/* we were a leader and somebody says that they have a more up
* to date ticket
* there was probably connectivity loss
* tricky
*/
static int leader_handle_newer_ticket(
struct ticket_config *tk,
struct booth_site *sender,
struct booth_site *leader,
struct boothc_ticket_msg *msg
)
{
update_term_from_msg(tk, msg);
if (leader != no_leader && leader && leader != local) {
/* eek, two leaders, split brain */
/* normally shouldn't happen; run election */
tk_log_error("from %s: ticket granted to %s! (revoking locally)",
site_string(sender),
site_string(leader)
);
} else if (term_time_left(tk)) {
/* eek, two leaders, split brain */
/* normally shouldn't happen; run election */
tk_log_error("from %s: ticket granted to %s! (revoking locally)",
site_string(sender),
site_string(leader)
);
}
set_next_state(tk, ST_LEADER);
return 0;
}
/* §5.2 */
static int answer_REQ_VOTE(
struct ticket_config *tk,
struct booth_site *sender,
struct booth_site *leader,
struct boothc_ticket_msg *msg
)
{
int valid;
struct boothc_ticket_msg omsg;
cmd_result_t inappr_reason;
int reason;
inappr_reason = test_reason(tk, sender, leader, msg);
if (inappr_reason)
return send_reject(sender, tk, inappr_reason, msg);
valid = term_time_left(tk);
reason = ntohl(msg->header.reason);
/* valid tickets are not allowed only if the sender thinks
* the ticket got lost */
if (sender != tk->leader && valid && reason != OR_STEPDOWN) {
tk_log_warn("election from %s with reason %s rejected "
"(we have %s as ticket owner), ticket still valid for %ds",
site_string(sender), state_to_string(reason),
site_string(tk->leader), valid);
return send_reject(sender, tk, RLT_TERM_STILL_VALID, msg);
}
if (term_too_low(tk, sender, leader, msg))
return 0;
/* set this, so that we know not to send status for the
* ticket */
tk->in_election = 1;
/* reset ticket's leader on not valid tickets */
if (!valid)
set_leader(tk, NULL);
/* if it's a newer term or ... */
if (newer_term(tk, sender, leader, msg, 1)) {
clear_election(tk);
goto vote_for_sender;
}
/* ... we didn't vote yet, then vote for the sender */
/* §5.2, §5.4 */
if (!tk->voted_for) {
vote_for_sender:
tk->voted_for = sender;
record_vote(tk, sender, leader);
}
init_ticket_msg(&omsg, OP_VOTE_FOR, OP_REQ_VOTE, RLT_SUCCESS, 0, tk);
omsg.ticket.leader = htonl(get_node_id(tk->voted_for));
return booth_udp_send_auth(sender, &omsg, sendmsglen(&omsg));
}
void update_ticket_state(struct ticket_config *tk, struct booth_site *sender)
{
if (tk->state == ST_CANDIDATE) {
tk_log_info("learned from %s about "
"newer ticket, stopping elections",
site_string(sender));
/* there could be rejects coming from others; don't log
* warnings unnecessarily */
tk->expect_more_rejects = 1;
}
if (tk->leader == local || tk->is_granted) {
/* message from a live leader with valid ticket? */
if (sender == tk->leader && term_time_left(tk)) {
if (tk->is_granted) {
tk_log_warn("ticket was granted here, "
"but it's live at %s (revoking here)",
site_string(sender));
} else {
tk_log_info("ticket live at %s",
site_string(sender));
}
disown_ticket(tk);
ticket_write(tk);
set_state(tk, ST_FOLLOWER);
set_next_state(tk, ST_FOLLOWER);
} else {
if (tk->state == ST_CANDIDATE) {
set_state(tk, ST_FOLLOWER);
}
set_next_state(tk, ST_LEADER);
}
} else {
if (!tk->leader || tk->leader == no_leader) {
if (sender)
tk_log_info("ticket is not granted");
else
tk_log_info("ticket is not granted (from CIB)");
set_state(tk, ST_INIT);
} else {
if (sender)
tk_log_info("ticket granted to %s (says %s)",
site_string(tk->leader),
tk->leader == sender ? "they" : site_string(sender));
else
tk_log_info("ticket granted to %s (from CIB)",
site_string(tk->leader));
set_state(tk, ST_FOLLOWER);
/* just make sure that we check the ticket soon */
set_next_state(tk, ST_FOLLOWER);
}
}
}
static int ticket_seems_ok(struct ticket_config *tk)
{
int left;
left = term_time_left(tk);
if (!left)
return 0; /* quite sure */
if (tk->state == ST_CANDIDATE)
return 0; /* in state of flux */
if (tk->state == ST_LEADER)
return 1; /* quite sure */
if (tk->state == ST_FOLLOWER &&
left >= tk->term_duration/3)
return 1; /* almost quite sure */
return 0;
}
int raft_answer(
struct ticket_config *tk,
struct booth_site *sender,
struct booth_site *leader,
struct boothc_ticket_msg *msg
)
{
int cmd, req;
int rv;
rv = 0;
cmd = ntohl(msg->header.cmd);
req = ntohl(msg->header.request);
if (req)
tk_log_debug("got %s (req %s) from %s",
state_to_string(cmd),
state_to_string(req),
site_string(sender));
else
tk_log_debug("got %s from %s",
state_to_string(cmd),
site_string(sender));
/* don't process tickets with invalid term
*/
if (cmd != OP_STATUS &&
msg_term_invalid(tk, sender, leader, msg))
return 0;
switch (cmd) {
case OP_REQ_VOTE:
rv = answer_REQ_VOTE(tk, sender, leader, msg);
break;
case OP_VOTE_FOR:
rv = process_VOTE_FOR(tk, sender, leader, msg);
break;
case OP_ACK:
if (tk->leader == local &&
tk->state == ST_LEADER)
rv = process_ACK(tk, sender, leader, msg);
break;
case OP_HEARTBEAT:
if ((tk->leader != local || !term_time_left(tk)) &&
(tk->state == ST_INIT || tk->state == ST_FOLLOWER ||
tk->state == ST_CANDIDATE))
rv = answer_HEARTBEAT(tk, sender, leader, msg);
else {
tk_log_warn("unexpected message %s, from %s",
state_to_string(cmd),
site_string(sender));
if (ticket_seems_ok(tk))
send_reject(sender, tk, RLT_TERM_STILL_VALID, msg);
rv = -EINVAL;
}
break;
case OP_UPDATE:
if (((tk->leader != local && tk->leader == leader) || !is_owned(tk)) &&
(tk->state == ST_INIT || tk->state == ST_FOLLOWER ||
tk->state == ST_CANDIDATE)) {
rv = process_UPDATE(tk, sender, leader, msg);
} else {
tk_log_warn("unexpected message %s, from %s",
state_to_string(cmd),
site_string(sender));
if (ticket_seems_ok(tk))
send_reject(sender, tk, RLT_TERM_STILL_VALID, msg);
rv = -EINVAL;
}
break;
case OP_REJECTED:
rv = process_REJECTED(tk, sender, leader, msg);
break;
case OP_REVOKE:
rv = process_REVOKE(tk, sender, leader, msg);
break;
case OP_MY_INDEX:
rv = process_MY_INDEX(tk, sender, leader, msg);
break;
case OP_STATUS:
if (!tk->in_election)
rv = send_msg(OP_MY_INDEX, tk, sender, msg);
break;
default:
tk_log_error("unknown message %s, from %s",
state_to_string(cmd), site_string(sender));
rv = -EINVAL;
}
return rv;
}
