net: expose transport types/session IDs of connections in RPC and logs

Co-authored-by: Dhruv Mehta <856960+dhruv@users.noreply.github.com>

8 files changed, 102 insertions, 4 deletions

diff --git a/src/net.cpp b/src/net.cpp
index a3f1a18fe7..a3792b7d49 100644
--- a/src/net.cpp
+++ b/src/net.cpp
@@ -667,6 +667,9 @@ void CNode::CopyStats(CNodeStats& stats)
         LOCK(cs_vRecv);
         X(mapRecvBytesPerMsgType);
         X(nRecvBytes);
+        Transport::Info info = m_transport->GetInfo();
+        stats.m_transport_type = info.transport_type;
+        if (info.session_id) stats.m_session_id = HexStr(*info.session_id);
     }
     X(m_permission_flags);
 
@@ -734,6 +737,11 @@ V1Transport::V1Transport(const NodeId node_id, int nTypeIn, int nVersionIn) noex
     Reset();
 }
 
+Transport::Info V1Transport::GetInfo() const noexcept
+{
+    return {.transport_type = TransportProtocolType::V1, .session_id = {}};
+}
+
 int V1Transport::readHeader(Span<const uint8_t> msg_bytes)
 {
     AssertLockHeld(m_recv_mutex);
@@ -1582,6 +1590,27 @@ size_t V2Transport::GetSendMemoryUsage() const noexcept
     return sizeof(m_send_buffer) + memusage::DynamicUsage(m_send_buffer);
 }
 
+Transport::Info V2Transport::GetInfo() const noexcept
+{
+    AssertLockNotHeld(m_recv_mutex);
+    LOCK(m_recv_mutex);
+    if (m_recv_state == RecvState::V1) return m_v1_fallback.GetInfo();
+
+    Transport::Info info;
+
+    // Do not report v2 and session ID until the version packet has been received
+    // and verified (confirming that the other side very likely has the same keys as us).
+    if (m_recv_state != RecvState::KEY_MAYBE_V1 && m_recv_state != RecvState::KEY &&
+        m_recv_state != RecvState::GARB_GARBTERM && m_recv_state != RecvState::VERSION) {
+        info.transport_type = TransportProtocolType::V2;
+        info.session_id = uint256(MakeUCharSpan(m_cipher.GetSessionID()));
+    } else {
+        info.transport_type = TransportProtocolType::DETECTING;
+    }
+
+    return info;
+}
+
 std::pair<size_t, bool> CConnman::SocketSendData(CNode& node) const
 {
     auto it = node.vSendMsg.begin();
diff --git a/src/net.h b/src/net.h
index 297e408320..2f7b832fba 100644
--- a/src/net.h
+++ b/src/net.h
@@ -232,6 +232,10 @@ public:
     Network m_network;
     uint32_t m_mapped_as;
     ConnectionType m_conn_type;
+    /** Transport protocol type. */
+    TransportProtocolType m_transport_type;
+    /** BIP324 session id string in hex, if any. */
+    std::string m_session_id;
 };
 
 
@@ -268,6 +272,15 @@ class Transport {
 public:
     virtual ~Transport() {}
 
+    struct Info
+    {
+        TransportProtocolType transport_type;
+        std::optional<uint256> session_id;
+    };
+
+    /** Retrieve information about this transport. */
+    virtual Info GetInfo() const noexcept = 0;
+
     // 1. Receiver side functions, for decoding bytes received on the wire into transport protocol
     // agnostic CNetMessage (message type & payload) objects.
 
@@ -426,6 +439,8 @@ public:
         return WITH_LOCK(m_recv_mutex, return CompleteInternal());
     }
 
+    Info GetInfo() const noexcept override;
+
     bool ReceivedBytes(Span<const uint8_t>& msg_bytes) override EXCLUSIVE_LOCKS_REQUIRED(!m_recv_mutex)
     {
         AssertLockNotHeld(m_recv_mutex);
@@ -664,6 +679,7 @@ public:
 
     // Miscellaneous functions.
     bool ShouldReconnectV1() const noexcept override EXCLUSIVE_LOCKS_REQUIRED(!m_recv_mutex, !m_send_mutex);
+    Info GetInfo() const noexcept override EXCLUSIVE_LOCKS_REQUIRED(!m_recv_mutex);
 };
 
 struct CNodeOptions
diff --git a/src/net_processing.cpp b/src/net_processing.cpp
index 03dee13512..06086d6804 100644
--- a/src/net_processing.cpp
+++ b/src/net_processing.cpp
@@ -3585,13 +3585,16 @@ void PeerManagerImpl::ProcessMessage(CNode& pfrom, const std::string& msg_type,
             return;
         }
 
