Merge bitcoin/bitcoin#26312: Remove Sock::Get() and Sock::Sock()

7df450836969b81e98322c9a09c08b35d1095a25 test: improve sock_tests/move_assignment (Vasil Dimov)
5086a99b84367a45706af7197da1016dd966e6d9 net: remove Sock default constructor, it's not necessary (Vasil Dimov)
7829272f7826511241defd34954e6040ea963f07 net: remove now unnecessary Sock::Get() (Vasil Dimov)
944b21b70ae490a5a746bcc1810a5074d74e9d34 net: don't check if the socket is valid in ConnectSocketDirectly() (Vasil Dimov)
aeac68d036e3cff57ce155f1a904d77f98b357d4 net: don't check if the socket is valid in GetBindAddress() (Vasil Dimov)
5ac1a51ee5a57da59f1ff1986b7d9054484d3c80 i2p: avoid using Sock::Get() for checking for a valid socket (Vasil Dimov)

Pull request description:

  _This is a piece of #21878, chopped off to ease review._

  Peeking at the underlying socket file descriptor of `Sock` and checkig if it is `INVALID_SOCKET` is bad encapsulation and stands in the way of testing/mocking/fuzzing.

  Instead use an empty `unique_ptr` to denote that there is no valid socket where appropriate or outright remove such checks where they are not necessary.

  The default constructor `Sock::Sock()` is unnecessary now after recent changes, thus remove it.

ACKs for top commit:
  ajtowns:
    ACK 7df450836969b81e98322c9a09c08b35d1095a25
  jonatack:
    ACK 7df450836969b81e98322c9a09c08b35d1095a25

Tree-SHA512: 9742aeeeabe8690530bf74caa6ba296787028c52f4a3342afd193b05dbbb1f6645935c33ba0a5230199a09af01c666bd3c7fb16b48692a0d185356ea59a8ddbf

9 files changed, 62 insertions, 55 deletions

diff --git a/src/i2p.cpp b/src/i2p.cpp
index f03e375adf..5a3dde54ce 100644
--- a/src/i2p.cpp
+++ b/src/i2p.cpp
@@ -119,7 +119,6 @@ Session::Session(const fs::path& private_key_file,
     : m_private_key_file{private_key_file},
       m_control_host{control_host},
       m_interrupt{interrupt},
-      m_control_sock{std::make_unique<Sock>(INVALID_SOCKET)},
       m_transient{false}
 {
 }
@@ -127,7 +126,6 @@ Session::Session(const fs::path& private_key_file,
 Session::Session(const CService& control_host, CThreadInterrupt* interrupt)
     : m_control_host{control_host},
       m_interrupt{interrupt},
-      m_control_sock{std::make_unique<Sock>(INVALID_SOCKET)},
       m_transient{true}
 {
 }
@@ -315,7 +313,7 @@ void Session::CheckControlSock()
     LOCK(m_mutex);
 
     std::string errmsg;
-    if (!m_control_sock->IsConnected(errmsg)) {
+    if (m_control_sock && !m_control_sock->IsConnected(errmsg)) {
         Log("Control socket error: %s", errmsg);
         Disconnect();
     }
@@ -364,7 +362,7 @@ Binary Session::MyDestination() const
 void Session::CreateIfNotCreatedAlready()
 {
     std::string errmsg;
-    if (m_control_sock->IsConnected(errmsg)) {
+    if (m_control_sock && m_control_sock->IsConnected(errmsg)) {
         return;
     }
 
@@ -437,14 +435,14 @@ std::unique_ptr<Sock> Session::StreamAccept()
 
