2 files changed, 241 insertions, 1 deletions

diff --git a/tests/integration/harness.py b/tests/integration/harness.py
index b98ce83..10aa6de 100644
--- a/tests/integration/harness.py
+++ b/tests/integration/harness.py
@@ -20,6 +20,9 @@ import urllib.error
 import urllib.parse
 import urllib.request
 
+# groupip_1 in src/ot_livesync.c
+LIVESYNC_GROUP = "224.0.23.5"
+
 TRACKER = os.environ.get("OPENTRACKER", os.path.join(os.path.dirname(__file__), "..", "..", "opentracker.debug"))
 
 
@@ -76,6 +79,9 @@ class Tracker:
 
     def __init__(self, extra_config="", files=None):
         self.port = free_port()
+        # Only used by a config that asks for live sync, but allocated either
+        # way so {livesync_port} always resolves.
+        self.livesync_port = free_port()
         self.dir = tempfile.mkdtemp(prefix="ot-integration-")
         self.log = None
         self.process = None
@@ -87,7 +93,7 @@ class Tracker:
             with open(self.config, "w") as handle:
                 handle.write("listen.tcp 127.0.0.1:%d\n" % self.port)
                 handle.write("listen.udp 127.0.0.1:%d\n" % self.port)
-                handle.write(extra_config.replace("{dir}", self.dir))
+                handle.write(extra_config.replace("{dir}", self.dir).replace("{livesync_port}", str(self.livesync_port)))
             self.log = open(os.path.join(self.dir, "tracker.log"), "w+b")
             # Leak detection is left at the sanitizer's own default, which is on
             # where LeakSanitizer exists and off where it does not. Asking for it
@@ -186,6 +192,32 @@ class Tracker:
     def torrent_count(self):
         return int(self.stats("torr").split()[0])
 
+    def livesync_send(self, payload, group=LIVESYNC_GROUP):
+        """Put a packet on the live sync group.
+
+        It has to go to the group rather than straight at the port: the
+        tracker binds two sockets there, the reader on the wildcard address
+        and the writer on the configured one, and the kernel gives a unicast
+        datagram to the more specific of the two, which nobody reads."""
+        sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
+        try:
+            sock.setsockopt(socket.IPPROTO_IP, socket.IP_MULTICAST_IF, socket.inet_aton("127.0.0.1"))
+            sock.setsockopt(socket.IPPROTO_IP, socket.IP_MULTICAST_LOOP, 1)
+            sock.setsockopt(socket.IPPROTO_IP, socket.IP_MULTICAST_TTL, 1)
+            sock.sendto(payload, (group, self.livesync_port))
+        finally:
+            sock.close()
+
+    def wait_until(self, predicate, timeout=5):
+        """A live sync packet is handled by another thread, so an effect of
+        one arrives some time after the send."""
+        deadline = time.time() + timeout
+        while time.time() < deadline:
+            if predicate():
+                return True
+            time.sleep(0.02)
+        return predicate()
+
     # ------------------------------------------------------------ over udp
 
