dcrubro
0e90f7d5db
Root cause: peers were keyed only by (IP, listen port). An IPv6 host holds several addresses at once, so one node appeared as several peers and could not recognise its own addresses. Protocol: - Added a random per-run node identity (localNodeId), advertised as a length-guarded trailing field in HELLO and ACK_HELLO — backwards compatible with peers that omit it - Added peerNodeId to tcp_connection_t; peers are now identified by this rather than by an endpoint - ACK_HELLO is now sent before any decision to drop the connection, so a rejected dialer learns whose address it reached instead of retrying forever Self-connection: - Identity match → close the connection and record that endpoint permanently as our own - Self-endpoint set preemptively seeded from getifaddrs() at startup, so a node knows its own addresses before ever dialing one - Node_ConnectPeer refuses self endpoints, which also kills the echo-back chain that could exhaust connection slots Duplicate connections and churn: - Dedup by identity per direction — one inbound and one outbound per physical peer, regardless of how many addresses it has - Moved dial history out of the peer table, so striking a peer no longer resets its connect-retry cooldown (this was the loop engine: strike → re-learn via gossip → redial next tick) - Node_HasOtherInboundFrom / Node_HasLiveConnectionTo now ignore connections that are already tearing down, and match on identity as well as endpoint Gossip hygiene: - Never hand a peer its own other addresses in a PEERS reply (matched on identity, not just the socket address) - Reject unusable endpoints: link-local without scope id, unspecified, multicast, site-local (loopback stays allowed for local testing) - Normalise IPv4-mapped IPv6 so one host cannot occupy two entries Two bugs found along the way: - All nodes drew the same identity — random_eight_byte() comes from srand(time(NULL)), so processes started in the same second produced identical values. Added random_secure_eight_byte() (/dev/urandom) for the identity, and mixed the pid into the seed so connection IDs stop colliding too - Identity dedup initially left inbound-only nodes mute — broadcasts traverse outbound connections only, so suppressing a dial-back because an inbound existed would have silenced such a node. Corrected to per-direction Other: - peers output now shows each entry's node identity and the node's own endpoints - Added _DEFAULT_SOURCE to the build so getifaddrs() stays visible on glibc
46 lines
2.7 KiB
C
46 lines
2.7 KiB
C
#ifndef NODEDISCOVERY_H
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#define NODEDISCOVERY_H
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#include <nets/net_node.h>
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#include <udpd/udpnode.h>
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// Create/destroy the peer-discovery state. Owns the known-peer table and its lock.
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node_discovery_t* NodeDiscovery_Create(net_node_t* node, udp_node_t* udpNode);
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void NodeDiscovery_Destroy(node_discovery_t* disc);
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// Periodic tick (driven by the node maintenance thread): seed currently-connected peers,
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// UDP-ping newly-learned ones, query a couple of connected peers for more, and connect to
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// the reachable peers with the lowest ping until we reach the target connection count.
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void NodeDiscovery_Iterate(node_discovery_t* disc);
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// UDP latency callbacks (forwarded from the udp node via net_node thunks).
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void NodeDiscovery_OnPong(node_discovery_t* disc, const struct sockaddr_storage* from, uint64_t nonce, uint64_t rttMs);
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void NodeDiscovery_OnPingTimeout(node_discovery_t* disc, const struct sockaddr_storage* dest, uint64_t nonce);
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// TCP peer-exchange handlers (called from the net_node packet dispatch).
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// Build a PEERS response (a sample of our peers, excluding the requester) and send it over fromConn.
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void NodeDiscovery_OnGetPeers(node_discovery_t* disc, tcp_connection_t* fromConn);
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// Decode a received PEERS payload and fold a couple of its endpoints into the known-peer table.
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void NodeDiscovery_OnPeersReceived(node_discovery_t* disc, tcp_connection_t* fromConn, const unsigned char* payload, size_t payloadLen);
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// Strike a peer (by its listen endpoint) from the known-peer table. Called when a peer becomes
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// logically disconnected (no remaining connection to it).
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void NodeDiscovery_RemovePeer(node_discovery_t* disc, const struct sockaddr_storage* endpoint);
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// Record the node identity behind an endpoint (learned from a completed HELLO/ACK_HELLO). Entries
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// carrying an identity we are already connected to are skipped by the connect picker, which is what
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// stops a multi-homed peer from being dialed once per address it is reachable on.
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void NodeDiscovery_NoteIdentity(node_discovery_t* disc, const struct sockaddr_storage* endpoint, uint64_t nodeId);
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// Mark an endpoint as one of our own, permanently. Self endpoints are never added to the known-peer
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// table, never pinged and never dialed. Seeded from the local interface addresses at creation and
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// extended whenever a handshake turns out to come from ourselves.
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void NodeDiscovery_MarkSelfEndpoint(node_discovery_t* disc, const struct sockaddr_storage* endpoint);
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// Returns non-zero if the endpoint is known to be one of our own.
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int NodeDiscovery_IsSelfEndpoint(node_discovery_t* disc, const struct sockaddr_storage* endpoint);
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// Dump the known-peer table to stdout (for the CLI `peers` command).
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void NodeDiscovery_PrintPeers(node_discovery_t* disc);
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#endif
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