Adjust the relayd protocol on version check

[lttng-tools.git] / src / bin / lttng-relayd / main.c

diff --git a/src/bin/lttng-relayd/main.c b/src/bin/lttng-relayd/main.c
index 082eb7975efd0adb1c41bfbfee65c621dd34abeb..995714faf40b6f6d34b6ed31319834baf99e2b6d 100644 (file)
--- a/src/bin/lttng-relayd/main.c
+++ b/src/bin/lttng-relayd/main.c
@@ -1240,7 +1240,7 @@ end:
  */
 static
 int relay_send_version(struct lttcomm_relayd_hdr *recv_hdr,
-               struct relay_command *cmd)
+               struct relay_command *cmd, struct lttng_ht *streams_ht)
 {
        int ret;
        struct lttcomm_relayd_version reply, msg;
@@ -1262,13 +1262,6 @@ int relay_send_version(struct lttcomm_relayd_hdr *recv_hdr,
                goto end;
        }
 
-       /*
-        * For now, we just ignore the received version but after 2.1 stable
-        * release, a check must be done to see if we either adapt to the other
-        * side version (which MUST be lower than us) or keep the latest data
-        * structure considering that the other side will adapt.
-        */
-
        ret = sscanf(VERSION, "%10u.%10u", &reply.major, &reply.minor);
        if (ret < 2) {
                ERR("Error in scanning version");
@@ -1282,8 +1275,25 @@ int relay_send_version(struct lttcomm_relayd_hdr *recv_hdr,
        if (ret < 0) {
                ERR("Relay sending version");
        }
-       DBG("Version check done (%u.%u)", be32toh(reply.major),
-                       be32toh(reply.minor));
+
+       /* Major versions must be the same */
+       if (reply.major != be32toh(msg.major)) {
+               DBG("Incompatible major versions, deleting session");
+               relay_delete_session(cmd, streams_ht);
+               ret = 0;
+               goto end;
+       }
+
+       cmd->session->major = reply.major;
+       /* We adapt to the lowest compatible version */
+       if (reply.minor <= be32toh(msg.minor)) {
+               cmd->session->minor = reply.minor;
+       } else {
+               cmd->session->minor = be32toh(msg.minor);
+       }
+
+       DBG("Version check done using protocol %u.%u", cmd->session->major,
+                       cmd->session->minor);
 
 end:
        return ret;
@@ -1593,7 +1603,7 @@ int relay_process_control(struct lttcomm_relayd_hdr *recv_hdr,
                ret = relay_recv_metadata(recv_hdr, cmd, streams_ht);
                break;
        case RELAYD_VERSION:
-               ret = relay_send_version(recv_hdr, cmd);
+               ret = relay_send_version(recv_hdr, cmd, streams_ht);
                break;
        case RELAYD_CLOSE_STREAM:
                ret = relay_close_stream(recv_hdr, cmd, streams_ht);