[Twisted-web] fix nevow exception in args parsing

[Andrea Arcangeli]

I noticed an exception in nevow, for example with divmod.com/?=x=x=x.

This is the fix, please apply this (or an equivalent one) to SVN:

Index: Nevow/nevow/url.py
===================================================================
--- Nevow/nevow/url.py	(revision 1748)
+++ Nevow/nevow/url.py	(working copy)
@@ -21,7 +21,7 @@
 def _uqf(query):
     for x in query.split('&'):
         if '=' in x:
-            yield tuple( [urllib.unquote_plus(s) for s in x.split('=')] )
+            yield tuple( [urllib.unquote_plus(s) for s in x.split('=')[:2]] )
         elif x:
             yield (urllib.unquote_plus(x), None)
 unquerify = lambda query: list(_uqf(query))


And here again my latest version of the usual caching patches based on
dialtone's stuff, that prevents high traffic pages to hurt.

Index: Nevow/nevow/rend.py
===================================================================
--- Nevow/nevow/rend.py	(revision 1748)
+++ Nevow/nevow/rend.py	(working copy)
@@ -476,6 +476,8 @@
         self.children[name] = child
     
 
+_CACHE = {}
+
 class Page(Fragment, ConfigurableFactory, ChildLookupMixin):
     """A page is the main Nevow resource and renders a document loaded
     via the document factory (docFactory).
@@ -489,8 +491,46 @@
     afterRender = None
     addSlash = None
 
+    cache = False
+    lifetime = 0
+
     flattenFactory = lambda self, *args: flat.flattenFactory(*args)
 
+    def hasCache(self, ctx):
+        if not self.cache:
+            return
+
+        c = self.lookupCache(ctx)
+
+        if c is None:
+            self.storeCache(ctx, [util.Deferred()])
+            return
+
+        if isinstance(c[0], util.Deferred):
+            d = util.Deferred()
+            c.append(d)
+            return d
+
+        if now() > c[1] + self.lifetime and self.lifetime > 0:
+            self.storeCache(ctx, [util.Deferred()])
+            return
+
+        return c[0]
+    def cacheRendered(self, ctx, data):
+        if self.cache:
+            defer_list = self.lookupCache(ctx)
+            assert(isinstance(defer_list[0], util.Deferred))
+            # overwrite the deferred with the data
+            self.storeCache(ctx, (data, now()))
+            for d in defer_list:
+                d.callback(data)
+    def cacheIDX(self, ctx):
+        return str(url.URL.fromContext(ctx))
+    def storeCache(self, ctx, c):
+        _CACHE[self.cacheIDX(ctx)] = c
+    def lookupCache(self, ctx):
+        return _CACHE.get(self.cacheIDX(ctx))
+
     def renderHTTP(self, ctx):
         if self.beforeRender is not None:
             return util.maybeDeferred(self.beforeRender,ctx).addCallback(
@@ -515,11 +555,18 @@
             if self.afterRender is not None:
                 return util.maybeDeferred(self.afterRender,ctx)
 
-        if self.buffered:
+        c = self.hasCache(ctx)
+        if c is not None:
+            finishRequest()
+            return c
+
+        if self.buffered or self.cache:
             io = StringIO()
             writer = io.write
             def finisher(result):
-                request.write(io.getvalue())
+                c = io.getvalue()
+                self.cacheRendered(ctx, c)
+                request.write(c)
                 return util.maybeDeferred(finishRequest).addCallback(lambda r: result)
         else:
             writer = request.write

And here the fix to avoid wget to write garbage in filenames under
the nevow guard (I suggest to merge it).

Index: Nevow/nevow/guard.py
===================================================================
--- Nevow/nevow/guard.py	(revision 1748)
+++ Nevow/nevow/guard.py	(working copy)
@@ -297,7 +297,8 @@
         if path.startswith(SESSION_KEY):
             key = path[len(SESSION_KEY):]
             if key not in self.sessions:
-                return urlToChild(request, *segments[1:], **{'__start_session__':1}), ()
+                #return urlToChild(request, *segments[1:], **{'__start_session__':1}), ()
+                return urlToChild(request, *segments[1:]), ()
             self.sessions[key].setLifetime(self.sessionLifetime)
             if cookie == key:
                 # /sessionized-url/${SESSION_KEY}aef9c34aecc3d9148/foo
@@ -305,7 +306,8 @@
                 #                  we are this getChild
                 # with a matching cookie
                 self.sessions[key].sessionJustStarted = True
-                return urlToChild(request, *segments[1:], **{'__session_just_started__':1}), ()
+                #return urlToChild(request, *segments[1:], **{'__session_just_started__':1}), ()
+                return urlToChild(request, *segments[1:]), ()
             else:
                 # We attempted to negotiate the session but failed (the user
                 # probably has cookies disabled): now we're going to return the

Keep up the great work, thanks!

PS. While sending this email I take the opportunity to point you to the
nevow sourcecode of a little GPL nevow appserver I developed last
weekend, any suggestion for improvements is welcome ;).

	http://klive.cpushare.com/downloads/