 void Session::Disconnect()
 {
-    if (m_control_sock->Get() != INVALID_SOCKET) {
+    if (m_control_sock) {
         if (m_session_id.empty()) {
             Log("Destroying incomplete SAM session");
         } else {
             Log("Destroying SAM session %s", m_session_id);
         }
+        m_control_sock.reset();
     }
-    m_control_sock = std::make_unique<Sock>(INVALID_SOCKET);
     m_session_id.clear();
 }
 } // namespace sam
diff --git a/src/i2p.h b/src/i2p.h
index c9c99292d9..cb9da64816 100644
--- a/src/i2p.h
+++ b/src/i2p.h
@@ -261,6 +261,7 @@ private:
      * ("SESSION CREATE"). With the established session id we later open
      * other connections to the SAM service to accept incoming I2P
      * connections and make outgoing ones.
+     * If not connected then this unique_ptr will be empty.
      * See https://geti2p.net/en/docs/api/samv3
      */
     std::unique_ptr<Sock> m_control_sock GUARDED_BY(m_mutex);
diff --git a/src/net.cpp b/src/net.cpp
index 6b2ef5f43d..13f4430424 100644
--- a/src/net.cpp
+++ b/src/net.cpp
@@ -429,12 +429,10 @@ static CAddress GetBindAddress(const Sock& sock)
     CAddress addr_bind;
     struct sockaddr_storage sockaddr_bind;
     socklen_t sockaddr_bind_len = sizeof(sockaddr_bind);
-    if (sock.Get() != INVALID_SOCKET) {
-        if (!sock.GetSockName((struct sockaddr*)&sockaddr_bind, &sockaddr_bind_len)) {
-            addr_bind.SetSockAddr((const struct sockaddr*)&sockaddr_bind);
-        } else {
-            LogPrintLevel(BCLog::NET, BCLog::Level::Warning, "getsockname failed\n");
-        }
+    if (!sock.GetSockName((struct sockaddr*)&sockaddr_bind, &sockaddr_bind_len)) {
+        addr_bind.SetSockAddr((const struct sockaddr*)&sockaddr_bind);
+    } else {
+        LogPrintLevel(BCLog::NET, BCLog::Level::Warning, "getsockname failed\n");
     }
     return addr_bind;
 }
diff --git a/src/netbase.cpp b/src/netbase.cpp
index a8419217f4..ca1a80d72f 100644
--- a/src/netbase.cpp
+++ b/src/netbase.cpp
@@ -514,10 +514,6 @@ bool ConnectSocketDirectly(const CService &addrConnect, const Sock& sock, int nT
     // Create a sockaddr from the specified service.
     struct sockaddr_storage sockaddr;
     socklen_t len = sizeof(sockaddr);
-    if (sock.Get() == INVALID_SOCKET) {
-        LogPrintf("Cannot connect to %s: invalid socket\n", addrConnect.ToStringAddrPort());
-        return false;
-    }
     if (!addrConnect.GetSockAddr((struct sockaddr*)&sockaddr, &len)) {
         LogPrintf("Cannot connect to %s: unsupported network\n", addrConnect.ToStringAddrPort());
         return false;
diff --git a/src/test/fuzz/util/net.cpp b/src/test/fuzz/util/net.cpp
index 1545e11065..d23e997719 100644
--- a/src/test/fuzz/util/net.cpp
+++ b/src/test/fuzz/util/net.cpp
@@ -77,9 +77,10 @@ template CNetAddr::SerParams ConsumeDeserializationParams(FuzzedDataProvider&) n
 template CAddress::SerParams ConsumeDeserializationParams(FuzzedDataProvider&) noexcept;
 
 FuzzedSock::FuzzedSock(FuzzedDataProvider& fuzzed_data_provider)
-    : m_fuzzed_data_provider{fuzzed_data_provider}, m_selectable{fuzzed_data_provider.ConsumeBool()}
+    : Sock{fuzzed_data_provider.ConsumeIntegralInRange<SOCKET>(INVALID_SOCKET - 1, INVALID_SOCKET)},
+      m_fuzzed_data_provider{fuzzed_data_provider},
+      m_selectable{fuzzed_data_provider.ConsumeBool()}
 {
-    m_socket = fuzzed_data_provider.ConsumeIntegralInRange<SOCKET>(INVALID_SOCKET - 1, INVALID_SOCKET);
 }
 
 FuzzedSock::~FuzzedSock()
diff --git a/src/test/sock_tests.cpp b/src/test/sock_tests.cpp
index 26ee724bf8..5dd73dc101 100644
--- a/src/test/sock_tests.cpp
+++ b/src/test/sock_tests.cpp
@@ -38,7 +38,7 @@ BOOST_AUTO_TEST_CASE(constructor_and_destructor)
 {
     const SOCKET s = CreateSocket();
     Sock* sock = new Sock(s);
-    BOOST_CHECK_EQUAL(sock->Get(), s);
+    BOOST_CHECK(*sock == s);
     BOOST_CHECK(!SocketIsClosed(s));
     delete sock;
     BOOST_CHECK(SocketIsClosed(s));
@@ -51,22 +51,34 @@ BOOST_AUTO_TEST_CASE(move_constructor)
     Sock* sock2 = new Sock(std::move(*sock1));
     delete sock1;
     BOOST_CHECK(!SocketIsClosed(s));
-    BOOST_CHECK_EQUAL(sock2->Get(), s);
+    BOOST_CHECK(*sock2 == s);
     delete sock2;
     BOOST_CHECK(SocketIsClosed(s));
 }
 
