TUN-528: Move cloudflared into a separate repo

vendor/github.com/mholt/caddy/caddyhttp/rewrite/to.go

@@ -0,0 +1,103 @@
+// Copyright 2015 Light Code Labs, LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package rewrite
+
+import (
+	"log"
+	"net/http"
+	"net/url"
+	"path"
+	"strings"
+
+	"github.com/mholt/caddy/caddyhttp/httpserver"
+)
+
+// To attempts rewrite. It attempts to rewrite to first valid path
+// or the last path if none of the paths are valid.
+func To(fs http.FileSystem, r *http.Request, to string, replacer httpserver.Replacer) Result {
+	tos := strings.Fields(to)
+
+	// try each rewrite paths
+	t := ""
+	query := ""
+	for _, v := range tos {
+		t = replacer.Replace(v)
+		tparts := strings.SplitN(t, "?", 2)
+		t = path.Clean(tparts[0])
+
+		if len(tparts) > 1 {
+			query = tparts[1]
+		}
+
+		// add trailing slash for directories, if present
+		if strings.HasSuffix(tparts[0], "/") && !strings.HasSuffix(t, "/") {
+			t += "/"
+		}
+
+		// validate file
+		if validFile(fs, t) {
+			break
+		}
+	}
+
+	// validate resulting path
+	u, err := url.Parse(t)
+	if err != nil {
+		// Let the user know we got here. Rewrite is expected but
+		// the resulting url is invalid.
+		log.Printf("[ERROR] rewrite: resulting path '%v' is invalid. error: %v", t, err)
+		return RewriteIgnored
+	}
+
+	// perform rewrite
+	r.URL.Path = u.Path
+	if query != "" {
+		// overwrite query string if present
+		r.URL.RawQuery = query
+	}
+	if u.Fragment != "" {
+		// overwrite fragment if present
+		r.URL.Fragment = u.Fragment
+	}
+
+	return RewriteDone
+}
+
+// validFile checks if file exists on the filesystem.
+// if file ends with `/`, it is validated as a directory.
+func validFile(fs http.FileSystem, file string) bool {
+	if fs == nil {
+		return false
+	}
+
+	f, err := fs.Open(file)
+	if err != nil {
+		return false
+	}
+	defer f.Close()
+
+	stat, err := f.Stat()
+	if err != nil {
+		return false
+	}
+
+	// directory
+	if strings.HasSuffix(file, "/") {
+		return stat.IsDir()
+	}
+
+	// file
+	return !stat.IsDir()
+}