allow http protocol to switch to https

switch protocols at random is a bad idea if e.g. http can switch to
file, so we limit the possibilities to http to http and http to https.

As very few people (less than 1% according to popcon) have https
installed this likely changes nothing in terms of failure. The commit is
adding a friendly hint which package needs to be installed though.

1 files changed, 6 insertions, 1 deletions

diff --git a/apt-pkg/acquire-worker.cc b/apt-pkg/acquire-worker.cc
index 44a84216a..44c3e4e17 100644
--- a/apt-pkg/acquire-worker.cc
+++ b/apt-pkg/acquire-worker.cc
@@ -109,7 +109,12 @@ bool pkgAcquire::Worker::Start()
    // Get the method path
    string Method = _config->FindDir("Dir::Bin::Methods") + Access;
    if (FileExists(Method) == false)
-      return _error->Error(_("The method driver %s could not be found."),Method.c_str());
+   {
+      _error->Error(_("The method driver %s could not be found."),Method.c_str());
+      if (Access == "https")
+	 _error->Notice(_("Is the package %s installed?"), "apt-transport-https");
+      return false;
+   }
 
    if (Debug == true)
       clog << "Starting method '" << Method << '\'' << endl;