/// <summary>
/// Asynchronously parses a message from the stream.
/// </summary>
/// <remarks>
/// Parses a message from the stream.
/// </remarks>
/// <returns>The parsed message.</returns>
/// <param name="cancellationToken">The cancellation token.</param>
/// <exception cref="System.OperationCanceledException">
/// The operation was canceled via the cancellation token.
/// </exception>
/// <exception cref="System.FormatException">
/// There was an error parsing the message.
/// </exception>
/// <exception cref="System.IO.IOException">
/// An I/O error occurred.
/// </exception>
public async Task <MimeMessage> ParseMessageAsync(CancellationToken cancellationToken = default(CancellationToken))
{
// Note: if a previously parsed MimePart's content has been read,
// then the stream position will have moved and will need to be
// reset.
if (persistent && stream.Position != position)
{
stream.Seek(position, SeekOrigin.Begin);
}
// scan the from-line if we are parsing an mbox
while (state != MimeParserState.MessageHeaders)
{
switch (await StepAsync(cancellationToken).ConfigureAwait(false))
{
case MimeParserState.Error:
throw new FormatException("Failed to find mbox From marker.");
case MimeParserState.Eos:
throw new FormatException("End of stream.");
}
}
toplevel = true;
// parse the headers
var beginLineNumber = lineNumber;
if (state < MimeParserState.Content && await StepAsync(cancellationToken).ConfigureAwait(false) == MimeParserState.Error)
{
throw new FormatException("Failed to parse message headers.");
}
var message = new MimeMessage(options, headers, RfcComplianceMode.Loose);
var messageArgs = new MimeMessageEndEventArgs(message)
{
HeadersEndOffset = headerBlockEnd,
BeginOffset = headerBlockBegin,
LineNumber = beginLineNumber
};
OnMimeMessageBegin(messageArgs);
if (format == MimeFormat.Mbox && options.RespectContentLength)
{
contentEnd = 0;
for (int i = 0; i < headers.Count; i++)
{
if (headers[i].Id != HeaderId.ContentLength)
{
continue;
}
var value = headers[i].RawValue;
int index = 0;
if (!ParseUtils.SkipWhiteSpace(value, ref index, value.Length))
{
continue;
}
if (!ParseUtils.TryParseInt32(value, ref index, value.Length, out int length))
{
continue;
}
contentEnd = GetOffset(inputIndex) + length;
break;
}
}
var type = GetContentType(null);
var entity = options.CreateEntity(type, headers, true, 0);
var entityArgs = new MimeEntityEndEventArgs(entity)
{
HeadersEndOffset = headerBlockEnd,
BeginOffset = headerBlockBegin,
LineNumber = beginLineNumber
};
OnMimeEntityBegin(entityArgs);
message.Body = entity;
if (entity is Multipart)
{
await ConstructMultipartAsync((Multipart)entity, entityArgs, 0, cancellationToken).ConfigureAwait(false);
}
else if (entity is MessagePart)
{
await ConstructMessagePartAsync((MessagePart)entity, entityArgs, 0, cancellationToken).ConfigureAwait(false);
}
else
{
await ConstructMimePartAsync((MimePart)entity, entityArgs, cancellationToken).ConfigureAwait(false);
}
var endOffset = GetEndOffset(inputIndex);
messageArgs.HeadersEndOffset = entityArgs.HeadersEndOffset = Math.Min(entityArgs.HeadersEndOffset, endOffset);
messageArgs.EndOffset = entityArgs.EndOffset = endOffset;
if (boundary != BoundaryType.Eos)
{
if (format == MimeFormat.Mbox)
{
state = MimeParserState.MboxMarker;
}
else
{
state = MimeParserState.Complete;
}
}
else
{
state = MimeParserState.Eos;
}
OnMimeEntityEnd(entityArgs);
OnMimeMessageEnd(messageArgs);
return(message);
}
async Task ConstructMessagePartAsync(MessagePart rfc822, MimeEntityEndEventArgs args, int depth, CancellationToken cancellationToken)
{
var beginOffset = GetOffset(inputIndex);
var beginLineNumber = lineNumber;
if (bounds.Count > 0)
{
int atleast = Math.Max(ReadAheadSize, GetMaxBoundaryLength());
if (await ReadAheadAsync(atleast, 0, cancellationToken).ConfigureAwait(false) <= 0)
{
boundary = BoundaryType.Eos;
return;
}
unsafe
{
fixed(byte *inbuf = input)
{
byte *start = inbuf + inputIndex;
byte *inend = inbuf + inputEnd;
byte *inptr = start;
*inend = (byte)'\n';
while (*inptr != (byte)'\n')
{
inptr++;
}
boundary = CheckBoundary(inputIndex, start, (int)(inptr - start));
switch (boundary)
{
case BoundaryType.ImmediateEndBoundary:
case BoundaryType.ImmediateBoundary:
case BoundaryType.ParentBoundary:
return;
case BoundaryType.ParentEndBoundary:
// ignore "From " boundaries, broken mailers tend to include these...
if (!IsMboxMarker(start))
{
return;
}
break;
}
}
}
}
// parse the headers...
state = MimeParserState.MessageHeaders;
if (await StepAsync(cancellationToken).ConfigureAwait(false) == MimeParserState.Error)
{
// Note: this either means that StepHeaders() found the end of the stream
// or an invalid header field name at the start of the message headers,
// which likely means that this is not a valid MIME stream?
boundary = BoundaryType.Eos;
return;
}
var message = new MimeMessage(options, headers, RfcComplianceMode.Loose);
var messageArgs = new MimeMessageEndEventArgs(message, rfc822)
{
HeadersEndOffset = headerBlockEnd,
BeginOffset = headerBlockBegin,
LineNumber = beginLineNumber
};
OnMimeMessageBegin(messageArgs);
if (preHeaderBuffer.Length > 0)
{
message.MboxMarker = new byte[preHeaderLength];
Buffer.BlockCopy(preHeaderBuffer, 0, message.MboxMarker, 0, preHeaderLength);
}
var type = GetContentType(null);
var entity = options.CreateEntity(type, headers, true, depth);
var entityArgs = new MimeEntityEndEventArgs(entity)
{
HeadersEndOffset = headerBlockEnd,
BeginOffset = headerBlockBegin,
LineNumber = beginLineNumber
};
OnMimeEntityBegin(entityArgs);
message.Body = entity;
if (entity is Multipart)
{
await ConstructMultipartAsync((Multipart)entity, entityArgs, depth + 1, cancellationToken).ConfigureAwait(false);
}
else if (entity is MessagePart)
{
await ConstructMessagePartAsync((MessagePart)entity, entityArgs, depth + 1, cancellationToken).ConfigureAwait(false);
}
else
{
await ConstructMimePartAsync((MimePart)entity, entityArgs, cancellationToken).ConfigureAwait(false);
}
rfc822.Message = message;
var endOffset = GetEndOffset(inputIndex);
messageArgs.HeadersEndOffset = entityArgs.HeadersEndOffset = Math.Min(entityArgs.HeadersEndOffset, endOffset);
messageArgs.EndOffset = entityArgs.EndOffset = endOffset;
OnMimeEntityEnd(entityArgs);
OnMimeMessageEnd(messageArgs);
args.Lines = GetLineCount(beginLineNumber, beginOffset, endOffset);
}
