More contracts

6 files changed, 58 insertions, 8 deletions

diff --git a/src/DotNetOpenAuth/Messaging/Channel.cs b/src/DotNetOpenAuth/Messaging/Channel.cs
index e2b7adc..161b0c4 100644
--- a/src/DotNetOpenAuth/Messaging/Channel.cs
+++ b/src/DotNetOpenAuth/Messaging/Channel.cs
@@ -447,6 +447,8 @@ namespace DotNetOpenAuth.Messaging {
 
 			ErrorUtilities.VerifyHttpContext();
 
+			Contract.Assume(HttpContext.Current.Request.Url != null);
+			Contract.Assume(HttpContext.Current.Request.RawUrl != null);
 			return new HttpRequestInfo(HttpContext.Current.Request);
 		}
 
@@ -513,6 +515,9 @@ namespace DotNetOpenAuth.Messaging {
 				}
 
 				responseFields = this.ReadFromResponseCore(response);
+				if (responseFields == null) {
+					return null;
+				}
 
 				responseMessage = this.MessageFactory.GetNewResponseMessage(request, responseFields);
 				if (responseMessage == null) {
@@ -737,6 +742,7 @@ namespace DotNetOpenAuth.Messaging {
 
 			MessageProtections appliedProtection = MessageProtections.None;
 			foreach (IChannelBindingElement bindingElement in this.outgoingBindingElements) {
+				Contract.Assume(bindingElement.Channel != null);
 				MessageProtections? elementProtection = bindingElement.ProcessOutgoingMessage(message);
 				if (elementProtection.HasValue) {
 					Logger.Bindings.DebugFormat("Binding element {0} applied to message.", bindingElement.GetType().FullName);
diff --git a/src/DotNetOpenAuth/Messaging/IMessageFactory.cs b/src/DotNetOpenAuth/Messaging/IMessageFactory.cs
index 9ce5f89..23c291a 100644
--- a/src/DotNetOpenAuth/Messaging/IMessageFactory.cs
+++ b/src/DotNetOpenAuth/Messaging/IMessageFactory.cs
@@ -7,11 +7,13 @@
 namespace DotNetOpenAuth.Messaging {
 	using System;
 	using System.Collections.Generic;
+	using System.Diagnostics.Contracts;
 
 	/// <summary>
 	/// A tool to analyze an incoming message to figure out what concrete class
 	/// is designed to deserialize it and instantiates that class.
 	/// </summary>
+	[ContractClass(typeof(IMessageFactoryContract))]
 	public interface IMessageFactory {
 		/// <summary>
 		/// Analyzes an incoming request message payload to discover what kind of 
@@ -39,4 +41,45 @@ namespace DotNetOpenAuth.Messaging {
 		/// </returns>
 		IDirectResponseProtocolMessage GetNewResponseMessage(IDirectedProtocolMessage request, IDictionary<string, string> fields);
 	}
+
+	/// <summary>
+	/// Code contract for the <see cref="IMessageFactory"/> interface.
+	/// </summary>
+	[ContractClassFor(typeof(IMessageFactory))]
+	internal class IMessageFactoryContract : IMessageFactory {
+		#region IMessageFactory Members
+
+		/// <summary>
+		/// Analyzes an incoming request message payload to discover what kind of
+		/// message is embedded in it and returns the type, or null if no match is found.
+		/// </summary>
+		/// <param name="recipient">The intended or actual recipient of the request message.</param>
+		/// <param name="fields">The name/value pairs that make up the message payload.</param>
+		/// <returns>
+		/// A newly instantiated <see cref="IProtocolMessage"/>-derived object that this message can
+		/// deserialize to.  Null if the request isn't recognized as a valid protocol message.
+		/// </returns>
+		IDirectedProtocolMessage IMessageFactory.GetNewRequestMessage(MessageReceivingEndpoint recipient, IDictionary<string, string> fields) {
+			Contract.Requires(fields != null);
+
+			throw new NotImplementedException();
+		}
+
+		/// <summary>
+		/// Analyzes an incoming request message payload to discover what kind of
+		/// message is embedded in it and returns the type, or null if no match is found.
+		/// </summary>
+		/// <param name="request">The message that was sent as a request that resulted in the response.</param>
+		/// <param name="fields">The name/value pairs that make up the message payload.</param>
+		/// <returns>
+		/// A newly instantiated <see cref="IProtocolMessage"/>-derived object that this message can
+		/// deserialize to.  Null if the request isn't recognized as a valid protocol message.
+		/// </returns>
+		IDirectResponseProtocolMessage IMessageFactory.GetNewResponseMessage(IDirectedProtocolMessage request, IDictionary<string, string> fields) {
+			Contract.Requires(fields != null);
+			throw new NotImplementedException();
+		}
+
+		#endregion
+	}
 }
diff --git a/src/DotNetOpenAuth/Messaging/NetworkDirectWebResponse.cs b/src/DotNetOpenAuth/Messaging/NetworkDirectWebResponse.cs
index 136b0d0..fd6e3ab 100644
--- a/src/DotNetOpenAuth/Messaging/NetworkDirectWebResponse.cs
+++ b/src/DotNetOpenAuth/Messaging/NetworkDirectWebResponse.cs
@@ -86,6 +86,8 @@ namespace DotNetOpenAuth.Messaging {
 		/// </remarks>
 		internal override CachedDirectWebResponse GetSnapshot(int maximumBytesToCache) {
 			ErrorUtilities.VerifyOperation(!this.streamReadBegun, "Network stream reading has already begun.");
+			ErrorUtilities.VerifyOperation(this.RequestUri != null, "RequestUri != null");
+			ErrorUtilities.VerifyOperation(this.httpWebResponse != null, "httpWebResponse != null");
 
