The sample basic authorization plugin, basic-auth.c, checks for basic HTTP
proxy authorization. In HTTP basic proxy authorization, client user names and
passwords are contained in the Proxy-Authorization header. The password is
encoded using base64 encoding. The plugin checks all incoming requests for
the authorization header, user name, and password. If the plugin does not find
all of the these, then it reenables with an error (effectively stopping the
transaction) and adds a transaction hook to the send response header event.
Creating the Plugin's Parent Continuation and Global Hook
The parent continuation and global hook are created as follows:
TSHttpHookAdd (TS_HTTP_OS_DNS_HOOK, TSContCreate (auth_plugin, NULL));

