Merge bitcoin/bitcoin#22112: Force port 0 in I2P

4101ec9d2e05a35c35f587a28f1feee6cebcc61b doc: mention that we enforce port=0 in I2P (Vasil Dimov)
e0a2b390c144e123e2fc8a289fdff36815476964 addrman: reset I2P ports to 0 when loading from disk (Vasil Dimov)
41cda9d075ebcab1dbb950160ebe9d0ba7b5745e test: ensure I2P ports are handled as expected (Vasil Dimov)
4f432bd738c420512a86a51ab3e00323f396b89e net: do not connect to I2P hosts on port!=0 (Vasil Dimov)
1f096f091ebd88efb18154b8894a38122c39624f net: distinguish default port per network (Vasil Dimov)
aeac3bce3ead1f24ca782079ef0defa86fd8cb98 net: change I2P seeds' ports to 0 (Vasil Dimov)
38f900290cc3a839e99bef13474d35e1c02e6b0d net: change assumed I2P port to 0 (Vasil Dimov)

Pull request description:

  _This is an alternative to https://github.com/bitcoin/bitcoin/pull/21514, inspired by https://github.com/bitcoin/bitcoin/pull/21514#issuecomment-815049933. They are mutually exclusive. Just one of them should be merged._

  Change assumed ports for I2P to 0 (instead of the default 8333) as this is closer to what actually happens underneath with SAM 3.1 (https://github.com/bitcoin/bitcoin/pull/21514#issuecomment-812632520, https://github.com/bitcoin/bitcoin/pull/21514#issuecomment-816564719).

  Don't connect to I2P peers with advertised port != 0 (we don't specify a port to our SAM 3.1 proxy and it always connects to port = 0).

  Note, this change:
  * Keeps I2P addresses with port != 0 in addrman and relays them to others via P2P gossip. There may be non-bitcoin-core-22.0 peers using SAM 3.2 and for them such addresses may be useful.
  * Silently refuses to connect to I2P hosts with port != 0. This is ok for automatically chosen peers from addrman. Not so ok for peers provided via `-addnode` or `-connect` - a user who specifies `foo.b32.i2p:1234` (non zero port) may wonder why "nothing is happening".

  Fixes #21389

ACKs for top commit:
  laanwj:
    Code review ACK 4101ec9d2e05a35c35f587a28f1feee6cebcc61b
  jonatack:
    re-ACK 4101ec9d2e05a35c35f587a28f1feee6cebcc61b per `git range-diff efff9c3 0b0ee03 4101ec9`, built with DDEBUG_ADDRMAN, did fairly extensive testing on mainnet both with and without a peers.dat / -dnsseeds=0 to test boostrapping.

Tree-SHA512: 0e3c019e1dc05e54f559275859d3450e0c735596d179e30b66811aad9d5b5fabe3dcc44571e8f7b99f9fe16453eee393d6e153454dd873b9ff14907d4e6354fe

1 files changed, 5 insertions, 3 deletions

diff --git a/src/net.cpp b/src/net.cpp
index dd667793d8..0078d71142 100644
--- a/src/net.cpp
+++ b/src/net.cpp
@@ -402,7 +402,8 @@ CNode* CConnman::ConnectNode(CAddress addrConnect, const char *pszDest, bool fCo
         pszDest ? 0.0 : (double)(GetAdjustedTime() - addrConnect.nTime)/3600.0);
 
     // Resolve
-    const uint16_t default_port{Params().GetDefaultPort()};
+    const uint16_t default_port{pszDest != nullptr ? Params().GetDefaultPort(pszDest) :
+                                                     Params().GetDefaultPort()};
     if (pszDest) {
         std::vector<CService> resolved;
         if (Lookup(pszDest, resolved,  default_port, fNameLookup && !HaveNameProxy(), 256) && !resolved.empty()) {
@@ -2059,8 +2060,9 @@ void CConnman::ThreadOpenConnections(const std::vector<std::string> connect)
             // from advertising themselves as a service on another host and
             // port, causing a DoS attack as nodes around the network attempt
             // to connect to it fruitlessly.
-            if (addr.GetPort() != Params().GetDefaultPort() && nTries < 50)
+            if (addr.GetPort() != Params().GetDefaultPort(addr.GetNetwork()) && nTries < 50) {
                 continue;
+            }
 
             addrConnect = addr;
             break;
@@ -2123,7 +2125,7 @@ std::vector<AddedNodeInfo> CConnman::GetAddedNodeInfo() const
     }
 
     for (const std::string& strAddNode : lAddresses) {
-        CService service(LookupNumeric(strAddNode, Params().GetDefaultPort()));
+        CService service(LookupNumeric(strAddNode, Params().GetDefaultPort(strAddNode)));
         AddedNodeInfo addedNode{strAddNode, CService(), false, false};
         if (service.IsValid()) {
             // strAddNode is an IP:port