app/publisher: use scheme from window.location

Also remove the scheme variable from the template that
tells what protocol the backend uses to talk to camlistore.

Fixes #920

Change-Id: Ia25e99d0f1b77077158f761f11a5c6bacfa2dc3b

app/publisher/gallery.html

@@ -12,7 +12,6 @@
 	var publishedRoot = {{$header.PublishedRoot}};
 	var pathPrefix = {{$header.PathPrefix}};
 	var host = {{$header.Host}};
-	var scheme = {{$header.Scheme}};
 	var camliViewIsOwner = {{$header.ViewerIsOwner}};
 	</script>
 	{{range $jsFile := $header.JSDeps}}

app/publisher/js/main.go

@@ -22,6 +22,7 @@ package main
 
 import (
 	"fmt"
+	"strings"
 
 	"camlistore.org/pkg/blob"
 
@@ -48,11 +49,15 @@ func host() (string, error) {
 }
 
 func scheme() (string, error) {
-	s := js.Global.Get("scheme")
-	if undefOrEmptyString(s) {
-		return "", fmt.Errorf("No Scheme in header")
+	// We can't rely on the publisher's server-side to set the scheme as a var,
+	// because it could be behind a proxy, serving for a scheme different
+	// from the one we're seeing from the outside.
+	// Ask the browser instead what scheme/protocol the current page was accessed with.
+	proto := js.Global.Get("location").Get("protocol")
+	if undefOrEmptyString(proto) {
+		return "", fmt.Errorf("window.location.protocol missing or invalid")
 	}
-	return s.String(), nil
+	return strings.TrimRight(proto.String(), ":"), nil
 }
 
 func subjectBasePath() (string, error) {

app/publisher/main.go

@@ -976,17 +976,12 @@ func (pr *publishRequest) fileSchemaRefFromBlob(des *search.DescribedBlob) (file
 // subjectHeader returns the PageHeader corresponding to the described subject.
 func (pr *publishRequest) subjectHeader(described map[string]*search.DescribedBlob) *publish.PageHeader {
 	subdes := described[pr.subject.String()]
-	scheme := "http"
-	if pr.req.TLS != nil {
-		scheme = "https"
-	}
 	header := &publish.PageHeader{
 		Title:           html.EscapeString(getTitle(subdes.BlobRef, described)),
 		CSSFiles:        pr.cssFiles(),
 		JSDeps:          pr.jsDeps(),
 		Subject:         pr.subject,
 		Host:            pr.req.Host,
-		Scheme:          scheme,
 		SubjectBasePath: pr.subjectBasePath,
 		PathPrefix:      pr.base,
 		PublishedRoot:   pr.publishedRoot,

pkg/publish/types.go

@@ -52,7 +52,6 @@ type PageHeader struct {
 	// "/pics/", or "/" if the request was not proxied through Camlistore.
 	PathPrefix string
 	Host       string
-	Scheme     string
 }
 
 // PageFile contains the file related data available to the subject template,