Merge #21187: Net processing: Only call PushAddress() from net_processing

3e68efa615968e0c9d68a7f197c7852478f6be78 [net] Move checks from GetLocalAddrForPeer to caller (John Newbery)
d21d2b264cd77c027a06f68289cf4c3f177d1ed0 [net] Change AdvertiseLocal to GetLocalAddrForPeer (John Newbery)

Pull request description:

  This is the first part of #21186. It slightly disentangles addr handling in net/net_processing by making it explicit that net_processing is responsible for pushing addr records into `vAddrToSend`.

ACKs for top commit:
  MarcoFalke:
    re-ACK 3e68efa615968e0c9d68a7f197c7852478f6be78 🍅

Tree-SHA512: 9af50c41f5a977e2e277f24a589db38e2980b353401def5e74b108ac5f493d9b5d6b1b8bf15323a4d66321495f04bc271450fcef7aa7d1c095f051a4f8e9b15f

4 files changed, 30 insertions, 26 deletions

diff --git a/src/net.cpp b/src/net.cpp
index 81176785a2..533815b755 100644
--- a/src/net.cpp
+++ b/src/net.cpp
@@ -201,31 +201,29 @@ bool IsPeerAddrLocalGood(CNode *pnode)
            IsReachable(addrLocal.GetNetwork());
 }
 
-// pushes our own address to a peer
-void AdvertiseLocal(CNode *pnode)
+Optional<CAddress> GetLocalAddrForPeer(CNode *pnode)
 {
-    if (fListen && pnode->fSuccessfullyConnected)
+    CAddress addrLocal = GetLocalAddress(&pnode->addr, pnode->GetLocalServices());
+    if (gArgs.GetBoolArg("-addrmantest", false)) {
+        // use IPv4 loopback during addrmantest
+        addrLocal = CAddress(CService(LookupNumeric("127.0.0.1", GetListenPort())), pnode->GetLocalServices());
+    }
+    // If discovery is enabled, sometimes give our peer the address it
+    // tells us that it sees us as in case it has a better idea of our
+    // address than we do.
+    FastRandomContext rng;
+    if (IsPeerAddrLocalGood(pnode) && (!addrLocal.IsRoutable() ||
+         rng.randbits((GetnScore(addrLocal) > LOCAL_MANUAL) ? 3 : 1) == 0))
     {
-        CAddress addrLocal = GetLocalAddress(&pnode->addr, pnode->GetLocalServices());
-        if (gArgs.GetBoolArg("-addrmantest", false)) {
-            // use IPv4 loopback during addrmantest
-            addrLocal = CAddress(CService(LookupNumeric("127.0.0.1", GetListenPort())), pnode->GetLocalServices());
-        }
-        // If discovery is enabled, sometimes give our peer the address it
-        // tells us that it sees us as in case it has a better idea of our
-        // address than we do.
-        FastRandomContext rng;
-        if (IsPeerAddrLocalGood(pnode) && (!addrLocal.IsRoutable() ||
-             rng.randbits((GetnScore(addrLocal) > LOCAL_MANUAL) ? 3 : 1) == 0))
-        {
-            addrLocal.SetIP(pnode->GetAddrLocal());
-        }
-        if (addrLocal.IsRoutable() || gArgs.GetBoolArg("-addrmantest", false))
-        {
-            LogPrint(BCLog::NET, "AdvertiseLocal: advertising address %s\n", addrLocal.ToString());
-            pnode->PushAddress(addrLocal, rng);
-        }
+        addrLocal.SetIP(pnode->GetAddrLocal());
+    }
+    if (addrLocal.IsRoutable() || gArgs.GetBoolArg("-addrmantest", false))
+    {
+        LogPrint(BCLog::NET, "Advertising address %s to peer=%d\n", addrLocal.ToString(), pnode->GetId());
+        return addrLocal;
     }
+    // Address is unroutable. Don't advertise.
+    return nullopt;
 }
 
 // learn a new local address
diff --git a/src/net.h b/src/net.h
index 682150d65a..67d1cf0e55 100644
--- a/src/net.h
+++ b/src/net.h
@@ -197,7 +197,8 @@ enum
 };
 
 bool IsPeerAddrLocalGood(CNode *pnode);
-void AdvertiseLocal(CNode *pnode);
+/** Returns a local address that we should advertise to this peer */
+Optional<CAddress> GetLocalAddrForPeer(CNode *pnode);
 
 /**
  * Mark a network as reachable or unreachable (no automatic connects to it)
diff --git a/src/net_processing.cpp b/src/net_processing.cpp
index ae45d3d807..d6289b882c 100644
--- a/src/net_processing.cpp
+++ b/src/net_processing.cpp
@@ -4416,7 +4416,9 @@ bool PeerManagerImpl::SendMessages(CNode* pto)
         // Address refresh broadcast
         auto current_time = GetTime<std::chrono::microseconds>();
 
-        if (pto->RelayAddrsWithConn() && !::ChainstateActive().IsInitialBlockDownload() && pto->m_next_local_addr_send < current_time) {
+        if (fListen && pto->RelayAddrsWithConn() &&
+            !::ChainstateActive().IsInitialBlockDownload() &&
+            pto->m_next_local_addr_send < current_time) {
             // If we've sent before, clear the bloom filter for the peer, so that our
             // self-announcement will actually go out.
             // This might be unnecessary if the bloom filter has already rolled
@@ -4426,7 +4428,10 @@ bool PeerManagerImpl::SendMessages(CNode* pto)
             if (pto->m_next_local_addr_send != 0us) {
                 pto->m_addr_known->reset();
             }
-            AdvertiseLocal(pto);
+            if (Optional<CAddress> local_addr = GetLocalAddrForPeer(pto)) {
+                FastRandomContext insecure_rand;
+                pto->PushAddress(*local_addr, insecure_rand);
+            }
             pto->m_next_local_addr_send = PoissonNextSend(current_time, AVG_LOCAL_ADDRESS_BROADCAST_INTERVAL);
         }
 
diff --git a/src/test/net_tests.cpp b/src/test/net_tests.cpp
index f52905e1ef..1c7c35528e 100644
--- a/src/test/net_tests.cpp
+++ b/src/test/net_tests.cpp
@@ -691,7 +691,7 @@ BOOST_AUTO_TEST_CASE(ipv4_peer_with_ipv6_addrMe_test)
     pnode->SetAddrLocal(addrLocal);
 
     // before patch, this causes undefined behavior detectable with clang's -fsanitize=memory
-    AdvertiseLocal(&*pnode);
+    GetLocalAddrForPeer(&*pnode);
 
     // suppress no-checks-run warning; if this test fails, it's by triggering a sanitizer
     BOOST_CHECK(1);