builder/vmware: Validate MD5

builder/vmware/builder.go

@@ -49,10 +49,9 @@ type config struct {
 	RawSSHWaitTimeout  string `mapstructure:"ssh_wait_timeout"`
 }
 
-func (b *Builder) Prepare(raw interface{}) (err error) {
+func (b *Builder) Prepare(raw interface{}) error {
-	err = mapstructure.Decode(raw, &b.config)
+	if err := mapstructure.Decode(raw, &b.config); err != nil {
-	if err != nil {
+		return err
-		return
 	}
 
 	if b.config.DiskName == "" {
@@ -88,6 +87,7 @@ func (b *Builder) Prepare(raw interface{}) (err error) {
 	}
 
 	// Accumulate any errors
+	var err error
 	errs := make([]error, 0)
 
 	if b.config.HTTPPortMin > b.config.HTTPPortMax {
@@ -96,6 +96,8 @@ func (b *Builder) Prepare(raw interface{}) (err error) {
 
 	if b.config.ISOMD5 == "" {
 		errs = append(errs, errors.New("Due to large file sizes, an iso_md5 is required"))
+	} else {
+		b.config.ISOMD5 = strings.ToLower(b.config.ISOMD5)
 	}
 
 	if b.config.ISOUrl == "" {

builder/vmware/builder_test.go

@@ -10,7 +10,7 @@ import (
 
 func testConfig() map[string]interface{} {
 	return map[string]interface{}{
-		"iso_md5": "foo",
+		"iso_md5":      "foo",
 		"iso_url":      "http://www.packer.io",
 		"ssh_username": "foo",
 	}
@@ -108,11 +108,15 @@ func TestBuilderPrepare_ISOMD5(t *testing.T) {
 	}
 
 	// Test good
-	config["iso_md5"] = "foo"
+	config["iso_md5"] = "FOo"
 	err = b.Prepare(config)
 	if err != nil {
 		t.Fatalf("should not have error: %s", err)
 	}
+
+	if b.config.ISOMD5 != "foo" {
+		t.Fatalf("should've lowercased: %s", b.config.ISOMD5)
+	}
 }
 
 func TestBuilderPrepare_ISOUrl(t *testing.T) {

builder/vmware/step_download_iso.go

@@ -1,6 +1,7 @@
 package vmware
 
 import (
+	"crypto/md5"
 	"fmt"
 	"github.com/mitchellh/multistep"
 	"github.com/mitchellh/packer/packer"
@@ -9,6 +10,7 @@ import (
 	"net/http"
 	"net/url"
 	"os"
+	"strings"
 	"time"
 )
 
@@ -32,43 +34,59 @@ func (s stepDownloadISO) Run(state map[string]interface{}) multistep.StepAction
 	cachePath := cache.Lock(config.ISOUrl)
 	defer cache.Unlock(config.ISOUrl)
 
-	url, err := url.Parse(config.ISOUrl)
+	err := s.checkMD5(cachePath, config.ISOMD5)
+	haveFile := err == nil
 	if err != nil {
-		ui.Error(fmt.Sprintf("Error parsing iso_url: %s", err))
+		if !os.IsNotExist(err) {
-		return multistep.ActionHalt
+			ui.Say(fmt.Sprintf("Error validating MD5 of ISO: %s", err))
-	}
+			return multistep.ActionHalt
-
-	// Start the download in a goroutine so that we cancel it and such.
-	var progress uint
-	downloadComplete := make(chan bool, 1)
-	go func() {
-		ui.Say("Copying or downloading ISO. Progress will be shown periodically.")
-		cachePath, err = s.downloadUrl(cachePath, url, &progress)
-		downloadComplete <- true
-	}()
-
-	progressTimer := time.NewTicker(15 * time.Second)
-	defer progressTimer.Stop()
-
-DownloadWaitLoop:
-	for {
-		select {
-		case <-downloadComplete:
-			log.Println("Download of ISO completed.")
-			break DownloadWaitLoop
-		case <-progressTimer.C:
-			ui.Say(fmt.Sprintf("Download progress: %d%%", progress))
-		case <-time.After(1 * time.Second):
-			if _, ok := state[multistep.StateCancelled]; ok {
-				ui.Say("Interrupt received. Cancelling download...")
-				return multistep.ActionHalt
-			}
 		}
 	}
 
-	if err != nil {
+	if !haveFile {
-		ui.Error(fmt.Sprintf("Error downloading ISO: %s", err))
+		url, err := url.Parse(config.ISOUrl)
-		return multistep.ActionHalt
+		if err != nil {
+			ui.Error(fmt.Sprintf("Error parsing iso_url: %s", err))
+			return multistep.ActionHalt
+		}
+
+		// Start the download in a goroutine so that we cancel it and such.
+		var progress uint
+		downloadComplete := make(chan bool, 1)
+		go func() {
+			ui.Say("Copying or downloading ISO. Progress will be shown periodically.")
+			cachePath, err = s.downloadUrl(cachePath, url, &progress)
+			downloadComplete <- true
+		}()
+
+		progressTimer := time.NewTicker(15 * time.Second)
+		defer progressTimer.Stop()
+
+	DownloadWaitLoop:
+		for {
+			select {
+			case <-downloadComplete:
+				log.Println("Download of ISO completed.")
+				break DownloadWaitLoop
+			case <-progressTimer.C:
+				ui.Say(fmt.Sprintf("Download progress: %d%%", progress))
+			case <-time.After(1 * time.Second):
+				if _, ok := state[multistep.StateCancelled]; ok {
+					ui.Say("Interrupt received. Cancelling download...")
+					return multistep.ActionHalt
+				}
+			}
+		}
+
+		if err != nil {
+			ui.Error(fmt.Sprintf("Error downloading ISO: %s", err))
+			return multistep.ActionHalt
+		}
+
+		if err = s.checkMD5(cachePath, config.ISOMD5); err != nil {
+			ui.Say(fmt.Sprintf("Error validating MD5 of ISO: %s", err))
+			return multistep.ActionHalt
+		}
 	}
 
 	log.Printf("Path to ISO on disk: %s", cachePath)
@@ -79,6 +97,22 @@ DownloadWaitLoop:
 
 func (stepDownloadISO) Cleanup(map[string]interface{}) {}
 
+func (stepDownloadISO) checkMD5(path string, expected string) error {
+	f, err := os.Open(path)
+	if err != nil {
+		return err
+	}
+
+	hash := md5.New()
+	io.Copy(hash, f)
+	result := strings.ToLower(string(hash.Sum(nil)))
+	if result != expected {
+		return fmt.Errorf("result != expected: %s != %s", result, expected)
+	}
+
+	return nil
+}
+
 func (stepDownloadISO) downloadUrl(path string, url *url.URL, progress *uint) (string, error) {
 	if url.Scheme == "file" {
 		// If it is just a file URL, then we already have the ISO