     def udp_connect(self):
diff --git a/tests/integration/test_livesync.py b/tests/integration/test_livesync.py
new file mode 100644
index 0000000..52e871f
--- /dev/null
+++ b/tests/integration/test_livesync.py
@@ -0,0 +1,208 @@
+"""Live sync, driven over the multicast group a cluster would use.
+
+Live sync sits behind WANT_SYNC_LIVE, so these only run against a binary
+built with it: make check-livesync. Against any other build they skip, which
+is what the feature list in -v is for.
+"""
+
+import socket
+import struct
+import subprocess
+import unittest
+
+from harness import TRACKER, TrackerTestCase
+
+# enum { OT_SYNC_PEER4, OT_SYNC_PEER6 } in src/ot_livesync.c
+SYNC_PEER4 = 0
+SYNC_PEER6 = 1
+
+# src/trackerlogic.h
+FLAG_SEEDING = 0x80
+FLAG_COMPLETED = 0x40
+FLAG_STOPPED = 0x20
+
+
+def has_livesync():
+    done = subprocess.run([TRACKER, "-v"], capture_output=True, timeout=30)
+    return b"WANT_SYNC_LIVE" in done.stderr
+
+
+def peer4(address, port, flags):
+    """Four bytes of address, two of port, one of flags, one the tracker
+    overwrites with its own idea of the time."""
+    return socket.inet_aton(address) + struct.pack("!H", port) + bytes([flags, 0])
+
+
+def peer6(address, port, flags):
+    return socket.inet_pton(socket.AF_INET6, address) + struct.pack("!H", port) + bytes([flags, 0])
+
+
+def packet(kind, entries, tracker_id=0xDEADBEEF):
+    body = b"".join(info_hash + peer for info_hash, peer in entries)
+    return struct.pack("!I", tracker_id) + struct.pack("!I", kind) + body
+
+
+@unittest.skipUnless(has_livesync(), "this build has no WANT_SYNC_LIVE")
+class LiveSyncIn(TrackerTestCase):
+    config = "livesync.cluster.listen 127.0.0.1:{livesync_port}\nlivesync.cluster.node_ip 127.0.0.1\n"
+
+    def counts(self, info_hash):
+        """Seeders and leechers a scrape reports for one torrent."""
+        files = self.tracker.scrape(info_hash)[b"files"]
+        if info_hash not in files:
+            return None
+        entry = files[info_hash]
+        return entry[b"complete"], entry[b"incomplete"]
+
+    def test_a_synced_seeder_arrives(self):
+        info_hash = self.hash_for("sync-seed")
+        self.tracker.livesync_send(packet(SYNC_PEER4, [(info_hash, peer4("10.1.2.3", 6881, FLAG_SEEDING))]))
+        self.assertTrue(self.tracker.wait_until(lambda: self.counts(info_hash) == (1, 0)),
+                        "scrape says %r" % (self.counts(info_hash),))
+
+    def test_a_synced_leecher_arrives(self):
+        info_hash = self.hash_for("sync-leech")
+        self.tracker.livesync_send(packet(SYNC_PEER4, [(info_hash, peer4("10.1.2.4", 6881, 0))]))
+        self.assertTrue(self.tracker.wait_until(lambda: self.counts(info_hash) == (0, 1)),
+                        "scrape says %r" % (self.counts(info_hash),))
+
+    def test_a_v6_peer_arrives(self):
+        info_hash = self.hash_for("sync-v6")
+        self.tracker.livesync_send(packet(SYNC_PEER6, [(info_hash, peer6("2001:db8::1", 6881, FLAG_SEEDING))]))
+        self.assertTrue(self.tracker.wait_until(lambda: self.counts(info_hash) == (1, 0)),
+                        "scrape says %r" % (self.counts(info_hash),))
+
+    def test_one_packet_carries_several_torrents(self):
+        hashes = [self.hash_for("sync-many-%d" % i) for i in range(4)]
+        self.tracker.livesync_send(packet(SYNC_PEER4, [(h, peer4("10.1.2.%d" % (5 + i), 6881, FLAG_SEEDING))
+                                                       for i, h in enumerate(hashes)]))
+        self.assertTrue(self.tracker.wait_until(lambda: all(self.counts(h) == (1, 0) for h in hashes)))
+
+    def test_a_stopped_peer_is_taken_away_again(self):
+        info_hash = self.hash_for("sync-stop")
+        peer = peer4("10.1.2.9", 6881, FLAG_SEEDING)
+        self.tracker.livesync_send(packet(SYNC_PEER4, [(info_hash, peer)]))
+        self.assertTrue(self.tracker.wait_until(lambda: self.counts(info_hash) == (1, 0)))
+
+        self.tracker.livesync_send(packet(SYNC_PEER4, [(info_hash, peer4("10.1.2.9", 6881, FLAG_STOPPED))]))
+        self.assertTrue(self.tracker.wait_until(lambda: self.counts(info_hash) in (None, (0, 0))),
+                        "scrape still says %r" % (self.counts(info_hash),))
+
+    def test_a_truncated_entry_is_dropped(self):
+        """The loop takes whole hash and peer pairs and leaves a short tail
+        where it is, so the complete entry before it still lands."""
+        good, short = self.hash_for("sync-good"), self.hash_for("sync-short")
+        payload = packet(SYNC_PEER4, [(good, peer4("10.1.2.10", 6881, FLAG_SEEDING))]) + short + b"\x0a\x01"
+        self.tracker.livesync_send(payload)
+        self.assertTrue(self.tracker.wait_until(lambda: self.counts(good) == (1, 0)))
+        self.assertIsNone(self.counts(short))
+
+    def test_an_unknown_packet_type_is_ignored(self):
+        info_hash = self.hash_for("sync-unknown")
+        self.tracker.livesync_send(packet(99, [(info_hash, peer4("10.1.2.11", 6881, FLAG_SEEDING))]))
+        self.assertFalse(self.tracker.wait_until(lambda: self.counts(info_hash) is not None, timeout=1))
+
+    def test_synced_peers_are_counted(self):
+        """The live sync worker keeps its own tally like every other worker,
