[lttng-dev] [PATCH lttng-tools 1/2] Fix: error handling on relay version check

[Julien Desfossez]

If we have a network error while performing the version check between
the session daemon and the relay, we should not report to the user that
there is a version mismatch. We now return LTTNG_ERR_RELAYD_VERSION_FAIL
on relayd_version_check() when the daemons are not compatible and the
negative value from sendmsg/recvmsg on network errors.

Signed-off-by: Julien Desfossez <jdesfossez at efficios.com>
---
 src/bin/lttng-sessiond/cmd.c | 7 +++++--
 src/common/relayd/relayd.c   | 5 +++--
 2 files changed, 8 insertions(+), 4 deletions(-)

diff --git a/src/bin/lttng-sessiond/cmd.c b/src/bin/lttng-sessiond/cmd.c
index 1edcffe..0317d52 100644
--- a/src/bin/lttng-sessiond/cmd.c
+++ b/src/bin/lttng-sessiond/cmd.c
@@ -877,8 +877,11 @@ static int create_connect_relayd(struct lttng_uri *uri,
 
 		/* Check relayd version */
 		ret = relayd_version_check(rsock);
-		if (ret < 0) {
-			ret = LTTNG_ERR_RELAYD_VERSION_FAIL;
+		if (ret == LTTNG_ERR_RELAYD_VERSION_FAIL) {
+			goto close_sock;
+		} else if (ret < 0) {
+			ERR("Unable to reach lttng-relayd");
+			ret = LTTNG_ERR_RELAYD_CONNECT_FAIL;
 			goto close_sock;
 		}
 		consumer->relay_major_version = rsock->major;
diff --git a/src/common/relayd/relayd.c b/src/common/relayd/relayd.c
index 2adcbe4..4cb1c1f 100644
--- a/src/common/relayd/relayd.c
+++ b/src/common/relayd/relayd.c
@@ -378,7 +378,8 @@ end:
  * If major versions are compatible, we assign minor_to_use to the
  * minor version of the procotol we are going to use for this session.
  *
- * Return 0 if compatible else negative value.
+ * Return 0 if the two daemons are compatible, LTTNG_ERR_RELAYD_VERSION_FAIL
+ * otherwise, or a negative value on network errors.
  */
 int relayd_version_check(struct lttcomm_relayd_sock *rsock)
 {
@@ -420,7 +421,7 @@ int relayd_version_check(struct lttcomm_relayd_sock *rsock)
 	 */
 	if (msg.major != rsock->major) {
 		/* Not compatible */
-		ret = -1;
+		ret = LTTNG_ERR_RELAYD_VERSION_FAIL;
 		DBG2("Relayd version is NOT compatible. Relayd version %u != %u (us)",
 				msg.major, rsock->major);
 		goto error;
-- 
2.7.4