/// <summary>
/// Extract a list of MIME parts from a multipart/* MIME encoded message.
/// </summary>
/// <param name="contentType">Content Type of the outermost MIME part.</param>
/// <param name="charSet">Character set of the outermost MIME part.</param>
/// <param name="contentTransferEncoding">Encoding of the outermost MIME part.</param>
/// <param name="body">The outermost MIME part's contents.</param>
/// <param name="depth">The nesting layer of this MIME part.</param>
/// <param name="processingFlags">Flags determining whether specialized properties are returned with a ReadOnlyMailMessage.</param>
public static List <MimePart> ExtractMIMEParts(string contentType, string charSet, string contentTransferEncoding, string body, ReadOnlyMailMessageProcessingFlags processingFlags, int depth)
{
List <MimePart> mimeParts = new List <MimePart>();
string contentTypeToUpper = contentType.ToUpper();
if (contentTypeToUpper.StartsWith("MULTIPART/"))
{
// Prepare to process each part of the multipart/* message.
int cursor = 0;
// Prepend and append to the body with a carriage return and linefeed for consistent boundary matching.
body = "\r\n" + body + "\r\n";
// Determine the outermost boundary name.
string boundaryName = Functions.ExtractMimeParameter(contentType, "boundary");
int boundaryNameLength = boundaryName.Length;
// Variables used for record keeping with signed S/MIME parts.
int signatureBlock = -1;
List <string> mimeBlocks = new List <string>();
cursor = body.IndexOf("\r\n--" + boundaryName, 0, StringComparison.Ordinal);
while (cursor > -1)
{
// Calculate the end boundary of the current MIME part.
int mimeStartPosition = cursor + boundaryNameLength + 4;
int mimeEndPosition = body.IndexOf("\r\n--" + boundaryName, mimeStartPosition, StringComparison.Ordinal);
if (mimeEndPosition > -1 && (mimeEndPosition + boundaryNameLength + 6 <= body.Length))
{
string afterBoundaryEnd = body.Substring(mimeEndPosition + 4 + boundaryNameLength, 2);
if (afterBoundaryEnd == "\r\n" || afterBoundaryEnd == "--")
{
string mimeContents = body.Substring(mimeStartPosition, mimeEndPosition - mimeStartPosition);
// Extract the header portion of the current MIME part.
int mimeDivider = mimeContents.IndexOf("\r\n\r\n");
string mimeHeaders, mimeBody;
if (mimeDivider > -1)
{
mimeHeaders = mimeContents.Substring(0, mimeDivider);
mimeBody = mimeContents.Substring(mimeDivider + 4);
}
else
{
// The following is a workaround to handle malformed MIME bodies.
mimeHeaders = mimeContents;
mimeBody = "";
int linePos = 0, lastLinePos = 0;
while (linePos > -1)
{
lastLinePos = linePos;
linePos = mimeHeaders.IndexOf("\r\n", lastLinePos);
if (linePos > -1)
{
string currentLine = mimeContents.Substring(lastLinePos, linePos - lastLinePos);
if (currentLine.Length > 0 && currentLine.IndexOf(":") < 0)
{
mimeBody = mimeContents.Substring(lastLinePos + 2, mimeContents.Length - lastLinePos - 4);
linePos = -1;
}
else
{
linePos += 2;
}
}
}
}
mimeBlocks.Add(mimeContents);
// Divide the MIME part's headers into its components.
string mimeCharSet = "", mimeContentDisposition = "", mimeContentID = "", mimeContentType = "", mimeContentTransferEncoding = "", mimeFileName = "";
ExtractMimeHeaders(mimeHeaders, out mimeContentType, out mimeCharSet, out mimeContentTransferEncoding, out mimeContentDisposition, out mimeFileName, out mimeContentID);
string mimeContentTypeToUpper = mimeContentType.ToUpper();
if (mimeContentTypeToUpper.StartsWith("MULTIPART/"))
{
// Recurse through embedded MIME parts.
