Add support for redirects24-add-redirects

Fix https://gitlab.com/gitlab-org/gitlab-pages/-/issues/24

3 files changed, 59 insertions, 20 deletions

diff --git a/internal/serving/disk/reader.go b/internal/serving/disk/reader.go
index 0d11a184..350d036b 100644
--- a/internal/serving/disk/reader.go
+++ b/internal/serving/disk/reader.go
@@ -5,12 +5,14 @@ import (
 	"fmt"
 	"io"
 	"net/http"
+	"os"
 	"strconv"
 	"strings"
 	"time"
 
 	"github.com/prometheus/client_golang/prometheus"
 
+	"gitlab.com/gitlab-org/gitlab-pages/internal/redirects"
 	"gitlab.com/gitlab-org/gitlab-pages/internal/serving"
 	"gitlab.com/gitlab-org/gitlab-pages/internal/serving/disk/symlink"
 	"gitlab.com/gitlab-org/gitlab-pages/internal/vfs"
@@ -22,6 +24,34 @@ type Reader struct {
 	vfs            vfs.VFS
 }
 
+// Show the user some validation messages for their _redirects file
+func (reader *Reader) serveRedirectsStatus(h serving.Handler, redirects *redirects.Redirects) error {
+	h.Writer.Header().Set("Content-Type", "text/plain; charset=utf-8")
+	h.Writer.Header().Set("X-Content-Type-Options", "nosniff")
+	h.Writer.WriteHeader(http.StatusOK)
+	_, err := fmt.Fprintln(h.Writer, redirects.Status())
+	return err
+}
+
+func (reader *Reader) tryRedirects(h serving.Handler) error {
+	ctx := h.Request.Context()
+	root, err := reader.vfs.Root(ctx, h.LookupPath.Path)
+	if err != nil {
+		return err
+	}
+
+	r := redirects.ParseRedirects(ctx, root)
+
+	rewrittenURL, status, err := r.Rewrite(h.Request.URL)
+	if err != nil {
+		return err
+	}
+
+	http.Redirect(h.Writer, h.Request, rewrittenURL.Path, status)
+
+	return nil
+}
+
 func (reader *Reader) tryFile(h serving.Handler) error {
 	ctx := h.Request.Context()
 
@@ -62,6 +92,18 @@ func (reader *Reader) tryFile(h serving.Handler) error {
 		return err
 	}
 
+	// Serve status of `_redirects` under `_redirects`
+	// We check if the final resolved path is `_redirects` after symlink traversal
+	if fullPath == redirects.ConfigFile {
+		if os.Getenv("FF_ENABLE_REDIRECTS") == "true" {
+			r := redirects.ParseRedirects(ctx, root)
+			return reader.serveRedirectsStatus(h, r)
+		}
+
+		h.Writer.WriteHeader(http.StatusForbidden)
+		return nil
+	}
+
 	return reader.serveFile(ctx, h.Writer, h.Request, root, fullPath, h.LookupPath.HasAccessControl)
 }
 
diff --git a/internal/serving/disk/serving.go b/internal/serving/disk/serving.go
index f95f983c..bb9b40d2 100644
--- a/internal/serving/disk/serving.go
+++ b/internal/serving/disk/serving.go
@@ -1,6 +1,8 @@
 package disk
 
 import (
+	"os"
+
 	"gitlab.com/gitlab-org/gitlab-pages/internal/httperrors"
 	"gitlab.com/gitlab-org/gitlab-pages/internal/serving"
 	"gitlab.com/gitlab-org/gitlab-pages/internal/vfs"
@@ -15,7 +17,17 @@ type Disk struct {
 // ServeFileHTTP serves a file from disk and returns true. It returns false
 // when a file could not been found.
 func (s *Disk) ServeFileHTTP(h serving.Handler) bool {
-	return s.reader.tryFile(h) == nil
+	if s.reader.tryFile(h) == nil {
+		return true
+	}
+
+	if os.Getenv("FF_ENABLE_REDIRECTS") == "true" {
+		if s.reader.tryRedirects(h) == nil {
+			return true
+		}
+	}
+
+	return false
 }
 
 // ServeNotFoundHTTP tries to read a custom 404 page
diff --git a/internal/serving/disk/symlink/path_test.go b/internal/serving/disk/symlink/path_test.go
index 23978037..8c1d19b3 100644
--- a/internal/serving/disk/symlink/path_test.go
+++ b/internal/serving/disk/symlink/path_test.go
@@ -16,28 +16,13 @@ import (
 	"github.com/stretchr/testify/require"
 
 	"gitlab.com/gitlab-org/gitlab-pages/internal/serving/disk/symlink"
+	"gitlab.com/gitlab-org/gitlab-pages/internal/testhelpers"
 	"gitlab.com/gitlab-org/gitlab-pages/internal/vfs"
 	"gitlab.com/gitlab-org/gitlab-pages/internal/vfs/local"
 )
 
 var fs = vfs.Instrumented(&local.VFS{}, "local")
 
-func tmpDir(t *testing.T) (vfs.Root, string, func()) {
-	tmpDir, err := ioutil.TempDir("", "symlink_tests")
-	require.NoError(t, err)
-
-	// On some systems `/tmp` can be a symlink
-	tmpDir, err = filepath.EvalSymlinks(tmpDir)
-	require.NoError(t, err)
-
-	root, err := fs.Root(context.Background(), tmpDir)
-	require.NoError(t, err)
-
-	return root, tmpDir, func() {
-		os.RemoveAll(tmpDir)
-	}
-}
-
 type EvalSymlinksTest struct {
 	// If dest is empty, the path is created; otherwise the dest is symlinked to the path.
 	path, dest string
@@ -100,7 +85,7 @@ func testEvalSymlinks(t *testing.T, wd, path, want string) {
 }
 
 func TestEvalSymlinks(t *testing.T) {
-	_, tmpDir, cleanup := tmpDir(t)
+	_, tmpDir, cleanup := testhelpers.TmpDir(t, "symlink_tests")
 	defer cleanup()
 
 	// Create the symlink farm using relative paths.
@@ -139,7 +124,7 @@ func TestEvalSymlinks(t *testing.T) {
 }
 
 func TestEvalSymlinksIsNotExist(t *testing.T) {
-	root, _, cleanup := tmpDir(t)
+	root, _, cleanup := testhelpers.TmpDir(t, "symlink_tests")
 	defer cleanup()
 
 	_, err := symlink.EvalSymlinks(context.Background(), root, "notexist")
@@ -160,7 +145,7 @@ func TestEvalSymlinksIsNotExist(t *testing.T) {
 }
 
 func TestIssue13582(t *testing.T) {
-	root, tmpDir, cleanup := tmpDir(t)
+	root, tmpDir, cleanup := testhelpers.TmpDir(t, "symlink_tests")
 	defer cleanup()
 
 	dir := filepath.Join(tmpDir, "dir")