Adds extensibility points for authenticating OAuth 2 clients at the client and authorization server ends.

Fixes #105
Related to #75

1 files changed, 165 insertions, 0 deletions

diff --git a/src/DotNetOpenAuth.OAuth2.Client/OAuth2/ClientCredentialApplicator.cs b/src/DotNetOpenAuth.OAuth2.Client/OAuth2/ClientCredentialApplicator.cs
new file mode 100644
index 0000000..2a9a8a7
--- /dev/null
+++ b/src/DotNetOpenAuth.OAuth2.Client/OAuth2/ClientCredentialApplicator.cs
@@ -0,0 +1,165 @@
+//-----------------------------------------------------------------------
+// <copyright file="ClientCredentialApplicator.cs" company="Andrew Arnott">
+//     Copyright (c) Andrew Arnott. All rights reserved.
+// </copyright>
+//-----------------------------------------------------------------------
+
+namespace DotNetOpenAuth.OAuth2 {
+	using System;
+	using System.Collections.Generic;
+	using System.Linq;
+	using System.Net;
+	using System.Text;
+	using DotNetOpenAuth.Messaging;
+	using DotNetOpenAuth.OAuth2.Messages;
+
+	/// <summary>
+	/// A base class for extensions that apply client authentication to messages for the authorization server in specific ways.
+	/// </summary>
+	public abstract class ClientCredentialApplicator {
+		/// <summary>
+		/// Initializes a new instance of the <see cref="ClientCredentialApplicator"/> class.
+		/// </summary>
+		protected ClientCredentialApplicator() {
+		}
+
+		/// <summary>
+		/// Transmits the secret the client shares with the authorization server as a parameter in the POST entity payload.
+		/// </summary>
+		/// <param name="clientSecret">The secret the client shares with the authorization server.</param>
+		/// <returns>The credential applicator to provide to the <see cref="ClientBase"/> instance.</returns>
+		public static ClientCredentialApplicator PostParameter(string clientSecret) {
+			Requires.NotNullOrEmpty(clientSecret, "clientSecret");
+			return new PostParameterApplicator(clientSecret);
+		}
+
+		/// <summary>
+		/// Transmits the client identifier and secret in the HTTP Authorization header via HTTP Basic authentication.
+		/// </summary>
+		/// <param name="credential">The client id and secret.</param>
+		/// <returns>The credential applicator to provide to the <see cref="ClientBase"/> instance.</returns>
+		public static ClientCredentialApplicator NetworkCredential(NetworkCredential credential) {
+			Requires.NotNull(credential, "credential");
+			return new NetworkCredentialApplicator(credential);
+		}
+
+		/// <summary>
+		/// Transmits the client identifier and secret in the HTTP Authorization header via HTTP Basic authentication.
+		/// </summary>
+		/// <param name="clientSecret">The secret the client shares with the authorization server.</param>
+		/// <returns>The credential applicator to provide to the <see cref="ClientBase"/> instance.</returns>
+		public static ClientCredentialApplicator NetworkCredential(string clientSecret) {
+			Requires.NotNullOrEmpty(clientSecret, "clientSecret");
+			return new NetworkCredentialApplicator(clientSecret);
+		}
+
+		/// <summary>
+		/// Never transmits a secret.  Useful for anonymous clients or clients unable to keep a secret.
+		/// </summary>
+		/// <returns>The credential applicator to provide to the <see cref="ClientBase"/> instance.</returns>
+		public static ClientCredentialApplicator NoSecret() {
+			return null;
+		}
+
+		/// <summary>
+		/// Applies the client identifier and (when applicable) the client authentication to an outbound message.
+		/// </summary>
+		/// <param name="clientIdentifier">The identifier by which the authorization server should recognize this client.</param>
+		/// <param name="request">The outbound message to apply authentication information to.</param>
+		public virtual void ApplyClientCredential(string clientIdentifier, AuthenticatedClientRequestBase request) {
+		}
+
+		/// <summary>
+		/// Applies the client identifier and (when applicable) the client authentication to an outbound message.
+		/// </summary>
