Merge branch 'allow-to-access-remote-archive' into 'master'

Allow to access remote archive

See merge request !180

cmd/gitlab-zip-cat/main.go

@@ -5,8 +5,15 @@ import (
 	"flag"
 	"fmt"
 	"io"
+	"net"
+	"net/http"
 	"os"
+	"strings"
+	"time"
 
+	"github.com/jfbus/httprs"
+
+	"gitlab.com/gitlab-org/gitlab-workhorse/internal/helper"
 	"gitlab.com/gitlab-org/gitlab-workhorse/internal/zipartifacts"
 )
 
@@ -16,6 +23,67 @@ var Version = "unknown"
 
 var printVersion = flag.Bool("version", false, "Print version and exit")
 
+var httpClient = &http.Client{
+	Transport: &http.Transport{
+		Proxy: http.ProxyFromEnvironment,
+		DialContext: (&net.Dialer{
+			Timeout:   30 * time.Second,
+			KeepAlive: 10 * time.Second,
+		}).DialContext,
+		IdleConnTimeout:       30 * time.Second,
+		TLSHandshakeTimeout:   10 * time.Second,
+		ExpectContinueTimeout: 10 * time.Second,
+		ResponseHeaderTimeout: 30 * time.Second,
+	},
+}
+
+func isURL(path string) bool {
+	return strings.HasPrefix(path, "http://") || strings.HasPrefix(path, "https://")
+}
+
+func openHTTPArchive(archivePath string) (*zip.Reader, func()) {
+	scrubbedArchivePath := helper.ScrubURLParams(archivePath)
+	resp, err := httpClient.Get(archivePath)
+	if err != nil {
+		fatalError(fmt.Errorf("HTTP GET %q: %v", scrubbedArchivePath, err))
+	} else if resp.StatusCode == http.StatusNotFound {
+		notFoundError(fmt.Errorf("HTTP GET %q: not found", scrubbedArchivePath))
+	} else if resp.StatusCode != http.StatusOK {
+		fatalError(fmt.Errorf("HTTP GET %q: %d: %v", scrubbedArchivePath, resp.StatusCode, resp.Status))
+	}
+
+	rs := httprs.NewHttpReadSeeker(resp, httpClient)
+
+	archive, err := zip.NewReader(rs, resp.ContentLength)
+	if err != nil {
+		notFoundError(fmt.Errorf("open %q: %v", scrubbedArchivePath, err))
+	}
+
+	return archive, func() {
+		resp.Body.Close()
+		rs.Close()
+	}
+}
+
+func openFileArchive(archivePath string) (*zip.Reader, func()) {
+	archive, err := zip.OpenReader(archivePath)
+	if err != nil {
+		notFoundError(fmt.Errorf("open %q: %v", archivePath, err))
+	}
+
+	return &archive.Reader, func() {
+		archive.Close()
+	}
+}
+
+func openArchive(archivePath string) (*zip.Reader, func()) {
+	if isURL(archivePath) {
+		return openHTTPArchive(archivePath)
+	}
+
+	return openFileArchive(archivePath)
+}
+
 func main() {
 	flag.Parse()
 
@@ -25,32 +93,34 @@ func main() {
 		os.Exit(0)
 	}
 
-	if len(os.Args) != 3 {
-		fmt.Fprintf(os.Stderr, "Usage: %s FILE.ZIP ENTRY\n", progName)
+	archivePath := os.Getenv("ARCHIVE_PATH")
+	encodedFileName := os.Getenv("ENCODED_FILE_NAME")
+
+	if len(os.Args) != 1 || archivePath == "" || encodedFileName == "" {
+		fmt.Fprintf(os.Stderr, "Usage: %s\n", progName)
+		fmt.Fprintf(os.Stderr, "Env: ARCHIVE_PATH=https://path.to/archive.zip or /path/to/archive.zip\n")
+		fmt.Fprintf(os.Stderr, "Env: ENCODED_FILE_NAME=base64-encoded-file-name\n")
 		os.Exit(1)
 	}
 
-	archiveFileName := os.Args[1]
+	scrubbedArchivePath := helper.ScrubURLParams(archivePath)
 
-	fileName, err := zipartifacts.DecodeFileEntry(os.Args[2])
+	fileName, err := zipartifacts.DecodeFileEntry(encodedFileName)
 	if err != nil {
-		fatalError(fmt.Errorf("decode entry %q: %v", os.Args[2], err))
+		fatalError(fmt.Errorf("decode entry %q: %v", encodedFileName, err))
 	}
 
-	archive, err := zip.OpenReader(archiveFileName)
-	if err != nil {
-		notFoundError(fmt.Errorf("open %q: %v", archiveFileName, err))
-	}
-	defer archive.Close()
+	archive, cleanFn := openArchive(archivePath)
+	defer cleanFn()
 
-	file := findFileInZip(fileName, &archive.Reader)
+	file := findFileInZip(fileName, archive)
 	if file == nil {
-		notFoundError(fmt.Errorf("find %q in %q: not found", fileName, archiveFileName))
+		notFoundError(fmt.Errorf("find %q in %q: not found", fileName, scrubbedArchivePath))
 	}
 	// Start decompressing the file
 	reader, err := file.Open()
 	if err != nil {
-		fatalError(fmt.Errorf("open %q in %q: %v", fileName, archiveFileName, err))
+		fatalError(fmt.Errorf("open %q in %q: %v", fileName, scrubbedArchivePath, err))
 	}
 	defer reader.Close()
 
@@ -59,7 +129,7 @@ func main() {
 	}
 
 	if _, err := io.Copy(os.Stdout, reader); err != nil {
-		fatalError(fmt.Errorf("write %q from %q to stdout: %v", fileName, archiveFileName, err))
+		fatalError(fmt.Errorf("write %q from %q to stdout: %v", fileName, scrubbedArchivePath, err))
 	}
 }
 

internal/artifacts/entry.go

@@ -55,13 +55,17 @@ func detectFileContentType(fileName string) string {
 	return contentType
 }
 
-func unpackFileFromZip(archiveFileName, encodedFilename string, headers http.Header, output io.Writer) error {
+func unpackFileFromZip(archivePath, encodedFilename string, headers http.Header, output io.Writer) error {
 	fileName, err := zipartifacts.DecodeFileEntry(encodedFilename)
 	if err != nil {
 		return err
 	}
 
