i2p: use pointers to Sock to accommodate mocking

Change the types of `i2p::Connection::sock` and
`i2p::sam::Session::m_control_sock` from `Sock` to
`std::unique_ptr<Sock>`.

Using pointers would allow us to sneak `FuzzedSock` instead of `Sock`
and have the methods of the former called.

After this change a test only needs to replace `CreateSock()` with
a function that returns `FuzzedSock`.

3 files changed, 30 insertions, 26 deletions

diff --git a/src/i2p.cpp b/src/i2p.cpp
index 13e7ce3515..a44f09f043 100644
--- a/src/i2p.cpp
+++ b/src/i2p.cpp
@@ -20,6 +20,7 @@
 #include <util/system.h>
 
 #include <chrono>
+#include <memory>
 #include <stdexcept>
 #include <string>
 
@@ -115,7 +116,8 @@ namespace sam {
 Session::Session(const fs::path& private_key_file,
                  const CService& control_host,
                  CThreadInterrupt* interrupt)
-    : m_private_key_file(private_key_file), m_control_host(control_host), m_interrupt(interrupt)
+    : m_private_key_file(private_key_file), m_control_host(control_host), m_interrupt(interrupt),
+      m_control_sock(std::make_unique<Sock>(INVALID_SOCKET))
 {
 }
 
@@ -145,7 +147,7 @@ bool Session::Accept(Connection& conn)
     try {
         while (!*m_interrupt) {
             Sock::Event occurred;
-            conn.sock.Wait(MAX_WAIT_FOR_IO, Sock::RECV, &occurred);
+            conn.sock->Wait(MAX_WAIT_FOR_IO, Sock::RECV, &occurred);
 
             if ((occurred & Sock::RECV) == 0) {
                 // Timeout, no incoming connections within MAX_WAIT_FOR_IO.
@@ -153,7 +155,7 @@ bool Session::Accept(Connection& conn)
             }
 
             const std::string& peer_dest =
-                conn.sock.RecvUntilTerminator('\n', MAX_WAIT_FOR_IO, *m_interrupt, MAX_MSG_SIZE);
+                conn.sock->RecvUntilTerminator('\n', MAX_WAIT_FOR_IO, *m_interrupt, MAX_MSG_SIZE);
 
             conn.peer = CService(DestB64ToAddr(peer_dest), Params().GetDefaultPort());
 
@@ -171,7 +173,7 @@ bool Session::Connect(const CService& to, Connection& conn, bool& proxy_error)
     proxy_error = true;
 
     std::string session_id;
-    Sock sock;
+    std::unique_ptr<Sock> sock;
     conn.peer = to;
 
     try {
@@ -184,12 +186,12 @@ bool Session::Connect(const CService& to, Connection& conn, bool& proxy_error)
         }
 
         const Reply& lookup_reply =
-            SendRequestAndGetReply(sock, strprintf("NAMING LOOKUP NAME=%s", to.ToStringIP()));
+            SendRequestAndGetReply(*sock, strprintf("NAMING LOOKUP NAME=%s", to.ToStringIP()));
 
         const std::string& dest = lookup_reply.Get("VALUE");
 
         const Reply& connect_reply = SendRequestAndGetReply(
-            sock, strprintf("STREAM CONNECT ID=%s DESTINATION=%s SILENT=false", session_id, dest),
+            *sock, strprintf("STREAM CONNECT ID=%s DESTINATION=%s SILENT=false", session_id, dest),
             false);
 
         const std::string& result = connect_reply.Get("RESULT");
@@ -271,7 +273,7 @@ Session::Reply Session::SendRequestAndGetReply(const Sock& sock,
     return reply;
 }
 
-Sock Session::Hello() const
+std::unique_ptr<Sock> Session::Hello() const
 {
     auto sock = CreateSock(m_control_host);
 
@@ -285,7 +287,7 @@ Sock Session::Hello() const
 
     SendRequestAndGetReply(*sock, "HELLO VERSION MIN=3.1 MAX=3.1");
 
-    return std::move(*sock);
+    return sock;
 }
 
 void Session::CheckControlSock()
@@ -293,7 +295,7 @@ void Session::CheckControlSock()
     LOCK(m_mutex);
 
     std::string errmsg;
-    if (!m_control_sock.IsConnected(errmsg)) {
+    if (!m_control_sock->IsConnected(errmsg)) {
         Log("Control socket error: %s", errmsg);
         Disconnect();
     }
@@ -341,26 +343,26 @@ Binary Session::MyDestination() const
 void Session::CreateIfNotCreatedAlready()
 {
     std::string errmsg;
-    if (m_control_sock.IsConnected(errmsg)) {
+    if (m_control_sock->IsConnected(errmsg)) {
         return;
     }
 
     Log("Creating SAM session with %s", m_control_host.ToString());
 
-    Sock sock = Hello();
+    auto sock = Hello();
 
     const auto& [read_ok, data] = ReadBinaryFile(m_private_key_file);
     if (read_ok) {
         m_private_key.assign(data.begin(), data.end());
     } else {
-        GenerateAndSavePrivateKey(sock);
+        GenerateAndSavePrivateKey(*sock);
     }
 
     const std::string& session_id = GetRandHash().GetHex().substr(0, 10); // full is an overkill, too verbose in the logs
     const std::string& private_key_b64 = SwapBase64(EncodeBase64(m_private_key));
 
