nginx: fix hkp routes

Changes handling of hkp routes:
- uri decode the search paramter before passing to /pks/internal/$op/$query
- strip <> surrounded text in lua, instead of an nginx rule

hagrid-routes.conf

@@ -74,14 +74,13 @@ location /vks/v1/ {
 
 # Common HKP requests.
 location /pks/lookup {
-    # if the search argument contains angle brackets, strip everything around them
-    if ($arg_search ~ ".*\<([^&<>]+)\>.*") {
-        set $arg_search "$1";
-    }
-
     # rewrite this to a path we can match on (right below)
     if ($args ~ "op=.*search=") {
-        rewrite . /pks/internal/$arg_op/$arg_search last;
+        # urldecode the search parameter
+        set_by_lua $arg_search_decoded "return ngx.arg[1]:gsub(\"%%(%x%x)\", function(x) return string.char(tonumber(x, 16)) end)" $arg_search;
+        # if the search argument contains angle brackets, strip everything around them
+        set_by_lua $arg_search_decoded "return ngx.arg[1]:gsub(\"^.*<([^>]-)>.*$\", \"%1\")" $arg_search_decoded;
+        rewrite . /pks/internal/$arg_op/$arg_search_decoded last;
     }
 
     add_header 'Access-Control-Allow-Origin' '*';