1 files changed, 30 insertions, 0 deletions
diff --git a/payload.py b/payload.py
new file mode 100644
index 0000000..36f33ba
--- /dev/null
+++ b/payload.py
@@ -0,0 +1,30 @@
+
+import struct
+
+from twisted.internet.protocol import Protocol
+
+s32 = struct.Struct("<i")
+
+class PayloadStream(Protocol):
+	"""'Payloads' are length-prefixed binary blobs used in NetSockets."""
+	def __init__(self):
+		self.__length = None
+		self.__buffer = b""
+	def dataReceived(self, data):
+		self.__buffer += data
+		while True:
+			if self.__length is None and len(self.__buffer) >= 4:
+				self.__length = s32.unpack(self.__buffer[:4])[0]
+				self.__buffer = self.__buffer[4:]
+				if self.__length < 0:
+					raise ValueError(f"Invalid (negative) payload length {self.__length}")
+			if self.__length is not None and len(self.__buffer) >= self.__length:
+				payload = self.__buffer[:self.__length]
+				self.__buffer = self.__buffer[self.__length:]
+				self.__length = None
+				self.payloadReceived(payload)
+				continue
+			break
+	def sendPayload(self, data):
+		self.transport.write(s32.pack(len(data)) + data)
+