+		/// <param name="clientIdentifier">The identifier by which the authorization server should recognize this client.</param>
+		/// <param name="request">The outbound message to apply authentication information to.</param>
+		public virtual void ApplyClientCredential(string clientIdentifier, HttpWebRequest request) {
+		}
+
+		/// <summary>
+		/// Authenticates the client via HTTP Basic.
+		/// </summary>
+		private class NetworkCredentialApplicator : ClientCredentialApplicator {
+			/// <summary>
+			/// The client identifier and secret.
+			/// </summary>
+			private readonly NetworkCredential credential;
+
+			/// <summary>
+			/// The client secret.
+			/// </summary>
+			private readonly string clientSecret;
+
+			/// <summary>
+			/// Initializes a new instance of the <see cref="NetworkCredentialApplicator"/> class.
+			/// </summary>
+			/// <param name="clientSecret">The client secret.</param>
+			internal NetworkCredentialApplicator(string clientSecret) {
+				Requires.NotNullOrEmpty(clientSecret, "clientSecret");
+				this.clientSecret = clientSecret;
+			}
+
+			/// <summary>
+			/// Initializes a new instance of the <see cref="NetworkCredentialApplicator"/> class.
+			/// </summary>
+			/// <param name="credential">The client credential.</param>
+			internal NetworkCredentialApplicator(NetworkCredential credential) {
+				Requires.NotNull(credential, "credential");
+				this.credential = credential;
+			}
+
+			/// <summary>
+			/// Applies the client identifier and (when applicable) the client authentication to an outbound message.
+			/// </summary>
+			/// <param name="clientIdentifier">The identifier by which the authorization server should recognize this client.</param>
+			/// <param name="request">The outbound message to apply authentication information to.</param>
+			public override void ApplyClientCredential(string clientIdentifier, AuthenticatedClientRequestBase request) {
+				// When using network credentials, the client authentication is not done as standard message parts.
+				request.ClientIdentifier = null;
+				request.ClientSecret = null;
+			}
+
+			/// <summary>
+			/// Applies the client identifier and (when applicable) the client authentication to an outbound message.
+			/// </summary>
+			/// <param name="clientIdentifier">The identifier by which the authorization server should recognize this client.</param>
+			/// <param name="request">The outbound message to apply authentication information to.</param>
+			public override void ApplyClientCredential(string clientIdentifier, HttpWebRequest request) {
+				if (this.credential != null && this.credential.UserName == clientIdentifier) {
+					ErrorUtilities.VerifyHost(false, "Client identifiers \"{0}\" and \"{1}\" do not match.", this.credential.UserName, clientIdentifier);
+				}
+
+				request.Credentials = this.credential ?? new NetworkCredential(clientIdentifier, this.clientSecret);
+			}
+		}
+
+		/// <summary>
+		/// Authenticates the client via a client_secret parameter in the message.
+		/// </summary>
+		private class PostParameterApplicator : ClientCredentialApplicator {
+			/// <summary>
+			/// The client secret.
+			/// </summary>
+			private readonly string secret;
+
+			/// <summary>
+			/// Initializes a new instance of the <see cref="PostParameterApplicator"/> class.
+			/// </summary>
+			/// <param name="clientSecret">The client secret.</param>
+			internal PostParameterApplicator(string clientSecret) {
+				Requires.NotNullOrEmpty(clientSecret, "clientSecret");
+				this.secret = clientSecret;
+			}
+
+			/// <summary>
+			/// Applies the client identifier and (when applicable) the client authentication to an outbound message.
+			/// </summary>
+			/// <param name="clientIdentifier">The identifier by which the authorization server should recognize this client.</param>
+			/// <param name="request">The outbound message to apply authentication information to.</param>
+			public override void ApplyClientCredential(string clientIdentifier, AuthenticatedClientRequestBase request) {
+				request.ClientSecret = this.secret;
+			}
+		}
+	}
+}