Merge bitcoin/bitcoin#20234: net: don't bind on 0.0.0.0 if binds are restricted to Tor

2feec3ce3130961f98ceb030951d0e46d3b9096c net: don't bind on 0.0.0.0 if binds are restricted to Tor (Vasil Dimov)

Pull request description:

  The semantic of `-bind` is to restrict the binding only to some address.
  If not specified, then the user does not care and we bind to `0.0.0.0`.
  If specified then we should honor the restriction and bind only to the
  specified address.

  Before this change, if no `-bind` is given then we would bind to
  `0.0.0.0:8333` and to `127.0.0.1:8334` (incoming Tor) which is ok -
  the user does not care to restrict the binding.

  However, if only `-bind=addr:port=onion` is given (without ordinary
  `-bind=`) then we would bind to `addr:port` _and_ to `0.0.0.0:8333` in
  addition.

  Change the above to not do the additional bind: if only
  `-bind=addr:port=onion` is given (without ordinary `-bind=`) then bind
  to `addr:port` (only) and consider incoming connections to that as Tor
  and do not advertise it. I.e. a Tor-only node.

ACKs for top commit:
  laanwj:
    Code review ACK 2feec3ce3130961f98ceb030951d0e46d3b9096c
  jonatack:
    utACK 2feec3ce3130961f98ceb030951d0e46d3b9096c per `git diff a004833 2feec3c`
  hebasto:
    ACK 2feec3ce3130961f98ceb030951d0e46d3b9096c, tested on Linux Mint 20.1 (x86_64):

Tree-SHA512: a04483af601706da928958b92dc560f9cfcc78ab0bb9d74414636eed1c6f29ed538ce1fb5a17d41ed82c9c9a45ca94899d0966e7ef93da809c9bcdcdb1d1f040

1 files changed, 4 insertions, 4 deletions

diff --git a/src/net.h b/src/net.h
index 01658e8973..e1f109a2c4 100644
--- a/src/net.h
+++ b/src/net.h
@@ -768,6 +768,9 @@ public:
         std::vector<NetWhitebindPermissions> vWhiteBinds;
         std::vector<CService> vBinds;
         std::vector<CService> onion_binds;
+        /// True if the user did not specify -bind= or -whitebind= and thus
+        /// we should bind on `0.0.0.0` (IPv4) and `::` (IPv6).
+        bool bind_on_any;
         bool m_use_addrman_outgoing = true;
         std::vector<std::string> m_specified_outgoing;
         std::vector<std::string> m_added_nodes;
@@ -962,10 +965,7 @@ private:
 
     bool BindListenPort(const CService& bindAddr, bilingual_str& strError, NetPermissionFlags permissions);
     bool Bind(const CService& addr, unsigned int flags, NetPermissionFlags permissions);
-    bool InitBinds(
-        const std::vector<CService>& binds,
-        const std::vector<NetWhitebindPermissions>& whiteBinds,
-        const std::vector<CService>& onion_binds);
+    bool InitBinds(const Options& options);
 
     void ThreadOpenAddedConnections();
     void AddAddrFetch(const std::string& strDest);