List <MimePart> returnedMIMEParts = ExtractMIMEParts(mimeContentType, mimeCharSet, mimeContentTransferEncoding, mimeBody, processingFlags, depth + 1);
foreach (MimePart returnedMIMEPart in returnedMIMEParts)
{
mimeParts.Add(returnedMIMEPart);
}
}
else
{
// Keep track of whether this MIME part's body has already been processed.
bool processed = false;
if (mimeContentTypeToUpper.StartsWith("APPLICATION/PKCS7-SIGNATURE") || mimeContentTypeToUpper.StartsWith("APPLICATION/X-PKCS7-SIGNATURE"))
{
// Unless a flag has been set to include this *.p7s block, exclude it from attachments.
if ((processingFlags & ReadOnlyMailMessageProcessingFlags.IncludeSmimeSignedData) == 0)
{
processed = true;
}
// Remember the signature block to use for later verification.
signatureBlock = mimeBlocks.Count() - 1;
}
else if (mimeContentTypeToUpper.StartsWith("APPLICATION/PKCS7-MIME") || mimeContentTypeToUpper.StartsWith("APPLICATION/X-PKCS7-MIME"))
{
// Unless a flag has been set to include this *.p7m block, exclude it from attachments.
processed = (processingFlags & ReadOnlyMailMessageProcessingFlags.IncludeSmimeEncryptedEnvelopeData) == 0;
// Decrypt the MIME part and recurse through embedded MIME parts.
List <MimePart> returnedMIMEParts = ReturnDecryptedMimeParts(mimeContentType, mimeContentTransferEncoding, mimeBody, processingFlags, depth + 1);
if (returnedMIMEParts != null)
{
foreach (MimePart returnedMIMEPart in returnedMIMEParts)
{
mimeParts.Add(returnedMIMEPart);
}
}
else
{
// If we were unable to decrypt, return this MIME part as-is.
processed = false;
}
}
else if (mimeContentTypeToUpper.StartsWith("APPLICATION/MS-TNEF") || mimeFileName.ToUpper() == "WINMAIL.DAT")
{
// Process the TNEF encoded message.
processed = true;
TnefEncoding tnef = new TnefEncoding(Convert.FromBase64String(mimeBody));
// If we were unable to extract content from this MIME, include it as an attachment.
if ((tnef.Body.Length < 1 && tnef.MimeAttachments.Count < 1) || (processingFlags & ReadOnlyMailMessageProcessingFlags.IncludeWinMailData) > 0)
{
processed = false;
}
else
{
// Unless a flag has been set to include this winmail.dat block, exclude it from attachments.
if ((processingFlags & ReadOnlyMailMessageProcessingFlags.IncludeWinMailData) > 0)
{
if (!string.IsNullOrEmpty(tnef.Body))
{
mimeParts.Add(new MimePart("winmail.dat", tnef.ContentType, "", "", mimeContentTransferEncoding, Encoding.UTF8.GetBytes(tnef.Body)));
}
}
foreach (MimePart mimePart in tnef.MimeAttachments)
{
mimeParts.Add(mimePart);
}
}
}
else if (mimeContentTypeToUpper == "MESSAGE/RFC822")
{
if ((processingFlags & ReadOnlyMailMessageProcessingFlags.IncludeNestedRFC822Messages) > 0)
{
// Recurse through the RFC822 container.
processed = true;
mimeDivider = mimeBody.IndexOf("\r\n\r\n");
if (mimeDivider > -1)
{
mimeHeaders = Functions.UnfoldWhitespace(mimeBody.Substring(0, mimeDivider));
mimeBody = mimeBody.Substring(mimeDivider + 4);
mimeContentType = Functions.ReturnBetween(mimeHeaders, "Content-Type:", "\r\n").Trim();
mimeContentTransferEncoding = Functions.ReturnBetween(mimeHeaders, "Content-Transfer-Encoding:", "\r\n").Trim();
mimeCharSet = Functions.ExtractMimeParameter(mimeContentType, "charset").Replace("\"", "");
List <MimePart> returnedMIMEParts = ExtractMIMEParts(mimeContentType, mimeCharSet, mimeContentTransferEncoding, mimeBody, processingFlags, depth + 1);
foreach (MimePart returnedMIMEPart in returnedMIMEParts)
{
mimeParts.Add(returnedMIMEPart);
}
}
}
}
if (!processed)
{
// Decode and add the message to the MIME parts collection.
