1/***
2  This file is part of avahi.
3
4  avahi is free software; you can redistribute it and/or modify it
5  under the terms of the GNU Lesser General Public License as
6  published by the Free Software Foundation; either version 2.1 of the
7  License, or (at your option) any later version.
8
9  avahi is distributed in the hope that it will be useful, but WITHOUT
10  ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
11  or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General
12  Public License for more details.
13
14  You should have received a copy of the GNU Lesser General Public
15  License along with avahi; if not, write to the Free Software
16  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
17  USA.
18***/
19
20using System;
21using System.Collections;
22using System.Net;
23using System.Runtime.InteropServices;
24using System.Text;
25using Mono.Unix;
26
27namespace Avahi
28{
29
30    internal delegate void HostNameResolverCallback (IntPtr resolver, int iface, Protocol proto,
31                                                     ResolverEvent revent, IntPtr hostname, IntPtr address,
32                                                     LookupResultFlags flags, IntPtr userdata);
33
34    public class HostNameResolver : ResolverBase, IDisposable
35    {
36        private IntPtr handle;
37        private Client client;
38        private int iface;
39        private Protocol proto;
40        private string hostname;
41        private Protocol aproto;
42        private LookupFlags flags;
43        private HostNameResolverCallback cb;
44
45        private IPAddress currentAddress;
46        private string currentHost;
47
48        private ArrayList foundListeners = new ArrayList ();
49        private ArrayList timeoutListeners = new ArrayList ();
50
51        [DllImport ("avahi-client")]
52        private static extern IntPtr avahi_host_name_resolver_new (IntPtr client, int iface, Protocol proto,
53                                                                   byte[] hostname, Protocol aproto, LookupFlags flags,
54                                                                   HostNameResolverCallback cb, IntPtr userdata);
55
56        [DllImport ("avahi-client")]
57        private static extern void avahi_host_name_resolver_free (IntPtr handle);
58
59        public event HostAddressHandler Found
60        {
61            add {
62                foundListeners.Add (value);
63                Start ();
64            }
65            remove {
66                foundListeners.Remove (value);
67                Stop (false);
68            }
69        }
70
71        public event EventHandler Timeout
72        {
73            add {
74                timeoutListeners.Add (value);
75                Start ();
76            }
77            remove {
78                timeoutListeners.Remove (value);
79                Stop (false);
80            }
81        }
82
83        public IPAddress Address
84        {
85            get { return currentAddress; }
86        }
87
88        public string HostName
89        {
90            get { return currentHost; }
91        }
92
93        public HostNameResolver (Client client, string hostname) : this (client, -1, Protocol.Unspecified,
94                                                                         hostname, Protocol.Unspecified,
95                                                                         LookupFlags.None)
96        {
97        }
98
99        public HostNameResolver (Client client, int iface, Protocol proto, string hostname,
100                                 Protocol aproto, LookupFlags flags)
101        {
102            this.client = client;
103            this.iface = iface;
104            this.proto = proto;
105            this.hostname = hostname;
106            this.aproto = aproto;
107            this.flags = flags;
108            cb = OnHostNameResolverCallback;
109        }
110
111        ~HostNameResolver ()
112        {
113            Dispose ();
114        }
115
116        public void Dispose ()
117        {
118            Stop (true);
119        }
120
121        private void Start ()
122        {
123            if (client.Handle == IntPtr.Zero || handle != IntPtr.Zero ||
124                (foundListeners.Count == 0 && timeoutListeners.Count == 0))
125                return;
126
127            lock (client) {
128                handle = avahi_host_name_resolver_new (client.Handle, iface, proto,
129                                                       Utility.StringToBytes (hostname), aproto, flags,
130                                                       cb, IntPtr.Zero);
131
132                if (handle == IntPtr.Zero)
133                    client.ThrowError ();
134            }
135        }
136
137        private void Stop (bool force)
138        {
139            if (client.Handle != IntPtr.Zero && handle != IntPtr.Zero &&
140                (force || (foundListeners.Count == 0 && timeoutListeners.Count == 0))) {
141
142                lock (client) {
143                    avahi_host_name_resolver_free (handle);
144                    handle = IntPtr.Zero;
145                }
146            }
147        }
148
149        private void OnHostNameResolverCallback (IntPtr resolver, int iface, Protocol proto,
150                                                 ResolverEvent revent, IntPtr hostname, IntPtr address,
151                                                 LookupResultFlags flags, IntPtr userdata)
152        {
153            switch (revent) {
154            case ResolverEvent.Found:
155                currentAddress = Utility.PtrToAddress (address);
156                currentHost = Utility.PtrToString (hostname);
157
158                foreach (HostAddressHandler handler in foundListeners)
159                    handler (this, new HostAddressArgs (currentHost, currentAddress));
160                break;
161            case ResolverEvent.Failure:
162                EmitFailure (client.LastError);
163                break;
164            }
165        }
166    }
167}
168