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Don't send diffs to slaves with not yet know version

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This commit is contained in:
Viktor Dukhovni
2019-09-16 18:17:09 -04:00
committed by Nico Williams
parent 7680c92047
commit 20557e2255
1 changed files with 34 additions and 5 deletions
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39
lib/kadm5/ipropd_master.c
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@@ -134,6 +134,7 @@ struct slave {
unsigned long flags;
#define SLAVE_F_DEAD 0x1
#define SLAVE_F_AYT 0x2
#define SLAVE_F_READY 0x4
struct slave *next;
};
@@ -679,6 +680,13 @@ send_diffs (kadm5_server_context *server_context, slave *s, int log_fd,
krb5_data data;
int ret = 0;
/*
* Don't send any diffs until slave has sent an I_HAVE telling us the
* initial version number!
*/
if ((s->flags & SLAVE_F_READY) == 0)
return 0;
if (s->flags & SLAVE_F_DEAD) {
krb5_warnx(context, "not sending diffs to dead slave %s", s->name);
return 0;
@@ -902,17 +910,38 @@ process_msg (kadm5_server_context *server_context, slave *s, int log_fd,
krb5_warnx(context, "process_msg: client send too little I_HAVE data");
break;
}
/* new started slave that have old log */
if (s->version == 0 && tmp != 0) {
/*
* New slave whose version number we've not yet seen. If the version
* number is zero, the slave has no data, and we'll send a complete
* database. Otherwise, we'll record a non-zero initial version and
* attempt an incremental update.
*
* NOTE!: Once the slave is "ready" (its first I_HAVE has conveyed its
* initial version), we MUST NOT update s->version to the slave's
* I_HAVE version, since we may already have sent later updates, and
* MUST NOT send them again, otherwise we can get further and further
* out of sync resending larger and larger diffs. The "not yet ready"
* is an essential precondition for setting s->version to the value
* in the I_HAVE message. This happens only once when the slave
* first connects.
*/
if (!(s->flags & SLAVE_F_READY)) {
if (current_version < tmp) {
krb5_warnx(context, "Slave %s (version %u) has later version "
"than the master (version %u) OUT OF SYNC",
s->name, tmp, current_version);
}
if (verbose)
krb5_warnx(context, "slave %s updated from %u to %u",
s->name, s->version, tmp);
/*
* Mark the slave as ready for updates based on incoming signals.
* Prior to the initial I_HAVE, we don't know the slave's version
* number, and MUST not send it anything, since we'll needlessly
* attempt to send the whole database!
*/
s->version = tmp;
s->flags |= SLAVE_F_READY;
if (verbose)
krb5_warnx(context, "slave %s ready for updates from version %u",
s->name, tmp);
}
if ((s->version_ack = tmp) < s->version)
break;