switch (mimeContentTransferEncoding.ToLower())
{
case "base64":
mimeBody = mimeBody.Replace("\r\n", "");
if (mimeBody.Length % 4 != 0)
{
mimeBody += new String('=', 4 - (mimeBody.Length % 4));
}
mimeParts.Add(new MimePart(mimeFileName, mimeContentType, mimeCharSet, mimeContentID, mimeContentTransferEncoding, Convert.FromBase64String(mimeBody)));
break;
case "quoted-printable":
mimeParts.Add(new MimePart(mimeFileName, mimeContentType, mimeCharSet, mimeContentID, mimeContentTransferEncoding, Functions.FromQuotedPrintable(mimeBody, mimeCharSet, null)));
break;
case "binary":
case "7bit":
case "8bit":
default:
mimeParts.Add(new MimePart(mimeFileName, mimeContentType, mimeCharSet, mimeContentID, mimeContentTransferEncoding, mimeBody));
break;
}
}
}
}
cursor = mimeEndPosition;
}
else
{
cursor = -1;
}
}
// If a PKCS signature was found and there's one other MIME part, verify the signature.
if (signatureBlock > -1 && mimeBlocks.Count == 2)
{
// Verify the signature and track the signing certificates.
X509Certificate2Collection signingCertificates;
if (VerifySignature(mimeBlocks[signatureBlock], mimeBlocks[1 - signatureBlock], out signingCertificates))
{
// Stamp each MIME part found so far as signed, and if relevant, triple wrapped.
foreach (MimePart mimePart in mimeParts)
{
mimePart.SmimeSigningCertificates = signingCertificates;
if (mimePart.SmimeSigned && mimePart.SmimeEncryptedEnvelope)
{
mimePart.SmimeTripleWrapped = true;
}
mimePart.SmimeSigned = true;
}
}
}
}
else if (contentTypeToUpper.StartsWith("APPLICATION/MS-TNEF"))
{
// Process the TNEF encoded message.
TnefEncoding tnef = new TnefEncoding(Convert.FromBase64String(body));
// Unless a flag has been set to include this winmail.dat block, exclude it from attachments.
if ((processingFlags & ReadOnlyMailMessageProcessingFlags.IncludeWinMailData) > 0)
{
if (!string.IsNullOrEmpty(tnef.Body))
{
mimeParts.Add(new MimePart("winmail.dat", tnef.ContentType, "", "", "", Encoding.UTF8.GetBytes(tnef.Body)));
}
}
foreach (MimePart mimePart in tnef.MimeAttachments)
{
mimeParts.Add(mimePart);
}
}
else if (contentTypeToUpper.StartsWith("APPLICATION/PKCS7-MIME") || contentTypeToUpper.StartsWith("APPLICATION/X-PKCS7-MIME"))
{
// Don't attempt to decrypt if this is a signed message only.
if (contentType.IndexOf("smime-type=signed-data") < 0)
{
// Unless a flag has been set to include this *.p7m block, exclude it from attachments.
if ((processingFlags & ReadOnlyMailMessageProcessingFlags.IncludeSmimeEncryptedEnvelopeData) > 0)
{
mimeParts.Add(new MimePart("smime.p7m", contentType, "", "", "", body));
}
// Decrypt the MIME part and recurse through embedded MIME parts.
List <MimePart> returnedMIMEParts = ReturnDecryptedMimeParts(contentType, contentTransferEncoding, body, processingFlags, depth + 1);
if (returnedMIMEParts != null)
{
foreach (MimePart returnedMIMEPart in returnedMIMEParts)
{
mimeParts.Add(returnedMIMEPart);
}
}
else
{
// If we were unable to decrypt the message, pass it along as-is.
mimeParts.Add(new MimePart(Functions.ReturnBetween(contentType + ";", "name=", ";").Replace("\"", ""), contentType, "", "", contentTransferEncoding, body));
}
}
else
{
// Hydrate the signature CMS object.
