From 4a800e5c56a3f9c1090cab7c0e29f2446d3b9df2 Mon Sep 17 00:00:00 2001
From: Alex Stokes <r.alex.stokes@gmail.com>
Date: Tue, 24 Sep 2019 18:21:04 -0700
Subject: [PATCH] Add first-pass at `ping` protocol

---
 libp2p/host/ping.py | 41 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 41 insertions(+)
 create mode 100644 libp2p/host/ping.py

diff --git a/libp2p/host/ping.py b/libp2p/host/ping.py
new file mode 100644
index 0000000..a01609d
--- /dev/null
+++ b/libp2p/host/ping.py
@@ -0,0 +1,41 @@
+import logging
+
+from libp2p.network.stream.net_stream_interface import INetStream
+from libp2p.peer.id import ID
+
+ID = "/ipfs/ping/1.0.0"
+PING_LENGTH = 32
+RESP_TIMEOUT = 60
+
+logger = logging.getLogger("libp2p.host.ping")
+
+
+async def _handle_ping(stream: INetStream, peer_id: ID) -> None:
+    try:
+        payload = await asyncio.wait_for(stream.read(PING_LENGTH), RESP_TIMEOUT)
+    except asyncio.TimeoutError as error:
+        logger.debug("Timed out waiting for ping from %s: %s", peer_id, error)
+        raise
+    # TODO: handle the other end closing the stream
+    except Exception as error:
+        logger.debug("Error while waiting to read ping for %s: %s", peer_id, error)
+        raise
+
+    logger.debug("Received ping from %s with data: 0x%s", peer_id, payload.hex())
+
+    await stream.write(payload)
+
+
+async def handle_ping(self, stream: INetStream) -> None:
+    """
+    ``handle_ping`` responds to incoming ping requests until one side
+    errors or closes the ``stream``.
+    """
+    peer_id = stream.muxed_conn.peer_id
+
+    while True:
+        try:
+            await _handle_ping(stream, peer_id)
+        except Exception:
+            await stream.reset()
+            return