-	catFile := exec.Command("gitlab-zip-cat", archiveFileName, encodedFilename)
+	catFile := exec.Command("gitlab-zip-cat")
+	catFile.Env = []string{
+		"ARCHIVE_PATH=" + archivePath,
+		"ENCODED_FILE_NAME=" + encodedFilename,
+	}
 	catFile.Stderr = os.Stderr
 	catFile.SysProcAttr = &syscall.SysProcAttr{Setpgid: true}
 	stdout, err := catFile.StdoutPipe()

internal/artifacts/entry_test.go

@@ -8,17 +8,18 @@ import (
 	"net/http"
 	"net/http/httptest"
 	"os"
+	"path/filepath"
 	"testing"
 
+	"github.com/stretchr/testify/require"
+
 	"gitlab.com/gitlab-org/gitlab-workhorse/internal/testhelper"
 )
 
 func testEntryServer(t *testing.T, archive string, entry string) *httptest.ResponseRecorder {
 	mux := http.NewServeMux()
 	mux.HandleFunc("/url/path", func(w http.ResponseWriter, r *http.Request) {
-		if r.Method != "GET" {
-			t.Fatal("Expected GET request")
-		}
+		require.Equal(t, "GET", r.Method)
 
 		encodedEntry := base64.StdEncoding.EncodeToString([]byte(entry))
 		jsonParams := fmt.Sprintf(`{"Archive":"%s","Entry":"%s"}`, archive, encodedEntry)
@@ -28,9 +29,7 @@ func testEntryServer(t *testing.T, archive string, entry string) *httptest.Respo
 	})
 
 	httpRequest, err := http.NewRequest("GET", "/url/path", nil)
-	if err != nil {
-		t.Fatal(err)
-	}
+	require.NoError(t, err)
 	response := httptest.NewRecorder()
 	mux.ServeHTTP(response, httpRequest)
 	return response
@@ -38,18 +37,14 @@ func testEntryServer(t *testing.T, archive string, entry string) *httptest.Respo
 
 func TestDownloadingFromValidArchive(t *testing.T) {
 	tempFile, err := ioutil.TempFile("", "uploads")
-	if err != nil {
-		t.Fatal(err)
-	}
+	require.NoError(t, err)
 	defer tempFile.Close()
 	defer os.Remove(tempFile.Name())
 
 	archive := zip.NewWriter(tempFile)
 	defer archive.Close()
 	fileInArchive, err := archive.Create("test.txt")
-	if err != nil {
-		t.Fatal(err)
-	}
+	require.NoError(t, err)
 	fmt.Fprint(fileInArchive, "testtest")
 	archive.Close()
 
@@ -67,11 +62,43 @@ func TestDownloadingFromValidArchive(t *testing.T) {
 	testhelper.AssertResponseBody(t, response, "testtest")
 }
 
+func TestDownloadingFromValidHTTPArchive(t *testing.T) {
+	tempDir, err := ioutil.TempDir("", "uploads")
+	require.NoError(t, err)
+	defer os.RemoveAll(tempDir)
+
+	f, err := os.Create(filepath.Join(tempDir, "archive.zip"))
+	require.NoError(t, err)
+	defer f.Close()
+
+	archive := zip.NewWriter(f)
+	defer archive.Close()
+	fileInArchive, err := archive.Create("test.txt")
+	require.NoError(t, err)
+	fmt.Fprint(fileInArchive, "testtest")
+	archive.Close()
+	f.Close()
+
+	fileServer := httptest.NewServer(http.FileServer(http.Dir(tempDir)))
+	defer fileServer.Close()
+
+	response := testEntryServer(t, fileServer.URL+"/archive.zip", "test.txt")
+
+	testhelper.AssertResponseCode(t, response, 200)
+
+	testhelper.AssertResponseWriterHeader(t, response,
+		"Content-Type",
+		"text/plain; charset=utf-8")
+	testhelper.AssertResponseWriterHeader(t, response,
+		"Content-Disposition",
+		"attachment; filename=\"test.txt\"")
+
+	testhelper.AssertResponseBody(t, response, "testtest")
+}
+
 func TestDownloadingNonExistingFile(t *testing.T) {
 	tempFile, err := ioutil.TempFile("", "uploads")
-	if err != nil {
-		t.Fatal(err)
-	}
+	require.NoError(t, err)
 	defer tempFile.Close()
 	defer os.Remove(tempFile.Name())
 
@@ -92,3 +119,16 @@ func TestIncompleteApiResponse(t *testing.T) {
 	response := testEntryServer(t, "", "")
 	testhelper.AssertResponseCode(t, response, 500)
 }
+
+func TestDownloadingFromNonExistingHTTPArchive(t *testing.T) {
+	tempDir, err := ioutil.TempDir("", "uploads")
+	require.NoError(t, err)
+	defer os.RemoveAll(tempDir)
+
+	fileServer := httptest.NewServer(http.FileServer(http.Dir(tempDir)))
+	defer fileServer.Close()
+
+	response := testEntryServer(t, fileServer.URL+"/not-existing-archive-file.zip", "test.txt")
+
+	testhelper.AssertResponseCode(t, response, 404)
+}

internal/helper/helpers.go

@@ -18,7 +18,7 @@ import (
 
 const NginxResponseBufferHeader = "X-Accel-Buffering"
 
-var scrubRegexp = regexp.MustCompile(`([\?&](?:private|authenticity|rss)[\-_]token)=[^&]*`)
+var scrubRegexp = regexp.MustCompile(`(?i)([\?&]((?:private|authenticity|rss)[\-_]token)|X-AMZ-Signature)=[^&]*`)
 
 func Fail500(w http.ResponseWriter, r *http.Request, err error) {
 	http.Error(w, "Internal server error", 500)

internal/helper/helpers_test.go

@@ -127,6 +127,9 @@ func TestScrubURLParams(t *testing.T) {
 		"?private-token=&authenticity_token=&bar":                           "?private-token=[FILTERED]&authenticity_token=[FILTERED]&bar",
 		"?private-token=foo&authenticity_token=bar":                         "?private-token=[FILTERED]&authenticity_token=[FILTERED]",
 		"?private_token=foo&authenticity-token=bar":                         "?private_token=[FILTERED]&authenticity-token=[FILTERED]",
+		"?X-AMZ-Signature=foo":                                              "?X-AMZ-Signature=[FILTERED]",
+		"&X-AMZ-Signature=foo":                                              "&X-AMZ-Signature=[FILTERED]",
+		"?x-amz-signature=foo":                                              "?x-amz-signature=[FILTERED]",
 	} {
 		after := ScrubURLParams(before)
 		assert.Equal(t, expected, after, "Scrubbing %q", before)