SignedCms signedCms = new SignedCms();
try
{
// Attempt to decode the signature block and verify the passed in signature.
signedCms.Decode(Convert.FromBase64String(body));
signedCms.CheckSignature(true);
string mimeContents = Encoding.UTF8.GetString(signedCms.ContentInfo.Content);
int mimeDivider = mimeContents.IndexOf("\r\n\r\n");
string mimeHeaders;
if (mimeDivider > -1)
{
mimeHeaders = mimeContents.Substring(0, mimeDivider);
}
else
{
mimeHeaders = mimeContents;
}
if (mimeHeaders.Length > 0)
{
// Extract the body portion of the current MIME part.
string mimeBody = mimeContents.Substring(mimeDivider + 4);
string mimeCharSet = "", mimeContentDisposition = "", mimeContentID = "", mimeContentType = "", mimeContentTransferEncoding = "", mimeFileName = "";
ExtractMimeHeaders(mimeHeaders, out mimeContentType, out mimeCharSet, out mimeContentTransferEncoding, out mimeContentDisposition, out mimeFileName, out mimeContentID);
List <MimePart> returnedMIMEParts = ExtractMIMEParts(mimeContentType, mimeCharSet, mimeContentTransferEncoding, mimeBody, processingFlags, depth + 1);
foreach (MimePart returnedMIMEPart in returnedMIMEParts)
{
mimeParts.Add(returnedMIMEPart);
}
}
}
catch
{
// If an exception occured, the signature could not be verified.
}
}
}
else if (contentTypeToUpper == "MESSAGE/RFC822")
{
int mimeDivider = body.IndexOf("\r\n\r\n");
if (mimeDivider > -1)
{
string mimeHeaders = Functions.UnfoldWhitespace(body.Substring(0, mimeDivider));
string mimeBody = body.Substring(mimeDivider + 4);
string mimeContentType = Functions.ReturnBetween(mimeHeaders, "Content-Type:", "\r\n").Trim();
string mimeContentTransferEncoding = Functions.ReturnBetween(mimeHeaders, "Content-Transfer-Encoding:", "\r\n").Trim();
string mimeCharSet = Functions.ExtractMimeParameter(mimeContentType, "charset");
List <MimePart> returnedMIMEParts = ExtractMIMEParts(mimeContentType, mimeCharSet, mimeContentTransferEncoding, mimeBody, processingFlags, depth + 1);
foreach (MimePart returnedMIMEPart in returnedMIMEParts)
{
mimeParts.Add(returnedMIMEPart);
}
}
}
else
{
// Decode the message.
switch (contentTransferEncoding.ToLower())
{
case "base64":
body = Functions.FromBase64(body);
break;
case "quoted-printable":
body = Functions.FromQuotedPrintable(body, charSet, null);
break;
case "binary":
case "7bit":
case "8bit":
break;
}
// If we're beyond the first layer, process the MIME part. Otherwise, the message isn't MIME encoded.
if (depth > 0)
{
// Extract the headers from this MIME part.
string mimeHeaders;
int mimeDivider = body.IndexOf("\r\n\r\n");
if (mimeDivider > -1)
{
mimeHeaders = body.Substring(0, mimeDivider);
}
else
{
mimeHeaders = body;
}
// Divide the MIME part's headers into its components.
string mimeCharSet = "", mimeContentDisposition = "", mimeContentID = "", mimeContentType = "", mimeContentTransferEncoding = "", mimeFileName = "";
ExtractMimeHeaders(mimeHeaders, out mimeContentType, out mimeCharSet, out mimeContentTransferEncoding, out mimeContentDisposition, out mimeFileName, out mimeContentID);
// If this MIME part's content type is null, fall back to the overall content type.
if ((string.IsNullOrEmpty(mimeContentType) && !string.IsNullOrEmpty(contentType)) || (contentTypeToUpper.StartsWith("MESSAGE/PARTIAL")))
{
mimeCharSet = charSet;
mimeContentType = contentType;
}
else
{
if (body.Length > (mimeDivider + 4))
{
body = body.Substring(mimeDivider + 4);
}
else
{
body = "";
}
}
// Add the message to the MIME parts collection.
mimeParts.Add(new MimePart(mimeFileName, mimeContentType, mimeCharSet, mimeContentID, mimeContentTransferEncoding, body));
}
else
{
// If the content type contains a character set, extract it.
charSet = Functions.NormalizeCharSet(Functions.ExtractMimeParameter(contentType, "charset"));
int semicolonPos = contentType.IndexOf(";");
if (semicolonPos > -1)
{
contentType = contentType.Substring(0, semicolonPos);
}
// Add the message as-is.
mimeParts.Add(new MimePart("", contentType, charSet, "", contentTransferEncoding, body));
}
}
return(mimeParts);
}
/// <summary>
/// Extract a list of MIME parts from a multipart/* MIME encoded message.
