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Implement mDNS client

This commit is contained in:
Santiago Lo Coco 2024-11-02 22:54:14 +01:00
parent 1a5558370d
commit abf8bab179
2 changed files with 232 additions and 2 deletions
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2
Assets/Scripts/EndpointLoader.cs
View File

@ -13,7 +13,7 @@ public class EndpointLoader : MonoBehaviour
public ServiceDiscovery serviceDiscovery;
private bool triedMulticast = false;
private string apiUrl = "http://windows.loca:5000/api/endpoints";
private string apiUrl = "http://windows.loca:5000/api/endpoints"; // Typo on purpose
private const string defaultEndpoint1 = "http://windows.local:8100/mystream/";
private const string defaultEndpoint2 = "http://windows.local:8200/mystream/";
private bool defaultEndpoint1Loaded = false;

232
Assets/Scripts/ServiceDiscovery.cs
View File

@ -18,6 +18,13 @@ public class ServiceDiscovery : MonoBehaviour
private const string multicastAddress = "224.0.0.251";
private const int multicastPort = 5353;
/*
private void Start()
{
StartListening((ip, port) => Debug.Log($"Service found at {ip}:{port}"));
}
*/
public void StartListening(Action<string, string> action)
{
try
@ -31,6 +38,8 @@ public class ServiceDiscovery : MonoBehaviour
Debug.Log("Listening for service announcements...");
SendMdnsQuery("_http._tcp.local");
udpClient.BeginReceive(OnReceive, null);
}
catch (Exception ex)
@ -39,6 +48,223 @@ public class ServiceDiscovery : MonoBehaviour
}
}
private void SendMdnsQuery(string serviceName)
{
byte[] query = CreateMdnsQuery(serviceName);
Debug.Log($"Sending mDNS query for {serviceName}");
/*
string hex = "";
foreach (byte b in query)
{
//hex += b.ToString("X2");
hex += $"{b:X2}";
hex += " ";
}
Debug.Log($"Sending message: {hex}");
*/
udpClient.Send(query, query.Length, new IPEndPoint(IPAddress.Parse(multicastAddress), multicastPort));
}
private byte[] CreateMdnsQuery(string serviceName)
{
ushort transactionId = 0;
ushort flags = 0x0100;
ushort questions = 1;
byte[] header = new byte[12];
Array.Copy(BitConverter.GetBytes((ushort)IPAddress.HostToNetworkOrder((short)transactionId)), 0, header, 0, 2);
Array.Copy(BitConverter.GetBytes((ushort)IPAddress.HostToNetworkOrder((short)flags)), 0, header, 2, 2);
Array.Copy(BitConverter.GetBytes((ushort)IPAddress.HostToNetworkOrder((short)questions)), 0, header, 4, 2);
byte[] name = EncodeName(serviceName);
byte[] query = new byte[header.Length + name.Length + 4];
Array.Copy(header, query, header.Length);
Array.Copy(name, 0, query, header.Length, name.Length);
query[query.Length - 4] = 0x00;
query[query.Length - 3] = 0x0C;
query[query.Length - 2] = 0x00;
query[query.Length - 1] = 0x01;
return query;
}
private byte[] EncodeName(string name)
{
string[] parts = name.Split('.');
byte[] result = new byte[name.Length + 2];
int offset = 0;
foreach (string part in parts)
{
result[offset++] = (byte)part.Length;
Array.Copy(Encoding.UTF8.GetBytes(part), 0, result, offset, part.Length);
offset += part.Length;
}
result[offset] = 0;
return result;
}
private void OnReceive(IAsyncResult result)
{
if (udpClient == null)
{
return;
}
try
{
IPEndPoint remoteEndPoint = new IPEndPoint(IPAddress.Any, multicastPort);
byte[] receivedBytes = udpClient.EndReceive(result, ref remoteEndPoint);
ushort flags = BitConverter.ToUInt16(new byte[] { receivedBytes[3], receivedBytes[2] }, 0);
Debug.Log($"Flags: {flags:X2}");
if (flags == 0x0100) // Standard query
{
Debug.Log("Ignoring non-response packet");
udpClient?.BeginReceive(OnReceive, null);
return;
}
Debug.Log($"Received message: {receivedBytes} from {remoteEndPoint}");
ParseMdnsResponse(receivedBytes);
if (receivedIp != null && receivedPort != null)
{
messageReceived = true;
StopListening();
}
else
