HTTPd, websrv_lib: implement extendable OPTIONS handler.

For CalDAV, we need to allow the handler to fine-tune its OPTIONS response.
So, better cleanup the API and allow request handlers to define their OPTIONS.

bzr revid: p_christ@hol.gr-20100726093336-afzp15rys9oua4a0

bin/service/http_server.py

@@ -297,7 +297,7 @@ def init_xmlrpc():
 
 class StaticHTTPHandler(HttpLogHandler, FixSendError, HttpOptions, HTTPHandler):
     _logger = logging.getLogger('httpd')
-    _HTTP_OPTIONS = 'OPTIONS GET HEAD'
+    _HTTP_OPTIONS = { 'Allow': ['OPTIONS', 'GET', 'HEAD'] }
 
     def __init__(self,request, client_address, server):
         HTTPHandler.__init__(self,request,client_address,server)

bin/service/websrv_lib.py

@@ -179,17 +179,37 @@ class FixSendError:
             self.wfile.write(content)
 
 class HttpOptions:
-    _HTTP_OPTIONS = 'OPTIONS'
+    _HTTP_OPTIONS = {'Allow': ['OPTIONS' ] }
 
     def do_OPTIONS(self):
         """return the list of capabilities """
 
+        opts = self._HTTP_OPTIONS
+        nopts = self._prep_OPTIONS(opts)
+        if nopts:
+            opts = nopts
+
         self.send_response(200)
         self.send_header("Content-Length", 0)
 
-        self.send_header('Allow', self._HTTP_OPTIONS)
+        for key, value in opts.items():
+            if isinstance(value, basestring):
+                self.send_header(key, value)
+            elif isinstance(value, (tuple, list)):
+                self.send_header(key, ', '.join(value))
         self.end_headers()
 
+    def _prep_OPTIONS(self, opts):
+        """Prepare the OPTIONS response, if needed
+        
+        Sometimes, like in special DAV folders, the OPTIONS may contain
+        extra keywords, perhaps also dependant on the request url. 
+        @param the options already. MUST be copied before being altered
+        @return the updated options.
+        
+        """
+        return opts
+
 class MultiHTTPHandler(FixSendError, HttpOptions, BaseHTTPRequestHandler):
     """ this is a multiple handler, that will dispatch each request
         to a nested handler, iff it matches