Fixed serialization for embedded message/* parts

Fixes issue #228

MimeKit/Multipart.cs

@@ -436,13 +436,19 @@ public override void Prepare (EncodingConstraint constraint, int maxLineLength =
 
 			if (cancellable != null) {
 				for (int i = 0; i < children.Count; i++) {
+					var msg = children[i] as MessagePart;
 					var multi = children[i] as Multipart;
 					var part = children[i] as MimePart;
 
 					cancellable.Write (boundary, 0, boundary.Length - 2, cancellationToken);
 					cancellable.Write (options.NewLineBytes, 0, options.NewLineBytes.Length, cancellationToken);
 					children[i].WriteTo (options, stream, false, cancellationToken);
 
+					if (msg != null && msg.Message != null && msg.Message.Body != null) {
+						multi = msg.Message.Body as Multipart;
+						part = msg.Message.Body as MimePart;
+					}
+
 					if ((part != null && part.ContentObject == null) ||
 						(multi != null && !multi.WriteEndBoundary))
 						continue;
@@ -459,6 +465,7 @@ public override void Prepare (EncodingConstraint constraint, int maxLineLength =
 					cancellable.Write (options.NewLineBytes, 0, options.NewLineBytes.Length, cancellationToken);
 			} else {
 				for (int i = 0; i < children.Count; i++) {
+					var msg = children[i] as MessagePart;
 					var multi = children[i] as Multipart;
 					var part = children[i] as MimePart;
 
@@ -467,6 +474,11 @@ public override void Prepare (EncodingConstraint constraint, int maxLineLength =
 					stream.Write (options.NewLineBytes, 0, options.NewLineBytes.Length);
 					children[i].WriteTo (options, stream, false, cancellationToken);
 
+					if (msg != null && msg.Message != null && msg.Message.Body != null) {
+						multi = msg.Message.Body as Multipart;
+						part = msg.Message.Body as MimePart;
+					}
+
 					if ((part != null && part.ContentObject == null) ||
 						(multi != null && !multi.WriteEndBoundary))
 						continue;

UnitTests/MimeMessageTests.cs

@@ -183,6 +183,101 @@ This is the body.
 			Assert.AreEqual (rawMessageText, result, "Reserialized message is not identical to the original.");
 		}
 
+		[Test]
+		public void TestReserializationMessageParts ()
+		{
+			string rawMessageText = @"Path: flop.mcom.com!news.Stanford.EDU!agate!tcsi.tcs.com!uunet!vixen.cso.uiuc.edu!gateway
+From: Internet-Drafts@CNRI.Reston.VA.US
+Subject: I-D ACTION:draft-smith-ipatm-bcast-00.txt
+Date: 25 Apr 95 15:09:13 GMT
+Organization: University of Illinois at Urbana
+Lines: 96
+Approved: Usenet@ux1.cso.uiuc.edu
+Message-ID: <9504251109.aa04587@IETF.CNRI.Reston.VA.US>
+Reply-To: Internet-Drafts@CNRI.Reston.VA.US
+NNTP-Posting-Host: ux1.cso.uiuc.edu
+Mime-Version: 1.0
+Content-Type: Multipart/Mixed; Boundary=""NextPart""
+Originator: daemon@ux1.cso.uiuc.edu
+
+--NextPart
+
+here are a couple of external bodies:
+
+--NextPart
+Content-Type: Multipart/MIXED; Boundary=""OtherAccess""
+
+--OtherAccess
+Content-Type:  Message/External-body;
+        access-type=""mail-server"";
+        server=""mailserv@ds.internic.net""
+
+Content-Type: text/plain
+Content-ID: <19950424144009.I-D@CNRI.Reston.VA.US>
+
+ENCODING mime
+FILE /internet-drafts/draft-smith-ipatm-bcast-00.txt
+
+--OtherAccess
+Content-Type:   Message/External-body;
+        name=""draft-smith-ipatm-bcast-00.txt"";
+        site=""ds.internic.net"";
+        access-type=""anon-ftp"";
+        directory=""internet-drafts""
+
+Content-Type: text/plain
+Content-ID: <19950424144009.I-D@CNRI.Reston.VA.US>
+
+--OtherAccess
+Content-Type: message/external-body;
+        access-type=""URL"";
+        url=""http://home.netscape.com/
+		people/
+		jwz/
+		index.html""
+
+Content-Type: TEXT/HTML
+Content-ID: <spankulate@hubba.hubba.hubba>
+
+--OtherAccess
+Content-Type: message/external-body;
+        access-type=""local-file"";
+        name=""/some/directory/loser.gif""
+
+Content-Type: image/gif
+Content-ID: <spankulate3@hubba.hubba.hubba>
+
+--OtherAccess
+Content-Type: message/external-body;
+        access-type=""afs"";
+        name=""/afs/directory/loser.gif""
+
+Content-Type: image/gif
+Content-ID: <spankulate4@hubba.hubba.hubba>
+
+--OtherAccess--
+
+--NextPart--
+".Replace ("\r\n", "\n");
+			string result;
+
+			using (var source = new MemoryStream (Encoding.UTF8.GetBytes (rawMessageText))) {
+				var parser = new MimeParser (source, MimeFormat.Default);
+				var message = parser.ParseMessage ();
+
+				using (var serialized = new MemoryStream ()) {
+					var options = FormatOptions.Default.Clone ();
+					options.NewLineFormat = NewLineFormat.Unix;
+
+					message.WriteTo (options, serialized);
+
+					result = Encoding.UTF8.GetString (serialized.ToArray ());
+				}
+			}
+
+			Assert.AreEqual (rawMessageText, result, "Reserialized message is not identical to the original.");
+		}
+
 		[Test]
 		public void TestMailMessageToMimeMessage ()
 		{

UnitTests/MimeParserTests.cs

@@ -273,7 +273,7 @@ public void TestJwzPersistentMbox ()
 
 					// Force the various MimePart objects to write their content streams.
 					// The idea is that by forcing the MimeParts to seek in their content,
-					// we will test to make sure that parser correctly deals with it.
+					// we will test to make sure that the parser correctly deals with it.
 					message.WriteTo (Stream.Null);
 				}
 			}