vendor/github.com/jfbus/httprs/LICENSE

+Copyright (c) 2015 Jean-François Bustarret
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in
+all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+THE SOFTWARE.
\ No newline at end of file

vendor/github.com/jfbus/httprs/README.md

+# httprs
+A ReadSeeker for http.Response.Body
+
+[![wercker status](https://app.wercker.com/status/b8ab18faefae7d1f88f9f23d642f0847/s/master "wercker status")](https://app.wercker.com/project/bykey/b8ab18faefae7d1f88f9f23d642f0847)
+
+## Usage
+
+```
+import "github.com/jfbus/httprs"
+
+resp, err := http.Get(url)
+
+rs := httprs.NewHttpReadSeeker(resp)
+defer rs.Close()
+io.ReadFull(rs, buf) // reads the first bytes from the response
+rs.Seek(1024, 0) // moves the position
+io.ReadFull(rs, buf) // does an additional range request and reads the first bytes from the second response
+```
+if you use a specific http.Client :
+```
+rs := httprs.NewHttpReadSeeker(resp, client)
+```
+
+## Doc
+
+See http://godoc.org/github.com/jfbus/httprs
+
+## LICENSE
+
+MIT - See LICENSE
\ No newline at end of file

vendor/github.com/jfbus/httprs/httprs.go

+/*
+Package httprs provides a ReadSeeker for http.Response.Body.
+
+Usage :
+
+	resp, err := http.Get(url)
+	rs := httprs.NewHttpReadSeeker(resp)
+	defer rs.Close()
+	io.ReadFull(rs, buf) // reads the first bytes from the response body
+	rs.Seek(1024, 0) // moves the position, but does no range request
+	io.ReadFull(rs, buf) // does a range request and reads from the response body
+
+If you want use a specific http.Client for additional range requests :
+	rs := httprs.NewHttpReadSeeker(resp, client)
+*/
+package httprs
+
+import (
+	"errors"
+	"fmt"
+	"io"
+	"io/ioutil"
+	"net/http"
+
+	"github.com/mitchellh/copystructure"
+)
+
+const shortSeekBytes = 1024
+
+// A HttpReadSeeker reads from a http.Response.Body. It can Seek
+// by doing range requests.
+type HttpReadSeeker struct {
+	c       *http.Client
+	req     *http.Request
+	res     *http.Response
+	r       io.ReadCloser
+	pos     int64
+	canSeek bool
+
+	Requests int
+}
+
+var _ io.ReadCloser = (*HttpReadSeeker)(nil)
+var _ io.Seeker = (*HttpReadSeeker)(nil)
+
+var (
+	// ErrNoContentLength is returned by Seek when the initial http response did not include a Content-Length header
+	ErrNoContentLength = errors.New("Content-Length was not set")
+	// ErrRangeRequestsNotSupported is returned by Seek and Read
+	// when the remote server does not allow range requests (Accept-Ranges was not set)
+	ErrRangeRequestsNotSupported = errors.New("Range requests are not supported by the remote server")
+	// ErrInvalidRange is returned by Read when trying to read past the end of the file
+	ErrInvalidRange = errors.New("Invalid range")
+	// ErrContentHasChanged is returned by Read when the content has changed since the first request
+	ErrContentHasChanged = errors.New("Content has changed since first request")
+)
+
+// NewHttpReadSeeker returns a HttpReadSeeker, using the http.Response and, optionaly, the http.Client
+// that needs to be used for future range requests. If no http.Client is given, http.DefaultClient will
+// be used.
+//
+// res.Request will be reused for range requests, headers may be added/removed
+func NewHttpReadSeeker(res *http.Response, client ...*http.Client) *HttpReadSeeker {
+	r := &HttpReadSeeker{
+		req:     res.Request,
+		res:     res,
+		r:       res.Body,
+		canSeek: (res.Header.Get("Accept-Ranges") == "bytes"),
+	}
+	if len(client) > 0 {
+		r.c = client[0]
+	} else {
+		r.c = http.DefaultClient
+	}
+	return r
+}
+
+// Clone clones the reader to enable parallel downloads of ranges
+func (r *HttpReadSeeker) Clone() (*HttpReadSeeker, error) {
+	req, err := copystructure.Copy(r.req)
+	if err != nil {
+		return nil, err
+	}
+	return &HttpReadSeeker{
+		req:     req.(*http.Request),
+		res:     r.res,
+		r:       nil,
+		canSeek: r.canSeek,
+		c:       r.c,
+	}, nil
+}
+
+// Read reads from the response body. It does a range request if Seek was called before.
+//
+// May return ErrRangeRequestsNotSupported, ErrInvalidRange or ErrContentHasChanged
+func (r *HttpReadSeeker) Read(p []byte) (n int, err error) {
+	if r.r == nil {
+		err = r.rangeRequest()
+	}
+	if r.r != nil {
+		n, err = r.r.Read(p)
+		r.pos += int64(n)
+	}
+	return
+}
+
+// ReadAt reads from the response body starting at offset off.
+//
+// May return ErrRangeRequestsNotSupported, ErrInvalidRange or ErrContentHasChanged
+func (r *HttpReadSeeker) ReadAt(p []byte, off int64) (n int, err error) {
+	r.Seek(off, 0)
+	return r.Read(p)
+}
+
+// Close closes the response body
+func (r *HttpReadSeeker) Close() error {
+	if r.r != nil {
+		return r.r.Close()
+	}
+	return nil
+}
+
+// Seek moves the reader position to a new offset.
+//
+// It does not send http requests, allowing for multiple seeks without overhead.
+// The http request will be sent by the next Read call.
+//
+// May return ErrNoContentLength or ErrRangeRequestsNotSupported
+func (r *HttpReadSeeker) Seek(offset int64, whence int) (int64, error) {
+	if !r.canSeek {
+		return 0, ErrRangeRequestsNotSupported
+	}
+	var err error
+	switch whence {
+	case 0:
+	case 1:
+		offset += r.pos
+	case 2:
+		if r.res.ContentLength <= 0 {
+			return 0, ErrNoContentLength
+		}
+		offset = r.res.ContentLength - offset
+	}
+	if r.r != nil {
+		// Try to read, which is cheaper than doing a request
+		if r.pos < offset && offset-r.pos <= shortSeekBytes {
+			_, err := io.CopyN(ioutil.Discard, r, offset-r.pos)
+			if err != nil {
+				return 0, err
+			}
+		}
+
+		if r.pos != offset {
+			err = r.r.Close()
+			r.r = nil
+		}
+	}
+	r.pos = offset
+	return r.pos, err
+}
+
+func (r *HttpReadSeeker) rangeRequest() error {
+	r.req.Header.Set("Range", fmt.Sprintf("bytes=%d-", r.pos))
+	etag, last := r.res.Header.Get("ETag"), r.res.Header.Get("Last-Modified")
+	switch {
+	case last != "":
+		r.req.Header.Set("If-Range", last)
+	case etag != "":
+		r.req.Header.Set("If-Range", etag)
+	}
+
+	r.Requests++
+
+	res, err := r.c.Do(r.req)
+	if err != nil {
+		return err
+	}
+	switch res.StatusCode {
+	case http.StatusRequestedRangeNotSatisfiable:
+		return ErrInvalidRange
+	case http.StatusOK:
+		return ErrContentHasChanged
+	case http.StatusPartialContent:
+		r.r = res.Body
+		return nil
+	}
+	return ErrRangeRequestsNotSupported
+}

