initial commit

Quasar.Common/DNS/Host.cs

@@ -0,0 +1,33 @@
+using System.Net;
+
+namespace Quasar.Common.DNS
+{
+    public class Host
+    {
+        /// <summary>
+        /// Stores the hostname of the Host.
+        /// </summary>
+        /// <remarks>
+        /// Can be an IPv4, IPv6 address or hostname.
+        /// </remarks>
+        public string Hostname { get; set; }
+
+        /// <summary>
+        /// Stores the IP address of host. 
+        /// </summary>
+        /// <remarks>
+        /// Can be an IPv4 or IPv6 address.
+        /// </remarks>
+        public IPAddress IpAddress { get; set; }
+
+        /// <summary>
+        /// Stores the port of the Host.
+        /// </summary>
+        public ushort Port { get; set; }
+
+        public override string ToString()
+        {
+            return Hostname + ":" + Port;
+        }
+    }
+}

Quasar.Common/DNS/HostsConverter.cs

@@ -0,0 +1,40 @@
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+
+namespace Quasar.Common.DNS
+{
+    public class HostsConverter
+    {
+        public List<Host> RawHostsToList(string rawHosts)
+        {
+            List<Host> hostsList = new List<Host>();
+
+            if (string.IsNullOrEmpty(rawHosts)) return hostsList;
+
+            var hosts = rawHosts.Split(';');
+
+            foreach (var host in hosts)
+            {
+                if ((string.IsNullOrEmpty(host) || !host.Contains(':'))) continue; // invalid host, ignore
+
+                ushort port;
+                if (!ushort.TryParse(host.Substring(host.LastIndexOf(':') + 1), out port)) continue; // invalid, ignore host
+
+                hostsList.Add(new Host { Hostname = host.Substring(0, host.LastIndexOf(':')), Port = port });
+            }
+
+            return hostsList;
+        }
+
+        public  string ListToRawHosts(IList<Host> hosts)
+        {
+            StringBuilder rawHosts = new StringBuilder();
+
+            foreach (var host in hosts)
+                rawHosts.Append(host + ";");
+
+            return rawHosts.ToString();
+        }
+    }
+}

Quasar.Common/DNS/HostsManager.cs

@@ -0,0 +1,63 @@
+using System.Collections.Generic;
+using System.Net;
+using System.Net.Sockets;
+
+namespace Quasar.Common.DNS
+{
+    public class HostsManager
+    {
+        public bool IsEmpty => _hosts.Count == 0;
+
+        private readonly Queue<Host> _hosts = new Queue<Host>();
+
+        public HostsManager(List<Host> hosts)
+        {
+            foreach(var host in hosts)
+                _hosts.Enqueue(host);
+        }
+
+        public Host GetNextHost()
+        {
+            var temp = _hosts.Dequeue();
+            _hosts.Enqueue(temp); // add to the end of the queue
+
+            temp.IpAddress = ResolveHostname(temp);
+            return temp;
+        }
+
+        private static IPAddress ResolveHostname(Host host)
+        {
+            if (string.IsNullOrEmpty(host.Hostname)) return null;
+
+            IPAddress ip;
+            if (IPAddress.TryParse(host.Hostname, out ip))
+            {
+                if (ip.AddressFamily == AddressFamily.InterNetworkV6)
+                {
+                    if (!Socket.OSSupportsIPv6) return null;
+                }
+                return ip;
+            }
+
+            var ipAddresses = Dns.GetHostEntry(host.Hostname).AddressList;
+            foreach (IPAddress ipAddress in ipAddresses)
+            {
+                switch (ipAddress.AddressFamily)
+                {
+                    case AddressFamily.InterNetwork:
+                        return ipAddress;
+                    case AddressFamily.InterNetworkV6:
+                        /* Only use resolved IPv6 if no IPv4 address available,
+                         * otherwise it could be possible that the router the client
+                         * is using to connect to the internet doesn't support IPv6.
+                         */
+                        if (ipAddresses.Length == 1)
+                            return ipAddress;
+                        break;
+                }
+            }
+
+            return ip;
+        }
+    }
+}