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feat(core): TCP in the simulation core

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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>
This commit is contained in:
julian.kiedaisch
2026-09-30 10:03:16 +00:00
co-authored by Claude Opus 5.5
parent e80be3bbdf
commit 12849b1535
14 changed files with 20973 additions and 22 deletions
Download Patch File Download Diff File Expand all files Collapse all files
packages/core/test/scenarios/tcp-lan.scenario.json
+215
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{
"seed": 31,
"nodes": [
{
"id": "00000000-0000-0000-0000-000000000101",
"kind": "pc",
"ports": [
{
"id": "00000000-0000-0000-0000-000000000111",
"label": "eth0"
}
]
},
{
"id": "00000000-0000-0000-0000-000000000102",
"kind": "pc",
"ports": [
{
"id": "00000000-0000-0000-0000-000000000112",
"label": "eth0"
}
]
},
{
"id": "00000000-0000-0000-0000-000000000103",
"kind": "pc",
"ports": [
{
"id": "00000000-0000-0000-0000-000000000113",
"label": "eth0"
}
]
},
{
"id": "00000000-0000-0000-0000-000000000104",
"kind": "networkSwitch",
"ports": [
{
"id": "00000000-0000-0000-0000-000000000121",
"label": "sw1"
},
{
"id": "00000000-0000-0000-0000-000000000122",
"label": "sw2"
},
{
"id": "00000000-0000-0000-0000-000000000123",
"label": "sw3"
},
{
"id": "00000000-0000-0000-0000-000000000124",
"label": "sw4"
}
]
}
],
"links": [
{
"id": "00000000-0000-0000-0000-00000000F001",
"sourceNode": "00000000-0000-0000-0000-000000000101",
"sourcePort": "00000000-0000-0000-0000-000000000111",
"targetNode": "00000000-0000-0000-0000-000000000104",
"targetPort": "00000000-0000-0000-0000-000000000121"
},
{
"id": "00000000-0000-0000-0000-00000000F002",
"sourceNode": "00000000-0000-0000-0000-000000000102",
"sourcePort": "00000000-0000-0000-0000-000000000112",
"targetNode": "00000000-0000-0000-0000-000000000104",
"targetPort": "00000000-0000-0000-0000-000000000122"
},
{
"id": "00000000-0000-0000-0000-00000000F003",
"sourceNode": "00000000-0000-0000-0000-000000000103",
"sourcePort": "00000000-0000-0000-0000-000000000113",
"targetNode": "00000000-0000-0000-0000-000000000104",
"targetPort": "00000000-0000-0000-0000-000000000123"
}
],
"devices": {
"00000000-0000-0000-0000-000000000101": {
"ip": "192.168.0.10",
"mask": "255.255.255.0"
},
"00000000-0000-0000-0000-000000000102": {
"ip": "192.168.0.20",
"mask": "255.255.255.0"
},
"00000000-0000-0000-0000-000000000103": {
"ip": "192.168.0.30",
"mask": "255.255.255.0"
}
},
"switches": {
"00000000-0000-0000-0000-000000000104": {
"ssid": "lab",
"retention": 5000
}
},
"steps": [
{
"op": "openTcpServer",
"node": "00000000-0000-0000-0000-000000000101",
"port": 80
},
{
"op": "openTcpServer",
"node": "00000000-0000-0000-0000-000000000101",
"port": 80
},
{
"op": "openTcpClient",
"node": "00000000-0000-0000-0000-000000000102",
"target": "192.168.0.10",
"port": 80
},
{
"op": "connectTcp",
"socket": "00000000-0000-0000-0000-000000000002"
},
{
"op": "acceptedTcp",
"socket": "00000000-0000-0000-0000-000000000001"
},
{
"op": "peerTcp",
"socket": "00000000-0000-0000-0000-000000000002"
},
{
"op": "sendTcp",
"socket": "00000000-0000-0000-0000-000000000002",
"payload": "GET /"
},
{
"op": "receiveTcp",
"socket": "00000000-0000-0000-0000-000000000003"
},
{
"op": "sendTcp",
"socket": "00000000-0000-0000-0000-000000000003",
"payload": "x",
"repeatCount": 3000
},
{
"op": "receiveTcp",
"socket": "00000000-0000-0000-0000-000000000002"
},
{
"op": "receiveTcp",
"socket": "00000000-0000-0000-0000-000000000002"
},
{
"op": "closeSocket",
"socket": "00000000-0000-0000-0000-000000000002"
},
{
"op": "advance",
"to": 3000
},
{
"op": "closeSocket",
"socket": "00000000-0000-0000-0000-000000000003"
},
{
"op": "advance",
"to": 4000
},
{
"op": "advance",
"to": 8000
},
{
"op": "cleanTcp",
"socket": "00000000-0000-0000-0000-000000000002"
},
{
"op": "cleanTcp",
"socket": "00000000-0000-0000-0000-000000000001"
},
{
"op": "connectTcp",
"socket": "00000000-0000-0000-0000-000000000001"
},
{
"op": "openTcpClient",
"node": "00000000-0000-0000-0000-000000000103",
"target": "192.168.0.10",
"port": 81
},
{
"op": "sendTcp",
"socket": "00000000-0000-0000-0000-000000000004",
"payload": "ohne Verbindung"
},
{
"op": "connectTcp",
"socket": "00000000-0000-0000-0000-000000000004"
},
{
"op": "openTcpClient",
"node": "00000000-0000-0000-0000-000000000103",
"target": "192.168.0.99",
"port": 80,
"localPort": 5000
},
{
"op": "connectTcp",
"socket": "00000000-0000-0000-0000-000000000005"
},
{
"op": "closeSocket",
"socket": "00000000-0000-0000-0000-000000000001"
}
]
}