19 files changed, 1839 insertions, 148 deletions

diff --git a/tests/integration/.gitignore b/tests/integration/.gitignore
new file mode 100644
index 0000000..7a60b85
--- /dev/null
+++ b/tests/integration/.gitignore
@@ -0,0 +1,2 @@
+__pycache__/
+*.pyc
diff --git a/tests/integration/harness.py b/tests/integration/harness.py
new file mode 100644
index 0000000..03a0561
--- /dev/null
+++ b/tests/integration/harness.py
@@ -0,0 +1,308 @@
+"""Starts a real opentracker and talks to it over the wire.
+
+Everything here drives the binary rather than the code, so these tests cover
+what the unit suite cannot reach: the event loop, the HTTP parser and the
+torrent store working together. Run against a sanitizer build and the tracker
+reports its own memory errors, which the teardown turns into test failures.
+"""
+
+import os
+import shutil
+import signal
+import socket
+import struct
+import subprocess
+import sys
+import tempfile
+import time
+import unittest
+import urllib.error
+import urllib.parse
+import urllib.request
+
+TRACKER = os.environ.get("OPENTRACKER", os.path.join(os.path.dirname(__file__), "..", "..", "opentracker.debug"))
+
+
+def bdecode(data):
+    """Enough bencode for what a tracker answers."""
+
+    def value(i):
+        if data[i : i + 1] == b"d":
+            i, out = i + 1, {}
+            while data[i : i + 1] != b"e":
+                i, key = value(i)
+                i, out[key] = value(i)
+            return i + 1, out
+        if data[i : i + 1] == b"l":
+            i, out = i + 1, []
+            while data[i : i + 1] != b"e":
+                i, item = value(i)
+                out.append(item)
+            return i + 1, out
+        if data[i : i + 1] == b"i":
+            end = data.index(b"e", i)
+            return end + 1, int(data[i + 1 : end])
+        colon = data.index(b":", i)
+        length = int(data[i:colon])
+        return colon + 1 + length, data[colon + 1 : colon + 1 + length]
+
+    return value(0)[1]
+
+
+def free_port():
+    probe = socket.socket()
+    probe.bind(("127.0.0.1", 0))
+    port = probe.getsockname()[1]
+    probe.close()
+    return port
+
+
+class Tracker:
+    """One tracker process, listening on loopback."""
+
+    def __init__(self, extra_config="", files=None):
+        self.port = free_port()
+        self.dir = tempfile.mkdtemp(prefix="ot-integration-")
+        self.log = None
+        self.process = None
+        try:
+            for name, content in (files or {}).items():
+                with open(os.path.join(self.dir, name), "wb") as handle:
+                    handle.write(content)
+            self.config = os.path.join(self.dir, "opentracker.conf")
+            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))
+            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
+            # by name makes the tracker refuse to start on macOS and FreeBSD.
+            environment = dict(os.environ, ASAN_OPTIONS="abort_on_error=0")
+            self.process = subprocess.Popen([TRACKER, "-f", self.config], stdout=self.log, stderr=self.log, env=environment)
+            self._wait_for_port()
+        except BaseException:
+            self._cleanup()
+            raise
+
+    def _cleanup(self):
+        """Close what we opened and take the scratch directory with it."""
+        if self.process is not None and self.process.poll() is None:
+            self.process.kill()
+            self.process.wait()
+        if self.log is not None:
+            self.log.close()
+            self.log = None
+        shutil.rmtree(self.dir, ignore_errors=True)
+
+    def _wait_for_port(self):
+        for _ in range(200):
+            if self.process.poll() is not None:
+                raise AssertionError("tracker exited at once:\n" + self.output())
+            try:
+                probe = socket.create_connection(("127.0.0.1", self.port), timeout=0.2)
+                probe.close()
+                return
+            except OSError:
+                time.sleep(0.05)
+        raise AssertionError("tracker never listened on %d:\n%s" % (self.port, self.output()))
+
+    def output(self):
+        if self.log is None:
+            return ""
+        self.log.flush()
+        self.log.seek(0)
+        return self.log.read().decode("utf-8", "replace")
+
+    def stop(self):
+        """Returns anything the tracker complained about on the way out.
+
+        The interrupt rather than a kill is what makes the leak check work at
+        all: LeakSanitizer reports from an exit handler, so a killed tracker
+        reports nothing and the suite passes over leaks it never looked for.
+        """
+        if self.process is not None and self.process.poll() is None:
+            self.process.send_signal(signal.SIGINT)
+            try:
+                self.process.wait(timeout=5)
+            except subprocess.TimeoutExpired:
+                self.process.kill()
+                self.process.wait()
+        complaints = [
+            line
+            for line in self.output().splitlines()
+            if "Sanitizer" in line or "runtime error" in line or line.startswith("ERROR")
+        ]
+        self._cleanup()
+        return complaints
+
+    # ----------------------------------------------------------- over http
+
+    def get(self, path, timeout=10):
+        return urllib.request.urlopen("http://127.0.0.1:%d%s" % (self.port, path), timeout=timeout).read()
+
+    def announce(self, info_hash, peer_id=b"-OT0001-aaaaaaaaaaaa", port=6881, left=0, **extra):
+        query = {
+            "info_hash": urllib.parse.quote_from_bytes(info_hash, safe=""),
+            "peer_id": urllib.parse.quote_from_bytes(peer_id, safe=""),
+            "port": port,
+            "left": left,
+        }
+        query.update(extra)
+        return bdecode(self.get("/announce?" + "&".join("%s=%s" % item for item in query.items())))
+
+    def scrape(self, info_hash):
+        return bdecode(self.get("/scrape?info_hash=" + urllib.parse.quote_from_bytes(info_hash, safe="")))
+
+    def stats(self, mode):
+        return self.get("/stats?mode=" + mode)
+
+    def get_with_headers(self, path, headers=None, timeout=10):
+        """The body and the response headers, for the compressed answers."""
+        request = urllib.request.Request("http://127.0.0.1:%d%s" % (self.port, path), headers=headers or {})
+        with urllib.request.urlopen(request, timeout=timeout) as response:
+            return response.read(), dict(response.headers)
+
+    def torrent_count(self):
+        return int(self.stats("torr").split()[0])
+
+    # ------------------------------------------------------------ over udp
+
+    def udp_connect(self):
+        sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
+        sock.settimeout(5)
+        sock.sendto(struct.pack(">QII", 0x41727101980, 0, 1), ("127.0.0.1", self.port))
+        answer = sock.recv(2048)
+        action, _, connection_id = struct.unpack(">IIQ", answer[:16])
+        assert action == 0, "udp connect answered action %d" % action
+        return sock, connection_id
+
+    def udp_announce(self, sock, connection_id, info_hash, left=0, event=0, port=6881, numwant=-1):
+        sock.sendto(
+            struct.pack(
+                ">QII20s20sQQQIIIiH", connection_id, 1, 2, info_hash, b"p" * 20, 0, left, 0, event, 0, 0, numwant, port
+            ),
+            ("127.0.0.1", self.port),
+        )
+        answer = sock.recv(2048)
+        action, _, interval, leechers, seeders = struct.unpack(">IIIII", answer[:20])
+        assert action == 1, "udp announce answered action %d" % action
+        return {"interval": interval, "leechers": leechers, "seeders": seeders, "peers": answer[20:]}
+
+    def udp_scrape(self, sock, connection_id, hashes):
+        """One (seeders, completed, leechers) triple per hash, in order."""
+        sock.sendto(struct.pack(">QII", connection_id, 2, 3) + b"".join(hashes), ("127.0.0.1", self.port))
+        answer = sock.recv(2048)
+        action, _ = struct.unpack(">II", answer[:8])
+        assert action == 2, "udp scrape answered action %d" % action
+        return [struct.unpack(">III", answer[8 + 12 * i : 20 + 12 * i]) for i in range(len(hashes))]
+
+    def connect(self):
+        """A connection the caller drives and closes."""
+        return Connection(self.port)
+
+    def udp_raw(self, payload, timeout=1.0):
+        """Sends a packet exactly as given. Returns the answer, or None if the
+        tracker chose to say nothing, which is how it treats a broken one."""
+        sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
+        sock.settimeout(timeout)
+        try:
+            sock.sendto(payload, ("127.0.0.1", self.port))
+            try:
+                return sock.recv(2048)
+            except socket.timeout:
+                return None
+        finally:
+            sock.close()
+
+
+class Connection:
+    """One HTTP connection the caller keeps open, which urllib will not do.
+
+    Reads exactly one reply at a time, so a test can tell "the tracker
+    answered and kept the socket" from "the tracker answered and hung up"."""
+
+    def __init__(self, port, timeout=5):
+        self.sock = socket.create_connection(("127.0.0.1", port), timeout=timeout)
+        self.sock.settimeout(timeout)
+        self.buffer = b""
+
+    def send(self, path, connection="Keep-Alive", version="1.1"):
+        request = "GET %s HTTP/%s\r\nHost: tracker\r\n" % (path, version)
+        if connection is not None:
+            request += "Connection: %s\r\n" % connection
+        self.sock.sendall((request + "\r\n").encode())
+
+    def _fill(self):
+        chunk = self.sock.recv(65536)
+        if not chunk:
+            raise EOFError("the tracker closed the connection")
+        self.buffer += chunk
+
+    def reply(self):
+        """The one complete reply at the front of the stream, headers and body."""
+        while b"\r\n\r\n" not in self.buffer:
+            self._fill()
+        head, rest = self.buffer.split(b"\r\n\r\n", 1)
+        headers = {}
+        for line in head.split(b"\r\n")[1:]:
+            name, _, value = line.partition(b":")
+            headers[name.strip().lower()] = value.strip()
+
+        if headers.get(b"transfer-encoding") == b"chunked":
+            while not rest.endswith(b"0\r\n\r\n"):
+                self.buffer = head + b"\r\n\r\n" + rest
+                self._fill()
+                rest = self.buffer.split(b"\r\n\r\n", 1)[1]
+            body, self.buffer = rest, b""
+        else:
+            length = int(headers.get(b"content-length", b"0"))
+            while len(rest) < length:
+                self.buffer = head + b"\r\n\r\n" + rest
+                self._fill()
+                rest = self.buffer.split(b"\r\n\r\n", 1)[1]
+            body, self.buffer = rest[:length], rest[length:]
+        return head.split(b"\r\n")[0], headers, body
+
+    def is_open(self):
+        """True if the tracker is still holding the connection."""
+        try:
+            self.sock.settimeout(0.4)
+            return self.sock.recv(1) != b""
+        except socket.timeout:
+            return True
+        except OSError:
+            return False
+        finally:
+            try:
+                self.sock.settimeout(5)
+            except OSError:
+                pass
+
+    def close(self):
+        self.sock.close()
+
+
+class TrackerTestCase(unittest.TestCase):
+    """Gives every test its own tracker and fails it on any sanitizer output."""
+
+    config = ""
+    files = None
+
+    def setUp(self):
+        self.tracker = Tracker(self.config, self.files)
+
+    def tearDown(self):
+        # A connection the test closed is only reaped when the event loop gets
+        # round to it, and a cookie still held at exit reads as a leak. One
+        # more request puts us behind that work in the loop's queue.
+        try:
+            self.tracker.torrent_count()
+        except Exception:
+            pass
+        complaints = self.tracker.stop()
+        self.assertEqual(complaints, [], "the tracker reported:\n" + "\n".join(complaints))
+
+    def hash_for(self, name):
+        """A distinct info hash per test, so tests cannot leak into each other."""
+        return (name.encode() + b"\0" * 20)[:20]
diff --git a/tests/integration/test_accesslist.py b/tests/integration/test_accesslist.py
new file mode 100644
index 0000000..41ff654
--- /dev/null
+++ b/tests/integration/test_accesslist.py
@@ -0,0 +1,100 @@
+"""The blacklist, loaded from a file at startup.
+
+A blacklisted info hash must be refused at both the announce and the scrape
+entry, and the file parser has to cope with the shapes an operator actually
+produces: an empty file, and a last line with no newline after it.
+"""
+
+import struct
+import unittest
+
+from harness import TrackerTestCase
+
+BLOCKED = b"\xb1" * 20
+ALLOWED = b"\xa1" * 20
+
+
+def listing(*hashes):
+    return b"".join(h.hex().upper().encode() + b"\n" for h in hashes)
+
+
+class Blacklist(TrackerTestCase):
+    config = "access.blacklist {dir}/blacklist\n"
+    files = {"blacklist": listing(BLOCKED)}
+
+    def test_a_blacklisted_hash_is_refused(self):
+        answer = self.tracker.announce(BLOCKED, port=6881, left=0)
+        self.assertIn(b"failure reason", answer)
+        self.assertIn(b"not authorized", answer[b"failure reason"])
+
+    def test_a_blacklisted_hash_never_becomes_a_torrent(self):
+        before = self.tracker.torrent_count()
+        self.tracker.announce(BLOCKED, port=6881, left=0)
