnce \|\| (failFast && err != nil) {
	// Exit after booting first device or if boot failed.
	return err
	} else if err != nil {
	// Error is an errIncompleteTransfer. Retry after some delay.
	logger.Errorf(ctx, "%v", err)
	time.Sleep(retryDelay)
	}
	}
	}

	func main() {
	flag.Parse()

	ctx := context.Background()
	if err := execute(ctx, flag.Args()); err != nil {
	logger.Fatalf(ctx, "%v", err)
	}
	}