Merge #17758: Fix CNetAddr::IsRFC2544 comment + tests

529d332 test: add IsRFC2544 tests (Mark Tyneway)
419ef3b CNetAddr: fix IsRFC2544 comment (Mark Tyneway)

Pull request description:

  The comment describing the functionality of `CNetAddr::IsRFC2544` is incorrect.

  https://github.com/bitcoin/bitcoin/blob/46d6930f8c7ba7cbcd7d86dd5d0117642fcbc819/src/netaddress.h#L57

  It should actually read `198.18.0.0/15` based on [RFC 3330](https://tools.ietf.org/html/rfc3330):

  ```
     198.18.0.0/15 - This block has been allocated for use in benchmark
     tests of network interconnect devices.  Its use is documented in
     [RFC2544].
  ```

  See [RFC 2544](https://tools.ietf.org/html/rfc2544) here.

  See the implementation here:

  https://github.com/bitcoin/bitcoin/blob/47d981e8273804a040d71665a4cb16038d6717e1/src/netaddress.cpp#L142-L145

  This PR also adds tests for the minimum and maximum values that are valid RFC 2544 addresses.

ACKs for top commit:
  practicalswift:
    ACK 529d332
  laanwj:
    ACK 529d332
  promag:
    ACK 529d332, nit could squash.
  jonatack:
    ACK 529d332

Tree-SHA512: 954a9582856d77564e0ea5fd2e3d287d0cfc4ecfe0588115692d01005e8ca7ad8ab20ff390ded867dc91af2bfb758d4e73a336e6c0b7798846c30a6d69b8ae3d

Author: laanwj

src/netaddress.h

@@ -54,7 +54,7 @@ class CNetAddr
         bool IsIPv4() const;    // IPv4 mapped address (::FFFF:0:0/96, 0.0.0.0/0)
         bool IsIPv6() const;    // IPv6 address (not mapped IPv4, not Tor)
         bool IsRFC1918() const; // IPv4 private networks (10.0.0.0/8, 192.168.0.0/16, 172.16.0.0/12)
-        bool IsRFC2544() const; // IPv4 inter-network communications (192.18.0.0/15)
+        bool IsRFC2544() const; // IPv4 inter-network communications (198.18.0.0/15)
         bool IsRFC6598() const; // IPv4 ISP-level NAT (100.64.0.0/10)
         bool IsRFC5737() const; // IPv4 documentation addresses (192.0.2.0/24, 198.51.100.0/24, 203.0.113.0/24)
         bool IsRFC3849() const; // IPv6 documentation address (2001:0DB8::/32)

src/test/netbase_tests.cpp

@@ -54,6 +54,8 @@ BOOST_AUTO_TEST_CASE(netbase_properties)
     BOOST_CHECK(ResolveIP("10.0.0.1").IsRFC1918());
     BOOST_CHECK(ResolveIP("192.168.1.1").IsRFC1918());
     BOOST_CHECK(ResolveIP("172.31.255.255").IsRFC1918());
+    BOOST_CHECK(ResolveIP("198.18.0.0").IsRFC2544());
+    BOOST_CHECK(ResolveIP("198.19.255.255").IsRFC2544());
     BOOST_CHECK(ResolveIP("2001:0DB8::").IsRFC3849());
     BOOST_CHECK(ResolveIP("169.254.1.1").IsRFC3927());
     BOOST_CHECK(ResolveIP("2002::1").IsRFC3964());