Fix: reply to version check even on protocol mismatch

In the relay, we currently put() the connection when we detect that
the major version from the session daemon is not compatible. We don't
reply to the version check message. The relay still holds a reference
on the connection so it is not closed and the session daemon is left
blocking in recvmsg.

The relay now replies to the version check so the session daemon knows
it is not compatible, and the relay completely closes the connection on
its side and removes the FD from the poll set.

Signed-off-by: Julien Desfossez <jdesfossez@efficios.com>
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>

diff --git a/src/bin/lttng-relayd/main.c b/src/bin/lttng-relayd/main.c
index 61f206fdf3c863041523ad6d92808d65a3033f33..cd4f058bf0243df63dd78e573e97fca202b751d3 100644 (file)
--- a/src/bin/lttng-relayd/main.c
+++ b/src/bin/lttng-relayd/main.c
@@ -1601,6 +1601,7 @@ static int relay_send_version(struct lttcomm_relayd_hdr *recv_hdr,
 {
        int ret;
        struct lttcomm_relayd_version reply, msg;
+       bool compatible = true;
 
        conn->version_check_done = 1;
 
@@ -1625,9 +1626,7 @@ static int relay_send_version(struct lttcomm_relayd_hdr *recv_hdr,
        if (reply.major != be32toh(msg.major)) {
                DBG("Incompatible major versions (%u vs %u), deleting session",
                                reply.major, be32toh(msg.major));
-               connection_put(conn);
-               ret = 0;
-               goto end;
+               compatible = false;
        }
 
        conn->major = reply.major;
@@ -1646,6 +1645,11 @@ static int relay_send_version(struct lttcomm_relayd_hdr *recv_hdr,
                ERR("Relay sending version");
        }
 
+       if (!compatible) {
+               ret = -1;
+               goto end;
+       }
+
        DBG("Version check done using protocol %u.%u", conn->major,
                        conn->minor);