net: use transient I2P session for outbound if -i2pacceptincoming=0

If not accepting I2P connections, then do not create
`CConnman::m_i2p_sam_session`.

When opening a new outbound I2P connection either use
`CConnman::m_i2p_sam_session` like before or create a temporary one and
store it in `CNode` for destruction later.

Author: vasild

src/net.cpp

@@ -485,18 +485,27 @@ CNode* CConnman::ConnectNode(CAddress addrConnect, const char *pszDest, bool fCo
     Proxy proxy;
     CAddress addr_bind;
     assert(!addr_bind.IsValid());
+    std::unique_ptr<i2p::sam::Session> i2p_transient_session;
 
     if (addrConnect.IsValid()) {
+        const bool use_proxy{GetProxy(addrConnect.GetNetwork(), proxy)};
         bool proxyConnectionFailed = false;
 
-        if (addrConnect.GetNetwork() == NET_I2P && m_i2p_sam_session.get() != nullptr) {
+        if (addrConnect.GetNetwork() == NET_I2P && use_proxy) {
             i2p::Connection conn;
-            if (m_i2p_sam_session->Connect(addrConnect, conn, proxyConnectionFailed)) {
-                connected = true;
+
+            if (m_i2p_sam_session) {
+                connected = m_i2p_sam_session->Connect(addrConnect, conn, proxyConnectionFailed);
+            } else {
+                i2p_transient_session = std::make_unique<i2p::sam::Session>(proxy.proxy, &interruptNet);
+                connected = i2p_transient_session->Connect(addrConnect, conn, proxyConnectionFailed);
+            }
+
+            if (connected) {
                 sock = std::move(conn.sock);
                 addr_bind = CAddress{conn.me, NODE_NONE};
             }
-        } else if (GetProxy(addrConnect.GetNetwork(), proxy)) {
+        } else if (use_proxy) {
             sock = CreateSock(proxy.proxy);
             if (!sock) {
                 return nullptr;
@@ -547,7 +556,8 @@ CNode* CConnman::ConnectNode(CAddress addrConnect, const char *pszDest, bool fCo
                              addr_bind,
                              pszDest ? pszDest : "",
                              conn_type,
-                             /*inbound_onion=*/false);
+                             /*inbound_onion=*/false,
+                             std::move(i2p_transient_session));
     pnode->AddRef();
 
     // We're making a new connection, harvest entropy from the time (and our peer count)
@@ -2260,7 +2270,7 @@ bool CConnman::Start(CScheduler& scheduler, const Options& connOptions)
     }
 
     Proxy i2p_sam;
-    if (GetProxy(NET_I2P, i2p_sam)) {
+    if (GetProxy(NET_I2P, i2p_sam) && connOptions.m_i2p_accept_incoming) {
         m_i2p_sam_session = std::make_unique<i2p::sam::Session>(gArgs.GetDataDirNet() / "i2p_private_key",
                                                                 i2p_sam.proxy, &interruptNet);
     }
@@ -2334,7 +2344,7 @@ bool CConnman::Start(CScheduler& scheduler, const Options& connOptions)
     // Process messages
     threadMessageHandler = std::thread(&util::TraceThread, "msghand", [this] { ThreadMessageHandler(); });
 
-    if (connOptions.m_i2p_accept_incoming && m_i2p_sam_session.get() != nullptr) {
+    if (m_i2p_sam_session) {
         threadI2PAcceptIncoming =
             std::thread(&util::TraceThread, "i2paccept", [this] { ThreadI2PAcceptIncoming(); });
     }

src/net.h

@@ -1090,7 +1090,8 @@ class CConnman
 
     /**
      * I2P SAM session.
-     * Used to accept incoming and make outgoing I2P connections.
+     * Used to accept incoming and make outgoing I2P connections from a persistent
+     * address.
      */
     std::unique_ptr<i2p::sam::Session> m_i2p_sam_session;