net: keep reference to each node during socket wait

Create the snapshot of `CConnman::vNodes` to operate on earlier in
`CConnman::SocketHandler()`, before calling `CConnman::SocketEvents()`
and pass the `vNodes` copy from the snapshot to `SocketEvents()`.

This will keep the refcount of each node incremented during
`SocketEvents()` so that the `CNode` object is not destroyed before
`SocketEvents()` has finished.

Currently in `SocketEvents()` we only remember file descriptor numbers
(when not holding `CConnman::cs_vNodes`) which is safe, but we will
change this to remember pointers to `CNode::m_sock`.

1 files changed, 27 insertions, 2 deletions

diff --git a/src/net.h b/src/net.h
index 7b97b98ae5..f03883ca54 100644
--- a/src/net.h
+++ b/src/net.h
@@ -983,8 +983,33 @@ private:
     void NotifyNumConnectionsChanged();
     /** Return true if the peer is inactive and should be disconnected. */
     bool InactivityCheck(const CNode& node) const;
-    bool GenerateSelectSet(std::set<SOCKET> &recv_set, std::set<SOCKET> &send_set, std::set<SOCKET> &error_set);
-    void SocketEvents(std::set<SOCKET> &recv_set, std::set<SOCKET> &send_set, std::set<SOCKET> &error_set);
+
+    /**
+     * Generate a collection of sockets to check for IO readiness.
+     * @param[in] nodes Select from these nodes' sockets.
+     * @param[out] recv_set Sockets to check for read readiness.
+     * @param[out] send_set Sockets to check for write readiness.
+     * @param[out] error_set Sockets to check for errors.
+     * @return true if at least one socket is to be checked (the returned set is not empty)
+     */
+    bool GenerateSelectSet(const std::vector<CNode*>& nodes,
+                           std::set<SOCKET>& recv_set,
+                           std::set<SOCKET>& send_set,
+                           std::set<SOCKET>& error_set);
+
+    /**
+     * Check which sockets are ready for IO.
+     * @param[in] nodes Select from these nodes' sockets.
+     * @param[out] recv_set Sockets which are ready for read.
+     * @param[out] send_set Sockets which are ready for write.
+     * @param[out] error_set Sockets which have errors.
+     * This calls `GenerateSelectSet()` to gather a list of sockets to check.
+     */
+    void SocketEvents(const std::vector<CNode*>& nodes,
+                      std::set<SOCKET>& recv_set,
+                      std::set<SOCKET>& send_set,
+                      std::set<SOCKET>& error_set);
+
     void SocketHandler();
     void ThreadSocketHandler();
     void ThreadDNSAddressSeed();