OVSDB reconfigure_remotes remotes can conflict with 0.0.0.0???

[legitYosal]

Hi, I was tweaking my OVSDB which had this error:

2024-10-07T07:16:18.321Z|04322|socket_util|ERR|Dropped 1652 log messages in last 59 seconds (most recently, 0 seconds ago) due to excessive rate
2024-10-07T07:16:18.321Z|04323|socket_util|ERR|6641:0.0.0.0: bind: Address already in use
2024-10-07T07:16:18.321Z|04324|ovsdb_jsonrpc_server|ERR|Dropped 1652 log messages in last 59 seconds (most recently, 0 seconds ago) due to excessive rate
2024-10-07T07:16:18.321Z|04325|ovsdb_jsonrpc_server|ERR|ptcp:6641:0.0.0.0: listen failed: Address already in use

Turns out if you have set 2 or more IP remote options, if one is 0.0.0.0, it will fail if they have the same port, for example, for me, I had a --remote=ptcp:6641:172.25.0.1 and another one in connections table:

# ovn-nbctl list connection
_uuid               : c234c805-78c0-40a0-9114-c68ae8a56126
external_ids        : {}
inactivity_probe    : []
is_connected        : false
max_backoff         : []
other_config        : {}
status              : {}
target              : "ptcp:6641:0.0.0.0"

I was thinking, this is miss use of OVSDB, but a validation step would be fine and adds to visibility, also fully 100% checking for this condition requires high big O, so a hint will suffice, for example we can change it in this way:

void check_remote_conflict(struct shash *resolved_remotes) {
    int number_of_ip_remotes = 0;
    bool ip_conflict_can_happen = false;
    SHASH_FOR_EACH (node, resolved_remotes) {
        const char *name = node->name;
        if (remote ptcp or pssl) {
            number_of_ip_remotes ++;
            if (remote is 0.0.0.0) 
              ip_conflict_can_happen = true;
            if (ip_conflict_can_happen and number_of_ip_remotes > 1 \
                  and is not 0.0.0.0) {
              VLOG_WARN("You are using two remotes with 0.0.0.0, can cause conflict")
            }
        }
    }
}
    ...
    check_remote_conflict(resolved_remotes)
    ovsdb_jsonrpc_server_set_remotes(jsonrpc, &resolved_remotes);
    free_remotes(&resolved_remotes);
    shash_destroy(&resolved_remotes);

    return errors.string;
}

What do you think about this?

@igsilya

[igsilya]

Sorry for the late replay. Yeah, it's not really an OVS's issue. I think, the expectation is that users will not configure overlapping addresses. The 'already in use' message in the log should be good enough to point in the right direction.