Add MusicCast discovery service

MusicCast.Net.Client/MusicCastDiscoveryService.cs

@@ -0,0 +1,162 @@
+using System.Net;
+using System.Net.NetworkInformation;
+using System.Net.Sockets;
+using System.Text;
+using System.Text.RegularExpressions;
+using System.Xml;
+using System.Xml.Linq;
+using System.Xml.XPath;
+
+namespace MusicCast.Net.Client;
+
+public partial class MusicCastDiscoveryService
+{
+    private static readonly byte[] MulticastPacket = """
+                                              M-SEARCH * HTTP/1.1
+                                              HOST: 239.255.255.250:1900
+                                              MAN: "ssdp:discover"
+                                              ST: urn:schemas-upnp-org:device:MediaRenderer:1
+                                              MX: 1
+
+
+                                              """u8.ToArray();
+
+    private static readonly HttpClient _httpClient = new();
+
+    private const string LocationUrlGroupName = "url";
+    [GeneratedRegex(@$"Location:\s(?<{LocationUrlGroupName}>http[s]?:\/\/.+\.xml)", RegexOptions.IgnoreCase)]
+    private static partial Regex LocationRegex();
+
+    /// <summary>
+    /// Get the ip address associated with the current local network.
+    /// If multiple networks cards are installed it only returns the first one.
+    /// </summary>
+    /// <returns></returns>
+    public IPAddress? GetLocalSubnetAddress()
+    {
+        // Get a list of all network interfaces (usually one per network card, dialup, and VPN connection)
+        var networkInterfaces = NetworkInterface.GetAllNetworkInterfaces();
+
+        foreach (NetworkInterface network in networkInterfaces)
+        {
+            // Read the IP configuration for each network
+            IPInterfaceProperties properties = network.GetIPProperties();
+
+            if (network.NetworkInterfaceType is NetworkInterfaceType.Ethernet or NetworkInterfaceType.Wireless80211 &&
+                network.OperationalStatus == OperationalStatus.Up &&
+                !network.Description.Contains("virtual", StringComparison.OrdinalIgnoreCase) &&
+                !network.Description.Contains("pseudo", StringComparison.OrdinalIgnoreCase))
+            {
+                // Each network interface may have multiple IP addresses
+                foreach (UnicastIPAddressInformation address in properties.UnicastAddresses)
+                {
+                    // We're only interested in IPv4 addresses for now
+                    if (address.Address.AddressFamily != AddressFamily.InterNetwork)
+                        continue;
+
+                    // Ignore loopback addresses (e.g., 127.0.0.1)
+                    if (IPAddress.IsLoopback(address.Address))
+                        continue;
+
+                    return address.Address;
+                }
+            }
+        }
+
+        return null;
+    }
+
+    public Task<HashSet<string>> GetMusicCastDeviceAddresses(IPAddress bindAddress)
+        => GetMusicCastDeviceAddresses(bindAddress, TimeSpan.FromSeconds(2));
+
+    /// <summary>
+    /// Scan for MusicCast devices on the network associated with the bind address. Only return devices that support
+    /// the YamahaExtendedControl v1 api
+    /// </summary>
+    /// <param name="bindAddress"></param>
+    /// <param name="scanDuration">Duration of the scan</param>
+    /// <returns></returns>
+    public async Task<HashSet<string>> GetMusicCastDeviceAddresses(IPAddress bindAddress, TimeSpan scanDuration)
+    {
+        using var client = new UdpClient(AddressFamily.InterNetwork);
+
+        client.Client.Bind(new IPEndPoint(bindAddress, 0));
+        client.JoinMulticastGroup(IPAddress.Parse("239.255.255.250"));
+
+        await client.SendAsync(MulticastPacket, "239.255.255.250", 1900);
+        await client.SendAsync(MulticastPacket, "239.255.255.250", 1900);
+        await client.SendAsync(MulticastPacket, "239.255.255.250", 1900);
+
+        var musicCastDevices = new HashSet<string>();
+
+        // Start scanning
+        var cancellationToken = new CancellationTokenSource(scanDuration).Token;
+
+        try
+        {
+            while (!cancellationToken.IsCancellationRequested)
+            {
+                var received = await client.ReceiveAsync(cancellationToken);
+                var message = Encoding.UTF8.GetString(received.Buffer);
+
+                // Try to find the location of the DLNA description file
+                var match = LocationRegex().Match(message);
+
+                if (!match.Success || !match.Groups.TryGetValue(LocationUrlGroupName, out var group))
+                {
+                    continue;
+                }
+
+                var location = group.Value;
+
+                var apiUrl = await GetApiUrlFromDlnaDescriptionFile(location, cancellationToken);
+
+                if (apiUrl is not null)
+                {
+                    musicCastDevices.Add(apiUrl);
+                }
+            }
+        }
+        catch (OperationCanceledException)
+        {
+            // Normal flow after scan duration
+        }
+
+        return musicCastDevices;
+    }
+
+    private static async Task<string?> GetApiUrlFromDlnaDescriptionFile(string location, CancellationToken cancellationToken)
+    {
+        try
+        {
+            var response = await _httpClient.GetAsync(location, cancellationToken);
+            await using var descriptionFileStream = await response.Content.ReadAsStreamAsync(cancellationToken);
+
+            var document = await XDocument.LoadAsync(descriptionFileStream, LoadOptions.None, cancellationToken);
+            XNamespace yamahaNamespace = "urn:schemas-yamaha-com:device-1-0";
+
+            var urlBaseNode = document.Descendants(yamahaNamespace + "X_URLBase").FirstOrDefault();
+
+            if (urlBaseNode is null)
+            {
+                return null;
+            }
+
+            var yamahaControlUrlNodes = document.Descendants(yamahaNamespace + "X_yxcControlURL");
+
+            foreach (var yamahaControlUrlNode in yamahaControlUrlNodes)
+            {
+                if (yamahaControlUrlNode is { Value: "/YamahaExtendedControl/v1/" })
+                {
+                    return urlBaseNode.Value;
+                }
+            }
+        }
+        catch (Exception)
+        {
+            // ignored
+        }
+
+        return null;
+    }
+}