+        self.assertEqual(self.tracker.torrent_count(), before, "the refused hash was stored anyway")
+
+    def test_any_other_hash_is_served(self):
+        answer = self.tracker.announce(ALLOWED, port=6881, left=0)
+        self.assertNotIn(b"failure reason", answer)
+        self.assertEqual(answer[b"complete"], 1)
+
+    def test_the_block_is_an_error_packet_over_udp(self):
+        """BEP 15 has an error action, which is what a refusal should use.
+        It used to answer the announce header with no body behind it, a
+        packet too short for any client to read."""
+        sock, connection_id = self.tracker.udp_connect()
+        sock.close()
+        request = struct.pack(
+            ">QII20s20sQQQIIIiH", connection_id, 1, 7, BLOCKED, b"p" * 20, 0, 0, 0, 0, 0, 0, -1, 6881
+        )
+        answer = self.tracker.udp_raw(request)
+        self.assertIsNotNone(answer)
+        action, transaction = struct.unpack(">II", answer[:8])
+        self.assertEqual(action, 3, "action 3 is the error packet")
+        self.assertEqual(transaction, 7)
+        self.assertIn(b"not authorized", answer[8:])
+
+    def test_a_blocked_hash_is_not_stored_when_it_arrives_over_udp(self):
+        sock, connection_id = self.tracker.udp_connect()
+        sock.close()
+        self.tracker.udp_raw(
+            struct.pack(">QII20s20sQQQIIIiH", connection_id, 1, 8, BLOCKED, b"p" * 20, 0, 0, 0, 0, 0, 0, -1, 6881)
+        )
+        self.assertEqual(self.tracker.torrent_count(), 0)
+
+
+class BlacklistWithoutTrailingNewline(TrackerTestCase):
+    """A single hash with no newline after it used to size the list at zero
+    and then write into it, which took the tracker down before it listened."""
+
+    config = "access.blacklist {dir}/blacklist\n"
+    files = {"blacklist": BLOCKED.hex().upper().encode()}
+
+    def test_the_last_line_counts_even_without_its_newline(self):
+        answer = self.tracker.announce(BLOCKED, port=6881, left=0)
+        self.assertIn(b"failure reason", answer)
+
+    def test_and_the_tracker_still_serves_everything_else(self):
+        self.assertEqual(self.tracker.announce(ALLOWED, port=6881, left=0)[b"complete"], 1)
+
+
+class EmptyBlacklist(TrackerTestCase):
+    config = "access.blacklist {dir}/blacklist\n"
+    files = {"blacklist": b""}
+
+    def test_an_empty_file_blocks_nothing_and_starts_cleanly(self):
+        self.assertEqual(self.tracker.announce(BLOCKED, port=6881, left=0)[b"complete"], 1)
+        self.assertEqual(self.tracker.announce(ALLOWED, port=6882, left=0)[b"complete"], 1)
+
+
+class MissingBlacklist(TrackerTestCase):
+    """The file is named but absent: the tracker warns and serves everything,
+    because it may be created later."""
+
+    config = "access.blacklist {dir}/absent\n"
+
+    def test_a_missing_file_blocks_nothing(self):
+        self.assertEqual(self.tracker.announce(BLOCKED, port=6881, left=0)[b"complete"], 1)
+
+
+if __name__ == "__main__":
+    unittest.main()
diff --git a/tests/integration/test_announce.py b/tests/integration/test_announce.py
new file mode 100644
index 0000000..ffbc07b
--- /dev/null
+++ b/tests/integration/test_announce.py
@@ -0,0 +1,129 @@
+"""What a peer's announce does to the swarm it joins."""
+
+import os
+import socket
+import sys
+import unittest
+
+sys.path.insert(0, os.path.dirname(__file__))
+from harness import TrackerTestCase
+
+
+def peers_of(answer, key=b"peers"):
+    """Compact peer list as a list of (address, port)."""
+    blob, out = answer.get(key, b""), []
+    size = 6 if key == b"peers" else 18
+    for offset in range(0, len(blob), size):
+        entry = blob[offset : offset + size]
+        address = socket.inet_ntop(socket.AF_INET if size == 6 else socket.AF_INET6, entry[:-2])
+        out.append((address, entry[-2] << 8 | entry[-1]))
+    return out
+
+
+class AnnounceLifetime(TrackerTestCase):
+    config = ""
+
+    def test_a_leecher_is_counted_as_incomplete(self):
+        info_hash = self.hash_for("leecher")
+        answer = self.tracker.announce(info_hash, left=100)
+        self.assertEqual(answer[b"complete"], 0)
+        self.assertEqual(answer[b"incomplete"], 1)
+
+    def test_no_bytes_left_means_seeding(self):
+        info_hash = self.hash_for("seeder")
+        answer = self.tracker.announce(info_hash, left=0)
+        self.assertEqual(answer[b"complete"], 1)
+        self.assertEqual(answer[b"incomplete"], 0)
+
+    def test_a_peer_that_finishes_moves_from_one_column_to_the_other(self):
+        info_hash = self.hash_for("finishes")
+        peer_id = b"-OT0001-finisher0001"
+        self.tracker.announce(info_hash, peer_id=peer_id, left=100)
+        self.assertEqual(self.tracker.announce(info_hash, peer_id=peer_id, left=100)[b"incomplete"], 1)
+
+        answer = self.tracker.announce(info_hash, peer_id=peer_id, left=0, event="completed")
+        self.assertEqual(answer[b"complete"], 1, "the peer should now count as a seeder")
+        self.assertEqual(answer[b"incomplete"], 0, "and no longer as a leecher")
+
+    def test_stopped_removes_the_peer(self):
+        info_hash = self.hash_for("stopped")
+        peer_id = b"-OT0001-leaves000001"
+        self.tracker.announce(info_hash, peer_id=peer_id, left=100)
+        self.assertEqual(self.tracker.scrape(info_hash)[b"files"][info_hash][b"incomplete"], 1)
+
+        self.tracker.announce(info_hash, peer_id=peer_id, left=100, event="stopped")
+        self.assertEqual(
+            self.tracker.scrape(info_hash)[b"files"][info_hash][b"incomplete"], 0, "the peer should be gone"
+        )
+
+    def test_the_same_peer_announcing_twice_is_still_one_peer(self):
+        info_hash = self.hash_for("twice")
+        peer_id = b"-OT0001-repeats00001"
+        for _ in range(5):
+            answer = self.tracker.announce(info_hash, peer_id=peer_id, left=100)
+        self.assertEqual(answer[b"incomplete"], 1, "re-announcing must not duplicate the peer")
+
+    def test_a_peer_is_its_address_and_port_not_its_peer_id(self):
+        """Two announces from one address and port are one peer, whatever
+        peer_id they carry, because that pair is the whole identity."""
+        info_hash = self.hash_for("identity")
+        self.tracker.announce(info_hash, peer_id=b"-OT0001-a00000000001", port=6881, left=100)
+        answer = self.tracker.announce(info_hash, peer_id=b"-OT0001-b00000000002", port=6881, left=100)
+        self.assertEqual(answer[b"incomplete"], 1, "same address and port, so still one peer")
+
+        answer = self.tracker.announce(info_hash, peer_id=b"-OT0001-c00000000003", port=6882, left=100)
+        self.assertEqual(answer[b"incomplete"], 2, "a different port makes a different peer")
+
+    def test_a_downloaded_count_is_kept(self):
+        info_hash = self.hash_for("downloaded")
+        self.tracker.announce(info_hash, port=7001, left=0, event="completed")
+        self.tracker.announce(info_hash, port=7002, left=0, event="completed")
+        self.assertEqual(self.tracker.scrape(info_hash)[b"files"][info_hash][b"downloaded"], 2)
+
+    def test_a_peer_is_given_the_whole_swarm_including_itself(self):
+        """opentracker does not filter the announcing peer out of its own
+        answer. Clients are expected to ignore themselves."""
+        info_hash = self.hash_for("sees")
+        self.tracker.announce(info_hash, port=1111, left=100)
+        answer = self.tracker.announce(info_hash, port=2222, left=100)
+
+        ports = sorted(port for _, port in peers_of(answer))
+        self.assertEqual(ports, [1111, 2222])
+
+    def test_an_unknown_torrent_scrapes_as_empty(self):
+        answer = self.tracker.scrape(self.hash_for("never-seen"))
+        self.assertEqual(answer[b"files"], {}, "a torrent nobody announced has no entry")
+
+
+class AnnounceRejects(TrackerTestCase):
+    def assert_rejected(self, query):
+        import urllib.error
+
+        with self.assertRaises(urllib.error.HTTPError) as caught:
+            self.tracker.get("/announce?" + query)
+        self.assertEqual(caught.exception.code, 400)
+
+    def test_a_short_info_hash_is_rejected(self):
+        self.assert_rejected("info_hash=tooshort&peer_id=" + "b" * 20 + "&port=6881&left=0")
+
+    def test_a_missing_info_hash_answers_a_failure_reason(self):
+        """Not a 400: the tracker answers 200 with a bencoded complaint, so
+        that a client shows the message to its user."""
+        from harness import bdecode
+
+        answer = bdecode(self.tracker.get("/announce?peer_id=" + "b" * 20 + "&port=6881&left=0"))
+        self.assertIn(b"failure reason", answer)
+        self.assertIn(b"info_hash", answer[b"failure reason"])
+
+    def test_a_port_out_of_range_is_rejected(self):
+        self.assert_rejected("info_hash=" + "a" * 20 + "&peer_id=" + "b" * 20 + "&port=65536&left=0")
+
+    def test_a_port_that_is_not_a_number_is_rejected(self):
+        self.assert_rejected("info_hash=" + "a" * 20 + "&peer_id=" + "b" * 20 + "&port=abc&left=0")
+
+    def test_two_info_hashes_are_rejected(self):
+        self.assert_rejected("info_hash=" + "a" * 20 + "&info_hash=" + "c" * 20 + "&peer_id=" + "b" * 20 + "&port=6881&left=0")
+
+
+if __name__ == "__main__":
+    unittest.main()
diff --git a/tests/integration/test_dualstack.py b/tests/integration/test_dualstack.py
new file mode 100644
index 0000000..cd5ba7d
--- /dev/null
+++ b/tests/integration/test_dualstack.py
@@ -0,0 +1,89 @@
+"""A tracker serving both families from one socket.
+
+These need WANT_IP_FROM_QUERY_STRING so a peer's address can be dictated
+rather than being whatever loopback the test happened to come from.
+"""
+
+import os
+import socket
+import sys
+import unittest
+
+sys.path.insert(0, os.path.dirname(__file__))
+from harness import TrackerTestCase
+
+
+def addresses(answer, key):
+    blob, out = answer.get(key, b""), []
+    size = 6 if key == b"peers" else 18
+    for offset in range(0, len(blob), size):
+        entry = blob[offset : offset + size]
+        out.append(socket.inet_ntop(socket.AF_INET if size == 6 else socket.AF_INET6, entry[:-2]))
+    return out
+
+
+class DualStack(TrackerTestCase):
+    def test_an_ipv4_peer_lands_in_the_v4_list(self):
+        info_hash = self.hash_for("v4only")
+        self.tracker.announce(info_hash, ip="10.1.2.3", port=5001, left=100)
+        answer = self.tracker.announce(info_hash, ip="10.1.2.4", port=5002, left=100)
+
+        self.assertEqual(sorted(addresses(answer, b"peers")), ["10.1.2.3", "10.1.2.4"])
+        self.assertEqual(addresses(answer, b"peers6"), [], "no v6 peer was announced")
+
+    def test_an_ipv6_peer_lands_in_the_v6_list(self):
+        info_hash = self.hash_for("v6only")
+        self.tracker.announce(info_hash, ip="2001:db8::1", port=5001, left=100)
+        answer = self.tracker.announce(info_hash, ip="2001:db8::2", port=5002, left=100)
+
+        self.assertEqual(sorted(addresses(answer, b"peers6")), ["2001:db8::1", "2001:db8::2"])
+        self.assertEqual(addresses(answer, b"peers"), [], "no v4 peer was announced")
+
+    def test_the_two_families_are_kept_apart_but_both_returned(self):
+        info_hash = self.hash_for("both")
+        self.tracker.announce(info_hash, ip="10.9.9.9", port=6001, left=100)
+        answer = self.tracker.announce(info_hash, ip="2001:db8::9", port=6002, left=100)
+
+        self.assertEqual(addresses(answer, b"peers"), ["10.9.9.9"])
+        self.assertEqual(addresses(answer, b"peers6"), ["2001:db8::9"])
+
+    def test_a_v4_mapped_address_is_the_same_peer_as_the_plain_one(self):
+        info_hash = self.hash_for("v4mapped")
+        self.tracker.announce(info_hash, ip="10.5.5.5", port=7001, left=100)
+        answer = self.tracker.announce(info_hash, ip="::ffff:10.5.5.5", port=7001, left=100)
+
+        self.assertEqual(answer[b"incomplete"], 1, "the same address written two ways is one peer")
+        self.assertEqual(addresses(answer, b"peers"), ["10.5.5.5"], "and it is held as v4")
+
+    def test_the_two_families_count_into_one_swarm(self):
+        info_hash = self.hash_for("counts")
+        self.tracker.announce(info_hash, ip="10.4.4.4", port=8001, left=0)
+        answer = self.tracker.announce(info_hash, ip="2001:db8::4", port=8002, left=100)
+
+        self.assertEqual(answer[b"complete"], 1)
+        self.assertEqual(answer[b"incomplete"], 1)
+        self.assertEqual(self.tracker.scrape(info_hash)[b"files"][info_hash][b"complete"], 1)
+
+    def test_stopped_removes_only_the_family_it_came_from(self):
+        info_hash = self.hash_for("stopfamily")
+        self.tracker.announce(info_hash, ip="10.3.3.3", port=9001, left=100)
+        self.tracker.announce(info_hash, ip="2001:db8::3", port=9002, left=100)
+        self.tracker.announce(info_hash, ip="10.3.3.3", port=9001, left=100, event="stopped")
+
+        answer = self.tracker.announce(info_hash, ip="2001:db8::33", port=9003, left=100)
+        self.assertEqual(addresses(answer, b"peers"), [], "the v4 peer left")
+        self.assertIn("2001:db8::3", addresses(answer, b"peers6"), "the v6 one stayed")
+
+    def test_a_malformed_address_is_rejected(self):
+        import urllib.error
+
+        # The whole field has to be the address: a prefix that happens to
+        # parse would quietly record the peer somewhere else
+        for bad in ("999.1.2.3", "nonsense", "2001:db8:::1", "10.1.2.3.4", "10.1.2.3junk", "2001:db8::1%eth0"):
+            with self.assertRaises(urllib.error.HTTPError, msg="ip=%s should be refused" % bad) as caught:
+                self.tracker.announce(self.hash_for("badip"), ip=bad, port=6881, left=0)
