# Validation

Every change is checked as a whole configuration before it is saved. An
**error** stops the change; a **warning** is reported with it, and stays
on the dashboard and in `steward status` until fixed. Each problem has a
stable code, shown by the CLI as `[code]` and in the API as
`problems[].code`. `stewardd check` runs the checks on the saved
configuration.

The warnings marked *host* compare the configuration with this machine's
interfaces. They come from stewardd, not from a configuration on its own.

## Settings

| Code | | When |
|---|---|---|
| `lease_time_range` | error | a lease time (settings or subnet) under 1 minute or over 365 days |
| `ping_timeout_range` | error | the ping timeout isn't 50 to 5000 ms |
| `decline_hold_range` | error | the decline hold isn't 1 minute to 30 days |

## Options

These apply to options anywhere (settings, subnets, reservations).

| Code | | When |
|---|---|---|
| `option_code` | error | a number outside 1 to 254 |
| `option_reserved` | error | an option Steward sets itself, such as the lease time or the subnet mask ([options.md](options.md#options-steward-sets-itself)) |
| `option_duplicate` | error | the same option twice in one place |
| `option_invalid` | error | a value that doesn't fit the option's type (`dns.example` for `domain-name-servers`) |

## Subnets

| Code | | When |
|---|---|---|
| `subnet_prefix` | error | not an IPv4 network, or host bits set (`10.0.10.5/24`; the message gives the network) |
| `subnet_size` | error | shorter than /8 or longer than /30 |
| `subnet_overlap` | error | it overlaps another subnet |
| `subnet_name` | error | the name has spaces, slashes or commas |
| `subnet_name_taken` | error | another subnet has the name (names are compared without case) |
| `subnet_interface_missing` | error | no interface given |
| `subnet_interface_name` | error | not an interface name (over 15 characters, or spaces, `/` or `:`) |
| `subnet_no_pools` | warning | no pools: only clients with a reservation get addresses |
| `pool_invalid` | error | a pool that ends before it starts |
| `pool_outside_subnet` | error | a pool not inside the subnet |
| `pool_network_address` | error | a pool with the network or broadcast address |
| `pool_overlap` | error | two pools overlap |
| `router_outside_subnet` | warning | a `routers` address outside the subnet: clients can't reach it |
| `router_in_pool` | warning | a `routers` address inside a pool. The ping check keeps it from being handed out while it answers, but take it out of the pool |
| `interface_unknown` | warning, host | the interface doesn't exist on this machine. It is served once it appears |
| `interface_no_address` | warning, host | the interface has no address in the subnet. Clients renew with that address, so give it one |
| `pool_includes_server` | warning, host | a pool has the server's own address. It is never handed out, but take it out of the pool |

## Reservations

| Code | | When |
|---|---|---|
| `reservation_no_client` | error | neither a MAC address nor a client identifier |
| `reservation_ip` | error | not an IPv4 address |
| `reservation_no_subnet` | error | the address is in no subnet; add the subnet first |
| `reservation_network_address` | error | the network or broadcast address of its subnet |
| `reservation_ip_taken` | error | the address is reserved already |
| `reservation_client_taken` | error | the client has a reservation in this subnet already (one per subnet; a device on two VLANs may have one in each) |
| `reservation_hostname` | error | not a host name (letters, digits and `-`, labels up to 63 characters) |
| `reservation_server_address` | warning, host | the server's own address |