add example which uses filt

examples/README

@@ -3,6 +3,7 @@ add_header.py             Simple script that just adds a header to every request
 change_upstream_proxy.py  Dynamically change the upstream proxy
 dns_spoofing.py           Use mitmproxy in a DNS spoofing scenario.
 dup_and_replay.py         Duplicates each request, changes it, and then replays the modified request.
+filt.py                   Use mitmproxy's filter expressions in your script.
 iframe_injector.py        Inject configurable iframe into pages.
 modify_form.py            Modify all form submissions to add a parameter.
 modify_querystring.py     Modify all query strings to add a parameters.

examples/filt.py

@@ -0,0 +1,15 @@
+# This scripts demonstrates how to use mitmproxy's filter pattern in inline scripts.
+# Usage: mitmdump -s "filt.py FILTER"
+
+from libmproxy import filt
+
+def start(context, argv):
+	print argv
+	if len(argv) != 2:
+		raise ValueError("Usage: -s 'filt.py FILTER'")
+	context.filter = filt.parse(argv[1])
+
+def response(context, flow):
+	if flow.match(context.filter):
+		print("Flow matches filter:")
+		print(flow)