Copied read/write from secio

libp2p/security/noise/connection.py

@@ -1,3 +1,5 @@
+import io
+
 from noise.connection import NoiseConnection as NoiseState
 
 from libp2p.crypto.keys import PrivateKey
@@ -8,6 +10,10 @@ from libp2p.security.noise.io import MsgReadWriter, NoiseTransportReadWriter
 
 
 class NoiseConnection(BaseSession):
+    buf: io.BytesIO
+    low_watermark: int
+    high_watermark: int
+
     read_writer: IRawConnection
     noise_state: NoiseState
 
@@ -19,20 +25,64 @@ class NoiseConnection(BaseSession):
         conn: IRawConnection,
         is_initiator: bool,
         noise_state: NoiseState,
+        # remote_permanent_pubkey
     ) -> None:
         super().__init__(local_peer, local_private_key, is_initiator, remote_peer)
         self.conn = conn
         self.noise_state = noise_state
+        self._reset_internal_buffer()
 
     def get_msg_read_writer(self) -> MsgReadWriter:
         return NoiseTransportReadWriter(self.conn, self.noise_state)
 
+    async def close(self) -> None:
+        await self.conn.close()
+
+    def _reset_internal_buffer(self) -> None:
+        self.buf = io.BytesIO()
+        self.low_watermark = 0
+        self.high_watermark = 0
+
+    def _drain(self, n: int) -> bytes:
+        if self.low_watermark == self.high_watermark:
+            return bytes()
+
+        data = self.buf.getbuffer()[self.low_watermark : self.high_watermark]
+
+        if n is None:
+            n = len(data)
+        result = data[:n].tobytes()
+        self.low_watermark += len(result)
+
+        if self.low_watermark == self.high_watermark:
+            del data  # free the memoryview so we can free the underlying BytesIO
+            self.buf.close()
+            self._reset_internal_buffer()
+        return result
+
     async def read(self, n: int = None) -> bytes:
-        # TODO: Use a buffer to handle buffered messages.
+        if n == 0:
+            return bytes()
+
+        data_from_buffer = self._drain(n)
+        if len(data_from_buffer) > 0:
+            return data_from_buffer
+
+        msg = await self.read_msg()
+
+        if n < len(msg):
+            self.buf.write(msg)
+            self.low_watermark = 0
+            self.high_watermark = len(msg)
+            return self._drain(n)
+        else:
+            return msg
+
+    async def read_msg(self) -> bytes:
         return await self.get_msg_read_writer().read_msg()
 
     async def write(self, data: bytes) -> None:
-        await self.get_msg_read_writer().write_msg(data)
+        await self.write_msg(data)
 
-    async def close(self) -> None:
-        await self.conn.close()
+    async def write_msg(self, msg: bytes) -> None:
+        await self.get_msg_read_writer().write_msg(msg)