/// <summary>
/// Sends the next part of the command to the server.
/// </summary>
/// <exception cref="System.OperationCanceledException">
/// The operation was canceled via the cancellation token.
/// </exception>
/// <exception cref="System.IO.IOException">
/// An I/O error occurred.
/// </exception>
/// <exception cref="ImapProtocolException">
/// An IMAP protocol error occurred.
/// </exception>
public async Task <bool> StepAsync(bool doAsync)
{
var supportsLiteralPlus = (Engine.Capabilities & ImapCapabilities.LiteralPlus) != 0;
int timeout = Engine.Stream.CanTimeout ? Engine.Stream.ReadTimeout : -1;
var idle = UserData as ImapIdleContext;
var result = ImapCommandResponse.None;
ImapToken token;
// construct and write the command tag if this is the initial state
if (current == 0)
{
Tag = string.Format(CultureInfo.InvariantCulture, "{0}{1:D8}", Engine.TagPrefix, Engine.Tag++);
var buf = Encoding.ASCII.GetBytes(Tag + " ");
if (doAsync)
{
await Engine.Stream.WriteAsync(buf, 0, buf.Length, CancellationToken).ConfigureAwait(false);
}
else
{
Engine.Stream.Write(buf, 0, buf.Length, CancellationToken);
}
}
do
{
var command = parts[current].Command;
if (doAsync)
{
await Engine.Stream.WriteAsync(command, 0, command.Length, CancellationToken).ConfigureAwait(false);
}
else
{
Engine.Stream.Write(command, 0, command.Length, CancellationToken);
}
// if the server doesn't support LITERAL+ (or LITERAL-), we'll need to wait
// for a "+" response before writing out the any literals...
if (parts[current].WaitForContinuation)
{
break;
}
// otherwise, we can write out any and all literal tokens we have...
await parts[current].Literal.WriteToAsync(Engine.Stream, doAsync, CancellationToken).ConfigureAwait(false);
if (current + 1 >= parts.Count)
{
break;
}
current++;
} while (true);
if (doAsync)
{
await Engine.Stream.FlushAsync(CancellationToken).ConfigureAwait(false);
}
else
{
Engine.Stream.Flush(CancellationToken);
}
// now we need to read the response...
do
{
if (Engine.State == ImapEngineState.Idle)
{
try {
if (Engine.Stream.CanTimeout)
{
Engine.Stream.ReadTimeout = -1;
}
token = await Engine.ReadTokenAsync(doAsync, idle.LinkedToken).ConfigureAwait(false);
if (Engine.Stream.CanTimeout)
{
Engine.Stream.ReadTimeout = timeout;
}
} catch (OperationCanceledException) {
if (Engine.Stream.CanTimeout)
{
Engine.Stream.ReadTimeout = timeout;
}
if (idle.IsCancellationRequested)
{
throw;
}
Engine.Stream.IsConnected = true;
token = await Engine.ReadTokenAsync(doAsync, CancellationToken).ConfigureAwait(false);
}
}
else
{
token = await Engine.ReadTokenAsync(doAsync, CancellationToken).ConfigureAwait(false);
}
if (token.Type == ImapTokenType.Atom && token.Value.ToString() == "+")
{
// we've gotten a continuation response from the server
var text = (await Engine.ReadLineAsync(doAsync, CancellationToken).ConfigureAwait(false)).Trim();
// if we've got a Literal pending, the '+' means we can send it now...
if (!supportsLiteralPlus && parts[current].Literal != null)
{
await parts[current].Literal.WriteToAsync(Engine.Stream, doAsync, CancellationToken).ConfigureAwait(false);
break;
}
if (ContinuationHandler != null)
{
await ContinuationHandler(Engine, this, text, doAsync).ConfigureAwait(false);
}
else if (doAsync)
{
await Engine.Stream.WriteAsync(NewLine, 0, NewLine.Length, CancellationToken).ConfigureAwait(false);
await Engine.Stream.FlushAsync(CancellationToken).ConfigureAwait(false);
}
else
{
Engine.Stream.Write(NewLine, 0, NewLine.Length, CancellationToken);
Engine.Stream.Flush(CancellationToken);
}
}
else if (token.Type == ImapTokenType.Asterisk)
{
// we got an untagged response, let the engine handle this...
await Engine.ProcessUntaggedResponseAsync(doAsync, CancellationToken).ConfigureAwait(false);
}
else if (token.Type == ImapTokenType.Atom && (string)token.Value == Tag)
{
// the next token should be "OK", "NO", or "BAD"
token = await Engine.ReadTokenAsync(doAsync, CancellationToken).ConfigureAwait(false);
ImapEngine.AssertToken(token, ImapTokenType.Atom, "Syntax error in tagged response. Unexpected token: {0}", token);
string atom = (string)token.Value;
switch (atom)
{
case "BAD": result = ImapCommandResponse.Bad; break;
case "OK": result = ImapCommandResponse.Ok; break;
case "NO": result = ImapCommandResponse.No; break;
default: throw ImapEngine.UnexpectedToken("Syntax error in tagged response. Unexpected token: {0}", token);
}
token = await Engine.ReadTokenAsync(doAsync, CancellationToken).ConfigureAwait(false);
if (token.Type == ImapTokenType.OpenBracket)
{
var code = await Engine.ParseResponseCodeAsync(true, doAsync, CancellationToken).ConfigureAwait(false);
RespCodes.Add(code);
break;
}
if (token.Type != ImapTokenType.Eoln)
{
// consume the rest of the line...
var line = await Engine.ReadLineAsync(doAsync, CancellationToken).ConfigureAwait(false);
ResponseText = ((string)(token.Value) + line).TrimEnd();
break;
}
}
else if (token.Type == ImapTokenType.OpenBracket)
{
// Note: this is a work-around for broken IMAP servers like Office365.com that
// return RESP-CODES that are not preceded by "* OK " such as the example in
// issue #115 (https://github.com/jstedfast/MailKit/issues/115).
var code = await Engine.ParseResponseCodeAsync(false, doAsync, CancellationToken).ConfigureAwait(false);
RespCodes.Add(code);
}
else
{
// no clue what we got...
throw ImapEngine.UnexpectedToken("Syntax error in response. Unexpected token: {0}", token);
}
} while (true);
// the status should always be Active at this point, but just to be sure...
if (Status == ImapCommandStatus.Active)
{
current++;
if (current >= parts.Count || result != ImapCommandResponse.None)
{
Status = ImapCommandStatus.Complete;
Response = result;
return(false);
}
}
return(true);
}
