///////////////////////////////////////////////////////////////////////////////
//
//  Microsoft Research Singularity
//
//  Copyright (c) Microsoft Corporation.  All rights reserved.
//
//  File:   DNSContract.gs
//  Note:   Contract definition for interacting with the DNS Module
//

// note This is all IPv4 flavored for now.

using Microsoft.Singularity.Channels;
using Microsoft.Singularity.Directory;

namespace NetStack.Contracts
{
    public contract DNSContract : ServiceContract
    {
        // This is the name under which the DNS module registers with the
        // name server
        public const string ModuleName = "/dev/dns";

        // Response messages
        out message NotFound();
        out message AddressList(uint[] in ExHeap addresses);
        out message DNSResults(uint[] in ExHeap addresses, char[][] in ExHeap names);
        out message IsValid(bool valid);
        out message Address(uint address);
        out message Ack();

        // Request messages
        in message AddNameServer(uint address);
        in message RemoveNameServer(uint address);
        in message RotateNameServers();
        in message GetNameServers();
        in message GetCurrentNameServer();
        in message IsValidName(char[] in ExHeap name);

        // host can be a host's textual name or the string of an address
        in message Resolve(char[] in ExHeap host);

        out message Ready();
        override state Start : Ready! -> ReadyState;

        state ReadyState : one
        {
            AddNameServer? -> Ack! -> ReadyState;
            RemoveNameServer? -> Ack! -> ReadyState;
            RotateNameServers? -> Ack! -> ReadyState;

            GetCurrentNameServer? -> Address! -> ReadyState;
            GetNameServers? -> AddressList! -> ReadyState;
            Resolve? -> (NotFound! or DNSResults!) -> ReadyState;
            IsValidName? -> IsValid! -> ReadyState;
        }
    }
}