-        if (!pfrom.IsInboundConn()) {
+        // Log succesful 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)};
-            LogPrintf("New outbound peer connected: version: %d, blocks=%d, peer=%d%s%s (%s)\n",
+            LogPrintf("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(), (fLogIPs ? strprintf(", peeraddr=%s", pfrom.addr.ToStringAddrPort()) : ""),
-                      (mapped_as ? strprintf(", mapped_as=%d", mapped_as) : ""),
-                      pfrom.ConnectionTypeAsString());
+                      (mapped_as ? strprintf(", mapped_as=%d", mapped_as) : ""));
         }
 
         if (pfrom.GetCommonVersion() >= SHORT_IDS_BLOCKS_VERSION) {
diff --git a/src/node/connection_types.cpp b/src/node/connection_types.cpp
index 904f4371aa..5e4dc5bf2e 100644
--- a/src/node/connection_types.cpp
+++ b/src/node/connection_types.cpp
@@ -24,3 +24,17 @@ std::string ConnectionTypeAsString(ConnectionType conn_type)
 
     assert(false);
 }
+
+std::string TransportTypeAsString(TransportProtocolType transport_type)
+{
+    switch (transport_type) {
+    case TransportProtocolType::DETECTING:
+        return "detecting";
+    case TransportProtocolType::V1:
+        return "v1";
+    case TransportProtocolType::V2:
+        return "v2";
+    } // no default case, so the compiler can warn about missing cases
+
+    assert(false);
+}
diff --git a/src/node/connection_types.h b/src/node/connection_types.h
index 5e1abcace6..a911b95f7e 100644
--- a/src/node/connection_types.h
+++ b/src/node/connection_types.h
@@ -6,6 +6,7 @@
 #define BITCOIN_NODE_CONNECTION_TYPES_H
 
 #include <string>
+#include <stdint.h>
 
 /** Different types of connections to a peer. This enum encapsulates the
  * information we have available at the time of opening or accepting the
@@ -79,4 +80,14 @@ enum class ConnectionType {
 /** Convert ConnectionType enum to a string value */
 std::string ConnectionTypeAsString(ConnectionType conn_type);
 
+/** Transport layer version */
+enum class TransportProtocolType : uint8_t {
+    DETECTING, //!< Peer could be v1 or v2
+    V1, //!< Unencrypted, plaintext protocol
+    V2, //!< BIP324 protocol
+};
+
+/** Convert TransportProtocolType enum to a string value */
+std::string TransportTypeAsString(TransportProtocolType transport_type);
+
 #endif // BITCOIN_NODE_CONNECTION_TYPES_H
diff --git a/src/rpc/net.cpp b/src/rpc/net.cpp
index 3be91f292c..8d796b8e9b 100644
--- a/src/rpc/net.cpp
+++ b/src/rpc/net.cpp
@@ -45,6 +45,12 @@ const std::vector<std::string> CONNECTION_TYPE_DOC{
         "feeler (short-lived automatic connection for testing addresses)"
 };
 
+const std::vector<std::string> TRANSPORT_TYPE_DOC{
+    "detecting (peer could be v1 or v2)",
+    "v1 (plaintext transport protocol)",
+    "v2 (BIP324 encrypted transport protocol)"
+};
+
 static RPCHelpMan getconnectioncount()
 {
     return RPCHelpMan{"getconnectioncount",
@@ -164,6 +170,8 @@ static RPCHelpMan getpeerinfo()
                     {RPCResult::Type::STR, "connection_type", "Type of connection: \n" + Join(CONNECTION_TYPE_DOC, ",\n") + ".\n"
                                                               "Please note this output is unlikely to be stable in upcoming releases as we iterate to\n"
                                                               "best capture connection behaviors."},
+                    {RPCResult::Type::STR, "transport_protocol_type", "Type of transport protocol: \n" + Join(TRANSPORT_TYPE_DOC, ",\n") + ".\n"},
+                    {RPCResult::Type::STR, "session_id", "The session ID for this connection, or \"\" if there is none (\"v2\" transport protocol only).\n"},
                 }},
             }},
         },
@@ -268,6 +276,8 @@ static RPCHelpMan getpeerinfo()
         }
         obj.pushKV("bytesrecv_per_msg", recvPerMsgType);
         obj.pushKV("connection_type", ConnectionTypeAsString(stats.m_conn_type));
+        obj.pushKV("transport_protocol_type", TransportTypeAsString(stats.m_transport_type));
+        obj.pushKV("session_id", stats.m_session_id);
 