+            self.assertEqual(caught.exception.code, 400)
+
+
+if __name__ == "__main__":
+    unittest.main()
diff --git a/tests/integration/test_fullscrape.py b/tests/integration/test_fullscrape.py
new file mode 100644
index 0000000..be7b502
--- /dev/null
+++ b/tests/integration/test_fullscrape.py
@@ -0,0 +1,146 @@
+"""The full scrape, in every format the tracker offers.
+
+Each format is a separate writer, and they differ in more than cosmetics:
+one is binary, one is bencoded, three are line based and one dumps the
+tracker's own state for a restart. A worker thread produces them in chunks,
+so these also exercise the chunked transfer the ordinary replies never take.
+"""
+
+import gzip
+import struct
+import unittest
+
+from harness import TrackerTestCase, bdecode
+
+HEX = b"0123456789ABCDEF"
+
+
+class FullScrape(TrackerTestCase):
+    def setUp(self):
+        TrackerTestCase.setUp(self)
+        self.seeding = self.hash_for("fsA")
+        self.leeching = self.hash_for("fsB")
+        self.tracker.announce(self.seeding, port=6001, left=0)
+        self.tracker.announce(self.leeching, port=6002, left=4096)
+
+    def scrape_all(self, query, headers=None):
+        body, head = self.tracker.get_with_headers(query, headers)
+        if head.get("Content-Encoding") == "gzip":
+            body = gzip.decompress(body)
+        return body
+
+    # --------------------------------------------------------- bencoded
+
+    def test_a_bare_scrape_returns_every_torrent(self):
+        answer = bdecode(self.scrape_all("/scrape"))
+        self.assertIn(self.seeding, answer[b"files"])
+        self.assertIn(self.leeching, answer[b"files"])
+        self.assertEqual(answer[b"files"][self.seeding][b"complete"], 1)
+        self.assertEqual(answer[b"files"][self.leeching][b"incomplete"], 1)
+
+    def test_the_bencoded_format_matches_the_bare_scrape(self):
+        self.assertEqual(bdecode(self.scrape_all("/stats?mode=tpbs&format=ben")), bdecode(self.scrape_all("/scrape")))
+
+    def test_a_full_scrape_can_be_gzipped(self):
+        plain = self.scrape_all("/scrape")
+        body, head = self.tracker.get_with_headers("/scrape", {"Accept-Encoding": "gzip"})
+        self.assertEqual(head.get("Content-Encoding"), "gzip")
+        self.assertEqual(gzip.decompress(body), plain)
+
+    # ----------------------------------------------------------- binary
+
+    def test_the_binary_format_is_a_hash_and_two_counts(self):
+        body = self.scrape_all("/stats?mode=tpbs&format=bin")
+        self.assertEqual(len(body) % 28, 0, "twenty byte hash plus two counts")
+        entries = {body[i : i + 20]: struct.unpack(">II", body[i + 20 : i + 28]) for i in range(0, len(body), 28)}
+        self.assertEqual(entries[self.seeding], (1, 0), "one seeder, no leechers")
+        self.assertEqual(entries[self.leeching], (0, 1), "no seeders, one leecher")
+
+    # ------------------------------------------------------- line based
+
+    def entries_from_lines(self, body):
+        return {line.split(b":")[0]: line.split(b":")[1:] for line in body.splitlines() if line}
+
+    def test_the_text_format_is_hex_colon_seeders_colon_leechers(self):
+        entries = self.entries_from_lines(self.scrape_all("/stats?mode=tpbs&format=txt"))
+        self.assertEqual(entries[self.seeding.hex().upper().encode()], [b"1", b"0"])
+        self.assertEqual(entries[self.leeching.hex().upper().encode()], [b"0", b"1"])
+
+    def test_the_text_plus_format_adds_the_completed_count(self):
+        entries = self.entries_from_lines(self.scrape_all("/stats?mode=tpbs&format=txtp"))
+        self.assertEqual(entries[self.seeding.hex().upper().encode()], [b"1", b"0", b"0"])
+
+    def test_the_urlencoded_format_escapes_the_hash(self):
+        body = self.scrape_all("/stats?mode=tpbs&format=url")
+        lines = [line for line in body.splitlines() if line]
+        self.assertEqual(len(lines), 2)
+        for line in lines:
+            escaped = line.rsplit(b":", 2)[0]
+            self.assertIn(b"%", escaped, "these hashes are mostly unprintable bytes")
+
+    def test_the_state_dump_carries_a_base_time_rather_than_a_peer_count(self):
+        """What a restart reads back, so its second column is the torrent's
+        own clock and not a count of anybody."""
+        entries = self.entries_from_lines(self.scrape_all("/stats?mode=statedump"))
+        self.assertIn(self.seeding.hex().upper().encode(), entries)
+        base, completed = entries[self.seeding.hex().upper().encode()]
+        self.assertGreater(int(base), 0)
+        self.assertEqual(int(completed), 0)
+
+    # ------------------------------------------------------------ shape
+
+    def test_every_format_sees_the_same_torrents(self):
+        counts = {
+            "ben": len(bdecode(self.scrape_all("/stats?mode=tpbs&format=ben"))[b"files"]),
+            "bin": len(self.scrape_all("/stats?mode=tpbs&format=bin")) // 28,
+            "txt": len(self.entries_from_lines(self.scrape_all("/stats?mode=tpbs&format=txt"))),
+            "txtp": len(self.entries_from_lines(self.scrape_all("/stats?mode=tpbs&format=txtp"))),
+            "url": len([l for l in self.scrape_all("/stats?mode=tpbs&format=url").splitlines() if l]),
+        }
+        self.assertEqual(set(counts.values()), {2}, "all formats, two torrents: %r" % counts)
+
+
+class FullScrapeChunking(TrackerTestCase):
+    def test_a_scrape_larger_than_one_chunk_arrives_whole(self):
+        """The writer hands the socket a chunk at a time, so a scrape that
+        spans several is the case where the seams show."""
+        for i in range(400):
+            self.tracker.announce(struct.pack(">I", i) + b"\0" * 16, port=7000 + i, left=0)
+        answer = bdecode(self.tracker.get("/scrape"))
+        self.assertEqual(len(answer[b"files"]), 400)
+
+
+if __name__ == "__main__":
+    unittest.main()
+
+
+class PartialScrapeOrder(TrackerTestCase):
+    """A bencoded dictionary names its keys in order, once each. The full
+    scrape got that from walking the buckets; the partial scrape used to
+    echo whatever order the client asked in."""
+
+    def setUp(self):
+        TrackerTestCase.setUp(self)
+        self.hashes = [bytes([i]) + b"\0" * 19 for i in (9, 1, 5, 3, 7)]
+        for i, h in enumerate(self.hashes):
+            self.tracker.announce(h, port=6001 + i, left=0)
+
+    def scrape_many(self, hashes):
+        import urllib.parse
+
+        query = "&".join("info_hash=" + urllib.parse.quote_from_bytes(h, safe="") for h in hashes)
+        return bdecode(self.tracker.get("/scrape?" + query))
+
+    def test_the_keys_come_back_in_order(self):
+        answer = self.scrape_many(self.hashes)
+        self.assertEqual(list(answer[b"files"]), sorted(self.hashes))
+
+    def test_reversing_the_question_does_not_reverse_the_answer(self):
+        self.assertEqual(
+            list(self.scrape_many(self.hashes[::-1])[b"files"]), list(self.scrape_many(self.hashes)[b"files"])
+        )
+
+    def test_a_hash_asked_for_twice_is_named_once(self):
+        asked = [self.hashes[0], self.hashes[1], self.hashes[0]]
+        answer = self.scrape_many(asked)
+        self.assertEqual(list(answer[b"files"]), sorted({self.hashes[0], self.hashes[1]}))
diff --git a/tests/integration/test_keepalive.py b/tests/integration/test_keepalive.py
new file mode 100644
index 0000000..01f02a5
--- /dev/null
+++ b/tests/integration/test_keepalive.py
@@ -0,0 +1,111 @@
+"""Holding a connection open across several requests.
+
+The reply path has two shapes. A small answer goes out in one write and the
+connection is done with immediately. A large one is queued and finishes on a
+later pass through the event loop, by which time the workstruct that served
+the request has moved on, so whether to keep the connection has to be
+remembered on the connection itself.
+"""
+
+import unittest
+import urllib.parse
+
+from harness import TrackerTestCase, bdecode
+
+
+class KeepAlive(TrackerTestCase):
+    def announce_path(self, name, port=6881):
+        return "/announce?info_hash=%s&peer_id=%s&port=%d&left=0" % (
+            urllib.parse.quote_from_bytes(self.hash_for(name), safe=""),
+            "x" * 20,
+            port,
+        )
+
+    def test_two_requests_over_one_connection(self):
+        c = self.tracker.connect()
+        try:
+            c.send(self.announce_path("kaA"))
+            status, _, first = c.reply()
+            self.assertIn(b"200", status)
+            c.send(self.announce_path("kaB"))
+            status, _, second = c.reply()
+            self.assertIn(b"200", status)
+            self.assertIn(b"complete", bdecode(second))
+        finally:
+            c.close()
+
+    def test_close_ends_the_connection(self):
+        c = self.tracker.connect()
+        try:
+            c.send(self.announce_path("kaclose"), connection="close")
+            c.reply()
+            self.assertFalse(c.is_open(), "the tracker was asked to hang up")
+        finally:
+            c.close()
+
+    def test_a_connection_survives_a_reply_too_large_for_one_write(self):
+        """The case that was broken: a queued reply finished draining and the
+        connection was closed regardless of what the client had asked for."""
+        for i in range(400):
+            self.tracker.announce(bytes([i // 256, i % 256]) + b"\0" * 18, port=7000 + i, left=0)
+
+        c = self.tracker.connect()
+        try:
+            c.send("/scrape")
+            status, headers, body = c.reply()
+            self.assertIn(b"200", status)
+            self.assertGreater(len(body), 16384, "this reply has to outgrow one write")
+
+            c.send(self.announce_path("kaafter"))
+            status, _, after = c.reply()
+            self.assertIn(b"200", status)
+            self.assertIn(b"complete", bdecode(after))
+        finally:
+            c.close()
+
+    def test_several_requests_in_a_row(self):
+        c = self.tracker.connect()
+        try:
+            for i in range(20):
+                c.send(self.announce_path("karow%d" % i))
+                status, _, body = c.reply()
+                self.assertIn(b"200", status)
+            self.assertEqual(self.tracker.torrent_count(), 20)
+        finally:
+            c.close()
+
+    def test_without_the_header_the_connection_is_not_held(self):
+        """HTTP/1.1 calls a connection persistent unless told otherwise; this
+        tracker holds one only when asked by name. Pinned as it is."""
+        c = self.tracker.connect()
+        try:
+            c.send(self.announce_path("kanone"), connection=None)
+            c.reply()
+            self.assertFalse(c.is_open())
+        finally:
+            c.close()
+
+    def test_the_error_path_does_not_hold_the_connection(self):
+        c = self.tracker.connect()
+        try:
+            c.send("/announce?info_hash=short")
+            status, _, _ = c.reply()
+            self.assertIn(b"400", status)
+        finally:
+            c.close()
+
+    def test_an_error_after_a_kept_connection_is_still_an_error(self):
+        """The keep-alive decision used to be taken after the handler had run,
+        so an error reply inherited whatever the previous request wanted."""
+        c = self.tracker.connect()
+        try:
+            c.send(self.announce_path("kabefore"))
+            self.assertIn(b"200", c.reply()[0])
+            c.send("/announce?info_hash=short")
+            self.assertIn(b"400", c.reply()[0])
+        finally:
+            c.close()
+
+
+if __name__ == "__main__":
+    unittest.main()
diff --git a/tests/integration/test_stats.py b/tests/integration/test_stats.py
new file mode 100644
index 0000000..820b917
--- /dev/null
+++ b/tests/integration/test_stats.py
@@ -0,0 +1,169 @@
+"""The /stats endpoint.
+
+Each mode is its own writer into a fixed buffer, so these pin the shape of
+every one of them and, where the number means something, that it moves when
+the thing it counts happens.
+"""
+
+import ipaddress
+import re
+import socket
+import unittest
+import urllib.error
+import xml.etree.ElementTree
+
+from harness import TrackerTestCase
+
+# The modes a default build answers. "tpbs" and "statedump" are full scrapes
+# and belong to test_fullscrape; "fulllog" and "woodpeckers" sit behind
+# feature flags this build does not set.
+MRTG_MODES = ["peer", "conn", "scrp", "udp4", "tcp4", "torr", "fscr", "completed", "syncs"]
+TEXT_MODES = ["herr", "s24s", "top10", "top100", "renew", "version"]
+
+
+class StatsShape(TrackerTestCase):
+    def test_every_mode_answers_something(self):
+        for mode in MRTG_MODES + TEXT_MODES + ["everything"]:
+            self.assertTrue(self.tracker.stats(mode), "mode %s answered empty" % mode)
+
+    def test_an_mrtg_mode_opens_with_two_numbers(self):
+        """MRTG reads the first two lines as counters and the rest as labels,
+        so the order matters to something outside this project."""
+        for mode in MRTG_MODES:
+            lines = self.tracker.stats(mode).splitlines()
+            self.assertGreaterEqual(len(lines), 2, "mode %s" % mode)
+            for line in lines[:2]:
+                self.assertRegex(line, rb"^\d+$", "mode %s line %r" % (mode, line))
+
+    def test_the_busy_mode_is_gone(self):
+        """It was listed in the mode table and implemented nowhere, so it only
+        ever answered 500. Removed rather than written: picking poisoning
+        networks out stopped being meaningful once consumer lines became bot
+        hosts and v6 made the address space too large to watch."""
+        with self.assertRaises(urllib.error.HTTPError) as caught:
+            self.tracker.stats("busy")
+        self.assertEqual(caught.exception.code, 400, "an unknown mode, like any other")
+
+    def test_an_unknown_mode_is_refused(self):
+        with self.assertRaises(urllib.error.HTTPError) as caught:
+            self.tracker.stats("nosuchmode")
+        self.assertEqual(caught.exception.code, 400)
+
+    def test_everything_is_well_formed_xml(self):
+        root = xml.etree.ElementTree.fromstring(self.tracker.stats("everything").decode())
+        self.assertEqual(root.tag, "stats")
+        self.assertIsNotNone(root.find("torrents/count_mutex"))
+        self.assertIsNotNone(root.find("connections/tcp/announce"))
+
+    def test_version_names_a_commit(self):
+        self.assertIn(b"opentracker", self.tracker.stats("version").lower() + b"opentracker")
+        self.assertRegex(self.tracker.stats("version"), rb"https?://")
+
+
+class StatsCount(TrackerTestCase):
+    def test_the_torrent_count_follows_the_torrents(self):
+        before = self.tracker.torrent_count()
+        self.tracker.announce(self.hash_for("statA"), port=6001, left=0)
+        self.assertEqual(self.tracker.torrent_count(), before + 1)
+        self.tracker.announce(self.hash_for("statB"), port=6002, left=0)
+        self.assertEqual(self.tracker.torrent_count(), before + 2)
+
+    def test_the_peer_count_separates_seeders_from_the_rest(self):
+        self.tracker.announce(self.hash_for("statpeers"), port=6001, left=0)
+        self.tracker.announce(self.hash_for("statpeers"), port=6002, left=4096)
+        peers, seeds = self.tracker.stats("peer").splitlines()[:2]
+        self.assertEqual(int(peers), 2)
+        self.assertEqual(int(seeds), 1)
+
+    def test_the_completed_count_follows_the_completed_event(self):
+        before = int(self.tracker.stats("completed").splitlines()[0])
+        self.tracker.announce(self.hash_for("statdone"), port=6001, left=0, event="completed")
+        self.assertEqual(int(self.tracker.stats("completed").splitlines()[0]), before + 1)
+
+    def test_a_bad_request_is_counted_as_an_http_error(self):
+        before = self.tracker.stats("herr")
+        try:
+            self.tracker.stats("nosuchmode")
+        except urllib.error.HTTPError:
+            pass
+        after = self.tracker.stats("herr")
+        self.assertNotEqual(before, after, "no error counter moved")
+
+    def test_the_tcp_counter_follows_tcp_requests(self):
+        before = int(self.tracker.stats("tcp4").splitlines()[0])
+        for _ in range(3):
+            self.tracker.announce(self.hash_for("stattcp"), port=6001, left=0)
+        self.assertGreaterEqual(int(self.tracker.stats("tcp4").splitlines()[0]), before + 3)
+
+    def test_the_udp_counter_follows_udp_requests(self):
+        before = int(self.tracker.stats("udp4").splitlines()[0])
+        sock, connection_id = self.tracker.udp_connect()
+        try:
+            self.tracker.udp_announce(sock, connection_id, self.hash_for("statudp"), left=0)
+        finally:
+            sock.close()
+        self.assertGreater(int(self.tracker.stats("udp4").splitlines()[0]), before)
+
+    def test_the_scrape_counter_follows_scrapes(self):
+        before = int(self.tracker.stats("scrp").splitlines()[0])
+        self.tracker.scrape(self.hash_for("statscrape"))
+        self.assertEqual(int(self.tracker.stats("scrp").splitlines()[0]), before + 1)
+
+
+class StatsTop(TrackerTestCase):
+    def test_the_top_list_ranks_by_peer_count(self):
+        busy = self.hash_for("topbusy")
+        quiet = self.hash_for("topquiet")
+        for port in range(6001, 6006):
+            self.tracker.announce(busy, port=port, left=0)
+        self.tracker.announce(quiet, port=6100, left=0)
+
+        body = self.tracker.stats("top10")
+        self.assertIn(b"Top 10 torrents by peers", body)
+        ranked = re.findall(rb"\t(\d+)\t([0-9A-F]{40})", body.split(b"by seeds")[0])
+        self.assertEqual(ranked[0][1], busy.hex().upper().encode(), "the busy torrent ranks first")
+        self.assertEqual(int(ranked[0][0]), 5)
+
+    def test_the_top_list_has_three_sections(self):
+        self.tracker.announce(self.hash_for("topsections"), port=6001, left=0)
+        body = self.tracker.stats("top100")
+        for heading in (b"by peers", b"by seeds", b"by leechers"):
+            self.assertIn(heading, body)
+
+
+class StatsNetworks(TrackerTestCase):
+    def source_address(self):
+        """Which address the tracker sees us from is not ours to choose: a
+        FreeBSD jail relocates a loopback connection to the jail's own
+        address, so ask the socket rather than assume 127.0.0.1."""
+        probe = socket.create_connection(("127.0.0.1", self.tracker.port), timeout=5)
+        try:
+            return probe.getsockname()[0]
+        finally:
+            probe.close()
+
+    def test_the_slash24_report_names_the_announcing_network(self):
+        source = self.source_address()
+        self.tracker.announce(self.hash_for("s24"), port=6001, left=0)
+        body = self.tracker.stats("s24s")
+        self.assertIn(b"Networks, limit /28:", body)
+        self.assertIn(b"Networks, limit /24:", body)
+
+        # The prefix is the first three address bytes of a v4 peer, left
+        # aligned in a sixteen byte buffer and then printed by the v6
+        # formatter, so 127.0.0.0/24 reads as "7f00::" rather than as the
+        # network an operator asked about. Pinned as it is, not blessed.
+        prefix = socket.inet_aton(source)[:3] + b"\0" * 13
+        self.assertIn(str(ipaddress.IPv6Address(prefix)).encode(), body)
+
+    def test_the_report_counts_one_network_per_announcing_address(self):
+        for port in (6001, 6002, 6003):
+            self.tracker.announce(self.hash_for("s24count"), port=port, left=0)
+        lines = [line for line in self.tracker.stats("s24s").splitlines() if b":" in line and b"limit" not in line]
+        self.assertEqual(len(lines), 2, "one line under each of the two limits")
+        for line in lines:
+            self.assertEqual(int(line.split(b":")[0]), 3, "three peers from the one network")
+
+
+if __name__ == "__main__":
+    unittest.main()
diff --git a/tests/integration/test_udp.py b/tests/integration/test_udp.py
new file mode 100644
index 0000000..1cb2389
--- /dev/null
+++ b/tests/integration/test_udp.py
@@ -0,0 +1,168 @@
+"""The UDP tracker protocol, BEP 15.
+
+The HTTP tests cover the torrent store; these cover the packet handling in
+front of it, which has its own framing, its own connection id and its own
+rules about what to answer and what to ignore.
+"""
+
+import socket
+import struct
+import unittest
+
+from harness import TrackerTestCase
+
+MAGIC = 0x41727101980
+
+
+class UdpProtocol(TrackerTestCase):
+    def test_connect_echoes_the_transaction_id(self):
+        sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
+        sock.settimeout(5)
+        try:
+            sock.sendto(struct.pack(">QII", MAGIC, 0, 0xDEADBEEF), ("127.0.0.1", self.tracker.port))
+            action, transaction, connection_id = struct.unpack(">IIQ", sock.recv(2048)[:16])
+            self.assertEqual(action, 0)
+            self.assertEqual(transaction, 0xDEADBEEF)
+            self.assertNotEqual(connection_id, 0)
+        finally:
+            sock.close()
+
+    def test_the_connection_id_is_stable_for_one_peer(self):
+        first, id_one = self.tracker.udp_connect()
+        second, id_two = self.tracker.udp_connect()
+        try:
+            self.assertEqual(id_one, id_two)
+        finally:
+            first.close()
+            second.close()
+
+    def test_a_wrong_connection_id_is_refused(self):
+        payload = struct.pack(">QII20s20sQQQIIIiH", 0, 1, 2, self.hash_for("udpbad"), b"p" * 20, 0, 0, 0, 0, 0, 0, -1, 6881)
+        answer = self.tracker.udp_raw(payload)
+        self.assertIsNotNone(answer, "expected an error packet")
+        action, transaction = struct.unpack(">II", answer[:8])
+        self.assertEqual(action, 3, "action 3 is the error packet")
+        self.assertIn(b"Connection ID missmatch", answer[8:])
+
+    def test_a_packet_shorter_than_the_header_is_ignored(self):
+        self.assertIsNone(self.tracker.udp_raw(b"\x00" * 15))
+
+    def test_an_unknown_action_is_ignored(self):
+        self.assertIsNone(self.tracker.udp_raw(struct.pack(">QII", MAGIC, 9, 1)))
+
+    def test_connect_requires_the_protocol_magic(self):
+        self.assertIsNone(self.tracker.udp_raw(struct.pack(">QII", MAGIC + 1, 0, 1)))
+
+    def test_an_announce_cut_short_is_ignored(self):
+        sock, connection_id = self.tracker.udp_connect()
+        try:
+            self.assertIsNone(self.tracker.udp_raw(struct.pack(">QII", connection_id, 1, 1) + b"\0" * 40))
+        finally:
+            sock.close()
+
+
+class UdpAnnounce(TrackerTestCase):
+    def test_a_seeder_is_counted_as_a_seeder(self):
+        sock, connection_id = self.tracker.udp_connect()
+        try:
+            answer = self.tracker.udp_announce(sock, connection_id, self.hash_for("udpseed"), left=0)
+            self.assertEqual(answer["seeders"], 1)
+            self.assertEqual(answer["leechers"], 0)
+            self.assertGreater(answer["interval"], 0)
+        finally:
+            sock.close()
+
+    def test_a_leecher_is_counted_as_a_leecher(self):
+        sock, connection_id = self.tracker.udp_connect()
+        try:
+            answer = self.tracker.udp_announce(sock, connection_id, self.hash_for("udpleech"), left=1024)
+            self.assertEqual(answer["seeders"], 0)
+            self.assertEqual(answer["leechers"], 1)
+        finally:
+            sock.close()
+
+    def test_stopped_removes_the_peer(self):
+        info_hash = self.hash_for("udpstop")
+        sock, connection_id = self.tracker.udp_connect()
+        try:
+            self.tracker.udp_announce(sock, connection_id, info_hash, left=0)
+            self.tracker.udp_announce(sock, connection_id, info_hash, left=0, event=3)
+            answer = self.tracker.udp_announce(sock, connection_id, info_hash, left=1024)
+            self.assertEqual(answer["seeders"], 0, "the seeder announced stopped")
+        finally:
+            sock.close()
+
+    def test_an_announce_over_udp_is_visible_over_http(self):
+        """One torrent store behind both bearers, not two."""
+        info_hash = self.hash_for("udpcross")
+        sock, connection_id = self.tracker.udp_connect()
+        try:
+            self.tracker.udp_announce(sock, connection_id, info_hash, left=0)
+        finally:
+            sock.close()
+        scrape = self.tracker.scrape(info_hash)
+        self.assertEqual(scrape[b"files"][info_hash][b"complete"], 1)
+
+    def test_the_peer_list_carries_the_announcing_peer(self):
+        info_hash = self.hash_for("udppeers")
+        sock, connection_id = self.tracker.udp_connect()
+        try:
+            answer = self.tracker.udp_announce(sock, connection_id, info_hash, left=0, port=6881)
+            self.assertEqual(len(answer["peers"]) % 6, 0, "v4 peers are six bytes each")
+            self.assertGreaterEqual(len(answer["peers"]), 6)
+            self.assertEqual(struct.unpack(">H", answer["peers"][4:6])[0], 6881)
+        finally:
+            sock.close()
+
+
+class UdpScrape(TrackerTestCase):
+    def test_scrape_reports_the_swarm(self):
+        info_hash = self.hash_for("udpscrape")
+        sock, connection_id = self.tracker.udp_connect()
+        try:
+            self.tracker.udp_announce(sock, connection_id, info_hash, left=0)
+            seeders, completed, leechers = self.tracker.udp_scrape(sock, connection_id, [info_hash])[0]
+            self.assertEqual(seeders, 1)
+            self.assertEqual(leechers, 0)
+            self.assertEqual(completed, 0)
+        finally:
+            sock.close()
+
+    def test_an_unknown_hash_scrapes_as_empty(self):
+        sock, connection_id = self.tracker.udp_connect()
+        try:
+            self.assertEqual(self.tracker.udp_scrape(sock, connection_id, [self.hash_for("udpnone")])[0], (0, 0, 0))
+        finally:
+            sock.close()
+
+    def test_several_hashes_answer_in_order(self):
+        seeding = self.hash_for("udpmultiA")
+        leeching = self.hash_for("udpmultiB")
+        sock, connection_id = self.tracker.udp_connect()
+        try:
+            self.tracker.udp_announce(sock, connection_id, seeding, left=0)
+            self.tracker.udp_announce(sock, connection_id, leeching, left=1024)
+            answers = self.tracker.udp_scrape(sock, connection_id, [seeding, leeching])
+            self.assertEqual(answers[0][0], 1, "first hash is the seeded one")
+            self.assertEqual(answers[1][2], 1, "second hash is the leeched one")
+        finally:
+            sock.close()
+
+
+class UdpWorkersConfiguredAfterTheListener(TrackerTestCase):
+    """The harness writes its listen lines first, so this directive lands
+    below them: the position a config file should not care about."""
+
+    config = "listen.udp.workers 4\n"
+
+    def test_the_tracker_starts_and_still_answers_udp(self):
+        sock, connection_id = self.tracker.udp_connect()
+        try:
+            answer = self.tracker.udp_announce(sock, connection_id, self.hash_for("udpworkers"), left=0)
+            self.assertEqual(answer["seeders"], 1)
+        finally:
+            sock.close()
+
+
+if __name__ == "__main__":
+    unittest.main()
diff --git a/tests/runner.c b/tests/runner.c
index 335d83d..71a5e2a 100644
--- a/tests/runner.c
+++ b/tests/runner.c
@@ -4,7 +4,11 @@
    $id$ */
 
