thirdparty/patches/libevent-1532.patch

diff --git a/evutil.c b/evutil.c
index 9817f08..e1803de 100644
--- a/evutil.c
+++ b/evutil.c
@@ -2763,3 +2763,137 @@ evutil_free_globals_(void)
 	evutil_free_secure_rng_globals_();
 	evutil_free_sock_err_globals();
 }
+
+int
+evutil_set_tcp_keepalive(evutil_socket_t fd, int on, int timeout)
+{
+	int idle;
+	int intvl;
+	int cnt;
+
+	/* Prevent compiler from complaining unused variables warnings. */
+	(void) idle;
+	(void) intvl;
+	(void) cnt;
+
+	if (timeout <= 0) 
+		return 0;
+
+	if (setsockopt(fd, SOL_SOCKET, SO_KEEPALIVE, &on, sizeof(on)))
+		return -1;
+	if (!on) 
+		return 0;
+
+	/* Unlike Unix-like OS's, TCP keep-alive mechanism on Windows is kind of a mess, 
+	 * setting TCP_KEEPIDLE, TCP_KEEPINTVL and TCP_KEEPCNT on Windows could be a bit tricky.
+	 * Check out https://learn.microsoft.com/en-us/windows/win32/winsock/sio-keepalive-vals,
+	 * https://learn.microsoft.com/en-us/windows/win32/winsock/ipproto-tcp-socket-options.
+	 * These three options are not available until Windows 10, version 1709 where we set them
+	 * by `setsockopt` (slightly different from Unix-like OS's pattern), while on older Windows, 
+	 * we have to use `WSAIoctl` instead.
+	 * Therefore, we skip setting those three options on Windows for now.
+	 * TODO(panjf2000): enable the full TCP keep-alive mechanism on Windows when we find a feasible way to do it.
+	 */
+#ifndef _WIN32
+
+	/* The implementation of TCP keep-alive on Solaris/SmartOS is a bit unusual 
+	 * compared to other Unix-like systems. 
+	 * Thus, we need to specialize it on Solaris. 
+	 */
+#ifdef __sun
+	/* There are two keep-alive mechanisms on Solaris:
+	 * - By default, the first keep-alive probe is sent out after a TCP connection is idle for two hours. 
+	 * If the peer does not respond to the probe within eight minutes, the TCP connection is aborted. 
+	 * You can alter the interval for sending out the first probe using the socket option TCP_KEEPALIVE_THRESHOLD 
+	 * in milliseconds or TCP_KEEPIDLE in seconds.
+	 * The system default is controlled by the TCP ndd parameter tcp_keepalive_interval. The minimum value is ten seconds. 
+	 * The maximum is ten days, while the default is two hours. If you receive no response to the probe, 
+	 * you can use the TCP_KEEPALIVE_ABORT_THRESHOLD socket option to change the time threshold for aborting a TCP connection.
+	 * The option value is an unsigned integer in milliseconds. The value zero indicates that TCP should never time out and 
+	 * abort the connection when probing. The system default is controlled by the TCP ndd parameter tcp_keepalive_abort_interval. 
+	 * The default is eight minutes.
+	 *
+	 * - The second implementation is activated if socket option TCP_KEEPINTVL and/or TCP_KEEPCNT are set. 
+	 * The time between each consequent probes is set by TCP_KEEPINTVL in seconds. 
+	 * The minimum value is ten seconds. The maximum is ten days, while the default is two hours. 
+	 * The TCP connection will be aborted after certain amount of probes, which is set by TCP_KEEPCNT, without receiving response.
+	 */
+
+	idle = timeout;
+	/* Kernel expects at least 10 seconds. */
+	if (idle < 10) 
+		idle = 10;
+	/* Kernel expects at most 10 days. */
+	if (idle > 10*24*60*60) 
+		idle = 10*24*60*60; 
+	
+	/* `TCP_KEEPIDLE`, `TCP_KEEPINTVL`, and `TCP_KEEPCNT` were not available on Solaris 
+	 * until version 11.4, but let's gamble here.
+	 */
+#if defined(TCP_KEEPIDLE) && defined(TCP_KEEPINTVL) && defined(TCP_KEEPCNT)
+	if (setsockopt(fd, IPPROTO_TCP, TCP_KEEPIDLE, &idle, sizeof(idle)))
+		return -1;
+	intvl = idle/3;
+	if (setsockopt(fd, IPPROTO_TCP, TCP_KEEPINTVL, &intvl, sizeof(intvl)))
+		return -1;
+	cnt = 3;
+	if (setsockopt(fd, IPPROTO_TCP, TCP_KEEPCNT, &cnt, sizeof(cnt)))
+		return -1;
+	return 0;
+#endif
+
+	/* Fall back to the first implementation of tcp-alive mechanism for older Solaris, 
+	 * simulate the tcp-alive mechanism on other platforms via `TCP_KEEPALIVE_THRESHOLD` + `TCP_KEEPALIVE_ABORT_THRESHOLD`.
+	 */
+	idle *= 1000; /* kernel expects milliseconds */
+	if (setsockopt(fd, IPPROTO_TCP, TCP_KEEPALIVE_THRESHOLD, &idle, sizeof(idle)))
+		return -1;
+
+	/* Note that the consequent probes will not be sent at equal intervals on Solaris, 
+	 * but will be sent using the exponential backoff algorithm.
+	 */
+	intvl = idle/3;
+	cnt = 3;
+	int time_to_abort = intvl * cnt;
+	if (setsockopt(fd, IPPROTO_TCP, TCP_KEEPALIVE_ABORT_THRESHOLD, &time_to_abort, sizeof(time_to_abort)))
+		return -1;
+
+	return 0;
+#endif
+
+#ifdef TCP_KEEPIDLE
+	idle = timeout;
+	if (setsockopt(fd, IPPROTO_TCP, TCP_KEEPIDLE, &idle, sizeof(idle)))
+		return -1;
+#elif defined(TCP_KEEPALIVE)
+	/* Darwin/macOS uses TCP_KEEPALIVE in place of TCP_KEEPIDLE. */
+	idle = timeout;
+	if (setsockopt(fd, IPPROTO_TCP, TCP_KEEPALIVE, &idle, sizeof(idle)))
+		return -1;
+#endif
+
+#ifdef TCP_KEEPINTVL
+	/* Set the interval between individual keep-alive probes as timeout / 3 
+	 * and the maximum number of keepalive probes as 3 to make it double timeout 
+	 * before aborting a dead connection. 
+	 */
+	intvl = timeout/3;
+	if (intvl == 0) 
+		intvl = 1;
+	if (setsockopt(fd, IPPROTO_TCP, TCP_KEEPINTVL, &intvl, sizeof(intvl)))
+		return -1;
+#endif
+
+#ifdef TCP_KEEPCNT
+	/* Set the maximum number of keepalive probes as 3 to collaborate with
+	 * TCP_KEEPINTVL, see the previous comment.
+	 */
+	cnt = 3;
+	if (setsockopt(fd, IPPROTO_TCP, TCP_KEEPCNT, &cnt, sizeof(cnt)))
+		return -1;
+#endif
+
+#endif /* !_WIN32 */
+
+	return 0;
+}
diff --git a/http.c b/http.c
index 53951cb..1ad60f8 100644
--- a/http.c
+++ b/http.c
@@ -4417,7 +4417,7 @@ create_bind_socket_nonblock(struct evutil_addrinfo *ai, int reuse)
 {
 	evutil_socket_t fd;
 
