BNetBuffer: add some error checks.

The allocation of fImpl can fail, and some methods used it without
checking. Return an error code (or NULL or 0) instead of crashing in
these cases.

Also InitCheck the fInputBuffer in BHttpRequest before trying to use it.

Fixes #11350.

src/kits/network/libnetapi/HttpRequest.cpp

@@ -330,6 +330,10 @@ BHttpRequest::_ProtocolLoop()
 			port = fContext->GetProxyPort();
 		}
 
+		status_t result = fInputBuffer.InitCheck();
+		if (result != B_OK)
+			return result;
+
 		if (!_ResolveHostName(host, port)) {
 			_EmitDebug(B_URL_PROTOCOL_DEBUG_ERROR,
 				"Unable to resolve hostname (%s), aborting.",

src/kits/network/libnetapi/NetBuffer.cpp

@@ -185,6 +185,9 @@ BNetBuffer::AppendString(const char* data)
 status_t
 BNetBuffer::AppendData(const void* data, size_t size)
 {
+	if (fInit != B_OK)
+		return B_NO_INIT;
+
 	ssize_t bytesWritten = fImpl->Write(data, size);
 	if (bytesWritten < 0)
 		return (status_t)bytesWritten;
@@ -335,6 +338,9 @@ BNetBuffer::RemoveString(char* data, size_t size)
 status_t
 BNetBuffer::RemoveData(void* data, size_t size)
 {
+	if (fInit != B_OK)
+		return B_NO_INIT;
+
 	ssize_t bytesRead = fImpl->Read(data, size);
 	if (bytesRead < 0)
 		return (status_t)bytesRead;
@@ -345,6 +351,9 @@ BNetBuffer::RemoveData(void* data, size_t size)
 status_t
 BNetBuffer::RemoveMessage(BMessage& data)
 {
+	if (fInit != B_OK)
+		return B_NO_INIT;
+
 	unsigned char* bufferPtr = fImpl->Data();
 
 	if (*(int32*)bufferPtr != B_MESSAGE_TYPE)
@@ -398,6 +407,9 @@ BNetBuffer::RemoveUint64(uint64& data)
 unsigned char*
 BNetBuffer::Data() const
 {
+	if (fInit != B_OK)
+		return NULL;
+
 	return fImpl->Data();
 }
 
@@ -405,6 +417,9 @@ BNetBuffer::Data() const
 size_t
 BNetBuffer::Size() const
 {
+	if (fInit != B_OK)
+		return 0;
+
 	return fImpl->Size();
 }
 
@@ -412,6 +427,9 @@ BNetBuffer::Size() const
 size_t
 BNetBuffer::BytesRemaining() const
 {
+	if (fInit != B_OK)
+		return 0;
+
 	return fImpl->BytesRemaining();
 }