To be able to label incoming tor connections as different from normal localhost connections in e.g. `getpeerinfo` and the peers list in the GUI it'd be useful to have them connect on an alternative local-only port. Or even better, a UNIX socket.

For manually set-up hidden services this would have to be configured manually and could add a `hsport` option or such. The external port would still appear as `XXXXXXXXX.onion:8333`, however internally it would redirect to a that port.

In the case of `torcontrol` this would be easy to set up automatically. It could add a new (localhost) binding port automatically and this code would have to be changed:
- https://github.com/bitcoin/bitcoin/blob/master/src/torcontrol.cpp#L441
- https://github.com/bitcoin/bitcoin/blob/master/src/torcontrol.cpp#L477

{
    if (reply.code == 250) {
        LogPrint(BCLog::TOR, "tor: SAFECOOKIE authentication challenge successful\n");
        std::pair<std::string,std::string> l = SplitTorReplyLine(reply.lines[0]);
        if (l.first == "AUTHCHALLENGE") {
            std::map<std::string,std::string> m = ParseTorReplyMapping(l.second);
            if (m.empty()) {
                LogPrintf("tor: Error parsing AUTHCHALLENGE parameters: %s\n", SanitizeString(l.second));
                return;
            }
            std::vector<uint8_t> serverHash = ParseHex(m["SERVERHASH"]);
            std::vector<uint8_t> serverNonce = ParseHex(m["SERVERNONCE"]);
            LogPrint(BCLog::TOR, "tor: AUTHCHALLENGE ServerHash %s ServerNonce %s\n", HexStr(serverHash), HexStr(serverNonce));
            if (serverNonce.size() != 32) {
                LogPrintf("tor: ServerNonce is not 32 bytes, as required by spec\n");
                return;
            }
            std::vector<uint8_t> computedServerHash = ComputeResponse(TOR_SAFE_SERVERKEY, cookie, clientNonce, serverNonce);
            if (computedServerHash != serverHash) {
                LogPrintf("tor: ServerHash %s does not match expected ServerHash %s\n", HexStr(serverHash), HexStr(computedServerHash));
                return;
            }