Merge bitcoin/bitcoin#34008: log: don't rate-limit "new peer" with -debug=net

d4d184e log: don't rate-limit "new peer" with -debug=net (0xb10c)

Pull request description:

  Previously, when `debug=net` is enabled, we log "New [..] peer connected" for new inbound peers with `LogInfo`. However, `LogInfo` will get rate-limited since bitcoin/bitcoin#32604. When we specifically turn on `debug=net`, we don't want these log messages to be rate-limited.

  To fix this, use `LogDebug(BCLog::NET, ...)` for potentially high-rate inbound connections. Otherwise use `LogInfo`. This means we don't rate-limit the messages for inbound peers when `debug=net` is turned on but will rate-limit if we created outbound at a high rate as these are logged via `LogInfo`.

  The new log messages look similar to:
  ```
  2025-12-08T00:00:00Z [net] New inbound peer connected: transport=v2 version=70016 blocks=0 peer=1
  2025-12-08T00:00:00Z New outbound-full-relay peer connected: transport=v2 version=70016 blocks=281738 peer=5
  ```

  --

  I ran into this message getting rate-limited on one of my monitoring nodes with `-logsourcelocations=1`: With logsourcelocations, one of these lines is about 338 chars (or 338 bytes) long. We rate-limit after more than 1048576 bytes per hour, which results in about 3100 in- and outbound connections per hour. With evicted and instantly reconnecting connections from an entity like LinkingLion, this can be reached fairly quickly.

ACKs for top commit:
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Tree-SHA512: 14dbf693fa44a74c9822590e7a08167d2deeb1bc6f4b8aeb00c1b035c0df7101087d5c80a3c0d637879d5c52f88b30f0cb4c0577cff6f647d2eb3300f49d8ea3

Author: glozow

src/net_processing.cpp

@@ -3666,16 +3666,22 @@ void PeerManagerImpl::ProcessMessage(CNode& pfrom, const std::string& msg_type,
             return;
         }
 
+        auto new_peer_msg = [&]() {
+            const auto mapped_as{m_connman.GetMappedAS(pfrom.addr)};
+            return strprintf("New %s peer connected: transport: %s, version: %d, blocks=%d peer=%d%s%s\n",
+                pfrom.ConnectionTypeAsString(),
+                TransportTypeAsString(pfrom.m_transport->GetInfo().transport_type),
+                pfrom.nVersion.load(), peer->m_starting_height,
+                pfrom.GetId(), pfrom.LogIP(fLogIPs),
+                (mapped_as ? strprintf(", mapped_as=%d", mapped_as) : ""));
+        };
+
         // Log successful connections unconditionally for outbound, but not for inbound as those
         // can be triggered by an attacker at high rate.
-        if (!pfrom.IsInboundConn() || LogAcceptCategory(BCLog::NET, BCLog::Level::Debug)) {
-            const auto mapped_as{m_connman.GetMappedAS(pfrom.addr)};
-            LogInfo("New %s %s peer connected: version: %d, blocks=%d, peer=%d%s%s\n",
-                      pfrom.ConnectionTypeAsString(),
-                      TransportTypeAsString(pfrom.m_transport->GetInfo().transport_type),
-                      pfrom.nVersion.load(), peer->m_starting_height,
-                      pfrom.GetId(), pfrom.LogIP(fLogIPs),
-                      (mapped_as ? strprintf(", mapped_as=%d", mapped_as) : ""));
+        if (pfrom.IsInboundConn()) {
+            LogDebug(BCLog::NET, "%s", new_peer_msg());
+        } else {
+            LogInfo("%s", new_peer_msg());
         }
 
         if (pfrom.GetCommonVersion() >= SHORT_IDS_BLOCKS_VERSION) {