private async Task <HttpResponse> ReadResponseAsync(Stream responseStream)
{
var headers = new HttpHeaders();
char currentChar = char.MinValue;
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;
const int bufferSize = 10;
// TODO: Get this from StringBuilderCache after we determine safe maximum capacity
var stringBuilder = new StringBuilder();
var chArray = new byte[bufferSize];
async Task GoNextChar()
{
var bytesRead = await responseStream.ReadAsync(chArray, offset : 0, count : 1).ConfigureAwait(false);
if (bytesRead == 0)
{
ThrowHelper.ThrowInvalidOperationException($"Unexpected end of stream at position {streamPosition}");
}
currentChar = Encoding.ASCII.GetChars(chArray)[0];
streamPosition++;
}
async Task SkipUntil(int requiredStreamPosition)
{
var requiredBytes = requiredStreamPosition - streamPosition;
if (requiredBytes < 0)
{
ThrowHelper.ThrowArgumentOutOfRangeException("StreamPosition already exceeds requiredStreamPosition", nameof(requiredStreamPosition));
}
var bytesRemaining = requiredBytes;
var lastBytesRead = 0;
while (bytesRemaining > 0)
{
var bytesToRead = Math.Min(bytesRemaining, bufferSize);
lastBytesRead = await responseStream.ReadAsync(chArray, offset : 0, count : bytesToRead).ConfigureAwait(false);
if (lastBytesRead == 0)
{
ThrowHelper.ThrowInvalidOperationException($"Unexpected end of stream at position {streamPosition}");
}
bytesRemaining -= lastBytesRead;
}
currentChar = Encoding.ASCII.GetChars(chArray)[lastBytesRead - 1];
streamPosition += requiredBytes;
}
async Task ReadUntil(StringBuilder builder, char stopChar)
{
while (!currentChar.Equals(stopChar))
{
builder.Append(currentChar);
await GoNextChar().ConfigureAwait(false);
}
}
async Task ReadUntilNewLine(StringBuilder builder)
{
do
{
if (await IsNewLine().ConfigureAwait(false))
{
break;
}
await ReadUntil(builder, DatadogHttpValues.CarriageReturn).ConfigureAwait(false);
}while (true);
}
async Task <bool> IsNewLine()
{
if (currentChar.Equals(DatadogHttpValues.CarriageReturn))
{
// end of headers
// Next character should be a LineFeed, regardless of Linux/Windows
// Skip the newline indicator
await GoNextChar().ConfigureAwait(false);
if (!currentChar.Equals(DatadogHttpValues.LineFeed))
{
ThrowHelper.ThrowException($"Unexpected character {currentChar} in headers: CR must be followed by LF");
}
return(true);
}
return(false);
}
// Skip to status code
await SkipUntil(statusCodeStart).ConfigureAwait(false);
// Read status code
while (streamPosition < statusCodeEnd)
{
await GoNextChar().ConfigureAwait(false);
stringBuilder.Append(currentChar);
}
var potentialStatusCode = stringBuilder.ToString();
stringBuilder.Clear();
if (!int.TryParse(potentialStatusCode, out var statusCode))
{
DatadogHttpRequestException.Throw("Invalid response, can't parse status code. Line was:" + potentialStatusCode);
}
// Skip to reason
await SkipUntil(startOfReasonPhrase).ConfigureAwait(false);
// Read reason
await GoNextChar().ConfigureAwait(false);
await ReadUntilNewLine(stringBuilder).ConfigureAwait(false);
var reasonPhrase = stringBuilder.ToString();
stringBuilder.Clear();
// Read headers
do
{
await GoNextChar().ConfigureAwait(false);
// Check for end of headers
if (await IsNewLine().ConfigureAwait(false))
{
// Empty line, content starts next
break;
}
// Read key
await ReadUntil(stringBuilder, stopChar : ':').ConfigureAwait(false);
var name = stringBuilder.ToString().Trim();
stringBuilder.Clear();
// skip separator
await GoNextChar().ConfigureAwait(false);
// Read value
await ReadUntilNewLine(stringBuilder).ConfigureAwait(false);
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)));
}
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)));
}