bugfix: setkeepalive failure on TLSv1.3

When TLSv1.3 is used, the server may send a NewSessionTicket message
after the handshake. While this message is ssl-layer data,
`tcpsock:sslhandshake` does not consume it.

In the implementation of `setkeepalive`, `recv` is used to confirm the
connection is still open and there is no unread data in the buffer. But
it treats the NewSessionTicket message as application layer data and
then `setkeepalive` fails with this error `connection in dubious state`.

In fact we don't need to peek here, because if the application data is
read successfully then the connection is going to be closed anyway.
Therefore, `c->recv` can be used instead which will consume the
ssl-layer data implicitly.

Author: catbro666

src/ngx_stream_lua_socket_tcp.c

@@ -5595,8 +5595,7 @@ ngx_stream_lua_socket_keepalive_close_handler(ngx_event_t *ev)
     ngx_stream_lua_socket_pool_t                *spool;
 
     int                n;
-    int                err;
-    char               buf[1];
+    unsigned char      buf[1];
     ngx_connection_t  *c;
 
     c = ev->data;
@@ -5618,20 +5617,10 @@ ngx_stream_lua_socket_keepalive_close_handler(ngx_event_t *ev)
                    "stream lua tcp socket keepalive close handler "
                    "check stale events");
 
-    n = recv(c->fd, buf, 1, MSG_PEEK);
-    err = ngx_socket_errno;
-#if (NGX_STREAM_SSL)
-    /* ignore ssl protocol data like change cipher spec */
-    if (n == 1 && c->ssl != NULL) {
-        n = c->recv(c, (unsigned char *) buf, 1);
-        if (n == NGX_AGAIN) {
-            n = -1;
-            err = NGX_EAGAIN;
-        }
-    }
-#endif  /* NGX_STREAM_SSL */
+    /* consume the possible ssl-layer data implicitly */
+    n = c->recv(c, buf, 1);
 
-    if (n == -1 && err == NGX_EAGAIN) {
+    if (n == NGX_AGAIN) {
         /* stale event */
 
         if (ngx_handle_read_event(c->read, 0) != NGX_OK) {

t/058-tcp-socket.t

@@ -4,12 +4,13 @@ use Test::Nginx::Socket::Lua::Stream;
 
 repeat_each(2);
 
-plan tests => repeat_each() * 221;
+plan tests => repeat_each() * 224;
 
 our $HtmlDir = html_dir;
 
 $ENV{TEST_NGINX_MEMCACHED_PORT} ||= 11211;
 $ENV{TEST_NGINX_RESOLVER} ||= '8.8.8.8';
+$ENV{TEST_NGINX_HTML_DIR} ||= html_dir();
 
 #log_level 'warn';
 log_level 'debug';
@@ -3545,3 +3546,58 @@ lua tcp socket calling receiveany() method to read at most 7 bytes
 
 --- error_log
 shutdown on a not connected socket: closed
+
+
+
+=== TEST 68: setkeepalive with TLSv1.3
+--- skip_openssl: 3: < 1.1.1
+--- stream_config
+    server {
+        listen unix:$TEST_NGINX_HTML_DIR/nginx.sock ssl;
+        ssl_certificate     ../../cert/test_ecdsa.crt;
+        ssl_certificate_key ../../cert/test_ecdsa.key;
+        ssl_protocols TLSv1.3;
+        content_by_lua_block {
+            local sock = assert(ngx.req.socket(true))
+            local data
+            while true do
+                data = assert(sock:receive())
+                assert(data == "hello")
+            end
+        }
+    }
+--- stream_server_config
+    lua_ssl_protocols TLSv1.3;
+    content_by_lua_block {
+        local sock = ngx.socket.tcp()
+        sock:settimeout(2000)
+        local ok, err = sock:connect("unix:$TEST_NGINX_HTML_DIR/nginx.sock")
+        if not ok then
+            ngx.say("failed to connect: ", err)
+            return
+        end
+        ngx.say("connected: ", ok)
+        local ok, err = sock:sslhandshake(false, nil, false)
+        if not ok then
+            ngx.say("failed to sslhandshake: ", err)
+            return
+        end
+        local ok, err = sock:send("hello\n")
+        if not ok then
+            ngx.say("failed to send: ", err)
+            return
+        end
+        -- sleep a while to make sure the NewSessionTicket message has arrived
+        ngx.sleep(1)
+        local ok, err = sock:setkeepalive()
+        if not ok then
+            ngx.say("failed to setkeepalive: ", err)
+        else
+            ngx.say("setkeepalive: ", ok)
+        end
+    }
+--- stream_response
+connected: 1
+setkeepalive: 1
+--- no_error_log
+[error]