HttpRequest: simplify and optimize receiving loop

* Do not start with a ridiculously small buffer for socket reads.
Sockets return data they have available, instead of trying to fill as
much of the buffer as possible. In some cases a single Ethernet frame
can hold a complete request.
* Remove some looping and try parsing all the request in sequence each
time we receive some bytes.
* Avoid reallocating a temporary buffer each time we read some data from
the socket. Instead, allocate it once, and grow it as needed. Since
servers usually send chunks of equal size, we should get away with one
reallocation on the first chunk.

src/kits/network/libnetapi/HttpRequest.cpp

@@ -463,6 +463,7 @@ BHttpRequest::_MakeRequest()
 					it.MultipartHeader().Length());
 
 				switch (currentField->Type()) {
+					default:
 					case B_HTTPFORM_UNKNOWN:
 						ASSERT(0);
 						break;
@@ -486,9 +487,9 @@ BHttpRequest::_MakeRequest()
 								readSize = upFile.Read(readBuffer,
 									sizeof(readBuffer));
 							}
-						}
-						break;
 
+							break;
+						}
 					case B_HTTPFORM_BUFFER:
 						fSocket->Write(currentField->Buffer(),
 							currentField->BufferSize());
@@ -539,18 +540,18 @@ BHttpRequest::_MakeRequest()
 	bool parseEnd = false;
 	bool readByChunks = false;
 	bool readError = false;
-	int32 receiveBufferSize = 32;
 	ssize_t bytesRead = 0;
 	ssize_t bytesReceived = 0;
 	ssize_t bytesTotal = 0;
-	char* inputTempBuffer = NULL;
+	char* inputTempBuffer = new char[kHttpBufferSize];
+	ssize_t inputTempSize = kHttpBufferSize;
 	ssize_t chunkSize = -1;
 
 	while (!fQuit && !(receiveEnd && parseEnd)) {
 		if (!receiveEnd) {
 			fSocket->WaitForReadable();
-			BNetBuffer chunk(receiveBufferSize);
-			bytesRead = fSocket->Read(chunk.Data(), receiveBufferSize);
+			BNetBuffer chunk(kHttpBufferSize);
+			bytesRead = fSocket->Read(chunk.Data(), kHttpBufferSize);
 
 			if (bytesRead < 0) {
 				readError = true;
@@ -568,11 +569,12 @@ BHttpRequest::_MakeRequest()
 			//! ProtocolHook:ResponseStarted
 			if (fRequestStatus >= kRequestStatusReceived && fListener != NULL)
 				fListener->ResponseStarted(this);
-		} else if (fRequestStatus < kRequestHeadersReceived) {
+		}
+
+		if (fRequestStatus < kRequestHeadersReceived) {
 			_ParseHeaders();
 
 			if (fRequestStatus >= kRequestHeadersReceived) {
-				receiveBufferSize = kHttpBufferSize;
 				_ResultHeaders() = fHeaders;
 
 				//! ProtocolHook:HeadersReceived
@@ -598,7 +600,9 @@ BHttpRequest::_MakeRequest()
 				else
 					bytesTotal = 0;
 			}
-		} else {
+		}
+
+		if (fRequestStatus >= kRequestHeadersReceived) {
 			// If Transfer-Encoding is chunked, we should read a complete
 			// chunk in buffer before handling it
 			if (readByChunks) {
@@ -606,20 +610,23 @@ BHttpRequest::_MakeRequest()
 					if ((ssize_t)fInputBuffer.Size() >= chunkSize + 2) {
 							// 2 more bytes to handle the closing CR+LF
 						bytesRead = chunkSize;
-						inputTempBuffer = new char[chunkSize + 2];
+						if (inputTempSize < chunkSize + 2)
+						{
+							delete[] inputTempBuffer;
+							inputTempSize = chunkSize + 2;
+							inputTempBuffer = new char[inputTempSize];
+						}
 						fInputBuffer.RemoveData(inputTempBuffer,
 							chunkSize + 2);
 						chunkSize = -1;
 					} else {
 						// Not enough data, try again later
 						bytesRead = -1;
-						inputTempBuffer = NULL;
 					}
 				} else {
 					BString chunkHeader;
 					if (_GetLine(chunkHeader) == B_ERROR) {
 						chunkSize = -1;
-						inputTempBuffer = NULL;
 						bytesRead = -1;
 					} else {
 						// Format of a chunk header:
@@ -639,7 +646,6 @@ BHttpRequest::_MakeRequest()
 							fRequestStatus = kRequestContentReceived;
 
 						bytesRead = -1;
-						inputTempBuffer = NULL;
 					}
 				}
 
@@ -651,7 +657,11 @@ BHttpRequest::_MakeRequest()
 				bytesRead = fInputBuffer.Size();
 
 				if (bytesRead > 0) {
-					inputTempBuffer = new char[bytesRead];
+					if (inputTempSize < bytesRead) {
+						inputTempSize = bytesRead;
+						delete[] inputTempBuffer;
+						inputTempBuffer = new char[bytesRead];
+					}
 					fInputBuffer.RemoveData(inputTempBuffer, bytesRead);
 				}
 			}
@@ -667,8 +677,6 @@ BHttpRequest::_MakeRequest()
 
 				if (bytesTotal > 0 && bytesReceived >= bytesTotal)
 					receiveEnd = true;
-
-				delete[] inputTempBuffer;
 			}
 		}
 
@@ -676,6 +684,7 @@ BHttpRequest::_MakeRequest()
 	}
 
 	fSocket->Disconnect();
+	delete[] inputTempBuffer;
 
 	if (readError)
 		return B_PROT_READ_FAILED;