Add a configuration option in webwork2.mojolicious.dist.yml for allowing unsecured rpc usage.

The option allow_unsecured_rpc (which defaults to off) allows the
html2xml and render_rpc endpoints to be used without cookies, and thus
skipping two factor authentication.  This should never be enabled for a
typical webwork server.  This should only be enabled if you want to
allow serving content via these endpoints to links in external websites
with usernames and passwords embedded in them such as for PreTeXt
textbooks.

Author: drgrice1

conf/webwork2.mojolicious.dist.yml

@@ -239,3 +239,10 @@ debug:
 hardcopy:
   # If 1, don't delete temporary files created when a hardcopy is generated.
   preserve_temp_files: 0
+
+# Set this to 1 to allow the html2xml and render_rpc endpoints to disable
+# cookies and thus skip two factor authentication. This should never be enabled
+# for a typical webwork server.  This should only be enabled if you want to
+# allow serving content via these endpoints to links in external websites with
+# usernames and passwords embedded in them such as for PreTeXt textbooks.
+allow_unsecured_rpc: 0

lib/WeBWorK.pm

@@ -91,12 +91,13 @@ async sub dispatch ($c) {
 	if ($c->current_route =~ /^(render_rpc|instructor_rpc|html2xml)$/) {
 		$c->{rpc} = 1;
 
-		$c->stash(disable_cookies => 1) if $c->current_route eq 'render_rpc' && $c->param('disableCookies');
+		$c->stash(disable_cookies => 1)
+			if $c->current_route eq 'render_rpc' && $c->param('disableCookies') && $c->config('allow_unsecured_rpc');
 
 		# This provides compatibility for legacy html2xml parameters.
 		# This should be deleted when the html2xml endpoint is removed.
 		if ($c->current_route eq 'html2xml') {
-			$c->stash(disable_cookies => 1);
+			$c->stash(disable_cookies => 1) if $c->config('allow_unsecured_rpc');
 			for ([ 'userID', 'user' ], [ 'course_password', 'passwd' ], [ 'session_key', 'key' ]) {
 				$c->param($_->[1], $c->param($_->[0])) if defined $c->param($_->[0]) && !defined $c->param($_->[1]);
 			}