dnssvc

type BindRetryConfig struct {
	// Enabled enables retrying to bind to listen addresses.
	Enabled bool

	// Interval is the interval to wait between retries.  It must be
	// non-negative.
	Interval time.Duration

	// Count is the maximum number of attempts excluding the first one.
	Count uint
}

type BootstrapConfig struct {
	// Addresses is the list of servers.
	Addresses []netip.AddrPort

	// Timeout is the timeout for DNS requests.
	Timeout time.Duration
}

type CacheConfig struct {
	// Enabled specifies if the cache should be used.
	Enabled bool

	// Size is the maximum size of the common cache.
	//
	// TODO(e.burkov):  Make it a [datasize.ByteSize] when dnsproxy uses it.
	Size int

	// ClientSize is the maximum size of each per-client cache.
	//
	// TODO(e.burkov):  Make it a [datasize.ByteSize] when dnsproxy uses it.
	ClientSize int
}

type ClientGetter interface {
	// Address returns the client's address.
	Address(dctx *proxy.DNSContext) (addr netip.AddrPort)
}

type Config struct {
	// BaseLogger used as the base logger for the DNS subservices.  It must not
	// be nil.
	BaseLogger *slog.Logger

	// Logger is the logger for the DNS service.  It must not be nil.
	Logger *slog.Logger

	// PrivateSubnets is the set of IP networks considered private.  The PTR
	// requests for ARPA domains considered private if the domain contains an IP
	// from one of the networks and the request came from the client within one
	// of the networks.  It must not be nil.
	PrivateSubnets netutil.SubnetSet

	// Cache is the configuration for the DNS results cache.  It must not be
	// nil.
	Cache *CacheConfig

	// Bootstrap describes bootstrapping DNS servers.  It must not be nil.
	Bootstrap *BootstrapConfig

	// Upstreams describes DNS upstream servers.  It must not be nil.
	Upstreams *UpstreamConfig

	// Fallbacks describes DNS fallback upstream servers.  It must not be nil.
	Fallbacks *FallbackConfig

	// ClientGetter is the function to get the client for a request.  It must
	// not be nil.
	ClientGetter ClientGetter

	// BindRetry is the configuration for retrying to bind to listen addresses.
	// It must not be nil.
	BindRetry *BindRetryConfig

	// PendingRequests is the configuration for duplicate requests handling.
	// It must not be nil.
	PendingRequests *PendingRequestsConfig

	// ListenAddrs is the list of served addresses.  It must contain at least
	// one entry.  It must not be empty and must contain only valid addresses.
	ListenAddrs []netip.AddrPort
}

type DNSService struct {
	// contains filtered or unexported fields
}

type DefaultClientGetter struct{}

type FallbackConfig struct {
	// Addresses is the list of servers.
	Addresses []string

	// Timeout is the timeout for DNS requests.  Zero value disables the
	// timeout.
	Timeout time.Duration
}

type MatchCriteria struct {
	// Client is the prefix to match the client address.
	Client netip.Prefix

	// QuestionDomain is the suffix to match the question domain.
	QuestionDomain string
}

type PendingRequestsConfig struct {
	// Enabled determines whether duplicate simultaneous requests should be
	// tracked and use the result of the first one.
	Enabled bool
}

type UpstreamConfig struct {
	// Groups is the list of groups.  It should contain at least a
	// [agdc.UpstreamGroupNameDefault] group.
	Groups []*UpstreamGroupConfig

	// Timeout is the timeout for DNS requests.  Zero value disables the
	// timeout.
	Timeout time.Duration
}

type UpstreamGroupConfig struct {
	// Name is the name of the group.
	Name agdc.UpstreamGroupName

	// Address is the address of the server.  It should not be empty.
	Address string

	// Match is the list of match criteria.
	Match []MatchCriteria
}