1 files changed, 74 insertions, 0 deletions
diff --git a/src/DotNetOpenAuth.OpenId/OpenId/RelyingParty/DuplicateRequestedHostsComparer.cs b/src/DotNetOpenAuth.OpenId/OpenId/RelyingParty/DuplicateRequestedHostsComparer.cs
new file mode 100644
index 0000000..94eb5ba
--- /dev/null
+++ b/src/DotNetOpenAuth.OpenId/OpenId/RelyingParty/DuplicateRequestedHostsComparer.cs
@@ -0,0 +1,74 @@
+//-----------------------------------------------------------------------
+// <copyright file="DuplicateRequestedHostsComparer.cs" company="Andrew Arnott">
+//     Copyright (c) Andrew Arnott. All rights reserved.
+// </copyright>
+//-----------------------------------------------------------------------
+
+namespace DotNetOpenAuth.OpenId.RelyingParty {
+	using System;
+	using System.Collections.Generic;
+	using System.Linq;
+	using System.Text;
+
+	/// <summary>
+	/// An authentication request comparer that judges equality solely on the OP endpoint hostname.
+	/// </summary>
+	internal class DuplicateRequestedHostsComparer : IEqualityComparer<IAuthenticationRequest> {
+		/// <summary>
+		/// The singleton instance of this comparer.
+		/// </summary>
+		private static IEqualityComparer<IAuthenticationRequest> instance = new DuplicateRequestedHostsComparer();
+
+		/// <summary>
+		/// Prevents a default instance of the <see cref="DuplicateRequestedHostsComparer"/> class from being created.
+		/// </summary>
+		private DuplicateRequestedHostsComparer() {
+		}
+
+		/// <summary>
+		/// Gets the singleton instance of this comparer.
+		/// </summary>
+		internal static IEqualityComparer<IAuthenticationRequest> Instance {
+			get { return instance; }
+		}
+
+		#region IEqualityComparer<IAuthenticationRequest> Members
+
+		/// <summary>
+		/// Determines whether the specified objects are equal.
+		/// </summary>
+		/// <param name="x">The first object to compare.</param>
+		/// <param name="y">The second object to compare.</param>
+		/// <returns>
+		/// true if the specified objects are equal; otherwise, false.
+		/// </returns>
+		public bool Equals(IAuthenticationRequest x, IAuthenticationRequest y) {
+			if (x == null && y == null) {
+				return true;
+			}
+
+			if (x == null || y == null) {
+				return false;
+			}
+
+			// We'll distinguish based on the host name only, which
+			// admittedly is only a heuristic, but if we remove one that really wasn't a duplicate, well,
+			// this multiple OP attempt thing was just a convenience feature anyway.
+			return string.Equals(x.Provider.Uri.Host, y.Provider.Uri.Host, StringComparison.OrdinalIgnoreCase);
+		}
+
+		/// <summary>
+		/// Returns a hash code for the specified object.
+		/// </summary>
+		/// <param name="obj">The <see cref="T:System.Object"/> for which a hash code is to be returned.</param>
+		/// <returns>A hash code for the specified object.</returns>
+		/// <exception cref="T:System.ArgumentNullException">
+		/// The type of <paramref name="obj"/> is a reference type and <paramref name="obj"/> is null.
+		/// </exception>
+		public int GetHashCode(IAuthenticationRequest obj) {
+			return obj.Provider.Uri.Host.GetHashCode();
+		}
+
+		#endregion
+	}
+}