net: use Sock in CNode

Change `CNode` to use a pointer to `Sock` instead of a bare `SOCKET`.
This will help mocking / testing / fuzzing more code.

1 files changed, 12 insertions, 3 deletions

diff --git a/src/net.h b/src/net.h
index 80fc93a5d0..e0e0e930bf 100644
--- a/src/net.h
+++ b/src/net.h
@@ -402,7 +402,17 @@ public:
 
     NetPermissionFlags m_permissionFlags{NetPermissionFlags::None};
     std::atomic<ServiceFlags> nServices{NODE_NONE};
-    SOCKET hSocket GUARDED_BY(cs_hSocket);
+
+    /**
+     * Socket used for communication with the node.
+     * May not own a Sock object (after `CloseSocketDisconnect()` or during tests).
+     * `shared_ptr` (instead of `unique_ptr`) is used to avoid premature close of
+     * the underlying file descriptor by one thread while another thread is
+     * poll(2)-ing it for activity.
+     * @see https://github.com/bitcoin/bitcoin/issues/21744 for details.
+     */
+    std::shared_ptr<Sock> m_sock GUARDED_BY(cs_hSocket);
+
     /** Total size of all vSendMsg entries */
     size_t nSendSize GUARDED_BY(cs_vSend){0};
     /** Offset inside the first vSendMsg already sent */
@@ -578,8 +588,7 @@ public:
      * criterium in CConnman::AttemptToEvictConnection. */
     std::atomic<std::chrono::microseconds> m_min_ping_time{std::chrono::microseconds::max()};
 
-    CNode(NodeId id, ServiceFlags nLocalServicesIn, SOCKET hSocketIn, const CAddress& addrIn, uint64_t nKeyedNetGroupIn, uint64_t nLocalHostNonceIn, const CAddress& addrBindIn, const std::string& addrNameIn, ConnectionType conn_type_in, bool inbound_onion);
-    ~CNode();
+    CNode(NodeId id, ServiceFlags nLocalServicesIn, std::shared_ptr<Sock> sock, const CAddress& addrIn, uint64_t nKeyedNetGroupIn, uint64_t nLocalHostNonceIn, const CAddress& addrBindIn, const std::string& addrNameIn, ConnectionType conn_type_in, bool inbound_onion);
     CNode(const CNode&) = delete;
     CNode& operator=(const CNode&) = delete;