IPClassifier: Add per-output pattern handlers.

Request from Momina Khan. Meraki has something like this.

elements/ip/ipclassifier.cc

@@ -21,6 +21,7 @@
 #include <click/glue.hh>
 #include <click/error.hh>
 #include <click/confparse.hh>
+#include <click/router.hh>
 CLICK_DECLS
 
 IPClassifier::IPClassifier()
@@ -42,11 +43,19 @@ IPClassifier::configure(Vector<String> &conf, ErrorHandler *errh)
     for (int i = 0; i < conf.size(); i++)
 	new_conf.push_back(String(i) + " " + conf[i]);
     int r = IPFilter::configure(new_conf, errh);
-    if (r >= 0)
+    if (r >= 0 && !router()->initialized())
 	_zprog.warn_unused_outputs(noutputs(), errh);
     return r;
 }
 
+void IPClassifier::add_handlers() {
+    IPFilter::add_handlers();
+    for (uintptr_t i = 0; i != (uintptr_t) noutputs(); ++i) {
+	add_read_handler("pattern" + String(i), read_positional_handler, (void*) i);
+	add_write_handler("pattern" + String(i), reconfigure_positional_handler, (void*) i);
+    }
+}
+
 CLICK_ENDDECLS
 ELEMENT_REQUIRES(IPFilter)
 EXPORT_ELEMENT(IPClassifier)

elements/ip/ipclassifier.hh

@@ -228,6 +228,10 @@ is using to classify packets. At each step in the program, four bytes
 of packet data are ANDed with a mask and compared against four bytes of
 classifier pattern.
 
+=h pattern0 rw
+Returns or sets the element's pattern 0. There are as many C<pattern>
+handlers as there are output ports.
+
 =a Classifier, IPFilter, CheckIPHeader, MarkIPHeader, CheckIPHeader2,
 tcpdump(1) */
 
@@ -240,6 +244,7 @@ class IPClassifier : public IPFilter { public:
   const char *processing() const		{ return PUSH; }
 
   int configure(Vector<String> &, ErrorHandler *) CLICK_COLD;
+  void add_handlers() CLICK_COLD;
 
 };