From b59c5d6ca11c8767a152a910666828f575644fc3 Mon Sep 17 00:00:00 2001
From: Alex Stokes <r.alex.stokes@gmail.com>
Date: Thu, 22 Aug 2019 17:54:49 +0200
Subject: [PATCH] Add "msgio" functions

---
 libp2p/io/__init__.py |  0
 libp2p/io/msgio.py    | 16 ++++++++++++++++
 2 files changed, 16 insertions(+)
 create mode 100644 libp2p/io/__init__.py
 create mode 100644 libp2p/io/msgio.py

diff --git a/libp2p/io/__init__.py b/libp2p/io/__init__.py
new file mode 100644
index 0000000..e69de29
diff --git a/libp2p/io/msgio.py b/libp2p/io/msgio.py
new file mode 100644
index 0000000..6ad11bc
--- /dev/null
+++ b/libp2p/io/msgio.py
@@ -0,0 +1,16 @@
+import asyncio
+
+SIZE_LEN_BYTES = 4
+
+# TODO unify w/ https://github.com/libp2p/py-libp2p/blob/1aed52856f56a4b791696bbcbac31b5f9c2e88c9/libp2p/utils.py#L85-L99
+
+
+def encode(msg_bytes: bytes) -> bytes:
+    len_prefix = len(msg_bytes).to_bytes(SIZE_LEN_BYTES, "big")
+    return len_prefix + msg_bytes
+
+
+async def read_next_message(reader: asyncio.StreamReader) -> bytes:
+    len_bytes = await reader.readexactly(SIZE_LEN_BYTES)
+    len_int = int.from_bytes(len_bytes, "big")
+    return await reader.readexactly(len_int)