net: extend Sock::Wait() to report a timeout

Previously `Sock::Wait()` would not have signaled to the caller whether
a timeout or one of the requested events occurred since that was not
needed by any of the callers.

Such functionality will be needed in the I2P implementation, thus extend
the `Sock::Wait()` method.

Author: vasild

src/util/sock.cpp

@@ -59,7 +59,7 @@ ssize_t Sock::Recv(void* buf, size_t len, int flags) const
     return recv(m_socket, static_cast<char*>(buf), len, flags);
 }
 
-bool Sock::Wait(std::chrono::milliseconds timeout, Event requested) const
+bool Sock::Wait(std::chrono::milliseconds timeout, Event requested, Event* occurred) const
 {
 #ifdef USE_POLL
     pollfd fd;
@@ -72,7 +72,21 @@ bool Sock::Wait(std::chrono::milliseconds timeout, Event requested) const
         fd.events |= POLLOUT;
     }
 
-    return poll(&fd, 1, count_milliseconds(timeout)) != SOCKET_ERROR;
+    if (poll(&fd, 1, count_milliseconds(timeout)) == SOCKET_ERROR) {
+        return false;
+    }
+
+    if (occurred != nullptr) {
+        *occurred = 0;
+        if (fd.revents & POLLIN) {
+            *occurred |= RECV;
+        }
+        if (fd.revents & POLLOUT) {
+            *occurred |= SEND;
+        }
+    }
+
+    return true;
 #else
     if (!IsSelectableSocket(m_socket)) {
         return false;
@@ -93,7 +107,21 @@ bool Sock::Wait(std::chrono::milliseconds timeout, Event requested) const
 
     timeval timeout_struct = MillisToTimeval(timeout);
 
-    return select(m_socket + 1, &fdset_recv, &fdset_send, nullptr, &timeout_struct) != SOCKET_ERROR;
+    if (select(m_socket + 1, &fdset_recv, &fdset_send, nullptr, &timeout_struct) == SOCKET_ERROR) {
+        return false;
+    }
+
+    if (occurred != nullptr) {
+        *occurred = 0;
+        if (FD_ISSET(m_socket, &fdset_recv)) {
+            *occurred |= RECV;
+        }
+        if (FD_ISSET(m_socket, &fdset_send)) {
+            *occurred |= SEND;
+        }
+    }
+
+    return true;
 #endif /* USE_POLL */
 }
 

src/util/sock.h

@@ -105,9 +105,14 @@ class Sock
      * 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
      */
-    virtual bool Wait(std::chrono::milliseconds timeout, Event requested) const;
+    virtual bool Wait(std::chrono::milliseconds timeout,
+                      Event requested,
+                      Event* occurred = nullptr) const;
 
 private:
     /**