/// </summary>
/// <param name="contentType">Content Type of the outermost MIME part.</param>
/// <param name="charSet">Character set of the outermost MIME part.</param>
/// <param name="contentTransferEncoding">Encoding of the outermost MIME part.</param>
/// <param name="body">The outermost MIME part's contents.</param>
/// <param name="processingFlags">Flags determining whether specialized properties are returned with a ReadOnlyMailMessage.</param>
public static List<MimePart> ExtractMIMEParts(string contentType, string charSet, string contentTransferEncoding, string body, ReadOnlyMailMessageProcessingFlags processingFlags)
{
List<MimePart> mimeParts = new List<MimePart>();
string contentTypeToUpper = contentType.ToUpper();
if (contentTypeToUpper.StartsWith("MULTIPART/"))
{
// Prepare to process each part of the multipart/* message.
int cursor = 0;
// Prepend the body with a carriage return and linefeed for consistent boundary matching.
body = "\r\n" + body;
// Determine the outermost boundary name.
string boundaryName = Functions.ReturnBetween(contentType, "boundary=\"", "\"");
if (boundaryName.Length < 1)
{
cursor = contentType.IndexOf("boundary=", StringComparison.OrdinalIgnoreCase);
if (cursor > -1)
boundaryName = contentType.Substring(cursor + 9);
cursor = boundaryName.IndexOf(";");
if (cursor > -1)
boundaryName = boundaryName.Substring(0, cursor);
if (boundaryName.StartsWith("\"") && boundaryName.EndsWith("\""))
boundaryName = boundaryName.Substring(1, boundaryName.Length - 2);
else
{
// Remove linear whitespace from boundary names.
boundaryName = boundaryName.Trim();
}
}
int boundaryNameLength = boundaryName.Length;
// Variables used for record keeping with signed S/MIME parts.
int signatureBlock = -1;
List<string> mimeBlocks = new List<string>();
cursor = body.IndexOf("\r\n--" + boundaryName, 0, StringComparison.Ordinal);
while (cursor > -1)
{
// Calculate the end boundary of the current MIME part.
int mimeStartPosition = cursor + boundaryNameLength + 4;
int mimeEndPosition = body.IndexOf("\r\n--" + boundaryName, mimeStartPosition, StringComparison.Ordinal);
if (mimeEndPosition > -1)
{
string afterBoundaryEnd = body.Substring(mimeEndPosition + 4 + boundaryNameLength, 2);
if (afterBoundaryEnd == "\r\n" || afterBoundaryEnd == "--")
{
string mimeContents = body.Substring(mimeStartPosition, mimeEndPosition - mimeStartPosition);
// Extract the header portion of the current MIME part.
int mimeDivider = mimeContents.IndexOf("\r\n\r\n");
string mimeHeaders, mimeBody;
if (mimeDivider > -1)
{
mimeHeaders = mimeContents.Substring(0, mimeDivider);
mimeBody = mimeContents.Substring(mimeDivider + 4);
}
else
{
// The following is a workaround to handle malformed MIME bodies.
mimeHeaders = mimeContents;
mimeBody = "";
int linePos = 0, lastLinePos = 0;
while (linePos > -1)
{
lastLinePos = linePos;
linePos = mimeHeaders.IndexOf("\r\n", lastLinePos);
if (linePos > -1)
{
string currentLine = mimeContents.Substring(lastLinePos, linePos - lastLinePos);
if (currentLine.Length > 0 && currentLine.IndexOf(":") < 0)
{
mimeBody = mimeContents.Substring(lastLinePos + 2, mimeContents.Length - lastLinePos - 4);
linePos = -1;
}
else
linePos += 2;
}
}
}
mimeBlocks.Add(mimeContents);
// Divide the MIME part's headers into its components.
string mimeCharSet = "", mimeContentDisposition = "", mimeContentID = "", mimeContentType = "", mimeContentTransferEncoding = "", mimeFileName = "";
ExtractMimeHeaders(mimeHeaders, out mimeContentType, out mimeCharSet, out mimeContentTransferEncoding, out mimeContentDisposition, out mimeFileName, out mimeContentID);
string mimeContentTypeToUpper = mimeContentType.ToUpper();
if (mimeContentTypeToUpper.StartsWith("MULTIPART/"))
{
// Recurse through embedded MIME parts.
