engine.ts ports Swift's "Java-compatible TCP sockets" in one piece, since
half a state machine could not be checked: server and client sockets (a
free port from Java's random numbers on their own seed), the three-way
handshake with its result (connected, invalid socket, unreachable, timed
out), segments of 1460 bytes, messages up to the push, a timeout of
3 × 2.5 s with at most three attempts, closing through every Java state
including TIME_WAIT (2.5 s), sequence numbers modulo 2^32.
Three scenarios match the Swift engine trace for trace: a LAN with data
over three segments, closing from both ends, a closed port and an
unreachable host; two networks through a router with a firewall rule,
data lost until the connection closes, and an accepted socket that does
not hold the port of its closed listener; CLOSING, reached by a lost FIN.
The engine delivers a FIN within the same close, so both ends close at
once only with packet loss; an empty message does not arrive in Swift (it
does not advance the sequence number), nor here.
Swift's four TCP engine tests are ported, with tests for stopping, a
foreign SYN+ACK at a listener and the flag names. 17 mutation probes, 16
caught; the other (delivered, not waited, not connected gives unreachable)
cannot be reached through Swift's engine, which never sends a reset and
always acknowledges correctly.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
engine.ts ports the UDP part of Swift's "UDP sockets and Router RIP": a
socket bound to a given port or to a free one drawn from 49152–65534 with
Java's random numbers on Swift's seed; sending, also as a limited broadcast
on every interface (or the bound one) with TTL 1; delivery into the queue
of every socket on the destination port, which then answers to the last
sender; receiving, with a timeout that advances the virtual clock; closing.
Stopping forgets sockets and queues. RIP stays not ported; Swift's DHCP
handling of a datagram has nothing to do until DHCP is in the snapshot.
The oracle gets the steps bindUdp, sendUdp, receiveUdp and closeSocket on
both sides and reports the sockets. Two new scenarios — a LAN, and two
networks through a router with a UDP firewall rule and a broadcast that
does not cross it — match the Swift engine trace for trace, the random
ports included. Swift's four UDP engine tests are ported, with a test for
stopping. 11 mutation probes were all caught (one only after the stop test
was added).
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
julian.kiedaischandClaude Opus 5.5