net: convert standalone SetSocketNonBlocking() to Sock::SetNonBlocking()

This further encapsulates syscalls inside the `Sock` class.

Co-authored-by: practicalswift <practicalswift@users.noreply.github.com>

src/netbase.cpp

@@ -304,8 +304,7 @@ enum class IntrRecvError {
  *          read.
  *
  * @see This function can be interrupted by calling InterruptSocks5(bool).
- *      Sockets can be made non-blocking with SetSocketNonBlocking(const
- *      SOCKET&).
+ *      Sockets can be made non-blocking with Sock::SetNonBlocking().
  */
 static IntrRecvError InterruptibleRecv(uint8_t* data, size_t len, int timeout, const Sock& sock)
 {
@@ -525,7 +524,7 @@ std::unique_ptr<Sock> CreateSockTCP(const CService& address_family)
     }
 
     // Set the non-blocking option on the socket.
-    if (!SetSocketNonBlocking(sock->Get())) {
+    if (!sock->SetNonBlocking()) {
         LogPrintf("Error setting socket to non-blocking: %s\n", NetworkErrorString(WSAGetLastError()));
         return nullptr;
     }

src/test/fuzz/util.cpp

@@ -254,6 +254,19 @@ int FuzzedSock::GetSockName(sockaddr* name, socklen_t* name_len) const
     return 0;
 }
 
+bool FuzzedSock::SetNonBlocking() const
+{
+    constexpr std::array setnonblocking_errnos{
+        EBADF,
+        EPERM,
+    };
+    if (m_fuzzed_data_provider.ConsumeBool()) {
+        SetFuzzedErrNo(m_fuzzed_data_provider, setnonblocking_errnos);
+        return false;
+    }
+    return true;
+}
+
 bool FuzzedSock::IsSelectable() const
 {
     return m_selectable;

src/test/fuzz/util.h

@@ -80,6 +80,8 @@ public:
 
     int GetSockName(sockaddr* name, socklen_t* name_len) const override;
 
+    bool SetNonBlocking() const override;
+
     bool IsSelectable() const override;
 
     bool Wait(std::chrono::milliseconds timeout, Event requested, Event* occurred = nullptr) const override;

src/test/util/net.h

@@ -166,6 +166,8 @@ public:
         return 0;
     }
 
+    bool SetNonBlocking() const override { return true; }
+
     bool IsSelectable() const override { return true; }
 
     bool Wait(std::chrono::milliseconds timeout,

src/util/sock.cpp

@@ -117,18 +117,22 @@ int Sock::GetSockName(sockaddr* name, socklen_t* name_len) const
     return getsockname(m_socket, name, name_len);
 }
 
-bool SetSocketNonBlocking(const SOCKET& hSocket)
+bool Sock::SetNonBlocking() const
 {
 #ifdef WIN32
-    u_long nOne = 1;
-    if (ioctlsocket(hSocket, FIONBIO, &nOne) == SOCKET_ERROR) {
-#else
-    int fFlags = fcntl(hSocket, F_GETFL, 0);
-    if (fcntl(hSocket, F_SETFL, fFlags | O_NONBLOCK) == SOCKET_ERROR) {
-#endif
+    u_long on{1};
+    if (ioctlsocket(m_socket, FIONBIO, &on) == SOCKET_ERROR) {
         return false;
     }
-
+#else
+    const int flags{fcntl(m_socket, F_GETFL, 0)};
+    if (flags == SOCKET_ERROR) {
+        return false;
+    }
+    if (fcntl(m_socket, F_SETFL, flags | O_NONBLOCK) == SOCKET_ERROR) {
+        return false;
+    }
+#endif
     return true;
 }
 

src/util/sock.h

@@ -133,6 +133,12 @@ public:
      */
     [[nodiscard]] virtual int GetSockName(sockaddr* name, socklen_t* name_len) const;
 
+    /**
+     * Set the non-blocking option on the socket.
+     * @return true if set successfully
+     */
+    [[nodiscard]] virtual bool SetNonBlocking() const;
+
     /**
      * Check if the underlying socket can be used for `select(2)` (or the `Wait()` method).
      * @return true if selectable
@@ -273,9 +279,6 @@ private:
     void Close();
 };
 
-/** Enable non-blocking mode for a socket */
-bool SetSocketNonBlocking(const SOCKET& hSocket);
-
 /** Return readable error string for a network error code */
 std::string NetworkErrorString(int err);