private HttpResponse ReadResponse(Stream responseStream)
{
var headers = new HttpHeaders();
char currentChar;
int streamPosition = 0;
// https://tools.ietf.org/html/rfc2616#section-4.2
// HTTP/1.1 200 OK
// HTTP/1.1 XXX MESSAGE
const int statusCodeStart = 9;
const int statusCodeEnd = 12;
const int startOfReasonPhrase = 13;
// TODO: Get this from StringBuilderCache after we determine safe maximum capacity
var stringBuilder = new StringBuilder();
var chArray = new byte[1];
void GoNextChar()
{
streamPosition++;
chArray[0] = (byte)responseStream.ReadByte();
currentChar = Encoding.ASCII.GetChars(chArray)[0];
}
bool IsNewLine()
{
if (currentChar.Equals(DatadogHttpValues.CarriageReturn))
{
// end of headers
if (DatadogHttpValues.CrLfLength > 1)
{
// Skip the newline indicator
GoNextChar();
}
return(true);
}
return(false);
}
// Skip to status code
while (streamPosition < statusCodeStart)
{
GoNextChar();
}
// Read status code
while (streamPosition < statusCodeEnd)
{
GoNextChar();
stringBuilder.Append(currentChar);
}
var potentialStatusCode = stringBuilder.ToString();
stringBuilder.Clear();
if (!int.TryParse(potentialStatusCode, out var statusCode))
{
throw new DatadogHttpRequestException("Invalid response, can't parse status code. Line was:" + potentialStatusCode);
}
// Skip to reason
while (streamPosition < startOfReasonPhrase)
{
GoNextChar();
}
// Read reason
do
{
GoNextChar();
if (IsNewLine())
{
break;
}
stringBuilder.Append(currentChar);
}while (true);
var reasonPhrase = stringBuilder.ToString();
stringBuilder.Clear();
// Read headers
do
{
GoNextChar();
// Check for end of headers
if (IsNewLine())
{
// Empty line, content starts next
break;
}
// Read key
do
{
if (currentChar.Equals(':'))
{
// Value portion starts
break;
}
stringBuilder.Append(currentChar);
GoNextChar();
}while (true);
var name = stringBuilder.ToString().Trim();
stringBuilder.Clear();
// Read value
do
{
GoNextChar();
if (IsNewLine())
{
// Next header pair starts
break;
}
stringBuilder.Append(currentChar);
}while (true);
var value = stringBuilder.ToString().Trim();
stringBuilder.Clear();
headers.Add(name, value);
}while (true);
var length = long.TryParse(headers.GetValue(ContentLengthHeaderKey), out var headerValue) ? headerValue : (long?)null;
return(new HttpResponse(statusCode, reasonPhrase, headers, new StreamContent(responseStream, length)));
}
