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fix(p2p): harden hello payload validation against malformed payloads … #140

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fix(p2p): harden hello payload validation against malformed payloads … #140

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34 changes: 31 additions & 3 deletions main.py
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Original file line number Diff line number Diff line change
Expand Up @@ -193,10 +193,28 @@ async def handler(data):
payload = data.get("data")
peer_addr = data.get("_peer_addr", "unknown")

if payload is None and msg_type in ("hello", "chain_request", "chain_response"):
return
if payload is None and msg_type in ("chain_request", "chain_response"):
return None

if msg_type in ("chain_request", "chain_response") and not isinstance(payload, dict):
logger.warning(
"Malformed %s from %s: payload is not a dict (got %s).",
msg_type, peer_addr, type(payload).__name__
)
return None

# Note: a null payload in a hello message deliberately falls through
# to the isinstance(payload, dict) guard below, which disconnects the peer.

if msg_type == "hello":
if not isinstance(payload, dict):
logger.warning(
"Malformed hello from %s: payload is not a dict (got %s). Disconnecting.",
peer_addr, type(payload).__name__
)
asyncio.create_task(network.disconnect_peer(peer_addr))
return ValidationStatus.MALFORMED

peer_chain_id = payload.get("chain_id")
peer_gen_hash = payload.get("genesis_hash")
if peer_chain_id != chain.chain_id:
Expand All @@ -208,8 +226,18 @@ async def handler(data):
asyncio.create_task(network.disconnect_peer(peer_addr))
return

logger.info("🔄 Handshake successful with %s", peer_addr)
peer_tip = payload.get("latest_block_index", 0)

if not isinstance(peer_tip, int) or isinstance(peer_tip, bool) or peer_tip < 0:
invalid_val = peer_tip if isinstance(peer_tip, int) and not isinstance(peer_tip, bool) else type(peer_tip).__name__
logger.warning(
"Malformed hello from %s: latest_block_index is not a valid integer (got %s). Disconnecting.",
peer_addr, invalid_val
)
asyncio.create_task(network.disconnect_peer(peer_addr))
return ValidationStatus.MALFORMED

logger.info("🔄 Handshake successful with %s", peer_addr)
if peer_tip > chain.last_block.index:
logger.info("📡 Peer %s is ahead (%d > %d). Initiating chunked sync...", peer_addr, peer_tip, chain.last_block.index)
request_chain(network, chain.last_block.index + 1, 500)
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