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Johnathan Corgan
6def31bcf6
The accept_connections gate at the top of handle_msg1 was applied unconditionally, so rekey msg1 from a peer with whom an established link already existed was dropped on the same path as fresh handshakes from strangers. Combined with the dual-init tie-breaker, this deadlocked at ~25 minutes when both sides' rekey timers fired near-simultaneously: the smaller-NodeAddr side wins as initiator and expects the larger side to consume its rekey msg1, but if the larger side has accept_connections=false the gate dropped it. Both sides retried at 1 Hz indefinitely; the affected peer fell out of MMP-active rotation. Extract the gate decision into Node::should_admit_msg1, which admits unconditionally when addr_to_link already has an entry for the (transport_id, remote_addr) pair (rekey/restart on an established session) and otherwise consults the transport's accept_connections(). Fresh msg1 from strangers is still rejected before any Noise crypto. Three unit tests pin the truth table: no transport (admit), accept_off no-link (reject, behavior unchanged), accept_off with-link (admit, the carve-out). The fix generalizes for free to BLE, which has the same Node-level gate. TCP and Tor were never subject to this deadlock because their accept condition is runtime state (bind_addr.is_some() / onion_address.is_some()), not a config flag.