vendor/github.com/jfbus/httprs/wercker.yml

+box: wercker/golang
+
+build:
+  steps:
+    - setup-go-workspace
+    - script:
+        name: Install goconvey
+        code: go get github.com/smartystreets/goconvey/convey
+    - script:
+        name: Go get
+        code: go get -v ./...
+    - script:
+        name: Go test
+        code: go test -p 1 -v ./...

vendor/github.com/mitchellh/copystructure/LICENSE

+The MIT License (MIT)
+
+Copyright (c) 2014 Mitchell Hashimoto
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in
+all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+THE SOFTWARE.

vendor/github.com/mitchellh/copystructure/README.md

+# copystructure
+
+copystructure is a Go library for deep copying values in Go.
+
+This allows you to copy Go values that may contain reference values
+such as maps, slices, or pointers, and copy their data as well instead
+of just their references.
+
+## Installation
+
+Standard `go get`:
+
+```
+$ go get github.com/mitchellh/copystructure
+```
+
+## Usage & Example
+
+For usage and examples see the [Godoc](http://godoc.org/github.com/mitchellh/copystructure).
+
+The `Copy` function has examples associated with it there.

vendor/github.com/mitchellh/copystructure/copier_time.go

+package copystructure
+
+import (
+	"reflect"
+	"time"
+)
+
+func init() {
+	Copiers[reflect.TypeOf(time.Time{})] = timeCopier
+}
+
+func timeCopier(v interface{}) (interface{}, error) {
+	// Just... copy it.
+	return v.(time.Time), nil
+}

