Merge #20564: Don't send 'sendaddrv2' to pre-70016 software, and send before 'verack'

1583498fb6781c01ca2f33c09319ed793964c574 Send and require SENDADDRV2 before VERACK (Pieter Wuille)
c5a89196602e43ebb1cdc9cd4f08d153419c13e1 Don't send 'sendaddrv2' to pre-70016 software (Pieter Wuille)

Pull request description:

  BIP155 defines addrv2 and sendaddrv2 for all protocol versions, but some implementations reject messages they don't know. As a courtesy, don't send it to nodes with a version before 70016, as no software is known to support BIP155 that doesn't announce at least that protocol version number.

  Also move the sending of sendaddrv2 earlier (before sending verack), as proposed in https://github.com/bitcoin/bips/pull/1043. This has the side effect that local address broadcast of torv3 will work (as it'll only trigger after we know whether or not the peer supports addrv2).

ACKs for top commit:
  MarcoFalke:
    ACK 1583498fb6781c01ca2f33c09319ed793964c574
  jnewbery:
    ACK 1583498fb6781c01ca2f33c09319ed793964c574
  jonatack:
    ACK 1583498fb6781c01ca2f33c09319ed793964c574
  vasild:
    ACK 1583498

Tree-SHA512: 3bd5833fa8c8567b6dedd99e4a9b6bb71c127aa66d5284b217503c86d597dc59aa7382c41f3a4bf561bb658b89db81d1a7703a700eef4ffc17cb916660e23a82

1 files changed, 20 insertions, 8 deletions

diff --git a/src/net_processing.cpp b/src/net_processing.cpp
index 2f2924b262..7c4ba458c3 100644
--- a/src/net_processing.cpp
+++ b/src/net_processing.cpp
@@ -2362,10 +2362,16 @@ void PeerManager::ProcessMessage(CNode& pfrom, const std::string& msg_type, CDat
             m_connman.PushMessage(&pfrom, msg_maker.Make(NetMsgType::WTXIDRELAY));
         }
 
-        m_connman.PushMessage(&pfrom, msg_maker.Make(NetMsgType::VERACK));
-
         // Signal ADDRv2 support (BIP155).
-        m_connman.PushMessage(&pfrom, msg_maker.Make(NetMsgType::SENDADDRV2));
+        if (greatest_common_version >= 70016) {
+            // BIP155 defines addrv2 and sendaddrv2 for all protocol versions, but some
+            // implementations reject messages they don't know. As a courtesy, don't send
+            // it to nodes with a version before 70016, as no software is known to support
+            // BIP155 that doesn't announce at least that protocol version number.
+            m_connman.PushMessage(&pfrom, msg_maker.Make(NetMsgType::SENDADDRV2));
+        }
+
+        m_connman.PushMessage(&pfrom, msg_maker.Make(NetMsgType::VERACK));
 
         pfrom.nServices = nServices;
         pfrom.SetAddrLocal(addrMe);
@@ -2535,6 +2541,17 @@ void PeerManager::ProcessMessage(CNode& pfrom, const std::string& msg_type, CDat
         return;
     }
 
+    if (msg_type == NetMsgType::SENDADDRV2) {
+        if (pfrom.fSuccessfullyConnected) {
+            // Disconnect peers that send SENDADDRV2 message after VERACK; this
+            // must be negotiated between VERSION and VERACK.
+            pfrom.fDisconnect = true;
+            return;
+        }
+        pfrom.m_wants_addrv2 = true;
+        return;
+    }
+
     if (!pfrom.fSuccessfullyConnected) {
         LogPrint(BCLog::NET, "Unsupported message \"%s\" prior to verack from peer=%d\n", SanitizeString(msg_type), pfrom.GetId());
         return;
@@ -2602,11 +2619,6 @@ void PeerManager::ProcessMessage(CNode& pfrom, const std::string& msg_type, CDat
         return;
     }
 
-    if (msg_type == NetMsgType::SENDADDRV2) {
-        pfrom.m_wants_addrv2 = true;
-        return;
-    }
-
     if (msg_type == NetMsgType::SENDHEADERS) {
         LOCK(cs_main);
         State(pfrom.GetId())->fPreferHeaders = true;