[Serusers] Check_from()

[Juha Heinanen]

Jiri Kuthan writes:

 > At iptel, we deploy the latter simple policy: 
 > 
 >   if (method=="REGISTER") {
 >         if (!www_authorize("iptel.org", "subscriber")) {
 >             # challenge if none or invalid credentials
 >             www_challenge("iptel.org", "0");
 >             break;
 >         };
 >        if (!check_to()) {
 >             log("LOG: To Cheating attempt\n");
 >             sl_send_reply("403", "That is ugly -- use To=id in REGISTERs");
 >             break;
 >         };

radius_www_authorize includes the above check_to test.  it checks that
the host part of To uri matches the realm in digest and passes the user
part as a check item to radius access request.

-- juha