vendor/github.com/mitchellh/copystructure/copystructure.go

+package copystructure
+
+import (
+	"errors"
+	"reflect"
+	"sync"
+
+	"github.com/mitchellh/reflectwalk"
+)
+
+// Copy returns a deep copy of v.
+func Copy(v interface{}) (interface{}, error) {
+	return Config{}.Copy(v)
+}
+
+// CopierFunc is a function that knows how to deep copy a specific type.
+// Register these globally with the Copiers variable.
+type CopierFunc func(interface{}) (interface{}, error)
+
+// Copiers is a map of types that behave specially when they are copied.
+// If a type is found in this map while deep copying, this function
+// will be called to copy it instead of attempting to copy all fields.
+//
+// The key should be the type, obtained using: reflect.TypeOf(value with type).
+//
+// It is unsafe to write to this map after Copies have started. If you
+// are writing to this map while also copying, wrap all modifications to
+// this map as well as to Copy in a mutex.
+var Copiers map[reflect.Type]CopierFunc = make(map[reflect.Type]CopierFunc)
+
+// Must is a helper that wraps a call to a function returning
+// (interface{}, error) and panics if the error is non-nil. It is intended
+// for use in variable initializations and should only be used when a copy
+// error should be a crashing case.
+func Must(v interface{}, err error) interface{} {
+	if err != nil {
+		panic("copy error: " + err.Error())
+	}
+
+	return v
+}
+
+var errPointerRequired = errors.New("Copy argument must be a pointer when Lock is true")
+
+type Config struct {
+	// Lock any types that are a sync.Locker and are not a mutex while copying.
+	// If there is an RLocker method, use that to get the sync.Locker.
+	Lock bool
+
+	// Copiers is a map of types associated with a CopierFunc. Use the global
+	// Copiers map if this is nil.
+	Copiers map[reflect.Type]CopierFunc
+}
+
+func (c Config) Copy(v interface{}) (interface{}, error) {
+	if c.Lock && reflect.ValueOf(v).Kind() != reflect.Ptr {
+		return nil, errPointerRequired
+	}
+
+	w := new(walker)
+	if c.Lock {
+		w.useLocks = true
+	}
+
+	if c.Copiers == nil {
+		c.Copiers = Copiers
+	}
+
+	err := reflectwalk.Walk(v, w)
+	if err != nil {
+		return nil, err
+	}
+
+	// Get the result. If the result is nil, then we want to turn it
+	// into a typed nil if we can.
+	result := w.Result
+	if result == nil {
+		val := reflect.ValueOf(v)
+		result = reflect.Indirect(reflect.New(val.Type())).Interface()
+	}
+
+	return result, nil
+}
+
+// Return the key used to index interfaces types we've seen. Store the number
+// of pointers in the upper 32bits, and the depth in the lower 32bits. This is
+// easy to calculate, easy to match a key with our current depth, and we don't
+// need to deal with initializing and cleaning up nested maps or slices.
+func ifaceKey(pointers, depth int) uint64 {
+	return uint64(pointers)<<32 | uint64(depth)
+}
+
+type walker struct {
+	Result interface{}
+
+	depth       int
+	ignoreDepth int
+	vals        []reflect.Value
+	cs          []reflect.Value
+
+	// This stores the number of pointers we've walked over, indexed by depth.
+	ps []int
+
+	// If an interface is indirected by a pointer, we need to know the type of
+	// interface to create when creating the new value.  Store the interface
+	// types here, indexed by both the walk depth and the number of pointers
+	// already seen at that depth. Use ifaceKey to calculate the proper uint64
+	// value.
+	ifaceTypes map[uint64]reflect.Type
+
+	// any locks we've taken, indexed by depth
+	locks []sync.Locker
+	// take locks while walking the structure
+	useLocks bool
+}
+
+func (w *walker) Enter(l reflectwalk.Location) error {
+	w.depth++
+
+	// ensure we have enough elements to index via w.depth
+	for w.depth >= len(w.locks) {
+		w.locks = append(w.locks, nil)
+	}
+
+	for len(w.ps) < w.depth+1 {
+		w.ps = append(w.ps, 0)
+	}
+
+	return nil
+}
+
+func (w *walker) Exit(l reflectwalk.Location) error {
+	locker := w.locks[w.depth]
+	w.locks[w.depth] = nil
+	if locker != nil {
+		defer locker.Unlock()
+	}
+
+	// clear out pointers and interfaces as we exit the stack
+	w.ps[w.depth] = 0
+
+	for k := range w.ifaceTypes {
+		mask := uint64(^uint32(0))
+		if k&mask == uint64(w.depth) {
+			delete(w.ifaceTypes, k)
+		}
+	}
+
+	w.depth--
+	if w.ignoreDepth > w.depth {
+		w.ignoreDepth = 0
+	}
+
+	if w.ignoring() {
+		return nil
+	}
+
+	switch l {
+	case reflectwalk.Array:
+		fallthrough
+	case reflectwalk.Map:
+		fallthrough
+	case reflectwalk.Slice:
+		w.replacePointerMaybe()
+
+		// Pop map off our container
+		w.cs = w.cs[:len(w.cs)-1]
+	case reflectwalk.MapValue:
+		// Pop off the key and value
+		mv := w.valPop()
+		mk := w.valPop()
+		m := w.cs[len(w.cs)-1]
+
+		// If mv is the zero value, SetMapIndex deletes the key form the map,
+		// or in this case never adds it. We need to create a properly typed
+		// zero value so that this key can be set.
+		if !mv.IsValid() {
+			mv = reflect.Zero(m.Elem().Type().Elem())
+		}
+		m.Elem().SetMapIndex(mk, mv)
+	case reflectwalk.ArrayElem:
+		// Pop off the value and the index and set it on the array
+		v := w.valPop()
+		i := w.valPop().Interface().(int)
+		if v.IsValid() {
+			a := w.cs[len(w.cs)-1]
+			ae := a.Elem().Index(i) // storing array as pointer on stack - so need Elem() call
+			if ae.CanSet() {
+				ae.Set(v)
+			}
+		}
+	case reflectwalk.SliceElem:
+		// Pop off the value and the index and set it on the slice
+		v := w.valPop()
+		i := w.valPop().Interface().(int)
+		if v.IsValid() {
+			s := w.cs[len(w.cs)-1]
+			se := s.Elem().Index(i)
+			if se.CanSet() {
+				se.Set(v)
+			}
+		}
+	case reflectwalk.Struct:
+		w.replacePointerMaybe()
+
+		// Remove the struct from the container stack
+		w.cs = w.cs[:len(w.cs)-1]
+	case reflectwalk.StructField:
+		// Pop off the value and the field
+		v := w.valPop()
+		f := w.valPop().Interface().(reflect.StructField)
+		if v.IsValid() {
+			s := w.cs[len(w.cs)-1]
+			sf := reflect.Indirect(s).FieldByName(f.Name)
+
+			if sf.CanSet() {
+				sf.Set(v)
+			}
+		}
+	case reflectwalk.WalkLoc:
+		// Clear out the slices for GC
+		w.cs = nil
+		w.vals = nil
+	}
+
+	return nil
+}
+
+func (w *walker) Map(m reflect.Value) error {
+	if w.ignoring() {
+		return nil
+	}
+	w.lock(m)
+
+	// Create the map. If the map itself is nil, then just make a nil map
+	var newMap reflect.Value
+	if m.IsNil() {
+		newMap = reflect.New(m.Type())
+	} else {
+		newMap = wrapPtr(reflect.MakeMap(m.Type()))
+	}
+
+	w.cs = append(w.cs, newMap)
+	w.valPush(newMap)
+	return nil
+}
+
+func (w *walker) MapElem(m, k, v reflect.Value) error {
+	return nil
+}
+
+func (w *walker) PointerEnter(v bool) error {
+	if v {
+		w.ps[w.depth]++
+	}
+	return nil
+}
+
+func (w *walker) PointerExit(v bool) error {
+	if v {
+		w.ps[w.depth]--
+	}
