Implement download for WinRM communicator

Signed-off-by: Mark DeLillo <mdelillo@pivotal.io>

communicator/winrm/communicator.go

@@ -1,8 +1,10 @@
 package winrm
 
 import (
+	"encoding/base64"
 	"fmt"
 	"io"
+	"io/ioutil"
 	"log"
 	"os"
 	"path/filepath"
@@ -143,7 +145,20 @@ func (c *Communicator) UploadDir(dst string, src string, exclude []string) error
 }
 
 func (c *Communicator) Download(src string, dst io.Writer) error {
-	return fmt.Errorf("WinRM doesn't support download.")
+	endpoint := winrm.NewEndpoint(c.endpoint.Host, c.endpoint.Port, c.config.Https, c.config.Insecure, nil, nil, nil, c.config.Timeout)
+	client, err := winrm.NewClient(endpoint, c.config.Username, c.config.Password)
+	if err != nil {
+		return err
+	}
+
+	encodeScript := `$file=[System.IO.File]::ReadAllBytes("%s"); Write-Output $([System.Convert]::ToBase64String($file))`
+
+	base64DecodePipe := &Base64Pipe{w: dst}
+
+	cmd := winrm.Powershell(fmt.Sprintf(encodeScript, src))
+	_, err = client.Run(cmd, base64DecodePipe, ioutil.Discard)
+
+	return err
 }
 
 func (c *Communicator) DownloadDir(src string, dst string, exclude []string) error {
@@ -164,3 +179,33 @@ func (c *Communicator) newCopyClient() (*winrmcp.Winrmcp, error) {
 		TransportDecorator:    c.config.TransportDecorator,
 	})
 }
+
+type Base64Pipe struct {
+	w io.Writer // underlying writer (file, buffer)
+}
+
+func (d *Base64Pipe) ReadFrom(r io.Reader) (int64, error) {
+	b, err := ioutil.ReadAll(r)
+	if err != nil {
+		return 0, err
+	}
+
+	var i int
+	i, err = d.Write(b)
+
+	if err != nil {
+		return 0, err
+	}
+
+	return int64(i), err
+}
+
+func (d *Base64Pipe) Write(p []byte) (int, error) {
+	dst := make([]byte, base64.StdEncoding.DecodedLen(len(p)))
+
+	if _, err := base64.StdEncoding.Decode(dst, p); err != nil {
+		return 0, err
+	}
+
+	return d.w.Write(dst)
+}

communicator/winrm/communicator_test.go

@@ -3,6 +3,7 @@ package winrm
 import (
 	"bytes"
 	"io"
+	"strings"
 	"testing"
 	"time"
 
@@ -10,6 +11,9 @@ import (
 	"github.com/hashicorp/packer/packer"
 )
 
+const PAYLOAD = "stuff"
+const BASE64_ENCODED_PAYLOAD = "c3R1ZmY="
+
 func newMockWinRMServer(t *testing.T) *winrmtest.Remote {
 	wrm := winrmtest.NewRemote()
 
@@ -26,9 +30,16 @@ func newMockWinRMServer(t *testing.T) *winrmtest.Remote {
 			return 0
 		})
 
+	wrm.CommandFunc(
+		winrmtest.MatchPattern(`^echo `+BASE64_ENCODED_PAYLOAD+` >> ".*"$`),
+		func(out, err io.Writer) int {
+			return 0
+		})
+
 	wrm.CommandFunc(
 		winrmtest.MatchPattern(`^powershell.exe -EncodedCommand .*$`),
 		func(out, err io.Writer) int {
+			out.Write([]byte(BASE64_ENCODED_PAYLOAD))
 			return 0
 		})
 
@@ -86,9 +97,21 @@ func TestUpload(t *testing.T) {
 	if err != nil {
 		t.Fatalf("error creating communicator: %s", err)
 	}
-
-	err = c.Upload("C:/Temp/packer.cmd", bytes.NewReader([]byte("something")), nil)
+	file := "C:/Temp/packer.cmd"
+	err = c.Upload(file, strings.NewReader(PAYLOAD), nil)
 	if err != nil {
 		t.Fatalf("error uploading file: %s", err)
 	}
+
+	dest := new(bytes.Buffer)
+	err = c.Download(file, dest)
+	if err != nil {
+		t.Fatalf("error downloading file: %s", err)
+	}
+	downloadedPayload := strings.TrimRight(dest.String(), "\x00")
+
+	if downloadedPayload != PAYLOAD {
+		t.Fatalf("files are not equal: expected [%s] length: %v, got [%s] length %v", PAYLOAD, len(PAYLOAD), downloadedPayload, len(downloadedPayload))
+	}
+
 }

vendor/github.com/masterzen/winrm/client.go

@@ -5,6 +5,7 @@ import (
 	"crypto/x509"
 	"fmt"
 	"io"
+	"sync"
 
 	"github.com/masterzen/winrm/soap"
 )
@@ -114,10 +115,21 @@ func (c *Client) Run(command string, stdout io.Writer, stderr io.Writer) (int, e
 		return 1, err
 	}
 
-	go io.Copy(stdout, cmd.Stdout)
-	go io.Copy(stderr, cmd.Stderr)
+	var wg sync.WaitGroup
+	wg.Add(2)
+
+	go func() {
+		defer wg.Done()
+		io.Copy(stdout, cmd.Stdout)
+	}()
+
+	go func() {
+		defer wg.Done()
+		io.Copy(stderr, cmd.Stderr)
+	}()
 
 	cmd.Wait()
+	wg.Wait()
 
 	return cmd.ExitCode(), cmd.err
 }