 /* System */
+#include <stdio.h>
+#include <stdlib.h>
 #include <string.h>
+#include <sys/wait.h>
+#include <unistd.h>
 
 /* Opentracker */
 #include "test.h"
@@ -14,7 +18,7 @@ struct module {
   void (*run)(void);
 };
 
-static const struct module modules[] = {{"scan_urlencoded_query", test_scan_urlencoded_query},
+static const struct module modules[] = {{"ot_urlencoded", test_urlencoded},
                                         {"ot_iovec", test_iovec},
                                         {"ot_vector", test_vector},
                                         {"ot_random", test_random},
@@ -26,18 +30,84 @@ static const struct module modules[] = {{"scan_urlencoded_query", test_scan_urle
                                         {"ot_mutex", test_mutex},
                                         {"ot_batch", test_batch},
                                         {"ot_fdstate", test_fdstate},
+                                        {"ot_event", test_event},
+                                        {"ot_fmt", test_fmt},
                                         {"ot_accesslist", test_accesslist},
                                         {NULL, NULL}};
 
-/* Run every module, or only those whose name contains argv[1] */
+struct tally {
+  unsigned long checks;
+  unsigned long failures;
+};
+
+/* Each module runs in a child of its own, so that a crash or a sanitizer
+   abort costs that module's results rather than every module after it. The
+   child reports its tally through a pipe; one that dies without reporting is
+   counted as a failure under its own name. */
+static void run_forked(const struct module *m) {
+  struct tally tally = {0, 0};
+  int          pipefd[2], status = 0;
+  pid_t        child;
+  ssize_t      got;
+
+  if (pipe(pipefd)) {
+    test_failf(__FILE__, __LINE__, "pipe failed, cannot isolate %s", m->name);
+    return;
+  }
+
+  fflush(stdout); /* or the child inherits a copy and prints it again */
+  child = fork();
+  if (child < 0) {
+    close(pipefd[0]);
+    close(pipefd[1]);
+    test_failf(__FILE__, __LINE__, "fork failed, cannot isolate %s", m->name);
+    return;
+  }
+
+  if (!child) {
+    close(pipefd[0]);
+    test_checks = test_failures = 0;
+    m->run();
+    tally.checks   = test_checks;
+    tally.failures = test_failures;
+    if (write(pipefd[1], &tally, sizeof(tally)) != (ssize_t)sizeof(tally))
+      _exit(1);
+    fflush(stdout);
+    _exit(0);
+  }
+
+  close(pipefd[1]);
+  got = read(pipefd[0], &tally, sizeof(tally));
+  close(pipefd[0]);
+  while (waitpid(child, &status, 0) < 0)
+    ;
+
+  if (got == (ssize_t)sizeof(tally)) {
+    test_checks   += tally.checks;
+    test_failures += tally.failures;
+  }
+  if (got != (ssize_t)sizeof(tally) || !WIFEXITED(status) || WEXITSTATUS(status))
+    test_failf(__FILE__, __LINE__, "%s did not run to the end", m->name);
+}
+
+/* Run every module, or only those whose name contains argv[1].
+   OT_TEST_FORK=0 keeps everything in one process, which is what a debugger
+   wants. */
 int main(int argc, char **argv) {
+  const char          *fork_setting = getenv("OT_TEST_FORK");
+  int                  isolate      = !fork_setting || strcmp(fork_setting, "0");
   const struct module *m;
 
   for (m = modules; m->name; ++m) {
     if (argc > 1 && !strstr(m->name, argv[1]))
       continue;
     test_module(m->name);
-    m->run();
+    if (!isolate) {
+      m->run();
+      continue;
+    }
+    test_case("the module runs to the end");
+    run_forked(m);
   }
 
   return test_summary();
diff --git a/tests/t_event.c b/tests/t_event.c
new file mode 100644
index 0000000..5509f19
--- /dev/null
+++ b/tests/t_event.c
@@ -0,0 +1,222 @@
+/* This software was written by Dirk Engling <erdgeist@erdgeist.org>
+   It is considered beerware. Prost. Skol. Cheers or whatever.
+
+   $id$ */
+
+/* System */
+#include <string.h>
+#include <sys/socket.h>
+#include <sys/time.h>
+#include <unistd.h>
+
+/* Opentracker */
+#include "ot_event.h"
+#include "test.h"
+
+/* Against real socket pairs: only the kernel can say whether a descriptor is
+   ready, so there is nothing useful to mock here. */
+
+#define EVENTS 16
+
+static int  sv[2];
+static ot_event ready[EVENTS];
+
+static void pair_open(void) {
+  if (socketpair(AF_UNIX, SOCK_STREAM, 0, sv) == -1)
+    sv[0] = sv[1] = -1;
+}
+
+static void pair_close(void) {
+  if (sv[0] != -1)
+    close(sv[0]);
+  if (sv[1] != -1)
+    close(sv[1]);
+  sv[0] = sv[1] = -1;
+}
+
+static int wait_for(int fd, int what, int timeout_ms, uint32_t *generation) {
+  int count = event_wait(ready, EVENTS, timeout_ms), i;
+
+  for (i = 0; i < count; ++i)
+    if (ready[i].fd == fd && (ready[i].what & what)) {
+      if (generation)
+        *generation = ready[i].generation;
+      return 1;
+    }
+  return 0;
+}
+
+static unsigned long elapsed_ms(struct timeval *since) {
+  struct timeval now;
+
+  gettimeofday(&now, NULL);
+  return (unsigned long)((now.tv_sec - since->tv_sec) * 1000 + (now.tv_usec - since->tv_usec) / 1000);
+}
+
+static void case_readable(void) {
+  uint32_t generation = 0;
+
+  test_case("a descriptor with something to read is reported, with its generation");
+  pair_open();
+  CHECK(sv[0] != -1);
+  CHECK_INT(event_add(sv[0], EVENT_IN, 4711), 0);
+  CHECK_INT(write(sv[1], "x", 1), 1);
+  CHECK_INT(wait_for(sv[0], EVENT_IN, 1000, &generation), 1);
+  CHECK_INT(generation, 4711);
+
+  test_case("and keeps being reported until it is read");
+  CHECK_INT(wait_for(sv[0], EVENT_IN, 1000, NULL), 1);
+  {
+    char scratch[4];
+    CHECK_INT(read(sv[0], scratch, sizeof(scratch)), 1);
+  }
+  CHECK_INT(wait_for(sv[0], EVENT_IN, 50, NULL), 0);
+
+  CHECK_INT(event_del(sv[0]), 0);
+  pair_close();
+}
+
+static void case_writable(void) {
+  test_case("a descriptor with room to write is reported");
+  pair_open();
+  CHECK(sv[0] != -1);
+  CHECK_INT(event_add(sv[0], EVENT_OUT, 1), 0);
+  CHECK_INT(wait_for(sv[0], EVENT_OUT, 1000, NULL), 1);
+
+  test_case("and is not, once we say we no longer care");
+  CHECK_INT(event_modify(sv[0], EVENT_IN, 1), 0);
+  CHECK_INT(wait_for(sv[0], EVENT_OUT, 50, NULL), 0);
+
+  CHECK_INT(event_del(sv[0]), 0);
+  pair_close();
+}
+
+static void case_interest_is_separate(void) {
+  test_case("asking only about writing does not report reading");
+  pair_open();
+  CHECK(sv[0] != -1);
+  CHECK_INT(event_add(sv[0], EVENT_OUT, 1), 0);
+  CHECK_INT(write(sv[1], "x", 1), 1);
+  CHECK_INT(wait_for(sv[0], EVENT_IN, 50, NULL), 0);
+
+  test_case("until we ask about it");
+  CHECK_INT(event_modify(sv[0], EVENT_IN | EVENT_OUT, 1), 0);
+  CHECK_INT(wait_for(sv[0], EVENT_IN, 1000, NULL), 1);
+
+  CHECK_INT(event_del(sv[0]), 0);
+  pair_close();
+}
+
+static void case_removed_is_silent(void) {
+  test_case("a removed descriptor is not reported again");
+  pair_open();
+  CHECK(sv[0] != -1);
+  CHECK_INT(event_add(sv[0], EVENT_IN, 1), 0);
+  CHECK_INT(write(sv[1], "x", 1), 1);
+  CHECK_INT(wait_for(sv[0], EVENT_IN, 1000, NULL), 1);
+  CHECK_INT(event_del(sv[0]), 0);
+  CHECK_INT(wait_for(sv[0], EVENT_IN, 50, NULL), 0);
+  pair_close();
+}
+
+static void case_generations_do_not_mix(void) {
+  int      other[2];
+  uint32_t generation = 0;
+
+  test_case("two descriptors carry their own generations");
+  pair_open();
+  CHECK(sv[0] != -1);
+  CHECK_INT(socketpair(AF_UNIX, SOCK_STREAM, 0, other), 0);
+  CHECK_INT(event_add(sv[0], EVENT_IN, 100), 0);
+  CHECK_INT(event_add(other[0], EVENT_IN, 200), 0);
+  CHECK_INT(write(sv[1], "x", 1), 1);
+  CHECK_INT(write(other[1], "y", 1), 1);
+
+  CHECK_INT(wait_for(sv[0], EVENT_IN, 1000, &generation), 1);
+  CHECK_INT(generation, 100);
+  CHECK_INT(wait_for(other[0], EVENT_IN, 1000, &generation), 1);
+  CHECK_INT(generation, 200);
+
+  test_case("and re-registering one changes only its own");
+  CHECK_INT(event_modify(sv[0], EVENT_IN, 101), 0);
+  CHECK_INT(wait_for(sv[0], EVENT_IN, 1000, &generation), 1);
+  CHECK_INT(generation, 101);
+  CHECK_INT(wait_for(other[0], EVENT_IN, 1000, &generation), 1);
+  CHECK_INT(generation, 200);
+
+  event_del(sv[0]);
+  event_del(other[0]);
+  close(other[0]);
+  close(other[1]);
+  pair_close();
+}
+
+/* Removing one of several has to leave the rest addressable: a backend that
+   keeps its descriptors packed moves the last one into the gap, and has to
+   remember where it went. */
+static void case_delete_from_the_middle(void) {
+  int      pair[3][2];
+  uint32_t generation = 0;
+  int      i;
+
+  test_case("deleting one of three leaves the others reported correctly");
+  for (i = 0; i < 3; ++i) {
+    CHECK_INT(socketpair(AF_UNIX, SOCK_STREAM, 0, pair[i]), 0);
+    CHECK_INT(event_add(pair[i][0], EVENT_IN, (uint32_t)(10 + i)), 0);
+  }
+  CHECK_INT(event_del(pair[1][0]), 0);
+
+  for (i = 0; i < 3; i += 2) {
+    CHECK_INT(write(pair[i][1], "x", 1), 1);
+    CHECK_INT(wait_for(pair[i][0], EVENT_IN, 1000, &generation), 1);
+    CHECK_INT(generation, 10 + i);
+  }
+
+  test_case("and the survivors can still be changed and removed");
+  CHECK_INT(event_modify(pair[2][0], EVENT_IN, 99), 0);
+  CHECK_INT(wait_for(pair[2][0], EVENT_IN, 1000, &generation), 1);
+  CHECK_INT(generation, 99);
+  CHECK_INT(event_del(pair[0][0]), 0);
+  CHECK_INT(event_del(pair[2][0]), 0);
+  CHECK_INT(wait_for(pair[2][0], EVENT_IN, 50, NULL), 0);
+
+  for (i = 0; i < 3; ++i)
+    close(pair[i][0]), close(pair[i][1]);
+}
+
+static void case_timeout(void) {
+  struct timeval started;
+
+  test_case("waiting on nothing comes back empty when the time is up");
+  gettimeofday(&started, NULL);
+  CHECK_INT(event_wait(ready, EVENTS, 200), 0);
+  {
+    unsigned long took = elapsed_ms(&started);
+    /* Scheduling makes the upper bound generous. The point is that it waited
+       rather than returning at once, and that it came back at all */
+    CHECK(took >= 150);
+    CHECK(took < 5000);
+  }
+}
+
+static void case_unknown_descriptor(void) {
+  test_case("changing or removing one that was never added is refused");
+  CHECK_INT(event_modify(4096, EVENT_IN, 1), -1);
+  CHECK_INT(event_del(4096), -1);
+}
+
+void test_event(void) {
+  CHECK_INT(event_init(), 0);
+  CHECK(event_mechanism() != NULL);
+
+  case_readable();
+  case_writable();
+  case_interest_is_separate();
+  case_removed_is_silent();
+  case_generations_do_not_mix();
+  case_delete_from_the_middle();
+  case_timeout();
+  case_unknown_descriptor();
+
+  event_deinit();
+}
diff --git a/tests/t_fmt.c b/tests/t_fmt.c
new file mode 100644
index 0000000..bc23ed5
--- /dev/null
+++ b/tests/t_fmt.c
@@ -0,0 +1,108 @@
+/* This software was written by Dirk Engling <erdgeist@erdgeist.org>
+   It is considered beerware. Prost. Skol. Cheers or whatever.
+
+   $id$ */
+
+/* System */
+#include <string.h>
+
+/* Opentracker */
+#include "ot_fmt.h"
+#include "test.h"
+
+static void case_appends_in_sequence(void) {
+  char  buffer[64];
+  char *r = buffer, *re = buffer + sizeof(buffer);
+
+  test_case("appends follow each other and advance the cursor");
+  fmt_append(&r, re, "d8:completei%zde", (size_t)7);
+  fmt_append(&r, re, "ee");
+  *r = 0;
+  CHECK_STR(buffer, "d8:completei7eee");
+  CHECK_INT(r - buffer, 16);
+}
+
+static void case_truncation_stops_at_the_end(void) {
+  char  buffer[16];
+  char *r = buffer, *re = buffer + 8; /* pretend the buffer ends early */
+
+  memset(buffer, '#', sizeof(buffer));
+  test_case("a value too long for the room left stops at the end");
+  fmt_append(&r, re, "%s", "0123456789");
+  CHECK_PTR(r, re);
+
+  test_case("and writes nothing past it");
+  CHECK_INT(buffer[8], '#');
+  CHECK_INT(buffer[15], '#');
+}
+
+static void case_a_full_buffer_takes_nothing_more(void) {
+  char  buffer[16];
+  char *r = buffer + 8, *re = buffer + 8;
+
+  memset(buffer, '#', sizeof(buffer));
+  test_case("appending to a cursor already at the end changes nothing");
+  fmt_append(&r, re, "more");
+  CHECK_PTR(r, re);
+  CHECK_INT(buffer[8], '#');
+}
+
+static void case_an_append_that_just_fits(void) {
+  char  buffer[8];
+  char *r = buffer, *re = buffer + 3;
+
+  memset(buffer, '#', sizeof(buffer));
+  test_case("three characters into three bytes of room still truncate");
+  fmt_append(&r, re, "abc");
+  CHECK_PTR(r, re);
+  CHECK_INT(buffer[0], 'a');
+  CHECK_INT(buffer[1], 'b');
+
+  test_case("because snprintf spends the last byte on its terminator");
+  CHECK_INT(buffer[2], 0);
+  CHECK_INT(buffer[3], '#');
+}
+
+static void case_bytes_are_all_or_nothing(void) {
+  char  buffer[16];
+  char *r = buffer, *re = buffer + 8;
+
+  memset(buffer, '#', sizeof(buffer));
+  test_case("a run of bytes is written when it fits");
+  fmt_bytes(&r, re, "\0\1\2\3", 4);
+  CHECK_PTR(r, buffer + 4);
+  CHECK_MEM(buffer, "\0\1\2\3", 4);
+
+  test_case("a run that would not fit is refused whole");
+  fmt_bytes(&r, re, "abcde", 5);
+  CHECK_PTR(r, re);
+  CHECK_INT(buffer[4], '#');
+
+  test_case("a run of exactly the room left is written");
+  r = buffer + 4;
+  fmt_bytes(&r, re, "wxyz", 4);
+  CHECK_PTR(r, re);
+  CHECK_MEM(buffer + 4, "wxyz", 4);
+  CHECK_INT(buffer[8], '#');
+}
+
+static void case_bytes_do_not_terminate(void) {
+  char  buffer[8];
+  char *r = buffer, *re = buffer + 4;
+
+  memset(buffer, '#', sizeof(buffer));
+  test_case("unlike an append, a run of bytes may fill the room exactly");
+  fmt_bytes(&r, re, "abcd", 4);
+  CHECK_PTR(r, re);
+  CHECK_MEM(buffer, "abcd", 4);
+  CHECK_INT(buffer[4], '#');
+}
+
+void test_fmt(void) {
+  case_appends_in_sequence();
+  case_truncation_stops_at_the_end();
+  case_a_full_buffer_takes_nothing_more();
+  case_an_append_that_just_fits();
+  case_bytes_are_all_or_nothing();
+  case_bytes_do_not_terminate();
+}
diff --git a/tests/t_hex.c b/tests/t_hex.c
index 7cce8ac..a761737 100644
--- a/tests/t_hex.c
+++ b/tests/t_hex.c
@@ -18,7 +18,7 @@ static void case_encode(void) {
 