+	return nil
+}
+
+func (w *walker) Interface(v reflect.Value) error {
+	if !v.IsValid() {
+		return nil
+	}
+	if w.ifaceTypes == nil {
+		w.ifaceTypes = make(map[uint64]reflect.Type)
+	}
+
+	w.ifaceTypes[ifaceKey(w.ps[w.depth], w.depth)] = v.Type()
+	return nil
+}
+
+func (w *walker) Primitive(v reflect.Value) error {
+	if w.ignoring() {
+		return nil
+	}
+	w.lock(v)
+
+	// IsValid verifies the v is non-zero and CanInterface verifies
+	// that we're allowed to read this value (unexported fields).
+	var newV reflect.Value
+	if v.IsValid() && v.CanInterface() {
+		newV = reflect.New(v.Type())
+		newV.Elem().Set(v)
+	}
+
+	w.valPush(newV)
+	w.replacePointerMaybe()
+	return nil
+}
+
+func (w *walker) Slice(s reflect.Value) error {
+	if w.ignoring() {
+		return nil
+	}
+	w.lock(s)
+
+	var newS reflect.Value
+	if s.IsNil() {
+		newS = reflect.New(s.Type())
+	} else {
+		newS = wrapPtr(reflect.MakeSlice(s.Type(), s.Len(), s.Cap()))
+	}
+
+	w.cs = append(w.cs, newS)
+	w.valPush(newS)
+	return nil
+}
+
+func (w *walker) SliceElem(i int, elem reflect.Value) error {
+	if w.ignoring() {
+		return nil
+	}
+
+	// We don't write the slice here because elem might still be
+	// arbitrarily complex. Just record the index and continue on.
+	w.valPush(reflect.ValueOf(i))
+
+	return nil
+}
+
+func (w *walker) Array(a reflect.Value) error {
+	if w.ignoring() {
+		return nil
+	}
+	w.lock(a)
+
+	newA := reflect.New(a.Type())
+
+	w.cs = append(w.cs, newA)
+	w.valPush(newA)
+	return nil
+}
+
+func (w *walker) ArrayElem(i int, elem reflect.Value) error {
+	if w.ignoring() {
+		return nil
+	}
+
+	// We don't write the array here because elem might still be
+	// arbitrarily complex. Just record the index and continue on.
+	w.valPush(reflect.ValueOf(i))
+
+	return nil
+}
+
+func (w *walker) Struct(s reflect.Value) error {
+	if w.ignoring() {
+		return nil
+	}
+	w.lock(s)
+
+	var v reflect.Value
+	if c, ok := Copiers[s.Type()]; ok {
+		// We have a Copier for this struct, so we use that copier to
+		// get the copy, and we ignore anything deeper than this.
+		w.ignoreDepth = w.depth
+
+		dup, err := c(s.Interface())
+		if err != nil {
+			return err
+		}
+
+		v = reflect.ValueOf(dup)
+	} else {
+		// No copier, we copy ourselves and allow reflectwalk to guide
+		// us deeper into the structure for copying.
+		v = reflect.New(s.Type())
+	}
+
+	// Push the value onto the value stack for setting the struct field,
+	// and add the struct itself to the containers stack in case we walk
+	// deeper so that its own fields can be modified.
+	w.valPush(v)
+	w.cs = append(w.cs, v)
+
+	return nil
+}
+
+func (w *walker) StructField(f reflect.StructField, v reflect.Value) error {
+	if w.ignoring() {
+		return nil
+	}
+
+	// If PkgPath is non-empty, this is a private (unexported) field.
+	// We do not set this unexported since the Go runtime doesn't allow us.
+	if f.PkgPath != "" {
+		return reflectwalk.SkipEntry
+	}
+
+	// Push the field onto the stack, we'll handle it when we exit
+	// the struct field in Exit...
+	w.valPush(reflect.ValueOf(f))
+	return nil
+}
+
+// ignore causes the walker to ignore any more values until we exit this on
+func (w *walker) ignore() {
+	w.ignoreDepth = w.depth
+}
+
+func (w *walker) ignoring() bool {
+	return w.ignoreDepth > 0 && w.depth >= w.ignoreDepth
+}
+
+func (w *walker) pointerPeek() bool {
+	return w.ps[w.depth] > 0
+}
+
+func (w *walker) valPop() reflect.Value {
+	result := w.vals[len(w.vals)-1]
+	w.vals = w.vals[:len(w.vals)-1]
+
+	// If we're out of values, that means we popped everything off. In
+	// this case, we reset the result so the next pushed value becomes
+	// the result.
+	if len(w.vals) == 0 {
+		w.Result = nil
+	}
+
+	return result
+}
+
+func (w *walker) valPush(v reflect.Value) {
+	w.vals = append(w.vals, v)
+
+	// If we haven't set the result yet, then this is the result since
+	// it is the first (outermost) value we're seeing.
+	if w.Result == nil && v.IsValid() {
+		w.Result = v.Interface()
+	}
+}
+
+func (w *walker) replacePointerMaybe() {
+	// Determine the last pointer value. If it is NOT a pointer, then
+	// we need to push that onto the stack.
+	if !w.pointerPeek() {
+		w.valPush(reflect.Indirect(w.valPop()))
+		return
+	}
+
+	v := w.valPop()
+
+	// If the expected type is a pointer to an interface of any depth,
+	// such as *interface{}, **interface{}, etc., then we need to convert
+	// the value "v" from *CONCRETE to *interface{} so types match for
+	// Set.
+	//
+	// Example if v is type *Foo where Foo is a struct, v would become
+	// *interface{} instead. This only happens if we have an interface expectation
+	// at this depth.
+	//
+	// For more info, see GH-16
+	if iType, ok := w.ifaceTypes[ifaceKey(w.ps[w.depth], w.depth)]; ok && iType.Kind() == reflect.Interface {
+		y := reflect.New(iType)           // Create *interface{}
+		y.Elem().Set(reflect.Indirect(v)) // Assign "Foo" to interface{} (dereferenced)
+		v = y                             // v is now typed *interface{} (where *v = Foo)
+	}
+
+	for i := 1; i < w.ps[w.depth]; i++ {
+		if iType, ok := w.ifaceTypes[ifaceKey(w.ps[w.depth]-i, w.depth)]; ok {
+			iface := reflect.New(iType).Elem()
+			iface.Set(v)
+			v = iface
+		}
+
+		p := reflect.New(v.Type())
+		p.Elem().Set(v)
+		v = p
+	}
+
+	w.valPush(v)
+}
+
+// if this value is a Locker, lock it and add it to the locks slice
+func (w *walker) lock(v reflect.Value) {
+	if !w.useLocks {
+		return
+	}
+
+	if !v.IsValid() || !v.CanInterface() {
+		return
+	}
+
+	type rlocker interface {
+		RLocker() sync.Locker
+	}
+
+	var locker sync.Locker
+
+	// We can't call Interface() on a value directly, since that requires
+	// a copy. This is OK, since the pointer to a value which is a sync.Locker
+	// is also a sync.Locker.
+	if v.Kind() == reflect.Ptr {
+		switch l := v.Interface().(type) {
+		case rlocker:
+			// don't lock a mutex directly
+			if _, ok := l.(*sync.RWMutex); !ok {
+				locker = l.RLocker()
+			}
+		case sync.Locker:
+			locker = l
+		}
+	} else if v.CanAddr() {
+		switch l := v.Addr().Interface().(type) {
+		case rlocker:
+			// don't lock a mutex directly
+			if _, ok := l.(*sync.RWMutex); !ok {
+				locker = l.RLocker()
+			}
+		case sync.Locker:
+			locker = l
+		}
+	}
+
+	// still no callable locker
+	if locker == nil {
+		return
+	}
+
+	// don't lock a mutex directly
+	switch locker.(type) {
+	case *sync.Mutex, *sync.RWMutex:
+		return
+	}
+
+	locker.Lock()
+	w.locks[w.depth] = locker
+}
+
+// wrapPtr is a helper that takes v and always make it *v. copystructure
+// stores things internally as pointers until the last moment before unwrapping
+func wrapPtr(v reflect.Value) reflect.Value {
+	if !v.IsValid() {
+		return v
+	}
+	vPtr := reflect.New(v.Type())
+	vPtr.Elem().Set(v)
+	return vPtr
+}