 BOOST_AUTO_TEST_CASE(move_assignment)
 {
-    const SOCKET s = CreateSocket();
-    Sock* sock1 = new Sock(s);
-    Sock* sock2 = new Sock();
+    const SOCKET s1 = CreateSocket();
+    const SOCKET s2 = CreateSocket();
+    Sock* sock1 = new Sock(s1);
+    Sock* sock2 = new Sock(s2);
+
+    BOOST_CHECK(!SocketIsClosed(s1));
+    BOOST_CHECK(!SocketIsClosed(s2));
+
     *sock2 = std::move(*sock1);
+    BOOST_CHECK(!SocketIsClosed(s1));
+    BOOST_CHECK(SocketIsClosed(s2));
+    BOOST_CHECK(*sock2 == s1);
+
     delete sock1;
-    BOOST_CHECK(!SocketIsClosed(s));
-    BOOST_CHECK_EQUAL(sock2->Get(), s);
+    BOOST_CHECK(!SocketIsClosed(s1));
+    BOOST_CHECK(SocketIsClosed(s2));
+    BOOST_CHECK(*sock2 == s1);
+
     delete sock2;
-    BOOST_CHECK(SocketIsClosed(s));
+    BOOST_CHECK(SocketIsClosed(s1));
+    BOOST_CHECK(SocketIsClosed(s2));
 }
 
 #ifndef WIN32 // Windows does not have socketpair(2).
@@ -98,7 +110,7 @@ BOOST_AUTO_TEST_CASE(send_and_receive)
     SendAndRecvMessage(*sock0, *sock1);
 
     Sock* sock0moved = new Sock(std::move(*sock0));
-    Sock* sock1moved = new Sock();
+    Sock* sock1moved = new Sock(INVALID_SOCKET);
     *sock1moved = std::move(*sock1);
 
     delete sock0;
diff --git a/src/test/util/net.h b/src/test/util/net.h
index 0d41cf550e..497292542b 100644
--- a/src/test/util/net.h
+++ b/src/test/util/net.h
@@ -108,10 +108,10 @@ constexpr auto ALL_NETWORKS = std::array{
 class StaticContentsSock : public Sock
 {
 public:
-    explicit StaticContentsSock(const std::string& contents) : m_contents{contents}
+    explicit StaticContentsSock(const std::string& contents)
+        : Sock{INVALID_SOCKET},
+          m_contents{contents}
     {
-        // Just a dummy number that is not INVALID_SOCKET.
-        m_socket = INVALID_SOCKET - 1;
     }
 
     ~StaticContentsSock() override { m_socket = INVALID_SOCKET; }
@@ -194,6 +194,11 @@ public:
         return true;
     }
 
+    bool IsConnected(std::string&) const override
+    {
+        return true;
+    }
+
 private:
     const std::string m_contents;
     mutable size_t m_consumed{0};
diff --git a/src/util/sock.cpp b/src/util/sock.cpp
index fd64cae404..d16dc56aa3 100644
--- a/src/util/sock.cpp
+++ b/src/util/sock.cpp
@@ -24,8 +24,6 @@ static inline bool IOErrorIsPermanent(int err)
     return err != WSAEAGAIN && err != WSAEINTR && err != WSAEWOULDBLOCK && err != WSAEINPROGRESS;
 }
 
-Sock::Sock() : m_socket(INVALID_SOCKET) {}
-
 Sock::Sock(SOCKET s) : m_socket(s) {}
 
 Sock::Sock(Sock&& other)
@@ -44,8 +42,6 @@ Sock& Sock::operator=(Sock&& other)
     return *this;
 }
 
-SOCKET Sock::Get() const { return m_socket; }
-
 ssize_t Sock::Send(const void* data, size_t len, int flags) const
 {
     return send(m_socket, static_cast<const char*>(data), len, flags);
@@ -411,6 +407,11 @@ void Sock::Close()
     m_socket = INVALID_SOCKET;
 }
 
+bool Sock::operator==(SOCKET s) const
+{
+    return m_socket == s;
+};
+
 std::string NetworkErrorString(int err)
 {
 #if defined(WIN32)
diff --git a/src/util/sock.h b/src/util/sock.h
index 6bac2dfd34..d78e01929b 100644
--- a/src/util/sock.h
+++ b/src/util/sock.h
@@ -21,16 +21,12 @@
 static constexpr auto MAX_WAIT_FOR_IO = 1s;
 
 /**
- * RAII helper class that manages a socket. Mimics `std::unique_ptr`, but instead of a pointer it
- * contains a socket and closes it automatically when it goes out of scope.
+ * RAII helper class that manages a socket and closes it automatically when it goes out of scope.
  */
 class Sock
 {
 public:
-    /**
-     * Default constructor, creates an empty object that does nothing when destroyed.
-     */
-    Sock();
+    Sock() = delete;
 