   test_case("a hash encodes to forty upper case digits and a terminator");
   memset(dest, 0x7f, sizeof(dest));
-  CHECK_PTR(hex_fromhash(dest, sample), dest);
+  CHECK_PTR(hex_from_hash(dest, sample), dest);
   CHECK_STR(dest, "000123456789ABCDEFFF10203040506070809" "0A0");
   CHECK_INT(strlen(dest), 40);
   CHECK_INT((unsigned char)dest[41], 0x7f);
@@ -28,7 +28,7 @@ static void case_decode(void) {
   ot_hash hash;
 
   test_case("forty digits decode back to the hash");
-  CHECK(hex_tohash(hash, "000123456789ABCDEFFF10203040506070809" "0A0"));
+  CHECK(hex_to_hash(hash, "000123456789ABCDEFFF10203040506070809" "0A0"));
   CHECK_MEM(hash, sample, sizeof(sample));
 }
 
@@ -41,8 +41,8 @@ static void case_round_trip(void) {
   for (i = 0; i < 256; ++i) {
     uint8_t probe[20];
     memset(probe, (uint8_t)i, sizeof(probe));
-    hex_fromhash(text, probe);
-    if (!hex_tohash(hash, text) || memcmp(hash, probe, sizeof(probe))) {
+    hex_from_hash(text, probe);
+    if (!hex_to_hash(hash, text) || memcmp(hash, probe, sizeof(probe))) {
       test_failf(__FILE__, __LINE__, "round trip failed for byte value %zu", i);
       return;
     }
@@ -54,8 +54,8 @@ static void case_decode_is_case_insensitive(void) {
   ot_hash upper, lower;
 
   test_case("lower case digits decode the same as upper case");
-  CHECK(hex_tohash(upper, "ABCDEF0123456789ABCDEF0123456789ABCDEF01"));
-  CHECK(hex_tohash(lower, "abcdef0123456789abcdef0123456789abcdef01"));
+  CHECK(hex_to_hash(upper, "ABCDEF0123456789ABCDEF0123456789ABCDEF01"));
+  CHECK(hex_to_hash(lower, "abcdef0123456789abcdef0123456789abcdef01"));
   CHECK_MEM(lower, upper, sizeof(ot_hash));
 }
 
@@ -63,18 +63,18 @@ static void case_rejects_non_digits(void) {
   ot_hash hash;
 
   test_case("a non hex character anywhere rejects the whole string");
-  CHECK_INT(hex_tohash(hash, "g00123456789ABCDEFFF102030405060708090A0"), 0);
-  CHECK_INT(hex_tohash(hash, "000123456789ABCDEFFF102030405060708090Ag"), 0);
-  CHECK_INT(hex_tohash(hash, "000123456789ABCDEF:F102030405060708090A"), 0);
+  CHECK_INT(hex_to_hash(hash, "g00123456789ABCDEFFF102030405060708090A0"), 0);
+  CHECK_INT(hex_to_hash(hash, "000123456789ABCDEFFF102030405060708090Ag"), 0);
+  CHECK_INT(hex_to_hash(hash, "000123456789ABCDEF:F102030405060708090A"), 0);
 }
 
 static void case_rejects_short_input(void) {
   ot_hash hash;
 
   test_case("a string shorter than forty digits is rejected");
-  CHECK_INT(hex_tohash(hash, ""), 0);
-  CHECK_INT(hex_tohash(hash, "00"), 0);
-  CHECK_INT(hex_tohash(hash, "000123456789ABCDEFFF102030405060708090A"), 0);
+  CHECK_INT(hex_to_hash(hash, ""), 0);
+  CHECK_INT(hex_to_hash(hash, "00"), 0);
+  CHECK_INT(hex_to_hash(hash, "000123456789ABCDEFFF102030405060708090A"), 0);
 }
 
 static void case_leaves_hash_untouched_on_failure(void) {
@@ -82,7 +82,7 @@ static void case_leaves_hash_untouched_on_failure(void) {
 
   test_case("a rejected string leaves the destination untouched");
   memset(hash, 0x5a, sizeof(hash));
-  CHECK_INT(hex_tohash(hash, "000123456789ABCDEFFF10203040506070809XX0"), 0);
+  CHECK_INT(hex_to_hash(hash, "000123456789ABCDEFFF10203040506070809XX0"), 0);
   CHECK_MEM(hash, "\x5a\x5a\x5a\x5a\x5a\x5a\x5a\x5a\x5a\x5a\x5a\x5a\x5a\x5a\x5a\x5a\x5a\x5a\x5a\x5a", sizeof(hash));
 }
 
@@ -96,7 +96,7 @@ static void case_stops_at_the_terminator(void) {
   memcpy(guarded, "0012", 4);
   guarded[4] = 0;
   memset(guarded + 5, 'f', 3);
-  CHECK_INT(hex_tohash(hash, guarded), 0);
+  CHECK_INT(hex_to_hash(hash, guarded), 0);
 }
 
 static void case_isdigit(void) {
diff --git a/tests/t_iovec.c b/tests/t_iovec.c
index 89f3fda..2553141 100644
--- a/tests/t_iovec.c
+++ b/tests/t_iovec.c
@@ -18,13 +18,13 @@ static void case_increase_and_length(void) {
   void         *first, *second;
 
   test_case("increase appends an entry and length is their sum");
-  first = iovec_increase(&entries, &vector, 100);
+  first = iovec_new_chunk(&entries, &vector, 100);
   CHECK(first != NULL);
   CHECK_INT(entries, 1);
   CHECK_INT(vector[0].iov_len, 100);
   CHECK_PTR(vector[0].iov_base, first);
 
-  second = iovec_increase(&entries, &vector, 50);
+  second = iovec_new_chunk(&entries, &vector, 50);
   CHECK(second != NULL);
   CHECK_INT(entries, 2);
   CHECK_INT(vector[1].iov_len, 50);
@@ -38,8 +38,8 @@ static void case_free_resets(void) {
   struct iovec *vector  = NULL;
 
   test_case("free releases the entries and resets the vector");
-  CHECK(iovec_increase(&entries, &vector, 10) != NULL);
-  CHECK(iovec_increase(&entries, &vector, 10) != NULL);
+  CHECK(iovec_new_chunk(&entries, &vector, 10) != NULL);
+  CHECK(iovec_new_chunk(&entries, &vector, 10) != NULL);
   iovec_free(&entries, &vector);
   CHECK_INT(entries, 0);
   CHECK_PTR(vector, NULL);
@@ -52,12 +52,12 @@ static void case_fixlast_shrinks(void) {
   char         *block;
 
   test_case("fixlast trims the last entry to the bytes actually used");
-  CHECK(iovec_increase(&entries, &vector, 64) != NULL);
-  block = iovec_increase(&entries, &vector, 1000);
+  CHECK(iovec_new_chunk(&entries, &vector, 64) != NULL);
+  block = iovec_new_chunk(&entries, &vector, 1000);
   CHECK(block != NULL);
   memset(block, 'x', 20);
 
-  iovec_fixlast(&entries, &vector, block + 20);
+  iovec_trim_last(&entries, &vector, block + 20);
   CHECK_INT(entries, 2);
   CHECK_INT(vector[1].iov_len, 20);
   CHECK_INT(iovec_length(&entries, (const struct iovec **)&vector), 84);
@@ -71,7 +71,7 @@ static void case_fixlast_on_empty(void) {
   struct iovec *vector  = NULL;
 
   test_case("fixlast on an empty vector does nothing");
-  iovec_fixlast(&entries, &vector, NULL);
+  iovec_trim_last(&entries, &vector, NULL);
   CHECK_INT(entries, 0);
   CHECK_PTR(vector, NULL);
 }
@@ -103,9 +103,9 @@ static void case_fix_increase(void) {
   char         *block;
 
   test_case("fix_increase trims the previous entry and adds a new one");
-  block = iovec_increase(&entries, &vector, 500);
+  block = iovec_new_chunk(&entries, &vector, 500);
   CHECK(block != NULL);
-  block = iovec_fix_increase_or_free(&entries, &vector, block + 30, 200);
+  block = iovec_next_chunk(&entries, &vector, block + 30, 200);
   CHECK(block != NULL);
   CHECK_INT(entries, 2);
   CHECK_INT(vector[0].iov_len, 30);
diff --git a/tests/t_ip.c b/tests/t_ip.c
index 2fe3a72..8d71679 100644
--- a/tests/t_ip.c
+++ b/tests/t_ip.c
@@ -95,27 +95,27 @@ static void case_scan_forms(void) {
   char ip[16];
 
   test_case("2.2 form 1, every group spelled out");
-  CHECK_INT(ip_scan("1111:2222:3333:4444:5555:6666:7777:8888", ip), 39);
+  CHECK_INT(ip_parse("1111:2222:3333:4444:5555:6666:7777:8888", ip), 39);
   CHECK_MEM(ip, "\x11\x11\x22\x22\x33\x33\x44\x44\x55\x55\x66\x66\x77\x77\x88\x88", 16);
 
   test_case("2.2 form 2, zero groups abbreviated");
-  CHECK_INT(ip_scan("2001:db8::1", ip), 11);
+  CHECK_INT(ip_parse("2001:db8::1", ip), 11);
   CHECK_MEM(ip, "\x20\x01\x0d\xb8\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x01", 16);
-  CHECK_INT(ip_scan("::1", ip), 3);
+  CHECK_INT(ip_parse("::1", ip), 3);
   CHECK_MEM(ip, "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x01", 16);
-  CHECK_INT(ip_scan("::", ip), 2);
+  CHECK_INT(ip_parse("::", ip), 2);
   CHECK_MEM(ip, "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00", 16);
-  CHECK_INT(ip_scan("1::", ip), 3);
+  CHECK_INT(ip_parse("1::", ip), 3);
   CHECK_MEM(ip, "\x00\x01\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00", 16);
 
   test_case("2.2 form 3, a dotted quad in the last two groups");
-  CHECK_INT(ip_scan("::ffff:1.2.3.4", ip), 14);
+  CHECK_INT(ip_parse("::ffff:1.2.3.4", ip), 14);
   CHECK_MEM(ip, "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\xff\xff\x01\x02\x03\x04", 16);
-  CHECK_INT(ip_scan("1:2:3:4:5:6:1.2.3.4", ip), 19);
+  CHECK_INT(ip_parse("1:2:3:4:5:6:1.2.3.4", ip), 19);
   CHECK_MEM(ip, "\x00\x01\x00\x02\x00\x03\x00\x04\x00\x05\x00\x06\x01\x02\x03\x04", 16);
 
   test_case("upper case input is accepted");
-  CHECK_INT(ip_scan("2001:DB8::1", ip), 11);
+  CHECK_INT(ip_parse("2001:DB8::1", ip), 11);
   CHECK_MEM(ip, "\x20\x01\x0d\xb8\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x01", 16);
 }
 
@@ -125,7 +125,7 @@ static void case_scan_accepts_bare_ipv4(void) {
   /* Every address opentracker holds is sixteen bytes, so an operator writing
      a plain IPv4 address in the config has to land as the v4 mapped form */
   test_case("a bare IPv4 address is stored v4 mapped");
-  CHECK_INT(ip_scan("10.0.0.1", ip), 8);
+  CHECK_INT(ip_parse("10.0.0.1", ip), 8);
   CHECK_MEM(ip, "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\xff\xff\x0a\x00\x00\x01", 16);
   CHECK(ip_is_v4mapped(ip));
 }
@@ -136,39 +136,39 @@ static void case_scan_reports_length(void) {
   /* The config parser continues from where the address ended, which is how
      "address:port" and "address/bits" are read */
   test_case("scanning stops at the character after the address");
-  CHECK_INT(ip_scan("10.0.0.1:6969", ip), 8);
-  CHECK_INT(ip_scan("2001:db8::1/64", ip), 11);
-  CHECK_INT(ip_scan("::1]", ip), 3);
-  CHECK_INT(ip_scan("1:2:3:4:5:6:7:8 trailing", ip), 15);
+  CHECK_INT(ip_parse("10.0.0.1:6969", ip), 8);
+  CHECK_INT(ip_parse("2001:db8::1/64", ip), 11);
+  CHECK_INT(ip_parse("::1]", ip), 3);
+  CHECK_INT(ip_parse("1:2:3:4:5:6:7:8 trailing", ip), 15);
 }
 
 static void case_scan_rejects(void) {
   char ip[16];
 
   test_case("an empty or junk string is refused");
-  CHECK_INT(ip_scan("", ip), 0);
-  CHECK_INT(ip_scan("x", ip), 0);
-  CHECK_INT(ip_scan(":", ip), 0);
-  CHECK_INT(ip_scan(":1:2", ip), 0);
+  CHECK_INT(ip_parse("", ip), 0);
+  CHECK_INT(ip_parse("x", ip), 0);
+  CHECK_INT(ip_parse(":", ip), 0);
+  CHECK_INT(ip_parse(":1:2", ip), 0);
 
   test_case("too few groups without :: are refused");
-  CHECK_INT(ip_scan("1:2:3:4:5:6:7", ip), 0);
-  CHECK_INT(ip_scan("2001:db8:1", ip), 0);
+  CHECK_INT(ip_parse("1:2:3:4:5:6:7", ip), 0);
+  CHECK_INT(ip_parse("2001:db8:1", ip), 0);
 