vendor/github.com/mitchellh/reflectwalk/LICENSE

+The MIT License (MIT)
+
+Copyright (c) 2013 Mitchell Hashimoto
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in
+all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+THE SOFTWARE.

vendor/github.com/mitchellh/reflectwalk/README.md

+# reflectwalk
+
+reflectwalk is a Go library for "walking" a value in Go using reflection,
+in the same way a directory tree can be "walked" on the filesystem. Walking
+a complex structure can allow you to do manipulations on unknown structures
+such as those decoded from JSON.

vendor/github.com/mitchellh/reflectwalk/location.go

+package reflectwalk
+
+//go:generate stringer -type=Location location.go
+
+type Location uint
+
+const (
+	None Location = iota
+	Map
+	MapKey
+	MapValue
+	Slice
+	SliceElem
+	Array
+	ArrayElem
+	Struct
+	StructField
+	WalkLoc
+)

vendor/github.com/mitchellh/reflectwalk/location_string.go

+// generated by stringer -type=Location location.go; DO NOT EDIT
+
+package reflectwalk
+
+import "fmt"
+
+const _Location_name = "NoneMapMapKeyMapValueSliceSliceElemStructStructFieldWalkLoc"
+
+var _Location_index = [...]uint8{0, 4, 7, 13, 21, 26, 35, 41, 52, 59}
+
+func (i Location) String() string {
+	if i+1 >= Location(len(_Location_index)) {
+		return fmt.Sprintf("Location(%d)", i)
+	}
+	return _Location_name[_Location_index[i]:_Location_index[i+1]]
+}

vendor/github.com/mitchellh/reflectwalk/reflectwalk.go

+// reflectwalk is a package that allows you to "walk" complex structures
+// similar to how you may "walk" a filesystem: visiting every element one
+// by one and calling callback functions allowing you to handle and manipulate
+// those elements.
+package reflectwalk
+
+import (
+	"errors"
+	"reflect"
+)
+
+// PrimitiveWalker implementations are able to handle primitive values
+// within complex structures. Primitive values are numbers, strings,
+// booleans, funcs, chans.
+//
+// These primitive values are often members of more complex
+// structures (slices, maps, etc.) that are walkable by other interfaces.
+type PrimitiveWalker interface {
+	Primitive(reflect.Value) error
+}
+
+// InterfaceWalker implementations are able to handle interface values as they
+// are encountered during the walk.
+type InterfaceWalker interface {
+	Interface(reflect.Value) error
+}
+
+// MapWalker implementations are able to handle individual elements
+// found within a map structure.
+type MapWalker interface {
+	Map(m reflect.Value) error
+	MapElem(m, k, v reflect.Value) error
+}
+
+// SliceWalker implementations are able to handle slice elements found
+// within complex structures.
+type SliceWalker interface {
+	Slice(reflect.Value) error
+	SliceElem(int, reflect.Value) error
+}
+
+// ArrayWalker implementations are able to handle array elements found
+// within complex structures.
+type ArrayWalker interface {
+	Array(reflect.Value) error
+	ArrayElem(int, reflect.Value) error
+}
+
+// StructWalker is an interface that has methods that are called for
+// structs when a Walk is done.
+type StructWalker interface {
+	Struct(reflect.Value) error
+	StructField(reflect.StructField, reflect.Value) error
+}
+
+// EnterExitWalker implementations are notified before and after
+// they walk deeper into complex structures (into struct fields,
+// into slice elements, etc.)
+type EnterExitWalker interface {
+	Enter(Location) error
+	Exit(Location) error
+}
+
+// PointerWalker implementations are notified when the value they're
+// walking is a pointer or not. Pointer is called for _every_ value whether
+// it is a pointer or not.
+type PointerWalker interface {
+	PointerEnter(bool) error
+	PointerExit(bool) error
+}
+
+// SkipEntry can be returned from walk functions to skip walking
+// the value of this field. This is only valid in the following functions:
+//
+//   - Struct: skips all fields from being walked
+//   - StructField: skips walking the struct value
+//
+var SkipEntry = errors.New("skip this entry")
+
+// Walk takes an arbitrary value and an interface and traverses the
+// value, calling callbacks on the interface if they are supported.
+// The interface should implement one or more of the walker interfaces
+// in this package, such as PrimitiveWalker, StructWalker, etc.
+func Walk(data, walker interface{}) (err error) {
+	v := reflect.ValueOf(data)
+	ew, ok := walker.(EnterExitWalker)
+	if ok {
+		err = ew.Enter(WalkLoc)
+	}
+
+	if err == nil {
+		err = walk(v, walker)
+	}
+
+	if ok && err == nil {
+		err = ew.Exit(WalkLoc)
+	}
+
+	return
+}
+
+func walk(v reflect.Value, w interface{}) (err error) {
+	// Determine if we're receiving a pointer and if so notify the walker.
+	// The logic here is convoluted but very important (tests will fail if
+	// almost any part is changed). I will try to explain here.
+	//
+	// First, we check if the value is an interface, if so, we really need
+	// to check the interface's VALUE to see whether it is a pointer.
+	//
+	// Check whether the value is then a pointer. If so, then set pointer
+	// to true to notify the user.
+	//
+	// If we still have a pointer or an interface after the indirections, then
+	// we unwrap another level
+	//
+	// At this time, we also set "v" to be the dereferenced value. This is
+	// because once we've unwrapped the pointer we want to use that value.
+	pointer := false
+	pointerV := v
+
+	for {
+		if pointerV.Kind() == reflect.Interface {
+			if iw, ok := w.(InterfaceWalker); ok {
+				if err = iw.Interface(pointerV); err != nil {
+					return
+				}
+			}
+
+			pointerV = pointerV.Elem()
+		}
+
+		if pointerV.Kind() == reflect.Ptr {
+			pointer = true
+			v = reflect.Indirect(pointerV)
+		}
+		if pw, ok := w.(PointerWalker); ok {
+			if err = pw.PointerEnter(pointer); err != nil {
+				return
+			}
+
+			defer func(pointer bool) {
+				if err != nil {
+					return
+				}
+
+				err = pw.PointerExit(pointer)
+			}(pointer)
+		}
+
+		if pointer {
+			pointerV = v
+		}
+		pointer = false
+
+		// If we still have a pointer or interface we have to indirect another level.
+		switch pointerV.Kind() {
+		case reflect.Ptr, reflect.Interface:
+			continue
+		}
+		break
+	}
+
+	// We preserve the original value here because if it is an interface
+	// type, we want to pass that directly into the walkPrimitive, so that
+	// we can set it.
+	originalV := v
+	if v.Kind() == reflect.Interface {
+		v = v.Elem()
+	}
+
+	k := v.Kind()
+	if k >= reflect.Int && k <= reflect.Complex128 {
+		k = reflect.Int
+	}
+
+	switch k {
+	// Primitives
+	case reflect.Bool, reflect.Chan, reflect.Func, reflect.Int, reflect.String, reflect.Invalid:
+		err = walkPrimitive(originalV, w)
+		return
+	case reflect.Map:
+		err = walkMap(v, w)
+		return
+	case reflect.Slice:
+		err = walkSlice(v, w)
+		return
+	case reflect.Struct:
+		err = walkStruct(v, w)
+		return
+	case reflect.Array:
+		err = walkArray(v, w)
+		return
+	default:
+		panic("unsupported type: " + k.String())
+	}
+}
+
+func walkMap(v reflect.Value, w interface{}) error {
+	ew, ewok := w.(EnterExitWalker)
+	if ewok {
+		ew.Enter(Map)
+	}
+
+	if mw, ok := w.(MapWalker); ok {
+		if err := mw.Map(v); err != nil {
+			return err
+		}
+	}
+
+	for _, k := range v.MapKeys() {
+		kv := v.MapIndex(k)
+
+		if mw, ok := w.(MapWalker); ok {
+			if err := mw.MapElem(v, k, kv); err != nil {
+				return err
+			}
+		}
+
+		ew, ok := w.(EnterExitWalker)
+		if ok {
+			ew.Enter(MapKey)
+		}
+
+		if err := walk(k, w); err != nil {
+			return err
+		}
+
+		if ok {
+			ew.Exit(MapKey)
+			ew.Enter(MapValue)
+		}
+
+		if err := walk(kv, w); err != nil {
+			return err
+		}
+
+		if ok {
+			ew.Exit(MapValue)
+		}
+	}
+
+	if ewok {
+		ew.Exit(Map)
+	}
+
+	return nil
+}
+
+func walkPrimitive(v reflect.Value, w interface{}) error {
+	if pw, ok := w.(PrimitiveWalker); ok {
+		return pw.Primitive(v)
+	}
+
+	return nil
+}
+
+func walkSlice(v reflect.Value, w interface{}) (err error) {
+	ew, ok := w.(EnterExitWalker)
+	if ok {
+		ew.Enter(Slice)
+	}
+
+	if sw, ok := w.(SliceWalker); ok {
+		if err := sw.Slice(v); err != nil {
+			return err
+		}
+	}
+
+	for i := 0; i < v.Len(); i++ {
+		elem := v.Index(i)
+
+		if sw, ok := w.(SliceWalker); ok {
+			if err := sw.SliceElem(i, elem); err != nil {
+				return err
+			}
+		}
+
+		ew, ok := w.(EnterExitWalker)
+		if ok {
+			ew.Enter(SliceElem)
+		}
+
+		if err := walk(elem, w); err != nil {
+			return err
+		}
+
+		if ok {
+			ew.Exit(SliceElem)
+		}
+	}
+
+	ew, ok = w.(EnterExitWalker)
+	if ok {
+		ew.Exit(Slice)
+	}
+
+	return nil
+}
+
+func walkArray(v reflect.Value, w interface{}) (err error) {
+	ew, ok := w.(EnterExitWalker)
+	if ok {
+		ew.Enter(Array)
+	}
+
+	if aw, ok := w.(ArrayWalker); ok {
+		if err := aw.Array(v); err != nil {
+			return err
+		}
+	}
+
+	for i := 0; i < v.Len(); i++ {
+		elem := v.Index(i)
+
+		if aw, ok := w.(ArrayWalker); ok {
+			if err := aw.ArrayElem(i, elem); err != nil {
+				return err
+			}
+		}
+
+		ew, ok := w.(EnterExitWalker)
+		if ok {
+			ew.Enter(ArrayElem)
+		}
+
+		if err := walk(elem, w); err != nil {
+			return err
+		}
+
+		if ok {
+			ew.Exit(ArrayElem)
+		}
+	}
+
+	ew, ok = w.(EnterExitWalker)
+	if ok {
+		ew.Exit(Array)
+	}
+
+	return nil
+}
+
+func walkStruct(v reflect.Value, w interface{}) (err error) {
+	ew, ewok := w.(EnterExitWalker)
+	if ewok {
+		ew.Enter(Struct)
+	}
+
+	skip := false
+	if sw, ok := w.(StructWalker); ok {
+		err = sw.Struct(v)
+		if err == SkipEntry {
+			skip = true
+			err = nil
+		}
+		if err != nil {
+			return
+		}
+	}
+
+	if !skip {
+		vt := v.Type()
+		for i := 0; i < vt.NumField(); i++ {
+			sf := vt.Field(i)
+			f := v.FieldByIndex([]int{i})
+
+			if sw, ok := w.(StructWalker); ok {
+				err = sw.StructField(sf, f)
+
+				// SkipEntry just pretends this field doesn't even exist
+				if err == SkipEntry {
+					continue
+				}
+
+				if err != nil {
+					return
+				}
+			}
+
+			ew, ok := w.(EnterExitWalker)
+			if ok {
+				ew.Enter(StructField)
+			}
+
+			err = walk(f, w)
+			if err != nil {
+				return
+			}
+
+			if ok {
+				ew.Exit(StructField)
+			}
+		}
+	}
+
+	if ewok {
+		ew.Exit(Struct)
+	}
+
+	return nil
+}

