addrman: Fix format string in deserialize error

Also add a regression test.

src/addrman.cpp

@@ -242,9 +242,9 @@ void CAddrMan::Unserialize(Stream& s_)
     const uint8_t lowest_compatible = compat - INCOMPATIBILITY_BASE;
     if (lowest_compatible > FILE_FORMAT) {
         throw std::ios_base::failure(strprintf(
-                    "Unsupported format of addrman database: %u. It is compatible with formats >=%u, "
-                    "but the maximum supported by this version of %s is %u.",
-                    format, lowest_compatible, PACKAGE_NAME, static_cast<uint8_t>(FILE_FORMAT)));
+            "Unsupported format of addrman database: %u. It is compatible with formats >=%u, "
+            "but the maximum supported by this version of %s is %u.",
+            uint8_t{format}, uint8_t{lowest_compatible}, PACKAGE_NAME, uint8_t{FILE_FORMAT}));
     }
 
     s >> nKey;

test/functional/feature_addrman.py

@@ -0,0 +1,87 @@
+#!/usr/bin/env python3
+# Copyright (c) 2021 The Bitcoin Core developers
+# Distributed under the MIT software license, see the accompanying
+# file COPYING or http://www.opensource.org/licenses/mit-license.php.
+"""Test addrman functionality"""
+
+import os
+import struct
+
+from test_framework.messages import ser_uint256, hash256
+from test_framework.p2p import MAGIC_BYTES
+from test_framework.test_framework import BitcoinTestFramework
+from test_framework.util import assert_equal
+
+
+def serialize_addrman(*, format=1, lowest_compatible=3):
+    new = []
+    tried = []
+    INCOMPATIBILITY_BASE = 32
+    r = MAGIC_BYTES["regtest"]
+    r += struct.pack("B", format)
+    r += struct.pack("B", INCOMPATIBILITY_BASE + lowest_compatible)
+    r += ser_uint256(1)
+    r += struct.pack("i", len(new))
+    r += struct.pack("i", len(tried))
+    ADDRMAN_NEW_BUCKET_COUNT = 1 << 10
+    r += struct.pack("i", ADDRMAN_NEW_BUCKET_COUNT ^ (1 << 30))
+    for _ in range(ADDRMAN_NEW_BUCKET_COUNT):
+        r += struct.pack("i", 0)
+    checksum = hash256(r)
+    r += checksum
+    return r
+
+
+def write_addrman(peers_dat, **kwargs):
+    with open(peers_dat, "wb") as f:
+        f.write(serialize_addrman(**kwargs))
+
+
+class AddrmanTest(BitcoinTestFramework):
+    def set_test_params(self):
+        self.num_nodes = 1
+
+    def run_test(self):
+        peers_dat = os.path.join(self.nodes[0].datadir, self.chain, "peers.dat")
+
+        self.log.info("Check that mocked addrman is valid")
+        self.stop_node(0)
+        write_addrman(peers_dat)
+        with self.nodes[0].assert_debug_log(["Loaded 0 addresses from peers.dat"]):
+            self.start_node(0, extra_args=["-checkaddrman=1"])
+        assert_equal(self.nodes[0].getnodeaddresses(), [])
+
+        self.log.info("Check that addrman from future cannot be read")
+        self.stop_node(0)
+        write_addrman(peers_dat, lowest_compatible=111)
+        with self.nodes[0].assert_debug_log([
+                f'ERROR: DeserializeDB: Deserialize or I/O error - Unsupported format of addrman database: 1. It is compatible with formats >=111, but the maximum supported by this version of {self.config["environment"]["PACKAGE_NAME"]} is 3.',
+                "Recreating peers.dat",
+        ]):
+            self.start_node(0)
+        assert_equal(self.nodes[0].getnodeaddresses(), [])
+
+        self.log.info("Check that corrupt addrman cannot be read")
+        self.stop_node(0)
+        with open(peers_dat, "wb") as f:
+            f.write(serialize_addrman()[:-1])
+        with self.nodes[0].assert_debug_log([
+                "ERROR: DeserializeDB: Deserialize or I/O error - CAutoFile::read: end of file",
+                "Recreating peers.dat",
+        ]):
+            self.start_node(0)
+        assert_equal(self.nodes[0].getnodeaddresses(), [])
+
+        self.log.info("Check that missing addrman is recreated")
+        self.stop_node(0)
+        os.remove(peers_dat)
+        with self.nodes[0].assert_debug_log([
+                f"Missing or invalid file {peers_dat}",
+                "Recreating peers.dat",
+        ]):
+            self.start_node(0)
+        assert_equal(self.nodes[0].getnodeaddresses(), [])
+
+
+if __name__ == "__main__":
+    AddrmanTest().main()

test/functional/test_runner.py

@@ -282,6 +282,7 @@ BASE_SCRIPTS = [
     'p2p_blockfilters.py',
     'p2p_message_capture.py',
     'feature_includeconf.py',
+    'feature_addrman.py',
     'feature_asmap.py',
     'mempool_unbroadcast.py',
     'mempool_compatibility.py',