vcs-test: add a /insecure handler that redirects to plain HTTP

Updates golang/go#29591

Change-Id: I5c9899a475ba7521b49c3eef2679c104df0ae0f7
Reviewed-on: https://go-review.googlesource.com/c/build/+/167710
Run-TryBot: Bryan C. Mills <[email protected]>
TryBot-Result: Gobot Gobot <[email protected]>
Reviewed-by: Brad Fitzpatrick <[email protected]>

vcs-test/vcweb/insecure.go

@@ -0,0 +1,30 @@
+// Copyright 2019 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build linux
+
+package main
+
+import (
+	"net/http"
+	"strings"
+)
+
+func insecureRedirectHandler() http.Handler {
+	return http.HandlerFunc(insecureRedirectDispatch)
+}
+
+func insecureRedirectDispatch(w http.ResponseWriter, r *http.Request) {
+	if !strings.HasPrefix(r.URL.Path, "/insecure/") {
+		http.Error(w, "path does not start with /insecure/", http.StatusInternalServerError)
+	}
+
+	url := *r.URL
+	url.Scheme = "http" // not "https"
+	if url.Host == "" {
+		url.Host = r.Host
+	}
+	url.Path = strings.TrimPrefix(url.Path, "/insecure")
+	http.Redirect(w, r, url.String(), http.StatusMovedPermanently)
+}

vcs-test/vcweb/main.go

@@ -67,6 +67,7 @@ func main() {
 	http.Handle("/svn/", svnHandler())
 	http.Handle("/fossil/", fossilHandler())
 	http.Handle("/bzr/", bzrHandler())
+	http.Handle("/insecure/", insecureRedirectHandler())
 
 	handler := logger(http.HandlerFunc(loadAndHandle))