List<MimePart> returnedMIMEParts = ExtractMIMEParts(mimeContentType, mimeCharSet, mimeContentTransferEncoding, mimeBody, processingFlags);
foreach (MimePart returnedMIMEPart in returnedMIMEParts)
mimeParts.Add(returnedMIMEPart);
}
else
{
// Keep track of whether this MIME part's body has already been processed.
bool processed = false;
if (mimeContentTypeToUpper.StartsWith("APPLICATION/PKCS7-SIGNATURE") || mimeContentTypeToUpper.StartsWith("APPLICATION/X-PKCS7-SIGNATURE"))
{
// Unless a flag has been set to include this *.p7s block, exclude it from attachments.
if ((processingFlags & ReadOnlyMailMessageProcessingFlags.IncludeSmimeSignedData) == 0)
processed = true;
// Remember the signature block to use for later verification.
signatureBlock = mimeBlocks.Count() - 1;
}
else if (mimeContentTypeToUpper.StartsWith("APPLICATION/PKCS7-MIME") || mimeContentTypeToUpper.StartsWith("APPLICATION/X-PKCS7-MIME"))
{
// Unless a flag has been set to include this *.p7m block, exclude it from attachments.
processed = (processingFlags & ReadOnlyMailMessageProcessingFlags.IncludeSmimeEncryptedEnvelopeData) == 0;
// Decrypt the MIME part and recurse through embedded MIME parts.
List<MimePart> returnedMIMEParts = ReturnDecryptedMimeParts(mimeContentType, mimeContentTransferEncoding, mimeBody, processingFlags);
if (returnedMIMEParts != null)
{
foreach (MimePart returnedMIMEPart in returnedMIMEParts)
mimeParts.Add(returnedMIMEPart);
}
else
{
// If we were unable to decrypt, return this MIME part as-is.
processed = false;
}
}
else if (mimeContentTypeToUpper.StartsWith("APPLICATION/MS-TNEF") || mimeFileName.ToUpper() == "WINMAIL.DAT")
{
// Process the TNEF encoded message.
processed = true;
TnefEncoding tnef = new TnefEncoding(Convert.FromBase64String(mimeBody));
// If we were unable to extract content from this MIME, include it as an attachment.
if ((tnef.Body.Length < 1 && tnef.MimeAttachments.Count < 1) || (processingFlags & ReadOnlyMailMessageProcessingFlags.IncludeWinMailData) > 0)
processed = false;
else
{
// Unless a flag has been set to include this winmail.dat block, exclude it from attachments.
if ((processingFlags & ReadOnlyMailMessageProcessingFlags.IncludeWinMailData) > 0)
{
if (!string.IsNullOrEmpty(tnef.Body))
mimeParts.Add(new MimePart("winmail.dat", tnef.ContentType, "", "", mimeContentTransferEncoding, Encoding.UTF8.GetBytes(tnef.Body)));
}
foreach (MimePart mimePart in tnef.MimeAttachments)
mimeParts.Add(mimePart);
}
}
else if (mimeContentTypeToUpper == "MESSAGE/RFC822")
{
if ((processingFlags & ReadOnlyMailMessageProcessingFlags.IncludeNestedRFC822Messages) > 0)
{
// Recurse through the RFC822 container.
processed = true;
mimeDivider = mimeBody.IndexOf("\r\n\r\n");
if (mimeDivider > -1)
{
mimeHeaders = Functions.UnfoldWhitespace(mimeBody.Substring(0, mimeDivider));
mimeBody = mimeBody.Substring(mimeDivider + 4);
mimeContentType = Functions.ReturnBetween(mimeHeaders, "Content-Type:", "\r\n").Trim();
mimeContentTransferEncoding = Functions.ReturnBetween(mimeHeaders, "Content-Transfer-Encoding:", "\r\n").Trim();
mimeCharSet = Functions.ExtractMimeParameter(mimeContentType, "charset").Replace("\"", "");
List<MimePart> returnedMIMEParts = ExtractMIMEParts(mimeContentType, mimeCharSet, mimeContentTransferEncoding, mimeBody, processingFlags);
foreach (MimePart returnedMIMEPart in returnedMIMEParts)
mimeParts.Add(returnedMIMEPart);
}
}
}
if (!processed)
{
// Decode and add the message to the MIME parts collection.
