added unbound to external deps

external/unbound/libunbound/python/doc/examples/example4.rst

@@ -0,0 +1,34 @@
+.. _example_examine:
+
+==============================
+DNSSEC validator
+==============================
+
+This example program performs DNSSEC validation of a DNS lookup.
+
+::
+
+	#!/usr/bin/python
+	import os
+	from unbound import ub_ctx,RR_TYPE_A,RR_CLASS_IN
+	
+	ctx = ub_ctx()
+	ctx.resolvconf("/etc/resolv.conf")
+	if (os.path.isfile("keys")):
+		ctx.add_ta_file("keys") #read public keys for DNSSEC verification
+	
+	status, result = ctx.resolve("www.nic.cz", RR_TYPE_A, RR_CLASS_IN)
+	if status == 0 and result.havedata:
+	
+	    print "Result:", result.data.address_list
+	
+	    if result.secure:
+	        print "Result is secure"
+	    elif result.bogus:
+	        print "Result is bogus"
+	    else:
+	        print "Result is insecure"
+
+More detailed informations can be seen in libUnbound DNSSEC tutorial `here`_.
+
+.. _here: http://www.unbound.net/documentation/libunbound-tutorial-6.html