// Licensed to the .NET Foundation under one or more agreements. // The .NET Foundation licenses this file to you under the MIT license. // See the LICENSE file in the project root for more information. // using System; using System.Collections; using System.Collections.Generic; using System.Diagnostics; using System.Diagnostics.Contracts; using System.IO; using System.Runtime.InteropServices; #if FEATURE_SERIALIZATION using System.Runtime.Serialization.Formatters.Binary; #endif // FEATURE_SERIALIZATION using System.Security.Permissions; namespace System.Security.Policy { /// /// Base class from which all objects to be used as Evidence must derive /// [ComVisible(true)] [Serializable] public abstract class EvidenceBase { protected EvidenceBase() { #if FEATURE_SERIALIZATION // All objects to be used as evidence must be serializable. Make sure that any derived types // are marked serializable to enforce this, since the attribute does not inherit down to derived // classes. if (!GetType().IsSerializable) { throw new InvalidOperationException(Environment.GetResourceString("Policy_EvidenceMustBeSerializable")); } #endif // FEATURE_SERIALIZATION } /// /// Since legacy evidence objects would be cloned by being serialized, the default implementation /// of EvidenceBase will do the same. /// public virtual EvidenceBase Clone() { #if FEATURE_SERIALIZATION using (MemoryStream memoryStream = new MemoryStream()) { BinaryFormatter formatter = new BinaryFormatter(); formatter.Serialize(memoryStream, this); memoryStream.Position = 0; return formatter.Deserialize(memoryStream) as EvidenceBase; } #else // !FEATURE_SERIALIZATION throw new NotImplementedException(); #endif // FEATURE_SERIALIZATION } } /// /// Interface for types which wrap Whidbey evidence objects for compatibility with v4 evidence rules /// internal interface ILegacyEvidenceAdapter { object EvidenceObject { get; } Type EvidenceType { get; } } /// /// Wrapper class to hold legacy evidence objects which do not derive from EvidenceBase, and allow /// them to be held in the Evidence collection which expects to maintain lists of EvidenceBase only /// [Serializable] internal sealed class LegacyEvidenceWrapper : EvidenceBase, ILegacyEvidenceAdapter { private object m_legacyEvidence; internal LegacyEvidenceWrapper(object legacyEvidence) { Debug.Assert(legacyEvidence != null); Debug.Assert(legacyEvidence.GetType() != typeof(EvidenceBase), "Attempt to wrap an EvidenceBase in a LegacyEvidenceWrapper"); Debug.Assert(legacyEvidence.GetType().IsSerializable, "legacyEvidence.GetType().IsSerializable"); m_legacyEvidence = legacyEvidence; } public object EvidenceObject { get { return m_legacyEvidence; } } public Type EvidenceType { get { return m_legacyEvidence.GetType(); } } public override bool Equals(object obj) { return m_legacyEvidence.Equals(obj); } public override int GetHashCode() { return m_legacyEvidence.GetHashCode(); } public override EvidenceBase Clone() { return base.Clone(); } } /// /// Pre-v4 versions of the runtime allow multiple pieces of evidence that all have the same type. /// This type wraps those evidence objects into a single type of list, allowing legacy code to continue /// to work with the Evidence collection that does not expect multiple evidences of the same type. /// /// This may not be limited to LegacyEvidenceWrappers, since it's valid for legacy code to add multiple /// objects of built-in evidence to an Evidence collection. The built-in evidence now derives from /// EvienceObject, so when the legacy code runs on v4, it may end up attempting to add multiple /// Hash evidences for intsance. /// [Serializable] internal sealed class LegacyEvidenceList : EvidenceBase, IEnumerable, ILegacyEvidenceAdapter { private List m_legacyEvidenceList = new List(); public object EvidenceObject { get { // We'll choose the first item in the list to represent us if we're forced to return only // one object. This can occur if multiple pieces of evidence are added via the legacy APIs, // and then the new APIs are used to retrieve that evidence. return m_legacyEvidenceList.Count > 0 ? m_legacyEvidenceList[0] : null; } } public Type EvidenceType { get { Debug.Assert(m_legacyEvidenceList.Count > 0, "No items in LegacyEvidenceList, cannot tell what type they are"); ILegacyEvidenceAdapter adapter = m_legacyEvidenceList[0] as ILegacyEvidenceAdapter; return adapter == null ? m_legacyEvidenceList[0].GetType() : adapter.EvidenceType; } } public void Add(EvidenceBase evidence) { Debug.Assert(evidence != null); Debug.Assert(m_legacyEvidenceList.Count == 0 || EvidenceType == evidence.GetType() || (evidence is LegacyEvidenceWrapper && (evidence as LegacyEvidenceWrapper).EvidenceType == EvidenceType), "LegacyEvidenceList must be homogeonous"); Debug.Assert(evidence.GetType() != typeof(LegacyEvidenceList), "Attempt to add a legacy evidence list to another legacy evidence list"); m_legacyEvidenceList.Add(evidence); } public IEnumerator GetEnumerator() { return m_legacyEvidenceList.GetEnumerator(); } IEnumerator System.Collections.IEnumerable.GetEnumerator() { return m_legacyEvidenceList.GetEnumerator(); } public override EvidenceBase Clone() { return base.Clone(); } } }