net: also wait for exceptional events in Sock::Wait()

This mimics closely `CConnman::SocketEvents()` and the underlying
`poll(2)`.

1 files changed, 13 insertions, 6 deletions

diff --git a/src/util/sock.h b/src/util/sock.h
index dd2913a66c..e6419eb8ce 100644
--- a/src/util/sock.h
+++ b/src/util/sock.h
@@ -130,21 +130,28 @@ public:
     /**
      * If passed to `Wait()`, then it will wait for readiness to read from the socket.
      */
-    static constexpr Event RECV = 0b01;
+    static constexpr Event RECV = 0b001;
 
     /**
      * If passed to `Wait()`, then it will wait for readiness to send to the socket.
      */
-    static constexpr Event SEND = 0b10;
+    static constexpr Event SEND = 0b010;
+
+    /**
+     * Ignored if passed to `Wait()`, but could be set in the occurred events if an
+     * exceptional condition has occurred on the socket or if it has been disconnected.
+     */
+    static constexpr Event ERR = 0b100;
 
     /**
      * Wait for readiness for input (recv) or output (send).
      * @param[in] timeout Wait this much for at least one of the requested events to occur.
      * @param[in] requested Wait for those events, bitwise-or of `RECV` and `SEND`.
-     * @param[out] occurred If not nullptr and `true` is returned, then upon return this
-     * indicates which of the requested events occurred. A timeout is indicated by return
-     * value of `true` and `occurred` being set to 0.
-     * @return true on success and false otherwise
+     * @param[out] occurred If not nullptr and the function returns `true`, then this
+     * indicates which of the requested events occurred (`ERR` will be added, even if
+     * not requested, if an exceptional event occurs on the socket).
+     * A timeout is indicated by return value of `true` and `occurred` being set to 0.
+     * @return true on success (or timeout, if `occurred` of 0 is returned), false otherwise
      */
     [[nodiscard]] virtual bool Wait(std::chrono::milliseconds timeout,
                                     Event requested,