/// <summary>
/// Process a MIME entity
///
/// A MIME entity consists of header and body.
/// Separator lines in the body might mark children MIME entities
/// </summary>
private MimeEntityReturnCode ProcessMimeEntity(RxMailMessage message, string parentBoundaryStart)
{
bool hasParentBoundary = parentBoundaryStart.Length > 0;
string parentBoundaryEnd = parentBoundaryStart + "--";
MimeEntityReturnCode boundaryMimeReturnCode;
//some format fields are inherited from parent, only the default for
//ContentType needs to be set here, otherwise the boundary parameter would be
//inherited too !
message.SetContentTypeFields("text/plain; charset=us-ascii");
//get header
//----------
string completeHeaderField = null; //consists of one start line and possibly several continuation lines
string response;
// read header lines until empty line is found (end of header)
while (true)
{
if (!readMultiLine(out response))
{
//POP3 server has not send any more lines
callGetEmailWarning("incomplete MIME entity header received");
//empty this message
while (readMultiLine(out response)) { }
System.Diagnostics.Debugger.Break(); //didn't have a sample email to test this
return MimeEntityReturnCode.problem;
}
if (response.Length < 1)
{
//empty line found => end of header
if (completeHeaderField != null)
{
ProcessHeaderField(message, completeHeaderField);
}
else
{
//there was only an empty header.
}
break;
}
//check if there is a parent boundary in the header (wrong format!)
if (hasParentBoundary && parentBoundaryFound(response, parentBoundaryStart, parentBoundaryEnd, out boundaryMimeReturnCode))
{
callGetEmailWarning("MIME entity header prematurely ended by parent boundary");
//empty this message
while (readMultiLine(out response)) { }
System.Diagnostics.Debugger.Break(); //didn't have a sample email to test this
return boundaryMimeReturnCode;
}
//read header field
//one header field can extend over one start line and multiple continuation lines
//a continuation line starts with at least 1 blank (' ') or tab
if (response[0] == ' ' || response[0] == '\t')
{
//continuation line found.
if (completeHeaderField == null)
{
callGetEmailWarning("Email header starts with continuation line");
//empty this message
while (readMultiLine(out response)) { }
System.Diagnostics.Debugger.Break(); //didn't have a sample email to test this
return MimeEntityReturnCode.problem;
}
else
{
// append space, if needed, and continuation line
if (completeHeaderField[completeHeaderField.Length - 1] != ' ')
{
//previous line did not end with a whitespace
//need to replace CRLF with a ' '
completeHeaderField += ' ' + response.TrimStart(WhiteSpaceChars);
}
else
{
//previous line did end with a whitespace
completeHeaderField += response.TrimStart(WhiteSpaceChars);
}
}
}
else
{
//a new header field line found
if (completeHeaderField == null)
{
//very first field, just copy it and then check for continuation lines
completeHeaderField = response;
}
else
{
//new header line found
ProcessHeaderField(message, completeHeaderField);
//save the beginning of the next line
completeHeaderField = response;
}
}
}//end while read header lines
//process body
//------------
MimeEntitySB.Length = 0; //empty StringBuilder. For speed reasons, reuse StringBuilder defined as member of class
string BoundaryDelimiterLineStart = null;
bool isBoundaryDefined = false;
if (message.ContentType.Boundary != null)
{
isBoundaryDefined = true;
BoundaryDelimiterLineStart = "--" + message.ContentType.Boundary;
}
//prepare return code for the case there is no boundary in the body
boundaryMimeReturnCode = MimeEntityReturnCode.bodyComplete;
//read body lines
while (readMultiLine(out response))
{
//check if there is a boundary line from this entity itself in the body
if (isBoundaryDefined && response.TrimEnd() == BoundaryDelimiterLineStart)
{
//boundary line found.
