[Bug] Memory leak in seen_outbound_block_requests

[elderhammer]

🐛 Bug Report

seen_outbound_block_requests may contain some old requests and never be cleaned up.

2024-06-23T15:27:56.042427Z DEBUG snarkos_node_router::helpers::cache: Block requests: {127.0.0.1:4132: {BlockRequest { start_height: 3517, end_height: 3518 }}, 127.0.0.1:42031: {}, 127.0.0.1:4203: {BlockRequest { start_height: 211, end_height: 216 }, BlockRequest { start_height: 21, end_height: 26 }, BlockRequest { start_height: 41, end_height: 46 }, BlockRequest { start_height: 61, end_height: 66 }, BlockRequest { start_height: 11, end_height: 16 }, BlockRequest { start_height: 121, end_height: 126 }, BlockRequest { start_height: 181, end_height: 186 }, BlockRequest { start_height: 186, end_height: 191 }, BlockRequest { start_height: 1, end_height: 6 }, BlockRequest { start_height: 116, end_height: 121 }, BlockRequest { start_height: 101, end_height: 106 }, BlockRequest { start_height: 126, end_height: 131 }, BlockRequest { start_height: 196, end_height: 201 }, BlockRequest { start_height: 216, end_height: 221 }, BlockRequest { start_height: 146, end_height: 151 }, BlockRequest { start_height: 26, end_height: 31 }, BlockRequest { start_height: 36, end_height: 41 }, BlockRequest { start_height: 221, end_height: 226 }, BlockRequest { start_height: 16, end_height: 21 }, BlockRequest { start_height: 96, end_height: 101 }, BlockRequest { start_height: 66, end_height: 71 }, BlockRequest { start_height: 111, end_height: 116 }, BlockRequest { start_height: 51, end_height: 56 }, BlockRequest { start_height: 136, end_height: 141 }, BlockRequest { start_height: 206, end_height: 211 }, BlockRequest { start_height: 226, end_height: 231 }, BlockRequest { start_height: 71, end_height: 76 }}}
...
2024-06-23T15:58:41.527649Z DEBUG snarkos_node_router::helpers::cache: Block requests: {127.0.0.1:42031: {}, 127.0.0.1:4201: {}, 127.0.0.1:4132: {BlockRequest { start_height: 10434, end_height: 10435 }}, 127.0.0.1:4203: {BlockRequest { start_height: 211, end_height: 216 }, BlockRequest { start_height: 21, end_height: 26 }, BlockRequest { start_height: 41, end_height: 46 }, BlockRequest { start_height: 61, end_height: 66 }, BlockRequest { start_height: 11, end_height: 16 }, BlockRequest { start_height: 121, end_height: 126 }, BlockRequest { start_height: 181, end_height: 186 }, BlockRequest { start_height: 186, end_height: 191 }, BlockRequest { start_height: 1, end_height: 6 }, BlockRequest { start_height: 116, end_height: 121 }, BlockRequest { start_height: 101, end_height: 106 }, BlockRequest { start_height: 126, end_height: 131 }, BlockRequest { start_height: 196, end_height: 201 }, BlockRequest { start_height: 216, end_height: 221 }, BlockRequest { start_height: 146, end_height: 151 }, BlockRequest { start_height: 26, end_height: 31 }, BlockRequest { start_height: 36, end_height: 41 }, BlockRequest { start_height: 221, end_height: 226 }, BlockRequest { start_height: 16, end_height: 21 }, BlockRequest { start_height: 96, end_height: 101 }, BlockRequest { start_height: 66, end_height: 71 }, BlockRequest { start_height: 111, end_height: 116 }, BlockRequest { start_height: 51, end_height: 56 }, BlockRequest { start_height: 136, end_height: 141 }, BlockRequest { start_height: 206, end_height: 211 }, BlockRequest { start_height: 226, end_height: 231 }, BlockRequest { start_height: 71, end_height: 76 }}}

Steps to Reproduce

1. When sending a block request to a peer, the block request will be recorded
   

   snarkOS/node/router/src/outbound.rs

   Lines 60 to 63 in 09aa62b

   	// If the message type is a block request, add it to the cache.
   	if let Message::BlockRequest(request) = message {
   	self.router().cache.insert_outbound_block_request(peer_ip, request);
   	}

2. The peer closes the connection
3. Since no block response will be received, the block request will not be cleaned up
   

   snarkOS/node/router/src/inbound.rs

   Lines 111 to 114 in 09aa62b

   	// Remove the block request, checking if this node previously sent a block request to this peer.
   	if !self.router().cache.remove_outbound_block_request(peer_ip, &request) {
   	bail!("Peer '{peer_ip}' is not following the protocol (unexpected block response)")
   	}

Expected Behavior

This shouldn't happen.

Your Environment

snarkOS Version: 5d4de02