test: a sixth fuzz target for the cron parsers, and tailnet address coverage

.github/workflows/fuzz.yml

@@ -43,7 +43,7 @@ jobs:
     strategy:
       fail-fast: false   # fuzz every target even if one finds a crash, so all findings surface
       matrix:
-        target: [ game_status, firewall, config, fail2ban, console ]
+        target: [ game_status, firewall, config, fail2ban, console, cron ]
     steps:
       - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7
 

tests/fuzz/corpus/cron/ansi_error

@@ -0,0 +1 @@
+G1szMW1FUlJPUhtbMG06IHVwZGF0ZSBmYWlsZWQNCnJldHJ5DQo=

tests/fuzz/corpus/cron/at_reboot

@@ -0,0 +1 @@
+@reboot /home/gmserver/gmserver start

tests/fuzz/corpus/cron/b64_broken

@@ -0,0 +1 @@
+not valid base64 !!!

tests/fuzz/corpus/cron/b64_status

@@ -0,0 +1 @@
+ZmV0Y2hpbmcgWyB4LmNzdiBdY3VybDogKDIyKSA0MDQKRVJST1IK

tests/fuzz/corpus/cron/comment

@@ -0,0 +1,3 @@
+# a comment line
+
+*/5 * * * * echo hi

tests/fuzz/corpus/cron/daily_restart

@@ -0,0 +1 @@
+0 5 * * * touch /home/gmserver/.restart-pending

tests/fuzz/corpus/cron/many_fields

@@ -0,0 +1 @@
+* * * * * * * * * * /home/gm/gmserver monitor

tests/fuzz/corpus/cron/monitor

@@ -0,0 +1 @@
+*/5 * * * * /home/gmserver/gmserver monitor

tests/fuzz/corpus/cron/names

@@ -0,0 +1 @@
+0 5 * * mon /home/gm/gmserver backup

tests/fuzz/corpus/cron/no_schedule

@@ -0,0 +1 @@
+just some text with no cron fields at all

tests/fuzz/corpus/cron/wrapped

@@ -0,0 +1 @@
+*/5 * * * * /usr/bin/flock -n /tmp/x /home/gm/.lgsm-cron-rec 3f2a /home/gm/gmserver update

tests/fuzz/fuzz_cron.py

@@ -0,0 +1,54 @@
+#!/usr/bin/env python3
+"""Atheris fuzz harness: the crontab / cron-status parsers (ssh_manager).
+
+Everything these read comes off a REMOTE host: the game user's crontab, and the base64-framed
+status blob the panel's own cron wrapper writes after each run. Both are outside the panel's
+control — a crontab can be edited by hand on the box, and the status blob carries whatever a
+LinuxGSM command printed to stderr, which for an update means text fetched off the internet.
+
+The Scheduled Tasks page renders all of it, and the panel's cron-status path has already produced
+one real bug this way (a `tr` that missed \\r truncated every record at the transport, so errors
+silently read as empty). These parsers are best-effort and must never raise: a crash here takes
+out the whole page rather than one row.
+
+Run locally (from anywhere):
+    pip install atheris
+    python tests/fuzz/fuzz_cron.py -max_total_time=60 tests/fuzz/corpus/cron
+"""
+import importlib
+import os
+import sys
+
+import atheris
+
+# Running `python tests/fuzz/fuzz_x.py` puts tests/fuzz (not the project root) on sys.path.
+sys.path.insert(0, os.path.dirname(os.path.dirname(os.path.dirname(os.path.abspath(__file__)))))
+
+# Pre-load ssh_manager's heavy dependencies UNINSTRUMENTED so instrument_imports() covers only the
+# parsers (faster, and the coverage signal stays on target).
+for _dep in ("paramiko", "eventlet.tpool", "config"):
+    importlib.import_module(_dep)
+
+with atheris.instrument_imports():
+    import ssh_manager
+
+
+def TestOneInput(data):
+    fdp = atheris.FuzzedDataProvider(data)
+    text = fdp.ConsumeUnicodeNoSurrogates(fdp.remaining_bytes())
+
+    ssh_manager._split_cron_line(text)              # "*/5 * * * * cmd" -> (schedule, command)
+    ssh_manager._unwrap_cron_command(text)          # strips the panel's recorder wrapper
+    ssh_manager._cron_role(text, "gm", "gmserver")  # autostart / daily-restart label
+    ssh_manager._cron_line_managed(text, "gm", "gmserver")
+    ssh_manager._cron_log_text(text)                # lenient base64 decode of a status blob
+    ssh_manager._clean_cron_error(text)             # terminal-render + trim for display
+
+
+def main():
+    atheris.Setup(sys.argv, TestOneInput)
+    atheris.Fuzz()
+
+
+if __name__ == "__main__":
+    main()

tests/unit_test.py

@@ -3289,6 +3289,40 @@ def _fake_post(url, data, headers):
 finally:
     N._cfg = _sv_cfg2
 
+# ── Tailscale address recognition ──────────────────────────────────────────────────────────────
+# is_tailscale_ip decides whether the panel treats a host as being on the tailnet, which changes
+# how it connects and what it exempts from fail2ban/UFW. A false positive would exempt a PUBLIC
+# address from the security rules, so the near-misses matter as much as the hits.
+import tailscale_integration as TS
+
+for _h in ("100.64.0.1", "100.115.92.7", "fd7a:115c:a1e0::1",
+           "ns106051.taile87e07.ts.net", "box.tail1234.ts.net", "host.taile87e07.example"):
+    check("tailnet: %r is recognised" % _h, TS.is_tailscale_ip(_h) is True)
+for _h in ("10.0.0.1", "192.168.1.5", "1.100.0.1", "203.0.113.9", "example.ts.net.evil.com",
+           "fd7b:115c::1", "", None, "100abc.example.com"):
+    check("tailnet: %r is NOT taken for a tailnet address" % (_h,), TS.is_tailscale_ip(_h) is False)
+
+# get_magic_url: the port is omitted for the standard ones and appended otherwise, and there is no
+# URL at all when the node has no MagicDNS name (rather than a broken "https://None").
+_sv_info = TS.get_tailscale_info
+try:
+    class _Info(object):
+        def __init__(self, dns): self.dns_name, self.tailscale_ips, self.peers = dns, [], []
+    TS.get_tailscale_info = lambda *a, **k: _Info("box.taile87e07.ts.net")
+    eq("magic url: no port for https", TS.get_magic_url(), "https://box.taile87e07.ts.net")
+    eq("magic url: 443 is left off", TS.get_magic_url(443), "https://box.taile87e07.ts.net")
+    eq("magic url: 80 is left off too", TS.get_magic_url(80), "https://box.taile87e07.ts.net")
+    eq("magic url: any other port is appended", TS.get_magic_url(5000),
+       "https://box.taile87e07.ts.net:5000")
+    eq("magic url: the protocol is honoured", TS.get_magic_url(8080, "http"),
+       "http://box.taile87e07.ts.net:8080")
+    TS.get_tailscale_info = lambda *a, **k: _Info("")
+    eq("magic url: no MagicDNS name means no URL, not a broken one", TS.get_magic_url(), None)
+finally:
+    TS.get_tailscale_info = _sv_info
+
+check("tailnet: the panel can name the OS user it runs as", bool(TS._current_os_user()))
+
 passed = sum(1 for ok, _, _ in results if ok)
 for ok, name, detail in results:
     line = ("PASS" if ok else "FAIL") + "  " + name