     /**
      * Take ownership of an existent socket.
@@ -63,43 +59,37 @@ public:
     virtual Sock& operator=(Sock&& other);
 
     /**
-     * Get the value of the contained socket.
-     * @return socket or INVALID_SOCKET if empty
-     */
-    [[nodiscard]] virtual SOCKET Get() const;
-
-    /**
-     * send(2) wrapper. Equivalent to `send(this->Get(), data, len, flags);`. Code that uses this
+     * send(2) wrapper. Equivalent to `send(m_socket, data, len, flags);`. Code that uses this
      * wrapper can be unit tested if this method is overridden by a mock Sock implementation.
      */
     [[nodiscard]] virtual ssize_t Send(const void* data, size_t len, int flags) const;
 
     /**
-     * recv(2) wrapper. Equivalent to `recv(this->Get(), buf, len, flags);`. Code that uses this
+     * recv(2) wrapper. Equivalent to `recv(m_socket, buf, len, flags);`. Code that uses this
      * wrapper can be unit tested if this method is overridden by a mock Sock implementation.
      */
     [[nodiscard]] virtual ssize_t Recv(void* buf, size_t len, int flags) const;
 
     /**
-     * connect(2) wrapper. Equivalent to `connect(this->Get(), addr, addrlen)`. Code that uses this
+     * connect(2) wrapper. Equivalent to `connect(m_socket, addr, addrlen)`. Code that uses this
      * wrapper can be unit tested if this method is overridden by a mock Sock implementation.
      */
     [[nodiscard]] virtual int Connect(const sockaddr* addr, socklen_t addr_len) const;
 
     /**
-     * bind(2) wrapper. Equivalent to `bind(this->Get(), addr, addr_len)`. Code that uses this
+     * bind(2) wrapper. Equivalent to `bind(m_socket, addr, addr_len)`. Code that uses this
      * wrapper can be unit tested if this method is overridden by a mock Sock implementation.
      */
     [[nodiscard]] virtual int Bind(const sockaddr* addr, socklen_t addr_len) const;
 
     /**
-     * listen(2) wrapper. Equivalent to `listen(this->Get(), backlog)`. Code that uses this
+     * listen(2) wrapper. Equivalent to `listen(m_socket, backlog)`. Code that uses this
      * wrapper can be unit tested if this method is overridden by a mock Sock implementation.
      */
     [[nodiscard]] virtual int Listen(int backlog) const;
 
     /**
-     * accept(2) wrapper. Equivalent to `std::make_unique<Sock>(accept(this->Get(), addr, addr_len))`.
+     * accept(2) wrapper. Equivalent to `std::make_unique<Sock>(accept(m_socket, addr, addr_len))`.
      * Code that uses this wrapper can be unit tested if this method is overridden by a mock Sock
      * implementation.
      * The returned unique_ptr is empty if `accept()` failed in which case errno will be set.
@@ -108,7 +98,7 @@ public:
 
     /**
      * getsockopt(2) wrapper. Equivalent to
-     * `getsockopt(this->Get(), level, opt_name, opt_val, opt_len)`. Code that uses this
+     * `getsockopt(m_socket, level, opt_name, opt_val, opt_len)`. Code that uses this
      * wrapper can be unit tested if this method is overridden by a mock Sock implementation.
      */
     [[nodiscard]] virtual int GetSockOpt(int level,
@@ -118,7 +108,7 @@ public:
 
     /**
      * setsockopt(2) wrapper. Equivalent to
-     * `setsockopt(this->Get(), level, opt_name, opt_val, opt_len)`. Code that uses this
+     * `setsockopt(m_socket, level, opt_name, opt_val, opt_len)`. Code that uses this
      * wrapper can be unit tested if this method is overridden by a mock Sock implementation.
      */
     [[nodiscard]] virtual int SetSockOpt(int level,
@@ -128,7 +118,7 @@ public:
 
     /**
      * getsockname(2) wrapper. Equivalent to
-     * `getsockname(this->Get(), name, name_len)`. Code that uses this
+     * `getsockname(m_socket, name, name_len)`. Code that uses this
      * wrapper can be unit tested if this method is overridden by a mock Sock implementation.
      */
     [[nodiscard]] virtual int GetSockName(sockaddr* name, socklen_t* name_len) const;
@@ -266,6 +256,11 @@ public:
      */
     [[nodiscard]] virtual bool IsConnected(std::string& errmsg) const;
 
+    /**
+     * Check if the internal socket is equal to `s`. Use only in tests.
+     */
+    bool operator==(SOCKET s) const;
+
 protected:
     /**
      * Contained socket. `INVALID_SOCKET` designates the object is empty.