[Tarantool-patches] [PATCH 1/2] swim: add SO_BROADCAST option

[Vladislav Shpilevoy]

On 19.03.2021 07:53, Cyrill Gorcunov via Tarantool-patches wrote:
> On Fri, Mar 19, 2021 at 12:18:46AM +0100, Vladislav Shpilevoy wrote:
>> I force updated the patch on the branch.
>>
>> Could you please check if it works on your machine? For
>> example, this test:
>>
>> 	uuid = require('uuid')
>> 	swim = require('swim')
>>
>> 	s = swim.new({uuid = uuid(), uri = '127.0.0.1:3313'})
>>
>> 	s:broadcast(3313)
>>
>> On Mac it used to print EADDRNOTAVAIL message. Probably
>> would fail with something on Linux too, but I don't know.
>> Might just work fine as well.
> 
> Ack. Thanks! FWIW on linux this fails with
>  | tarantool> SystemError sendto(177), called on fd 10, aka 127.0.0.1:3313: Invalid argument

I made the error not critical on Linux so it is ignored now. The
new patch:

====================
    swim: add SO_BROADCAST option
    
    Swim node couldn't talk to broadcast network interfaces because
    the option SO_BROADCAST wasn't set.
    
    It worked fine for localhost broadcast, but failed for all the
    other IPs. There is no a test, because the tests work for the
    localhost only anyway.
    
    It still fails on Mac though in case the swim node was bound to
    127.0.0.1. Then somewhy sendto() raises EADDRNOTAVAIL on attempt
    to broadcast beyond the local machine. It happens on Linux too,
    but with EINVAL error. These errors are ignored because are not
    critical.
    
    Part of #5864

diff --git a/src/lib/swim/swim_io.c b/src/lib/swim/swim_io.c
index c8558c43e..0002472fa 100644
--- a/src/lib/swim/swim_io.c
+++ b/src/lib/swim/swim_io.c
@@ -512,8 +512,26 @@ static inline void
 swim_complete_send(struct swim_scheduler *scheduler, struct swim_task *task,
 		   ssize_t size)
 {
-	if (size < 0)
-		diag_log();
+	if (size < 0) {
+		bool is_critical = true;
+		int err = diag_last_error(diag_get())->saved_errno;
+#if TARGET_OS_DARWIN
+		/*
+		 * On Mac this error happens regularly if SWIM is bound to
+		 * the localhost and tries to broadcast out of the machine. This
+		 * is not critical, because will happen in the tests a lot, and
+		 * in prod it simply should not bind to localhost if there are
+		 * multiple machines in the cluster. Besides, Mac as a platform
+		 * is not supposed to be used in prod.
+		 */
+		is_critical = (err != EADDRNOTAVAIL);
+#else
+		/* The same as EADDRNOTAVAIL, but happens on Linux as EINVAL. */
+		is_critical = (err != EINVAL);
+#endif
+		if (is_critical)
+			diag_log();
+	}
 	if (task->complete != NULL)
 		task->complete(task, scheduler, size);
 }
diff --git a/src/lib/swim/swim_transport_udp.c b/src/lib/swim/swim_transport_udp.c
index c0317a20b..12626cc49 100644
--- a/src/lib/swim/swim_transport_udp.c
+++ b/src/lib/swim/swim_transport_udp.c
@@ -80,25 +80,27 @@ swim_transport_bind(struct swim_transport *transport,
 		return 0;
 	}
 
+	int is_on = 1;
+	int real_port = new_addr->sin_port;
 	int fd = sio_socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP);
 	if (fd < 0)
 		return -1;
-	if (sio_bind(fd, (struct sockaddr *) addr, addr_len) != 0 ||
-	    evio_setsockopt_server(fd, AF_INET, SOCK_DGRAM) != 0) {
+	if (sio_bind(fd, (struct sockaddr *) addr, addr_len) != 0) {
 		if (errno == EADDRINUSE)
 			diag_set(SocketError, sio_socketname(fd), "bind");
-		close(fd);
-		return -1;
+		goto end_error;
 	}
-	int real_port = new_addr->sin_port;
+	if (sio_setsockopt(fd, SOL_SOCKET, SO_BROADCAST, &is_on,
+			   sizeof(is_on)) != 0)
+		goto end_error;
+	if (evio_setsockopt_server(fd, AF_INET, SOCK_DGRAM) != 0)
+		goto end_error;
 	if (is_new_port_any) {
 		struct sockaddr_in real_addr;
 		addr_len = sizeof(real_addr);
 		if (sio_getsockname(fd, (struct sockaddr *) &real_addr,
-				    &addr_len) != 0) {
-			close(fd);
-			return -1;
-		}
+				    &addr_len) != 0)
+			goto end_error;
 		real_port = real_addr.sin_port;
 	}
 	if (transport->fd != -1)
@@ -107,6 +109,9 @@ swim_transport_bind(struct swim_transport *transport,
 	transport->addr = *new_addr;
 	transport->addr.sin_port = real_port;
 	return 0;
+end_error:
+	close(fd);
+	return -1;
 }
 
 void