[rygel] server: Use base64url instead of base64

[Jens Georg <jensgeorg src gnome org>]

commit d3631e321b106d47e6a3e9fd46149b53b6f68a8b
Author: Jean-Baptiste Dubois <jean-baptiste dubois parrot com>
Date:   Fri Oct 25 15:23:20 2013 +0200

    server: Use base64url instead of base64
    
    Encoded base64 uris may have '/' chars which cause issues in function
    HTTPItemURI.from_string
    
    https://bugzilla.gnome.org/show_bug.cgi?id=710877

 src/librygel-server/rygel-http-item-uri.vala |   26 +++++++++++++++++++++-----
 1 files changed, 21 insertions(+), 5 deletions(-)
---
diff --git a/src/librygel-server/rygel-http-item-uri.vala b/src/librygel-server/rygel-http-item-uri.vala
index e1018b6..2b92237 100644
--- a/src/librygel-server/rygel-http-item-uri.vala
+++ b/src/librygel-server/rygel-http-item-uri.vala
@@ -119,6 +119,22 @@ internal class Rygel.HTTPItemURI : Object {
         }
     }
 
+    // Base 64 Encoding with URL and Filename Safe Alphabet
+    // http://tools.ietf.org/html/rfc4648#section-5
+    private string base64_urlencode (string data) {
+        var enc64 = Base64.encode ((uchar[]) data.to_utf8 ());
+        enc64 = enc64.replace ("/", "_");
+
+        return enc64.replace ("+", "-");
+    }
+
+    private uchar[] base64_urldecode (string data) {
+       var dec64 = data.replace ("_", "/");
+       dec64 = dec64.replace ("-", "+");
+
+       return Base64.decode (dec64);
+    }
+
     public HTTPItemURI.from_string (string     uri,
                                     HTTPServer http_server)
                                     throws HTTPRequestError {
@@ -148,7 +164,8 @@ internal class Rygel.HTTPItemURI : Object {
         for (int i = 1; i < parts.length - 1; i += 2) {
             switch (parts[i]) {
                 case "i":
-                    var data = Base64.decode (Soup.URI.decode (parts[i + 1]));
+                    var data = this.base64_urldecode
+                                        (Soup.URI.decode (parts[i + 1]));
                     StringBuilder builder = new StringBuilder ();
                     builder.append ((string) data);
                     this.item_id = builder.str;
@@ -184,10 +201,9 @@ internal class Rygel.HTTPItemURI : Object {
         // there seems to be a problem converting strings properly to arrays
         // you need to call to_utf8() and assign it to a variable to make it
         // work properly
-        var data = this.item_id.to_utf8 ();
-        var escaped = Uri.escape_string (Base64.encode ((uchar[]) data),
-                                         "",
-                                         true);
+
+        var data = this.base64_urlencode (this.item_id);
+        var escaped = Uri.escape_string (data, "", true);
         string path = "/i/" + escaped;
 
         if (this.transcode_target != null) {