[Tarantool-patches] [PATCH 1/1] iproto: show real port in logs and box.info.listen

[Vladislav Shpilevoy]

Box.cfg{listen = 0} automatically chooses a port. But it was
impossible to learn a real port the instance is bound to.

An ability to see a real port may help to make test-run more
robust, because it won't depend on which ports are free, and
won't need to pre-choose them in advance.

Now box.info.listen shows a real address, or nil when listen is
turned off. Also a real address is logged instead of the dummy
0-port one.

Closes #4620

@TarantoolBot document
Title: box.info.listen - real address

New value in box.info - listen. It is a real address to which the
instance was bound. For example, if box.cfg.listen was set with
a zero port, box.info.listen will show a real port. The address
is stored as a string:

    - unix/:<path> for UNIX domain sockets;
    - <ip>:<port> for IPv4;
    - [ip]:<port> for IPv6.

If the instance does not listen anything, box.info.listen is nil.
---
Branch: https://github.com/tarantool/tarantool/tree/gerold103/gh-4620-show-listen-port
Issue: https://github.com/tarantool/tarantool/issues/4620

 src/box/iproto.cc    | 31 +++++++++++++++++++++++++++++--
 src/box/iproto.h     |  7 +++++++
 src/box/lua/info.c   |  9 +++++++++
 src/lib/core/evio.c  |  8 ++++++++
 test/box/info.result |  1 +
 5 files changed, 54 insertions(+), 2 deletions(-)

diff --git a/src/box/iproto.cc b/src/box/iproto.cc
index 34c8f469a..522c066be 100644
--- a/src/box/iproto.cc
+++ b/src/box/iproto.cc
@@ -129,6 +129,23 @@ unsigned iproto_readahead = 16320;
 /* The maximal number of iproto messages in fly. */
 static int iproto_msg_max = IPROTO_MSG_MAX_MIN;
 
+/**
+ * Address the iproto listens for, stored in TX
+ * thread. Is kept in TX to be showed in box.info.
+ */
+static struct sockaddr_storage iproto_bound_address_storage;
+/** 0 means that no address is listened. */
+static socklen_t iproto_bound_address_len;
+
+const char *
+iproto_bound_address(void)
+{
+	if (iproto_bound_address_len == 0)
+		return NULL;
+	return sio_strfaddr((struct sockaddr *) &iproto_bound_address_storage,
+			    iproto_bound_address_len);
+}
+
 /**
  * How big is a buffer which needs to be shrunk before
  * it is put back into buffer cache.
@@ -2081,8 +2098,14 @@ struct iproto_cfg_msg: public cbus_call_msg
 	/** Operation to execute in iproto thread. */
 	enum iproto_cfg_op op;
 	union {
-		/** New URI to bind to. */
-		const char *uri;
+		struct {
+			/** New URI to bind to. */
+			const char *uri;
+			/** Result address. */
+			struct sockaddr_storage addr;
+			/** Address length. */
+			socklen_t addrlen;
+		};
 
 		/** New iproto max message count. */
 		int iproto_msg_max;
@@ -2118,6 +2141,8 @@ iproto_do_cfg_f(struct cbus_call_msg *m)
 			    (evio_service_bind(&binary, cfg_msg->uri) != 0 ||
 			     evio_service_listen(&binary) != 0))
 				diag_raise();
+			cfg_msg->addrlen = binary.addr_len;
+			cfg_msg->addr = binary.addrstorage;
 			break;
 		default:
 			unreachable();
@@ -2143,6 +2168,8 @@ iproto_listen(const char *uri)
 	iproto_cfg_msg_create(&cfg_msg, IPROTO_CFG_LISTEN);
 	cfg_msg.uri = uri;
 	iproto_do_cfg(&cfg_msg);
+	iproto_bound_address_storage = cfg_msg.addr;
+	iproto_bound_address_len = cfg_msg.addrlen;
 }
 
 size_t
diff --git a/src/box/iproto.h b/src/box/iproto.h
index edb24a7ed..201e09df5 100644
--- a/src/box/iproto.h
+++ b/src/box/iproto.h
@@ -80,6 +80,13 @@ iproto_request_count(void);
 void
 iproto_reset_stat(void);
 
+/**
+ * String representation of the address served by
+ * iproto. To be showed in box.info.
+ */
+const char *
+iproto_bound_address(void);
+
 #if defined(__cplusplus)
 } /* extern "C" */
 
diff --git a/src/box/lua/info.c b/src/box/lua/info.c
index 55382fd77..98579e8df 100644
--- a/src/box/lua/info.c
+++ b/src/box/lua/info.c
@@ -485,6 +485,14 @@ lbox_info_vinyl(struct lua_State *L)
 	return 1;
 }
 
+static int
+lbox_info_listen(struct lua_State *L)
+{
+	/* NULL is ok, no need to check. */
+	lua_pushstring(L, iproto_bound_address());
+	return 1;
+}
+
 static const struct luaL_Reg lbox_info_dynamic_meta[] = {
 	{"id", lbox_info_id},
 	{"uuid", lbox_info_uuid},
@@ -500,6 +508,7 @@ static const struct luaL_Reg lbox_info_dynamic_meta[] = {
 	{"memory", lbox_info_memory},
 	{"gc", lbox_info_gc},
 	{"vinyl", lbox_info_vinyl},
+	{"listen", lbox_info_listen},
 	{NULL, NULL}
 };
 
diff --git a/src/lib/core/evio.c b/src/lib/core/evio.c
index 2152c15e6..fc8f00e0e 100644
--- a/src/lib/core/evio.c
+++ b/src/lib/core/evio.c
@@ -269,6 +269,13 @@ evio_service_bind_addr(struct evio_service *service)
 		}
 	}
 
+	/*
+	 * After binding a result address may be different. For
+	 * example, if a port was 0.
+	 */
+	if (sio_getsockname(fd, &service->addr, &service->addr_len) != 0)
+		goto error;
+
 	say_info("%s: bound to %s", evio_service_name(service),
 		 sio_strfaddr(&service->addr, service->addr_len));
 
@@ -400,6 +407,7 @@ evio_service_stop(struct evio_service *service)
 
 	if (ev_is_active(&service->ev)) {
 		ev_io_stop(service->loop, &service->ev);
+		service->addr_len = 0;
 	}
 
 	if (service->ev.fd >= 0) {
diff --git a/test/box/info.result b/test/box/info.result
index af81f7add..4dc888616 100644
--- a/test/box/info.result
+++ b/test/box/info.result
@@ -77,6 +77,7 @@ t
 - - cluster
   - gc
   - id
+  - listen
   - lsn
   - memory
   - package
-- 
2.21.0 (Apple Git-122.2)