switch (mimeContentTransferEncoding.ToLower())
{
case "base64":
mimeBody = mimeBody.Replace("\r\n", "");
if (mimeBody.Length % 4 != 0)
mimeBody += new String('=', 4 - (mimeBody.Length % 4));
mimeParts.Add(new MimePart(mimeFileName, mimeContentType, mimeCharSet, mimeContentID, mimeContentTransferEncoding, Convert.FromBase64String(mimeBody)));
break;
case "quoted-printable":
mimeParts.Add(new MimePart(mimeFileName, mimeContentType, mimeCharSet, mimeContentID, mimeContentTransferEncoding, Functions.FromQuotedPrintable(mimeBody, mimeCharSet, null)));
break;
case "binary":
case "7bit":
case "8bit":
default:
mimeParts.Add(new MimePart(mimeFileName, mimeContentType, mimeCharSet, mimeContentID, mimeContentTransferEncoding, mimeBody));
break;
}
}
}
}
cursor = mimeEndPosition;
}
else
cursor = -1;
}
// If a PKCS signature was found and there's one other MIME part, verify the signature.
if (signatureBlock > -1 && mimeBlocks.Count == 2)
{
// Verify the signature and track the signing certificates.
X509Certificate2Collection signingCertificates;
if (VerifySignature(mimeBlocks[signatureBlock], mimeBlocks[1 - signatureBlock], out signingCertificates))
{
// Stamp each MIME part found so far as signed, and if relevant, triple wrapped.
foreach (MimePart mimePart in mimeParts)
{
mimePart.SmimeSigningCertificates = signingCertificates;
if (mimePart.SmimeSigned && mimePart.SmimeEncryptedEnvelope)
mimePart.SmimeTripleWrapped = true;
mimePart.SmimeSigned = true;
}
}
}
}
else if (contentTypeToUpper.StartsWith("APPLICATION/MS-TNEF"))
{
// Process the TNEF encoded message.
TnefEncoding tnef = new TnefEncoding(Convert.FromBase64String(body));
// Unless a flag has been set to include this winmail.dat block, exclude it from attachments.
if ((processingFlags & ReadOnlyMailMessageProcessingFlags.IncludeWinMailData) > 0)
{
if (!string.IsNullOrEmpty(tnef.Body))
mimeParts.Add(new MimePart("winmail.dat", tnef.ContentType, "", "", "", Encoding.UTF8.GetBytes(tnef.Body)));
}
foreach (MimePart mimePart in tnef.MimeAttachments)
mimeParts.Add(mimePart);
}
else if (contentTypeToUpper.StartsWith("APPLICATION/PKCS7-MIME") || contentTypeToUpper.StartsWith("APPLICATION/X-PKCS7-MIME"))
{
// Don't attempt to decrypt if this is a signed message only.
if (contentType.IndexOf("smime-type=signed-data") < 0)
{
// Unless a flag has been set to include this *.p7m block, exclude it from attachments.
if ((processingFlags & ReadOnlyMailMessageProcessingFlags.IncludeSmimeEncryptedEnvelopeData) > 0)
mimeParts.Add(new MimePart("smime.p7m", contentType, "", "", "", body));
// Decrypt the MIME part and recurse through embedded MIME parts.
List<MimePart> returnedMIMEParts = ReturnDecryptedMimeParts(contentType, contentTransferEncoding, body, processingFlags);
if (returnedMIMEParts != null)
{
foreach (MimePart returnedMIMEPart in returnedMIMEParts)
mimeParts.Add(returnedMIMEPart);
}
else
{
// If we were unable to decrypt the message, pass it along as-is.
mimeParts.Add(new MimePart(Functions.ReturnBetween(contentType + ";", "name=", ";").Replace("\"", ""), contentType, "", "", contentTransferEncoding, body));
}
}
else
{
// Hydrate the signature CMS object.