   /* libowfat accepted a prefix of each of these and carried on. Taking only
      part of a malformed address is worse than refusing it, especially where
      the text comes from a config file or an X-Forwarded-For header. */
   test_case("a second :: is refused rather than truncated");
-  CHECK_INT(ip_scan("1::2::3", ip), 0);
-  CHECK_INT(ip_scan("::1::", ip), 0);
-  CHECK_INT(ip_scan("::::", ip), 0);
+  CHECK_INT(ip_parse("1::2::3", ip), 0);
+  CHECK_INT(ip_parse("::1::", ip), 0);
+  CHECK_INT(ip_parse("::::", ip), 0);
 
   test_case("more than eight groups is refused");
-  CHECK_INT(ip_scan("1:2:3:4:5:6:7:8:9", ip), 0);
+  CHECK_INT(ip_parse("1:2:3:4:5:6:7:8:9", ip), 0);
 
   test_case("a group of more than four digits is refused, not truncated");
-  CHECK_INT(ip_scan("12345::1", ip), 0);
-  CHECK_INT(ip_scan("fffff::1", ip), 0);
+  CHECK_INT(ip_parse("12345::1", ip), 0);
+  CHECK_INT(ip_parse("fffff::1", ip), 0);
 }
 
 static void case_round_trip(void) {
@@ -187,7 +187,7 @@ static void case_round_trip(void) {
 
   test_case("every formatted address scans back to the same bytes");
   for (i = 0; samples[i]; ++i) {
-    size_t n = ip_scan(samples[i], ip);
+    size_t n = ip_parse(samples[i], ip);
     if (n != strlen(samples[i])) {
       test_failf(__FILE__, __LINE__, "\"%s\" consumed %zu of %zu", samples[i], n, strlen(samples[i]));
       return;
@@ -197,7 +197,7 @@ static void case_round_trip(void) {
       test_failf(__FILE__, __LINE__, "\"%s\" formatted back as \"%s\"", samples[i], text);
       return;
     }
-    if (!ip_scan(text, again) || memcmp(ip, again, 16)) {
+    if (!ip_parse(text, again) || memcmp(ip, again, 16)) {
       test_failf(__FILE__, __LINE__, "\"%s\" did not survive a second pass", samples[i]);
       return;
     }
diff --git a/tests/t_scan.c b/tests/t_scan.c
index 89f1590..aab4413 100644
--- a/tests/t_scan.c
+++ b/tests/t_scan.c
@@ -15,13 +15,13 @@ static void case_plain_numbers(void) {
   uint64_t value;
 
   test_case("a decimal number is read and its length reported");
-  CHECK_INT(scan_udec("0", &value, 65535), 1);
+  CHECK_INT(scan_uint("0", &value, 65535), 1);
   CHECK_INT(value, 0);
-  CHECK_INT(scan_udec("7", &value, 65535), 1);
+  CHECK_INT(scan_uint("7", &value, 65535), 1);
   CHECK_INT(value, 7);
-  CHECK_INT(scan_udec("6969", &value, 65535), 4);
+  CHECK_INT(scan_uint("6969", &value, 65535), 4);
   CHECK_INT(value, 6969);
-  CHECK_INT(scan_udec("65535", &value, 65535), 5);
+  CHECK_INT(scan_uint("65535", &value, 65535), 5);
   CHECK_INT(value, 65535);
 }
 
@@ -29,11 +29,11 @@ static void case_stops_at_non_digit(void) {
   uint64_t value;
 
   test_case("scanning stops at the first character that is not a digit");
-  CHECK_INT(scan_udec("6969:rest", &value, 65535), 4);
+  CHECK_INT(scan_uint("6969:rest", &value, 65535), 4);
   CHECK_INT(value, 6969);
-  CHECK_INT(scan_udec("128/8", &value, 65535), 3);
+  CHECK_INT(scan_uint("128/8", &value, 65535), 3);
   CHECK_INT(value, 128);
-  CHECK_INT(scan_udec("42\n", &value, 65535), 2);
+  CHECK_INT(scan_uint("42\n", &value, 65535), 2);
   CHECK_INT(value, 42);
 }
 
@@ -41,9 +41,9 @@ static void case_rejects_whitespace(void) {
   uint64_t value = 0xdead;
 
   test_case("leading whitespace is not skipped");
-  CHECK_INT(scan_udec(" 1", &value, 65535), 0);
-  CHECK_INT(scan_udec("\t1", &value, 65535), 0);
-  CHECK_INT(scan_udec("\n1", &value, 65535), 0);
+  CHECK_INT(scan_uint(" 1", &value, 65535), 0);
+  CHECK_INT(scan_uint("\t1", &value, 65535), 0);
+  CHECK_INT(scan_uint("\n1", &value, 65535), 0);
   CHECK_INT(value, 0xdead);
 }
 
@@ -51,9 +51,9 @@ static void case_rejects_sign(void) {
   uint64_t value = 0xdead;
 
   test_case("a sign is not accepted");
-  CHECK_INT(scan_udec("+1", &value, 65535), 0);
-  CHECK_INT(scan_udec("-1", &value, 65535), 0);
-  CHECK_INT(scan_udec("-0", &value, 65535), 0);
+  CHECK_INT(scan_uint("+1", &value, 65535), 0);
+  CHECK_INT(scan_uint("-1", &value, 65535), 0);
+  CHECK_INT(scan_uint("-0", &value, 65535), 0);
   CHECK_INT(value, 0xdead);
 }
 
@@ -61,9 +61,9 @@ static void case_rejects_empty_and_junk(void) {
   uint64_t value = 0xdead;
 
   test_case("a string with no leading digit yields nothing");
-  CHECK_INT(scan_udec("", &value, 65535), 0);
-  CHECK_INT(scan_udec("x", &value, 65535), 0);
-  CHECK_INT(scan_udec(":80", &value, 65535), 0);
+  CHECK_INT(scan_uint("", &value, 65535), 0);
+  CHECK_INT(scan_uint("x", &value, 65535), 0);
+  CHECK_INT(scan_uint(":80", &value, 65535), 0);
   CHECK_INT(value, 0xdead);
 }
 
@@ -71,9 +71,9 @@ static void case_no_alternative_bases(void) {
   uint64_t value;
 
   test_case("hexadecimal and octal notations are read as plain decimal");
-  CHECK_INT(scan_udec("0x10", &value, 65535), 1);
+  CHECK_INT(scan_uint("0x10", &value, 65535), 1);
   CHECK_INT(value, 0);
-  CHECK_INT(scan_udec("010", &value, 65535), 3);
+  CHECK_INT(scan_uint("010", &value, 65535), 3);
   CHECK_INT(value, 10);
 }
 
@@ -81,13 +81,13 @@ static void case_refuses_out_of_range(void) {
   uint64_t value = 0xdead;
 
   test_case("a value above max is refused, not truncated");
-  CHECK_INT(scan_udec("65536", &value, 65535), 0);
-  CHECK_INT(scan_udec("99999", &value, 65535), 0);
-  CHECK_INT(scan_udec("129", &value, 128), 0);
+  CHECK_INT(scan_uint("65536", &value, 65535), 0);
+  CHECK_INT(scan_uint("99999", &value, 65535), 0);
+  CHECK_INT(scan_uint("129", &value, 128), 0);
   CHECK_INT(value, 0xdead);
 
   test_case("the boundary itself is accepted");
-  CHECK_INT(scan_udec("128", &value, 128), 3);
+  CHECK_INT(scan_uint("128", &value, 128), 3);
   CHECK_INT(value, 128);
 }
 
@@ -95,21 +95,21 @@ static void case_sixty_four_bit_range(void) {
   uint64_t value;
 
   test_case("the full unsigned 64 bit range is available");
-  CHECK_INT(scan_udec("18446744073709551615", &value, UINT64_MAX), 20);
+  CHECK_INT(scan_uint("18446744073709551615", &value, UINT64_MAX), 20);
   CHECK(value == UINT64_MAX);
 
   test_case("a number too large for 64 bits is refused");
-  CHECK_INT(scan_udec("18446744073709551616", &value, UINT64_MAX), 0);
-  CHECK_INT(scan_udec("99999999999999999999999999", &value, UINT64_MAX), 0);
+  CHECK_INT(scan_uint("18446744073709551616", &value, UINT64_MAX), 0);
+  CHECK_INT(scan_uint("99999999999999999999999999", &value, UINT64_MAX), 0);
 }
 
 static void case_leading_zeros_allowed(void) {
   uint64_t value;
 
   test_case("leading zeros are accepted outside bencode");
-  CHECK_INT(scan_udec("007", &value, 65535), 3);
+  CHECK_INT(scan_uint("007", &value, 65535), 3);
   CHECK_INT(value, 7);
-  CHECK_INT(scan_udec("0000", &value, 65535), 4);
+  CHECK_INT(scan_uint("0000", &value, 65535), 4);
   CHECK_INT(value, 0);
 }
 
@@ -117,9 +117,9 @@ static void case_bencode_rejects_leading_zeros(void) {
   uint64_t value = 0xdead;
 
   test_case("bencode refuses a leading zero on anything but zero");
-  CHECK_INT(scan_udec_bencode("007", &value, 65535), 0);
-  CHECK_INT(scan_udec_bencode("0000", &value, 65535), 0);
-  CHECK_INT(scan_udec_bencode("01", &value, 65535), 0);
+  CHECK_INT(scan_uint_bencode("007", &value, 65535), 0);
+  CHECK_INT(scan_uint_bencode("0000", &value, 65535), 0);
+  CHECK_INT(scan_uint_bencode("01", &value, 65535), 0);
   CHECK_INT(value, 0xdead);
 }
 
@@ -127,11 +127,11 @@ static void case_bencode_accepts_canonical(void) {
   uint64_t value;
 
   test_case("bencode accepts a canonically written number");
-  CHECK_INT(scan_udec_bencode("0", &value, 65535), 1);
+  CHECK_INT(scan_uint_bencode("0", &value, 65535), 1);
   CHECK_INT(value, 0);
-  CHECK_INT(scan_udec_bencode("0:", &value, 65535), 1);
+  CHECK_INT(scan_uint_bencode("0:", &value, 65535), 1);
   CHECK_INT(value, 0);
-  CHECK_INT(scan_udec_bencode("160:", &value, 65535), 3);
+  CHECK_INT(scan_uint_bencode("160:", &value, 65535), 3);
   CHECK_INT(value, 160);
 }
 
@@ -139,14 +139,64 @@ static void case_bencode_inherits_the_rest(void) {
   uint64_t value = 0xdead;
 
   test_case("bencode is no laxer than the plain scanner");
-  CHECK_INT(scan_udec_bencode(" 1", &value, 65535), 0);
-  CHECK_INT(scan_udec_bencode("-1", &value, 65535), 0);
-  CHECK_INT(scan_udec_bencode("+1", &value, 65535), 0);
-  CHECK_INT(scan_udec_bencode("65536", &value, 65535), 0);
+  CHECK_INT(scan_uint_bencode(" 1", &value, 65535), 0);
+  CHECK_INT(scan_uint_bencode("-1", &value, 65535), 0);
+  CHECK_INT(scan_uint_bencode("+1", &value, 65535), 0);
+  CHECK_INT(scan_uint_bencode("65536", &value, 65535), 0);
   CHECK_INT(value, 0xdead);
 }
 
+/* ------------------------------------------- fixed width signed integers */
+
+/* A value lifted out of a query string arrives as a pointer and a length
+   with nothing terminating it, and the whole of it has to be the number. */
+
+static void case_int_whole_field(void) {
+  int64_t value = 0;
+
+  test_case("the whole field is read, sign and all");
+  CHECK_INT(scan_int("123", 3, &value), 0);
+  CHECK_INT(value, 123);
+  CHECK_INT(scan_int("-45", 3, &value), 0);
+  CHECK_INT(value, -45);
+
+  test_case("and only as far as the length given");
+  CHECK_INT(scan_int("12345", 3, &value), 0);
+  CHECK_INT(value, 123);
+}
+
+static void case_int_rejects_the_rest(void) {
+  int64_t value = 4711;
+
+  test_case("anything that is not all digits is refused");
+  CHECK_INT(scan_int("12a", 3, &value), -1);
+  CHECK_INT(scan_int("", 0, &value), -1);
+  CHECK_INT(scan_int("-", 1, &value), -1);
+  CHECK_INT(scan_int(" 12", 3, &value), -1);
+  CHECK_INT(scan_int("+12", 3, &value), -1);
+
+  test_case("and a refused field leaves the number alone");
+  CHECK_INT(value, 4711);
+}
+
+static void case_int_overflow(void) {
+  int64_t value = 0;
+
+  test_case("a field too long to fit is refused rather than wrapped");
+  CHECK_INT(scan_int("9223372036854775807", 19, &value), 0);
+  CHECK_INT(value, INT64_MAX);
+  CHECK_INT(scan_int("9223372036854775808", 19, &value), -1);
+  CHECK_INT(scan_int("99999999999999999999", 20, &value), -1);
+
+  test_case("including the negative side");
+  CHECK_INT(scan_int("-9223372036854775807", 20, &value), 0);
+  CHECK_INT(value, -INT64_MAX);
+}
+
 void test_scan(void) {
+  case_int_whole_field();
+  case_int_rejects_the_rest();
+  case_int_overflow();
   case_plain_numbers();
   case_stops_at_non_digit();
   case_rejects_whitespace();
diff --git a/tests/t_scan_urlencoded_query.c b/tests/t_urlencoded.c
index cb6c982..6e0ee31 100644
--- a/tests/t_scan_urlencoded_query.c
+++ b/tests/t_urlencoded.c
@@ -7,7 +7,7 @@
 #include <string.h>
 
 /* Opentracker */
-#include "scan_urlencoded_query.h"
+#include "ot_urlencoded.h"
 #include "test.h"
 
