MINOR: connection: reintroduce conn_prepare to set the protocol and transport

Now that we can assign conn->xprt regardless of the initialization state,
we can reintroduce conn_prepare() to set only the protocol, the transport
layer and initialize the transport layer's state.

include/proto/connection.h

@@ -468,6 +468,17 @@ static inline int conn_sock_shutw_pending(struct connection *c)
 	return (c->flags & (CO_FL_DATA_WR_SH | CO_FL_SOCK_WR_SH)) == CO_FL_DATA_WR_SH;
 }
 
+/* prepares a connection to work with protocol <proto> and transport <xprt>.
+ * The transport's context is initialized as well.
+ */
+static inline void conn_prepare(struct connection *conn, const struct protocol *proto, const struct xprt_ops *xprt)
+{
+	conn->ctrl = proto;
+	conn->xprt = xprt;
+	conn->xprt_st = 0;
+	conn->xprt_ctx = NULL;
+}
+
 /* Initializes all required fields for a new connection. Note that it does the
  * minimum acceptable initialization for a connection that already exists and
  * is about to be reused. It also leaves the addresses untouched, which makes
@@ -477,8 +488,6 @@ static inline void conn_init(struct connection *conn)
 {
 	conn->obj_type = OBJ_TYPE_CONN;
 	conn->flags = CO_FL_NONE;
-	conn->xprt_st = 0;
-	conn->xprt_ctx = NULL;
 	conn->data = NULL;
 	conn->owner = NULL;
 	conn->t.sock.fd = -1; /* just to help with debugging */

src/checks.c

@@ -1541,6 +1541,7 @@ static struct task *process_chk(struct task *t)
 
 		/* prepare a new connection */
 		conn_init(conn);
+		conn_prepare(conn, s->check_common.proto, s->check_common.xprt);
 		conn_assign(conn, &check_conn_cb, s->check_common.proto, s->check_common.xprt, check);
 		conn->target = &s->obj_type;
 

src/session.c

@@ -110,8 +110,8 @@ int session_accept(struct listener *l, int cfd, struct sockaddr_storage *addr)
 	 */
 	conn_init(cli_conn);
 	cli_conn->t.sock.fd = cfd;
-	cli_conn->ctrl = l->proto;
 	cli_conn->flags |= CO_FL_ADDR_FROM_SET;
+	conn_prepare(cli_conn, l->proto, l->xprt);
 	cli_conn->addr.from = *addr;
 	cli_conn->target = &l->obj_type;