//stop the processing here and start a delimited body processing
return ProcessDelimitedBody(message, BoundaryDelimiterLineStart, parentBoundaryStart, parentBoundaryEnd);
}
//check if there is a parent boundary in the body
if (hasParentBoundary &&
parentBoundaryFound(response, parentBoundaryStart, parentBoundaryEnd, out boundaryMimeReturnCode))
{
//a parent boundary is found. Decode the content of the body received so far, then end this MIME entity
//note that boundaryMimeReturnCode is set here, but used in the return statement
break;
}
//process next line
MimeEntitySB.Append(response + CRLF);
}
//a complete MIME body read
//convert received US ASCII characters to .NET string (Unicode)
string TransferEncodedMessage = MimeEntitySB.ToString();
bool isAttachmentSaved = false;
switch (message.ContentTransferEncoding)
{
case TransferEncoding.SevenBit:
//nothing to do
saveMessageBody(message, TransferEncodedMessage);
break;
case TransferEncoding.Base64:
//convert base 64 -> byte[]
byte[] bodyBytes = System.Convert.FromBase64String(TransferEncodedMessage);
message.ContentStream = new MemoryStream(bodyBytes, false);
if (message.MediaMainType == "text")
{
//convert byte[] -> string
message.Body = DecodeByteArryToString(bodyBytes, message.BodyEncoding);
}
else if (message.MediaMainType == "image" || message.MediaMainType == "application")
{
SaveAttachment(message);
isAttachmentSaved = true;
}
break;
case TransferEncoding.QuotedPrintable:
saveMessageBody(message, QuotedPrintable.Decode(TransferEncodedMessage));
break;
default:
saveMessageBody(message, TransferEncodedMessage);
//no need to raise a warning here, the warning was done when analising the header
break;
}
if (message.ContentDisposition != null && message.ContentDisposition.DispositionType.ToLowerInvariant() == "attachment" && !isAttachmentSaved)
{
SaveAttachment(message);
isAttachmentSaved = true;
}
return boundaryMimeReturnCode;
}
/// <summary>
/// Convert one MIME header field and update message accordingly
/// </summary>
private void ProcessHeaderField(RxMailMessage message, string headerField)
{
string headerLineType;
string headerLineContent;
int separatorPosition = headerField.IndexOf(':');
if (separatorPosition < 1)
{
// header field type not found, skip this line
callGetEmailWarning("character ':' missing in header format field: '{0}'", headerField);
}
else
{
//process header field type
headerLineType = headerField.Substring(0, separatorPosition).ToLowerInvariant();
headerLineContent = headerField.Substring(separatorPosition + 1).Trim(WhiteSpaceChars);
if (headerLineType == "" || headerLineContent == "")
{
//1 of the 2 parts missing, drop the line
return;
}
// add header line to headers
message.Headers.Add(headerLineType, headerLineContent);
//interpret if possible
switch (headerLineType)
{
case "bcc":
AddMailAddresses(headerLineContent, message.Bcc);
break;
case "cc":
AddMailAddresses(headerLineContent, message.CC);
break;
case "content-description":
message.ContentDescription = headerLineContent;
break;
case "content-disposition":
message.ContentDisposition = new ContentDisposition(headerLineContent);
break;
case "content-id":
message.ContentId = headerLineContent;
break;
case "content-transfer-encoding":
message.TransferType = headerLineContent;
message.ContentTransferEncoding = ConvertToTransferEncoding(headerLineContent);
break;
case "content-type":
message.SetContentTypeFields(headerLineContent);
break;
case "date":
message.DeliveryDate = ConvertToDateTime(headerLineContent);
break;
case "delivered-to":
message.DeliveredTo = ConvertToMailAddress(headerLineContent);
break;
case "from":
MailAddress address = ConvertToMailAddress(headerLineContent);
if (address != null)
{
message.From = address;
}
break;
case "message-id":
message.MessageId = headerLineContent;
break;
case "mime-version":
message.MimeVersion = headerLineContent;
//message.BodyEncoding = new Encoding();
break;
case "sender":
message.Sender = ConvertToMailAddress(headerLineContent);
break;
case "subject":
message.Subject = headerLineContent;
break;
case "received":
//throw mail routing information away
break;
case "reply-to":
message.ReplyToList.Add(ConvertToMailAddress(headerLineContent));
break;
case "return-path":
message.ReturnPath = ConvertToMailAddress(headerLineContent);
break;
case "to":
AddMailAddresses(headerLineContent, message.To);
break;
default:
message.UnknowHeaderlines.Add(headerField);
if (isCollectUnknowHeaderLines)
{
AllUnknowHeaderLines.Add(headerField);
}
break;
}
}
}