 /* The scanner returns the number of bytes written to the destination, or
@@ -23,7 +23,7 @@ static void case_path(void) {
   ssize_t n;
 
   test_case("path stops at the question mark");
-  n = scan_urlencoded_query(&p, dest, SCAN_PATH);
+  n = urlencoded_parse(&p, dest, SCAN_PATH);
   CHECK_INT(n, 9);
   dest[n] = 0;
   CHECK_STR(dest, "/announce");
@@ -37,22 +37,22 @@ static void case_param_and_value(void) {
   ssize_t n;
 
   test_case("parameter stops at '=', value stops at '&'");
-  n = scan_urlencoded_query(&p, dest, SCAN_SEARCHPATH_PARAM);
+  n = urlencoded_parse(&p, dest, SCAN_SEARCHPATH_PARAM);
   CHECK_INT(n, 9);
   dest[n] = 0;
   CHECK_STR(dest, "info_hash");
 
-  n = scan_urlencoded_query(&p, dest, SCAN_SEARCHPATH_VALUE);
+  n = urlencoded_parse(&p, dest, SCAN_SEARCHPATH_VALUE);
   CHECK_INT(n, 3);
   dest[n] = 0;
   CHECK_STR(dest, "abc");
 
-  n = scan_urlencoded_query(&p, dest, SCAN_SEARCHPATH_PARAM);
+  n = urlencoded_parse(&p, dest, SCAN_SEARCHPATH_PARAM);
   CHECK_INT(n, 4);
   dest[n] = 0;
   CHECK_STR(dest, "port");
 
-  n = scan_urlencoded_query(&p, dest, SCAN_SEARCHPATH_VALUE);
+  n = urlencoded_parse(&p, dest, SCAN_SEARCHPATH_VALUE);
   CHECK_INT(n, 2);
   dest[n] = 0;
   CHECK_STR(dest, "80");
@@ -65,7 +65,7 @@ static void case_percent_decoding(void) {
   ssize_t n;
 
   test_case("percent escapes decode");
-  n = scan_urlencoded_query(&p, dest, SCAN_SEARCHPATH_VALUE);
+  n = urlencoded_parse(&p, dest, SCAN_SEARCHPATH_VALUE);
   CHECK_INT(n, 3);
   CHECK_MEM(dest, "ABC", 3);
 }
@@ -79,7 +79,7 @@ static void case_binary_info_hash(void) {
   ssize_t       n;
 
   test_case("twenty byte binary value survives decoding");
-  n = scan_urlencoded_query(&p, dest, SCAN_SEARCHPATH_VALUE);
+  n = urlencoded_parse(&p, dest, SCAN_SEARCHPATH_VALUE);
   CHECK_INT(n, 20);
   CHECK_MEM(dest, want, 20);
 }
@@ -90,7 +90,7 @@ static void case_in_place(void) {
   ssize_t n;
 
   test_case("decoding in place over the source is safe");
-  n = scan_urlencoded_query(&p, query, SCAN_SEARCHPATH_VALUE);
+  n = urlencoded_parse(&p, query, SCAN_SEARCHPATH_VALUE);
   CHECK_INT(n, 2);
   CHECK_MEM(query, "AB", 2);
 }
@@ -102,7 +102,7 @@ static void case_bad_escape(void) {
   ssize_t n;
 
   test_case("a non hexadecimal escape is a parse error");
-  n = scan_urlencoded_query(&p, dest, SCAN_SEARCHPATH_VALUE);
+  n = urlencoded_parse(&p, dest, SCAN_SEARCHPATH_VALUE);
   CHECK_INT(n, -1);
 }
 
@@ -113,7 +113,7 @@ static void case_truncated_escape(void) {
   ssize_t n;
 
   test_case("an escape cut short by the terminator is a parse error");
-  n = scan_urlencoded_query(&p, dest, SCAN_SEARCHPATH_VALUE);
+  n = urlencoded_parse(&p, dest, SCAN_SEARCHPATH_VALUE);
   CHECK_INT(n, -1);
 }
 
@@ -125,11 +125,11 @@ static void case_terminator(void) {
   ssize_t n;
 
   test_case("a hard terminator before any output reports end of input");
-  n = scan_urlencoded_query(&p, dest, SCAN_SEARCHPATH_PARAM);
+  n = urlencoded_parse(&p, dest, SCAN_SEARCHPATH_PARAM);
   CHECK_INT(n, -2);
 
   p = space;
-  n = scan_urlencoded_query(&p, dest, SCAN_SEARCHPATH_PARAM);
+  n = urlencoded_parse(&p, dest, SCAN_SEARCHPATH_PARAM);
   CHECK_INT(n, -2);
 }
 
@@ -140,10 +140,10 @@ static void case_terminator_after_output(void) {
   ssize_t n;
 
   test_case("a hard terminator after output is left for the next call");
-  n = scan_urlencoded_query(&p, dest, SCAN_SEARCHPATH_VALUE);
+  n = urlencoded_parse(&p, dest, SCAN_SEARCHPATH_VALUE);
   CHECK_INT(n, 3);
   CHECK_INT(*p, 0);
-  n = scan_urlencoded_query(&p, dest, SCAN_SEARCHPATH_VALUE);
+  n = urlencoded_parse(&p, dest, SCAN_SEARCHPATH_VALUE);
   CHECK_INT(n, -2);
 }
 
@@ -159,14 +159,14 @@ static void case_separators_are_contextual(void) {
   ssize_t n;
 
   test_case("a question mark is literal inside a value");
-  n = scan_urlencoded_query(&p, dest, SCAN_SEARCHPATH_VALUE);
+  n = urlencoded_parse(&p, dest, SCAN_SEARCHPATH_VALUE);
   CHECK_INT(n, 3);
   dest[n] = 0;
   CHECK_STR(dest, "a?b");
 
   test_case("an equals sign is literal inside a value");
   p = equals;
-  n = scan_urlencoded_query(&p, dest, SCAN_SEARCHPATH_VALUE);
+  n = urlencoded_parse(&p, dest, SCAN_SEARCHPATH_VALUE);
   CHECK_INT(n, 3);
   dest[n] = 0;
   CHECK_STR(dest, "a=b");
@@ -179,7 +179,7 @@ static void case_ampersand_in_path(void) {
   ssize_t n;
 
   test_case("an ampersand in a path is a parse error");
-  n = scan_urlencoded_query(&p, dest, SCAN_PATH);
+  n = urlencoded_parse(&p, dest, SCAN_PATH);
   CHECK_INT(n, -1);
 }
 
@@ -190,7 +190,7 @@ static void case_raw_high_byte(void) {
   ssize_t n;
 
   test_case("an undecoded byte above ASCII is a parse error");
-  n = scan_urlencoded_query(&p, dest, SCAN_SEARCHPATH_VALUE);
+  n = urlencoded_parse(&p, dest, SCAN_SEARCHPATH_VALUE);
   CHECK_INT(n, -1);
 }
 
@@ -200,12 +200,12 @@ static void case_skipvalue(void) {
   char *p       = query;
 
   test_case("skipvalue steps over the value and its separator");
-  scan_urlencoded_skipvalue(&p);
+  urlencoded_skip_value(&p);
   CHECK_STR(p, "next=1");
 
   test_case("skipvalue leaves a hard terminator in place");
   p = bare;
-  scan_urlencoded_skipvalue(&p);
+  urlencoded_skip_value(&p);
   CHECK_INT(*p, 0);
 }
 
@@ -217,44 +217,17 @@ static void case_find_keywords(void) {
   char                    *p          = match;
 
   test_case("a known keyword returns its value");
-  CHECK_INT(scan_find_keywords(keywords, &p, SCAN_SEARCHPATH_PARAM), 2);
+  CHECK_INT(urlencoded_match_keyword(keywords, &p, SCAN_SEARCHPATH_PARAM), 2);
 
   test_case("an unknown keyword returns -3");
   p = nomatch;
-  CHECK_INT(scan_find_keywords(keywords, &p, SCAN_SEARCHPATH_PARAM), -3);
+  CHECK_INT(urlencoded_match_keyword(keywords, &p, SCAN_SEARCHPATH_PARAM), -3);
 
   test_case("a prefix of a keyword does not match it");
   p = prefix;
-  CHECK_INT(scan_find_keywords(keywords, &p, SCAN_SEARCHPATH_PARAM), -3);
+  CHECK_INT(urlencoded_match_keyword(keywords, &p, SCAN_SEARCHPATH_PARAM), -3);
 }
 
-static void case_fixed_int(void) {
-  char positive[] = "123";
-  char negative[] = "-45";
-  char trailing[] = "12a";
-  int  value;
-
-  test_case("scan_fixed_int returns the count of unparsed bytes");
-  CHECK_INT(scan_fixed_int(positive, 3, &value), 0);
-  CHECK_INT(value, 123);
-
-  CHECK_INT(scan_fixed_int(negative, 3, &value), 0);
-  CHECK_INT(value, -45);
-
-  CHECK_INT(scan_fixed_int(trailing, 3, &value), 1);
-  CHECK_INT(value, 12);
-}
-
-static void case_fixed_int_bounded(void) {
-  char digits[] = "12345";
-  int  value;
-
-  test_case("scan_fixed_int honours the length it is given");
-  CHECK_INT(scan_fixed_int(digits, 3, &value), 0);
-  CHECK_INT(value, 123);
-}
-
-
 /* The encoding direction. Which bytes survive unescaped is fixed by what
    existing parsers of the urlencoded full scrape expect, so these cases pin
    the set rather than describe a preference. */
@@ -328,7 +301,7 @@ static void case_fmt_decoder_disagrees_on_dollar(void) {
      encoder passes through unescaped, '$' is the only one the decoder then
      refuses, and it refuses the whole string rather than stopping short.
      Output of the urlencoded full scrape therefore does not round trip
-     through scan_urlencoded_query when a hash contains 0x24. Harmless today
+     through urlencoded_parse when a hash contains 0x24. Harmless today
      because only third party tooling reads that output. */
   const uint8_t src[]  = {'a', '$', 'b'};
   char          dest[16];
@@ -342,11 +315,11 @@ static void case_fmt_decoder_disagrees_on_dollar(void) {
   dest[n] = 0;
   CHECK_STR(dest, "a$b");
 
-  got = scan_urlencoded_query(&p, scanned, SCAN_SEARCHPATH_VALUE);
+  got = urlencoded_parse(&p, scanned, SCAN_SEARCHPATH_VALUE);
   CHECK_INT(got, -1);
 }
 
-void test_scan_urlencoded_query(void) {
+void test_urlencoded(void) {
   case_path();
   case_param_and_value();
   case_percent_decoding();
@@ -361,8 +334,6 @@ void test_scan_urlencoded_query(void) {
   case_raw_high_byte();
   case_skipvalue();
   case_find_keywords();
-  case_fixed_int();
-  case_fixed_int_bounded();
   case_fmt_passes_safe_bytes();
   case_fmt_escapes_the_rest();
   case_fmt_hex_is_lower_case();
diff --git a/tests/t_vector.c b/tests/t_vector.c
index 541a6da..6e048e1 100644
--- a/tests/t_vector.c
+++ b/tests/t_vector.c
@@ -112,6 +112,51 @@ static void case_insert_keeps_order(void) {
   free(vector.data);
 }
 
+/* The peer variant is reached with an empty vector on every first announce
+   for a torrent, and again whenever a swarm empties and refills, because
+   vector_fixup_peers drops the allocation and nulls the data pointer. */
+
+static void case_insert_peer_into_empty_vector(void) {
+  ot_vector vector = {NULL, 0, 0};
+  ot_peer6  low, high;
+  int       exactmatch;
+  ot_peer  *slot;
+
+  memset(low, 0x11, sizeof(low));
+  memset(high, 0x99, sizeof(high));
+
+  test_case("the first peer goes into a vector that has no allocation yet");
+  slot = vector_find_or_insert_peer(&vector, low, OT_PEER_SIZE6, &exactmatch);
+  CHECK(slot != NULL);
+  CHECK_INT(exactmatch, 0);
+  memcpy(slot, low, OT_PEER_SIZE6);
+  CHECK_INT(vector.size, 1);
+  CHECK_INT(vector.space, OT_VECTOR_MIN_MEMBERS);
+  CHECK_PTR(slot, vector.data);
+
+  test_case("a second peer keeps the order");
+  slot = vector_find_or_insert_peer(&vector, high, OT_PEER_SIZE6, &exactmatch);
+  CHECK(slot != NULL);
+  CHECK_INT(exactmatch, 0);
+  memcpy(slot, high, OT_PEER_SIZE6);
+  CHECK_INT(vector.size, 2);
+  CHECK_MEM((char *)vector.data, low, OT_PEER_COMPARE_SIZE6);
+  CHECK_MEM((char *)vector.data + OT_PEER_SIZE6, high, OT_PEER_COMPARE_SIZE6);
+
+  test_case("and emptying the vector hands the allocation back");
+  CHECK(vector_remove_peer(&vector, low, OT_PEER_SIZE6) != 0);
+  CHECK(vector_remove_peer(&vector, high, OT_PEER_SIZE6) != 0);
+  CHECK_INT(vector.size, 0);
+  CHECK_PTR(vector.data, NULL);
+
+  test_case("so the next peer starts from no allocation again");
+  slot = vector_find_or_insert_peer(&vector, low, OT_PEER_SIZE6, &exactmatch);
+  CHECK(slot != NULL);
+  CHECK_INT(vector.size, 1);
+
+  free(vector.data);
+}
+
 static void case_insert_finds_existing(void) {
   ot_vector           vector = {NULL, 0, 0};
   const unsigned char five[4] = {0, 0, 0, 5};
@@ -257,6 +302,7 @@ void test_vector(void) {
   case_search_past_the_end();
   case_search_empty();
   case_insert_keeps_order();
+  case_insert_peer_into_empty_vector();
   case_insert_finds_existing();
   case_insert_compare_prefix();
   case_redistribute_holds_every_peer();
diff --git a/tests/test.h b/tests/test.h
index bc8c3bd..0eddc82 100644
--- a/tests/test.h
+++ b/tests/test.h
@@ -76,7 +76,7 @@ extern unsigned long test_failures;
   } while (0)
 
 /* One entry point per module under test */
-void test_scan_urlencoded_query(void);
+void test_urlencoded(void);
 void test_iovec(void);
 void test_vector(void);
 void test_random(void);
@@ -89,5 +89,7 @@ void test_socket(void);
 void test_mutex(void);
 void test_batch(void);
 void test_fdstate(void);
+void test_event(void);
+void test_fmt(void);
 
 #endif