         ret.push_back(obj);
     }
diff --git a/src/test/fuzz/p2p_transport_serialization.cpp b/src/test/fuzz/p2p_transport_serialization.cpp
index 88d6e96eac..21d8dab536 100644
--- a/src/test/fuzz/p2p_transport_serialization.cpp
+++ b/src/test/fuzz/p2p_transport_serialization.cpp
@@ -328,6 +328,9 @@ void SimulationTest(Transport& initiator, Transport& responder, R& rng, FuzzedDa
     // Make sure all expected messages were received.
     assert(expected[0].empty());
     assert(expected[1].empty());
+
+    // Compare session IDs.
+    assert(transports[0]->GetInfo().session_id == transports[1]->GetInfo().session_id);
 }
 
 std::unique_ptr<Transport> MakeV1Transport(NodeId nodeid) noexcept
diff --git a/src/test/net_tests.cpp b/src/test/net_tests.cpp
index 1df08127ad..5976aa3713 100644
--- a/src/test/net_tests.cpp
+++ b/src/test/net_tests.cpp
@@ -1321,6 +1321,14 @@ public:
         SendPacket(contents);
     }
 
+    /** Test whether the transport's session ID matches the session ID we expect. */
+    void CompareSessionIDs() const
+    {
+        auto info = m_transport.GetInfo();
+        BOOST_CHECK(info.session_id);
+        BOOST_CHECK(uint256(MakeUCharSpan(m_cipher.GetSessionID())) == *info.session_id);
+    }
+
     /** Introduce a bit error in the data scheduled to be sent. */
     void Damage()
     {
@@ -1346,6 +1354,7 @@ BOOST_AUTO_TEST_CASE(v2transport_test)
         BOOST_REQUIRE(ret && ret->empty());
         tester.ReceiveGarbage();
         tester.ReceiveVersion();
+        tester.CompareSessionIDs();
         auto msg_data_1 = g_insecure_rand_ctx.randbytes<uint8_t>(InsecureRandRange(100000));
         auto msg_data_2 = g_insecure_rand_ctx.randbytes<uint8_t>(InsecureRandRange(1000));
         tester.SendMessage(uint8_t(4), msg_data_1); // cmpctblock short id
@@ -1386,6 +1395,7 @@ BOOST_AUTO_TEST_CASE(v2transport_test)
         BOOST_REQUIRE(ret && ret->empty());
         tester.ReceiveGarbage();
         tester.ReceiveVersion();
+        tester.CompareSessionIDs();
         auto msg_data_1 = g_insecure_rand_ctx.randbytes<uint8_t>(InsecureRandRange(100000));
         auto msg_data_2 = g_insecure_rand_ctx.randbytes<uint8_t>(InsecureRandRange(1000));
         tester.SendMessage(uint8_t(14), msg_data_1); // inv short id
@@ -1439,6 +1449,7 @@ BOOST_AUTO_TEST_CASE(v2transport_test)
         BOOST_REQUIRE(ret && ret->empty());
         tester.ReceiveGarbage();
         tester.ReceiveVersion();
+        tester.CompareSessionIDs();
         for (unsigned d = 0; d < num_decoys_1; ++d) {
             auto decoy_data = g_insecure_rand_ctx.randbytes<uint8_t>(InsecureRandRange(1000));
             tester.SendPacket(/*content=*/decoy_data, /*aad=*/{}, /*ignore=*/true);
@@ -1516,6 +1527,7 @@ BOOST_AUTO_TEST_CASE(v2transport_test)
         BOOST_REQUIRE(ret && ret->empty());
         tester.ReceiveGarbage();
         tester.ReceiveVersion();
+        tester.CompareSessionIDs();
         auto msg_data_1 = g_insecure_rand_ctx.randbytes<uint8_t>(4000000); // test that receiving 4M payload works
         auto msg_data_2 = g_insecure_rand_ctx.randbytes<uint8_t>(4000000); // test that sending 4M payload works
         tester.SendMessage(uint8_t(InsecureRandRange(223) + 33), {}); // unknown short id