 			this.streamReadBegun = true;
 			var result = new CachedDirectWebResponse(this.RequestUri, this.httpWebResponse, maximumBytesToCache);
diff --git a/src/DotNetOpenAuth/OpenId/Identifier.cs b/src/DotNetOpenAuth/OpenId/Identifier.cs
index 53f5094..9c5f8f9 100644
--- a/src/DotNetOpenAuth/OpenId/Identifier.cs
+++ b/src/DotNetOpenAuth/OpenId/Identifier.cs
@@ -194,6 +194,7 @@ namespace DotNetOpenAuth.OpenId {
 		/// <returns>
 		/// An initialized structure containing the discovered provider endpoint information.
 		/// </returns>
+		[Pure]
 		internal abstract IEnumerable<ServiceEndpoint> Discover(IDirectWebRequestHandler requestHandler);
 
 		/// <summary>
@@ -203,6 +204,7 @@ namespace DotNetOpenAuth.OpenId {
 		/// </summary>
 		/// <returns>A new <see cref="Identifier"/> instance if there was a 
 		/// fragment to remove, otherwise this same instance..</returns>
+		[Pure]
 		internal abstract Identifier TrimFragment();
 
 		/// <summary>
diff --git a/src/DotNetOpenAuth/OpenId/RelyingParty/OpenIdRelyingParty.cs b/src/DotNetOpenAuth/OpenId/RelyingParty/OpenIdRelyingParty.cs
index b665a4b..d468ea8 100644
--- a/src/DotNetOpenAuth/OpenId/RelyingParty/OpenIdRelyingParty.cs
+++ b/src/DotNetOpenAuth/OpenId/RelyingParty/OpenIdRelyingParty.cs
@@ -287,7 +287,9 @@ namespace DotNetOpenAuth.OpenId.RelyingParty {
 			Contract.Requires(realm != null);
 			Contract.Ensures(Contract.Result<IAuthenticationRequest>() != null);
 			try {
-				return this.CreateRequests(userSuppliedIdentifier, realm).First();
+				var result = this.CreateRequests(userSuppliedIdentifier, realm).First();
+				Contract.Assume(result != null);
+				return result;
 			} catch (InvalidOperationException ex) {
 				throw ErrorUtilities.Wrap(ex, OpenIdStrings.OpenIdEndpointNotFound);
 			}
diff --git a/src/DotNetOpenAuth/UriUtil.cs b/src/DotNetOpenAuth/UriUtil.cs
index d04491d..19a5380 100644
--- a/src/DotNetOpenAuth/UriUtil.cs
+++ b/src/DotNetOpenAuth/UriUtil.cs
@@ -30,8 +30,7 @@ namespace DotNetOpenAuth {
 		/// </returns>
 		[ContractVerification(false)] // bugs/limitations in CC static analysis
 		internal static bool QueryStringContainPrefixedParameters(this Uri uri, string prefix) {
-			Contract.Requires(prefix != null && prefix.Length > 0);
-			ErrorUtilities.VerifyNonZeroLength(prefix, "prefix");
+			Contract.Requires(!string.IsNullOrEmpty(prefix));
 			if (uri == null) {
 				return false;
 			}
@@ -49,10 +48,7 @@ namespace DotNetOpenAuth {
 		/// 	<c>true</c> if the URI represents an encrypted request; otherwise, <c>false</c>.
 		/// </returns>
 		internal static bool IsTransportSecure(this Uri uri) {
-			if (uri == null) {
-				throw new ArgumentNullException("uri");
-			}
-
+			Contract.Requires(uri != null);
 			return string.Equals(uri.Scheme, "https", StringComparison.OrdinalIgnoreCase);
 		}
 
@@ -65,7 +61,6 @@ namespace DotNetOpenAuth {
 		internal static string ToStringWithImpliedPorts(this UriBuilder builder) {
 			Contract.Requires(builder != null);
 			Contract.Ensures(Contract.Result<string>() != null);
-			ErrorUtilities.VerifyArgumentNotNull(builder, "builder");
 
 			// We only check for implied ports on HTTP and HTTPS schemes since those
 			// are the only ones supported by OpenID anyway.