-	int on = 1, r;
+	int r;
 	int serrno;
 
 	/* Create listen socket */
@@ -4428,7 +4428,8 @@ create_bind_socket_nonblock(struct evutil_addrinfo *ai, int reuse)
 			return (-1);
 	}
 
-	if (setsockopt(fd, SOL_SOCKET, SO_KEEPALIVE, (void *)&on, sizeof(on))<0)
+	/* TODO(panjf2000): make this TCP keep-alive value configurable */
+	if (evutil_set_tcp_keepalive(fd, 1, 300) < 0)
 		goto out;
 	if (reuse) {
 		if (evutil_make_listen_socket_reuseable(fd) < 0)
diff --git a/include/event2/util.h b/include/event2/util.h
index 02aa7ba..688b641 100644
--- a/include/event2/util.h
+++ b/include/event2/util.h
@@ -469,6 +469,18 @@ int evutil_closesocket(evutil_socket_t sock);
 EVENT2_EXPORT_SYMBOL
 int evutil_make_tcp_listen_socket_deferred(evutil_socket_t sock);
 
+/** Do platform-specific operations to set/unset TCP keep-alive options
+ * TCP_KEEPIDLE, TCP_KEEPINTVL and TCP_KEEPCNT on a socket.
+ *  
+ *  @param sock The socket to be set TCP keep-alive 
+ *  @param on nonzero value to enable TCP keep-alive, 0 to disable
+ *  @param timeout The timeout in seconds with no activity until 
+ * 	   the first keepalive probe is sent
+ *  @return 0 on success, -1 on failure
+*/ 
+EVENT2_EXPORT_SYMBOL
+int evutil_set_tcp_keepalive(evutil_socket_t sock, int on, int timeout);
+
 #ifdef _WIN32
 /** Return the most recent socket error.  Not idempotent on all platforms. */
 #define EVUTIL_SOCKET_ERROR() WSAGetLastError()