{
udpClient?.BeginReceive(OnReceive, null);
}
}
catch (Exception ex)
{
Debug.LogError($"Error receiving UDP message: {ex.Message}");
}
}
private void ParseMdnsResponse(byte[] data)
{
int offset = 12;
ushort questions = (ushort)IPAddress.NetworkToHostOrder(BitConverter.ToInt16(data, 4));
ushort answerRRs = (ushort)IPAddress.NetworkToHostOrder(BitConverter.ToInt16(data, 6));
ushort additionalRRs = (ushort)IPAddress.NetworkToHostOrder(BitConverter.ToInt16(data, 10));
Debug.Log($"Questions: {questions}, Answer RRs: {answerRRs}, Additional RRs: {additionalRRs}");
for (int i = 0; i < questions; i++)
{
offset = SkipName(data, offset);
offset += 4;
}
for (int i = 0; i < answerRRs; i++)
{
offset = ParseRecord(data, offset);
}
for (int i = 0; i < additionalRRs; i++)
{
offset = ParseRecord(data, offset);
}
}
private int ParseRecord(byte[] data, int offset)
{
string name;
(name, offset) = ReadName(data, offset);
ushort recordType = (ushort)IPAddress.NetworkToHostOrder(BitConverter.ToInt16(data, offset));
ushort recordClass = (ushort)IPAddress.NetworkToHostOrder(BitConverter.ToInt16(data, offset + 2));
uint ttl = (uint)IPAddress.NetworkToHostOrder(BitConverter.ToInt32(data, offset + 4));
ushort dataLength = (ushort)IPAddress.NetworkToHostOrder(BitConverter.ToInt16(data, offset + 8));
offset += 10;
if (recordType == 1) // A Record
{
IPAddress ipAddress = new IPAddress(new ArraySegment<byte>(data, offset, dataLength).ToArray());
Debug.Log($"A Record: {name} -> {ipAddress}");
receivedIp = ipAddress.ToString();
}
else if (recordType == 12) // PTR Record
{
string target;
(target, _) = ReadName(data, offset);
Debug.Log($"PTR Record: {name} -> {target}");
}
else if (recordType == 33) // SRV Record
{
ushort priority = (ushort)IPAddress.NetworkToHostOrder(BitConverter.ToInt16(data, offset));
ushort weight = (ushort)IPAddress.NetworkToHostOrder(BitConverter.ToInt16(data, offset + 2));
ushort port = (ushort)IPAddress.NetworkToHostOrder(BitConverter.ToInt16(data, offset + 4));
string target;
(target, _) = ReadName(data, offset + 6);
Debug.Log($"SRV Record: {name} -> {target}:{port} (priority: {priority}, weight: {weight})");
receivedPort = port.ToString();
}
else if (recordType == 16) // TXT Record
{
string txtData = Encoding.UTF8.GetString(data, offset, dataLength);
Debug.Log($"TXT Record: {name} -> {txtData}");
}
else if (recordType == 47) // NSEC Record
{
Debug.Log($"NSEC Record: {name}");
}
else
{
Debug.Log($"Unknown Record Type {recordType} for {name}");
}
return offset + dataLength;
}
private (string, int) ReadName(byte[] data, int offset)
{
StringBuilder name = new StringBuilder();
int originalOffset = offset;
bool jumped = false;
while (data[offset] != 0)
{
if ((data[offset] & 0xC0) == 0xC0)
{
if (!jumped)
{
originalOffset = offset + 2;
}
offset = ((data[offset] & 0x3F) << 8) | data[offset + 1];
jumped = true;
}
else
{
int length = data[offset++];
name.Append(Encoding.UTF8.GetString(data, offset, length) + ".");
offset += length;
}
}
return (name.ToString().TrimEnd('.'), jumped ? originalOffset : offset + 1);
}
private int SkipName(byte[] data, int offset)
{
while (data[offset] != 0)
{
if ((data[offset] & 0xC0) == 0xC0)
{
return offset + 2;
}
offset += data[offset] + 1;
}
return offset + 1;
}
/*
private void OnReceive(IAsyncResult result)
{
if (udpClient == null)
@ -74,17 +300,21 @@ public class ServiceDiscovery : MonoBehaviour
Debug.LogError($"Error receiving UDP message: {ex.Message}");
}
}
*/
private void Update()
{
if (messageReceived)
{
Debug.Log($"Invoking action with: {receivedIp}:{receivedPort}");
action?.Invoke(receivedIp, receivedPort);
messageReceived = false;
receivedIp = null;
receivedPort = null;
}
}
private void OnApplicationQuit()
private void OnDestroy()
{
StopListening();
}