vendor/vendor.json

@@ -53,6 +53,12 @@
 			"path": "github.com/gorilla/websocket",
 			"revision": "e8f0f8aaa98dfb6586cbdf2978d511e3199a960a"
 		},
+		{
+			"checksumSHA1": "g46WnPAlsmkyNDUFdObDgP6DP+s=",
+			"path": "github.com/jfbus/httprs",
+			"revision": "e879ae6bf984ca6c009eb44696e9f400ec3ed2d9",
+			"revisionTime": "2017-07-03T13:54:35Z"
+		},
 		{
 			"checksumSHA1": "oIkoHb8+rM5Etur5HhZVY/sDQKQ=",
 			"path": "github.com/jpillora/backoff",
@@ -65,6 +71,18 @@
 			"path": "github.com/matttproud/golang_protobuf_extensions/pbutil",
 			"revision": "c12348ce28de40eed0136aa2b644d0ee0650e56c"
 		},
+		{
+			"checksumSHA1": "kSmDazz+cokgcHQT7q56Na+IBe0=",
+			"path": "github.com/mitchellh/copystructure",
+			"revision": "f81071c9d77b7931f78c90b416a074ecdc50e959",
+			"revisionTime": "2017-01-16T00:44:49Z"
+		},
+		{
+			"checksumSHA1": "KqsMqI+Y+3EFYPhyzafpIneaVCM=",
+			"path": "github.com/mitchellh/reflectwalk",
+			"revision": "8d802ff4ae93611b807597f639c19f76074df5c6",
+			"revisionTime": "2017-05-08T17:38:06Z"
+		},
 		{
 			"checksumSHA1": "LuFv4/jlrmFNnDb/5SCSEPAM9vU=",
 			"path": "github.com/pmezard/go-difflib/difflib",