Merge #15689: netaddress: Update CNetAddr for ORCHIDv2

8be3f30 netaddress: Update CNetAddr for ORCHIDv2 (Carl Dong)

Pull request description:

  ```
  The original ORCHID prefix was deprecated as of 2014-03, the new
  ORCHIDv2 prefix was allocated by RFC7343 as of 2014-07. We did not
  consider the original ORCHID prefix routable, and I don't see any reason
  to consider the new one to be either.
  ```

  Would like to know if people think this kind of thing is even worth keeping the codebase updated for. Perhaps it'd be nice to write a devtool to pull the csv from [here](https://www.iana.org/assignments/iana-ipv6-special-registry/iana-ipv6-special-registry.xhtml) and generate the code.

ACKs for commit 8be3f3:
  laanwj:
    utACK 8be3f30
  ryanofsky:
    utACK 8be3f30. Only change since last review is rebasing after #15718 merge.

Tree-SHA512: 7c93317f597b1a6c1443e12dd690010392edb9d72a479a8201970db7d3444fbb99a80b98026caad6fbfbebb455ab4035d2dde79bc9263bfd1d0398cd218392e1

Author: laanwj

src/netaddress.cpp

@@ -204,6 +204,11 @@ bool CNetAddr::IsRFC4843() const
     return (GetByte(15) == 0x20 && GetByte(14) == 0x01 && GetByte(13) == 0x00 && (GetByte(12) & 0xF0) == 0x10);
 }
 
+bool CNetAddr::IsRFC7343() const
+{
+    return (GetByte(15) == 0x20 && GetByte(14) == 0x01 && GetByte(13) == 0x00 && (GetByte(12) & 0xF0) == 0x20);
+}
+
 /**
  * @returns Whether or not this is a dummy address that maps an onion address
  *          into IPv6.
@@ -289,7 +294,7 @@ bool CNetAddr::IsValid() const
  */
 bool CNetAddr::IsRoutable() const
 {
-    return IsValid() && !(IsRFC1918() || IsRFC2544() || IsRFC3927() || IsRFC4862() || IsRFC6598() || IsRFC5737() || (IsRFC4193() && !IsTor()) || IsRFC4843() || IsLocal() || IsInternal());
+    return IsValid() && !(IsRFC1918() || IsRFC2544() || IsRFC3927() || IsRFC4862() || IsRFC6598() || IsRFC5737() || (IsRFC4193() && !IsTor()) || IsRFC4843() || IsRFC7343() || IsLocal() || IsInternal());
 }
 
 /**

src/netaddress.h

@@ -63,7 +63,8 @@ class CNetAddr
         bool IsRFC3964() const; // IPv6 6to4 tunnelling (2002::/16)
         bool IsRFC4193() const; // IPv6 unique local (FC00::/7)
         bool IsRFC4380() const; // IPv6 Teredo tunnelling (2001::/32)
-        bool IsRFC4843() const; // IPv6 ORCHID (2001:10::/28)
+        bool IsRFC4843() const; // IPv6 ORCHID (deprecated) (2001:10::/28)
+        bool IsRFC7343() const; // IPv6 ORCHIDv2 (2001:20::/28)
         bool IsRFC4862() const; // IPv6 autoconfig (FE80::/64)
         bool IsRFC6052() const; // IPv6 well-known prefix for IPv4-embedded address (64:FF9B::/96)
         bool IsRFC6145() const; // IPv6 IPv4-translated address (::FFFF:0:0:0/96) (actually defined in RFC2765)

src/test/netbase_tests.cpp

@@ -59,6 +59,7 @@ BOOST_AUTO_TEST_CASE(netbase_properties)
     BOOST_CHECK(ResolveIP("FC00::").IsRFC4193());
     BOOST_CHECK(ResolveIP("2001::2").IsRFC4380());
     BOOST_CHECK(ResolveIP("2001:10::").IsRFC4843());
+    BOOST_CHECK(ResolveIP("2001:20::").IsRFC7343());
     BOOST_CHECK(ResolveIP("FE80::").IsRFC4862());
     BOOST_CHECK(ResolveIP("64:FF9B::").IsRFC6052());
     BOOST_CHECK(ResolveIP("FD87:D87E:EB43:edb1:8e4:3588:e546:35ca").IsTor());