Merge bitcoin/bitcoin#23542: net: open p2p connections to nodes that listen on non-default ports

36ee76d1af net: remove unused CNetAddr::GetHash() (Vasil Dimov)
d0abce9a50 net: include the port when deciding a relay destination (Vasil Dimov)
2e38a0e686 net: add CServiceHash constructor so the caller can provide the salts (Vasil Dimov)
97208634b9 net: open p2p connections to nodes that listen on non-default ports (Vasil Dimov)

Pull request description:

  By default, for mainnet, the p2p listening port is 8333. Bitcoin Core
  has a strong preference for only connecting to nodes that listen on that
  port.

  Remove that preference because connections over clearnet that involve
  port 8333 make it easy to detect, analyze, block or divert Bitcoin p2p
  traffic before the connection is even established (at TCP SYN time).

  For further justification see the OP of:
  https://github.com/bitcoin/bitcoin/pull/23306

ACKs for top commit:
  laanwj:
    Concept and light code review ACK 36ee76d1af
  prayank23:
    ACK 36ee76d1af
  stickies-v:
    tACK 36ee76d1a
  jonatack:
    ACK 36ee76d1af
  glozow:
    utACK 36ee76d1af

Tree-SHA512: 7f45ab7567c51c19fc50fabbaf84f0cc8883a8eef84272b76435c014c31d89144271d70dd387212cc1114213165d76b4d20a5ddb8dbc958fe7e74e6ddbd56d11

src/netbase.h

@@ -247,4 +247,13 @@ void InterruptSocks5(bool interrupt);
  */
 bool Socks5(const std::string& strDest, uint16_t port, const ProxyCredentials* auth, const Sock& socket);
 
+/**
+ * Determine if a port is "bad" from the perspective of attempting to connect
+ * to a node on that port.
+ * @see doc/p2p-bad-ports.md
+ * @param[in] port Port to check.
+ * @returns whether the port is bad
+ */
+bool IsBadPort(uint16_t port);
+
 #endif // BITCOIN_NETBASE_H