-    SendRequestAndGetReply(sock, strprintf("SESSION CREATE STYLE=STREAM ID=%s DESTINATION=%s",
-                                           session_id, private_key_b64));
+    SendRequestAndGetReply(*sock, strprintf("SESSION CREATE STYLE=STREAM ID=%s DESTINATION=%s",
+                                            session_id, private_key_b64));
 
     m_my_addr = CService(DestBinToAddr(MyDestination()), Params().GetDefaultPort());
     m_session_id = session_id;
@@ -370,12 +372,12 @@ void Session::CreateIfNotCreatedAlready()
               m_my_addr.ToString());
 }
 
-Sock Session::StreamAccept()
+std::unique_ptr<Sock> Session::StreamAccept()
 {
-    Sock sock = Hello();
+    auto sock = Hello();
 
     const Reply& reply = SendRequestAndGetReply(
-        sock, strprintf("STREAM ACCEPT ID=%s SILENT=false", m_session_id), false);
+        *sock, strprintf("STREAM ACCEPT ID=%s SILENT=false", m_session_id), false);
 
     const std::string& result = reply.Get("RESULT");
 
@@ -393,14 +395,14 @@ Sock Session::StreamAccept()
 
 void Session::Disconnect()
 {
-    if (m_control_sock.Get() != INVALID_SOCKET) {
+    if (m_control_sock->Get() != INVALID_SOCKET) {
         if (m_session_id.empty()) {
             Log("Destroying incomplete session");
         } else {
             Log("Destroying session %s", m_session_id);
         }
     }
-    m_control_sock.Reset();
+    m_control_sock->Reset();
     m_session_id.clear();
 }
 } // namespace sam
diff --git a/src/i2p.h b/src/i2p.h
index 1ebe7d0329..cb2efedba8 100644
--- a/src/i2p.h
+++ b/src/i2p.h
@@ -12,6 +12,7 @@
 #include <threadinterrupt.h>
 #include <util/sock.h>
 
+#include <memory>
 #include <optional>
 #include <string>
 #include <unordered_map>
@@ -29,7 +30,7 @@ using Binary = std::vector<uint8_t>;
  */
 struct Connection {
     /** Connected socket. */
-    Sock sock;
+    std::unique_ptr<Sock> sock;
 
     /** Our I2P address. */
     CService me;
@@ -166,7 +167,7 @@ private:
      * @return a connected socket
      * @throws std::runtime_error if an error occurs
      */
-    Sock Hello() const EXCLUSIVE_LOCKS_REQUIRED(m_mutex);
+    std::unique_ptr<Sock> Hello() const EXCLUSIVE_LOCKS_REQUIRED(m_mutex);
 
     /**
      * Check the control socket for errors and possibly disconnect.
@@ -204,10 +205,11 @@ private:
 
     /**
      * Open a new connection to the SAM proxy and issue "STREAM ACCEPT" request using the existing
-     * session id. Return the idle socket that is waiting for a peer to connect to us.
+     * session id.
+     * @return the idle socket that is waiting for a peer to connect to us
      * @throws std::runtime_error if an error occurs
      */
-    Sock StreamAccept() EXCLUSIVE_LOCKS_REQUIRED(m_mutex);
+    std::unique_ptr<Sock> StreamAccept() EXCLUSIVE_LOCKS_REQUIRED(m_mutex);
 
     /**
      * Destroy the session, closing the internally used sockets.
@@ -248,7 +250,7 @@ private:
      * connections and make outgoing ones.
      * See https://geti2p.net/en/docs/api/samv3
      */
-    Sock m_control_sock GUARDED_BY(m_mutex);
+    std::unique_ptr<Sock> m_control_sock GUARDED_BY(m_mutex);
 
     /**
      * Our .b32.i2p address.
diff --git a/src/net.cpp b/src/net.cpp
index 36065118d7..6ff51057b1 100644
--- a/src/net.cpp
+++ b/src/net.cpp
@@ -432,7 +432,7 @@ CNode* CConnman::ConnectNode(CAddress addrConnect, const char *pszDest, bool fCo
             i2p::Connection conn;
             if (m_i2p_sam_session->Connect(addrConnect, conn, proxyConnectionFailed)) {
                 connected = true;
-                sock = std::make_unique<Sock>(std::move(conn.sock));
+                sock = std::move(conn.sock);
                 addr_bind = CAddress{conn.me, NODE_NONE};
             }
         } else if (GetProxy(addrConnect.GetNetwork(), proxy)) {
@@ -2221,7 +2221,7 @@ void CConnman::ThreadI2PAcceptIncoming()
             continue;
         }
 
-        CreateNodeFromAcceptedSocket(conn.sock.Release(), NetPermissionFlags::PF_NONE,
+        CreateNodeFromAcceptedSocket(conn.sock->Release(), NetPermissionFlags::PF_NONE,
                                      CAddress{conn.me, NODE_NONE}, CAddress{conn.peer, NODE_NONE});
     }
 }