SignedCms signedCms = new SignedCms();
try
{
// Attempt to decode the signature block and verify the passed in signature.
signedCms.Decode(Convert.FromBase64String(body));
signedCms.CheckSignature(true);
string mimeContents = Encoding.UTF8.GetString(signedCms.ContentInfo.Content);
int mimeDivider = mimeContents.IndexOf("\r\n\r\n");
string mimeHeaders;
if (mimeDivider > -1)
mimeHeaders = mimeContents.Substring(0, mimeDivider);
else
mimeHeaders = mimeContents;
if (mimeHeaders.Length > 0)
{
// Extract the body portion of the current MIME part.
string mimeBody = mimeContents.Substring(mimeDivider + 4);
string mimeCharSet = "", mimeContentDisposition = "", mimeContentID = "", mimeContentType = "", mimeContentTransferEncoding = "", mimeFileName = "";
ExtractMimeHeaders(mimeHeaders, out mimeContentType, out mimeCharSet, out mimeContentTransferEncoding, out mimeContentDisposition, out mimeFileName, out mimeContentID);
List<MimePart> returnedMIMEParts = ExtractMIMEParts(mimeContentType, mimeCharSet, mimeContentTransferEncoding, mimeBody, processingFlags);
foreach (MimePart returnedMIMEPart in returnedMIMEParts)
mimeParts.Add(returnedMIMEPart);
}
}
catch
{
// If an exception occured, the signature could not be verified.
}
}
}
else if (contentTypeToUpper == "MESSAGE/RFC822")
{
int mimeDivider = body.IndexOf("\r\n\r\n");
if (mimeDivider > -1)
{
string mimeHeaders = Functions.UnfoldWhitespace(body.Substring(0, mimeDivider));
string mimeBody = body.Substring(mimeDivider + 4);
string mimeContentType = Functions.ReturnBetween(mimeHeaders, "Content-Type:", "\r\n").Trim();
string mimeContentTransferEncoding = Functions.ReturnBetween(mimeHeaders, "Content-Transfer-Encoding:", "\r\n").Trim();
string mimeCharSet = Functions.ExtractMimeParameter(mimeContentType, "charset");
List<MimePart> returnedMIMEParts = ExtractMIMEParts(mimeContentType, mimeCharSet, mimeContentTransferEncoding, mimeBody, processingFlags);
foreach (MimePart returnedMIMEPart in returnedMIMEParts)
mimeParts.Add(returnedMIMEPart);
}
}
else
{
// Decode the message.
switch (contentTransferEncoding.ToLower())
{
case "base64":
body = Functions.FromBase64(body);
break;
case "quoted-printable":
body = Functions.FromQuotedPrintable(body, charSet, null);
break;
case "binary":
case "7bit":
case "8bit":
break;
}
// Extract the headers from this MIME part.
string mimeHeaders;
int mimeDivider = body.IndexOf("\r\n\r\n");
if (mimeDivider > -1 )
mimeHeaders = body.Substring(0, mimeDivider);
else
mimeHeaders = body;
// Divide the MIME part's headers into its components.
string mimeCharSet = "", mimeContentDisposition = "", mimeContentID = "", mimeContentType = "", mimeContentTransferEncoding = "", mimeFileName = "";
ExtractMimeHeaders(mimeHeaders, out mimeContentType, out mimeCharSet, out mimeContentTransferEncoding, out mimeContentDisposition, out mimeFileName, out mimeContentID);
// If this MIME part's content type is null, fall back to the overall content type.
if ((string.IsNullOrEmpty(mimeContentType) && !string.IsNullOrEmpty(contentType)) || (contentTypeToUpper.StartsWith("MESSAGE/PARTIAL")))
{
mimeCharSet = charSet;
mimeContentType = contentType;
}
else
{
if (body.Length > (mimeDivider + 4))
body = body.Substring(mimeDivider + 4);
else
body = "";
}
// Add the message to the MIME parts collection.
mimeParts.Add(new MimePart(mimeFileName, mimeContentType, mimeCharSet, mimeContentID, mimeContentTransferEncoding, body));
}
return mimeParts;
}