+        and ?mode=syncs is the sum of them."""
+        before = int(self.tracker.stats("syncs").split()[0])
+        hashes = [self.hash_for("sync-count-%d" % i) for i in range(3)]
+        self.tracker.livesync_send(packet(SYNC_PEER4, [(h, peer4("10.1.2.%d" % (20 + i), 6881, FLAG_SEEDING))
+                                                       for i, h in enumerate(hashes)]))
+        self.assertTrue(self.tracker.wait_until(
+            lambda: int(self.tracker.stats("syncs").split()[0]) == before + 3),
+            "syncs says %s" % self.tracker.stats("syncs").split()[0])
+
+    def test_a_packet_with_nothing_but_a_header_is_ignored(self):
+        before = self.tracker.torrent_count()
+        self.tracker.livesync_send(struct.pack("!I", 0xDEADBEEF) + struct.pack("!I", SYNC_PEER4))
+        self.assertFalse(self.tracker.wait_until(lambda: self.tracker.torrent_count() != before, timeout=1))
+
+
+@unittest.skipUnless(has_livesync(), "this build has no WANT_SYNC_LIVE")
+class LiveSyncAccess(TrackerTestCase):
+    """Nothing blesses 127.0.0.1 here, so the tracker should take nothing
+    from it. Source address checking is all live sync has."""
+
+    config = "livesync.cluster.listen 127.0.0.1:{livesync_port}\nlivesync.cluster.node_ip 10.0.0.1\n"
+
+    def test_an_unblessed_sender_is_ignored(self):
+        info_hash = self.hash_for("sync-unblessed")
+        self.tracker.livesync_send(packet(SYNC_PEER4, [(info_hash, peer4("10.1.2.12", 6881, FLAG_SEEDING))]))
+        self.assertFalse(self.tracker.wait_until(lambda: self.tracker.torrent_count() != 0, timeout=1))
+
+
+@unittest.skipUnless(has_livesync(), "this build has no WANT_SYNC_LIVE")
+class LiveSyncUnconfigured(TrackerTestCase):
+    """A binary that has the feature but no cluster to join. Somebody whose
+    packager turned WANT_SYNC_LIVE on did not ask for live sync and should
+    not be able to tell that it is there."""
+
+    config = ""
+
+    def test_the_tracker_runs_anyway(self):
+        info_hash = self.hash_for("no-cluster")
+        self.tracker.announce(info_hash, port=6881, left=0)
+        self.assertEqual(self.tracker.torrent_count(), 1)
+
+    def test_nothing_is_said_about_the_missing_cluster(self):
+        self.assertNotIn("sync", self.tracker.output().lower())
+
+    def test_no_socket_is_bound_for_it(self):
+        """A configured tracker holds the wildcard address on that port, so
+        taking it here proves nothing was started."""
+        sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
+        try:
+            sock.bind(("0.0.0.0", self.tracker.livesync_port))
+        finally:
+            sock.close()
+
+    def test_announcing_stays_clean(self):
+        """Enough announces to pass the watermark that would flush an
+        outgoing buffer, if there were one to flush. The sanitizers in this
+        build turn anything the attempt touched into a failure."""
+        for i in range(200):
+            self.tracker.announce(self.hash_for("no-cluster-%d" % i), port=6881 + i, left=0)
+        self.assertEqual(self.tracker.torrent_count(), 200)
+
+
+# RFC 2365 sets 239.192.0.0/14 aside for exactly this kind of use
+OWN_GROUP = "239.192.0.7"
+
+
+@unittest.skipUnless(has_livesync(), "this build has no WANT_SYNC_LIVE")
+class LiveSyncGroup(TrackerTestCase):
+    config = ("livesync.cluster.group %s\n"
+              "livesync.cluster.listen 127.0.0.1:{livesync_port}\n"
+              "livesync.cluster.node_ip 127.0.0.1\n" % OWN_GROUP)
+
+    def test_the_configured_group_is_joined(self):
+        info_hash = self.hash_for("own-group")
+        self.tracker.livesync_send(packet(SYNC_PEER4, [(info_hash, peer4("10.1.3.1", 6881, FLAG_SEEDING))]),
+                                   group=OWN_GROUP)
+        self.assertTrue(self.tracker.wait_until(lambda: self.tracker.torrent_count() == 1))
+
+    def test_the_default_group_is_left_alone(self):
+        """A cluster that picked its own group should not hear the one every
+        other opentracker is on."""
+        info_hash = self.hash_for("not-our-group")
+        self.tracker.livesync_send(packet(SYNC_PEER4, [(info_hash, peer4("10.1.3.2", 6881, FLAG_SEEDING))]))
+        self.assertFalse(self.tracker.wait_until(lambda: self.tracker.torrent_count() != 0, timeout=1))
+
+
+@unittest.skipUnless(has_livesync(), "this build has no WANT_SYNC_LIVE")
+class LiveSyncGroupRefused(TrackerTestCase):
+    """A unicast address is not a group. The line is refused like any other
+    bad config line, which leaves the default standing."""
+
+    config = ("livesync.cluster.group 10.0.0.1\n"
+              "livesync.cluster.listen 127.0.0.1:{livesync_port}\n"
+              "livesync.cluster.node_ip 127.0.0.1\n")
+
+    def test_the_line_is_refused(self):
+        self.assertIn("Parse error", self.tracker.output())
+
+    def test_and_the_default_group_still_works(self):
+        info_hash = self.hash_for("fallback-group")
+        self.tracker.livesync_send(packet(SYNC_PEER4, [(info_hash, peer4("10.1.3.3", 6881, FLAG_SEEDING))]))
+        self.assertTrue(self.tracker.wait_until(lambda: self.tracker.torrent_count() == 1))