1 files changed, 82 insertions, 0 deletions
diff --git a/crypto/src/x509/X509ExtensionBase.cs b/crypto/src/x509/X509ExtensionBase.cs
new file mode 100644
index 000000000..aaf6695c0
--- /dev/null
+++ b/crypto/src/x509/X509ExtensionBase.cs
@@ -0,0 +1,82 @@
+using System;
+
+using Org.BouncyCastle.Asn1;
+using Org.BouncyCastle.Asn1.X509;
+using Org.BouncyCastle.Utilities.Collections;
+
+namespace Org.BouncyCastle.X509
+{
+	public abstract class X509ExtensionBase
+		: IX509Extension
+	{
+		protected abstract X509Extensions GetX509Extensions();
+
+		protected virtual ISet GetExtensionOids(
+			bool critical)
+		{
+			X509Extensions extensions = GetX509Extensions();
+			if (extensions != null)
+			{
+				HashSet set = new HashSet();
+				foreach (DerObjectIdentifier oid in extensions.ExtensionOids)
+				{
+					X509Extension ext = extensions.GetExtension(oid);
+					if (ext.IsCritical == critical)
+					{
+						set.Add(oid.Id);
+					}
+				}
+
+				return set;
+			}
+
+			return null;
+		}
+
+		/// <summary>
+		/// Get non critical extensions.
+		/// </summary>
+		/// <returns>A set of non critical extension oids.</returns>
+		public virtual ISet GetNonCriticalExtensionOids()
+		{
+			return GetExtensionOids(false);
+		}
+
+		/// <summary>
+		/// Get any critical extensions.
+		/// </summary>
+		/// <returns>A sorted list of critical entension.</returns>
+		public virtual ISet GetCriticalExtensionOids()
+		{
+			return GetExtensionOids(true);
+		}
+
+		/// <summary>
+		/// Get the value of a given extension.
+		/// </summary>
+		/// <param name="oid">The object ID of the extension. </param>
+		/// <returns>An Asn1OctetString object if that extension is found or null if not.</returns>
+		[Obsolete("Use version taking a DerObjectIdentifier instead")]
+		public Asn1OctetString GetExtensionValue(
+			string oid)
+		{
+			return GetExtensionValue(new DerObjectIdentifier(oid));
+		}
+
+		public virtual Asn1OctetString GetExtensionValue(
+			DerObjectIdentifier oid)
+		{
+			X509Extensions exts = GetX509Extensions();
+			if (exts != null)
+			{
+				X509Extension ext = exts.GetExtension(oid);
+				if (ext != null)
+				{
+					return ext.Value;
+				}
+			}
+
+			return null;
+		}
+	}
+}