async Task <(WebHeaderCollection, byte[], int)> ReadHeaders(Stream stream, CancellationToken cancellationToken)
{
byte[] retBuffer = null;
int status = 200;
byte[] buffer = new byte[1024];
MemoryStream ms = new MemoryStream();
while (true)
{
cancellationToken.ThrowIfCancellationRequested();
int n = await stream.ReadAsync(buffer, 0, 1024, cancellationToken).ConfigureAwait(false);
if (n == 0)
{
throw WebConnection.GetException(WebExceptionStatus.ServerProtocolViolation, null);
}
ms.Write(buffer, 0, n);
int start = 0;
string str = null;
bool gotStatus = false;
WebHeaderCollection headers = new WebHeaderCollection();
while (WebConnection.ReadLine(ms.GetBuffer(), ref start, (int)ms.Length, ref str))
{
if (str == null)
{
int contentLen;
var clengthHeader = headers["Content-Length"];
if (string.IsNullOrEmpty(clengthHeader) || !int.TryParse(clengthHeader, out contentLen))
{
contentLen = 0;
}
if (ms.Length - start - contentLen > 0)
{
// we've read more data than the response header and conents,
// give back extra data to the caller
retBuffer = new byte[ms.Length - start - contentLen];
Buffer.BlockCopy(ms.GetBuffer(), start + contentLen, retBuffer, 0, retBuffer.Length);
}
else
{
// haven't read in some or all of the contents for the response, do so now
FlushContents(stream, contentLen - (int)(ms.Length - start));
}
return(headers, retBuffer, status);
}
if (gotStatus)
{
headers.Add(str);
continue;
}
string[] parts = str.Split(' ');
if (parts.Length < 2)
{
throw WebConnection.GetException(WebExceptionStatus.ServerProtocolViolation, null);
}
if (String.Compare(parts[0], "HTTP/1.1", true) == 0)
{
ProxyVersion = HttpVersion.Version11;
}
else if (String.Compare(parts[0], "HTTP/1.0", true) == 0)
{
ProxyVersion = HttpVersion.Version10;
}
else
{
throw WebConnection.GetException(WebExceptionStatus.ServerProtocolViolation, null);
}
status = (int)UInt32.Parse(parts[1]);
if (parts.Length >= 3)
{
StatusDescription = String.Join(" ", parts, 2, parts.Length - 2);
}
gotStatus = true;
}
}
}
