1 files changed, 152 insertions, 0 deletions
diff --git a/internal/config/config.go b/internal/config/config.go
new file mode 100644
index 0000000..f2624c2
--- /dev/null
+++ b/internal/config/config.go
@@ -0,0 +1,152 @@
+package config
+
+import (
+	"flag"
+	"fmt"
+
+	"github.com/BurntSushi/toml"
+)
+
+type Config struct {
+	Server ServerConfig `toml:"server"`
+	Cache CacheConfig `toml:"cache"`
+	Resolver ResolverConfig `toml:"resolver"`
+	Blocklist BlocklistConfig `toml:"blocklist"`
+	Log LogConfig `toml:"log"`
+}
+
+type ServerConfig struct {
+	ListenUDP string `toml:"listen_udp"`
+	ListenTCP string `toml:"listen_tcp"`
+	ListenDOH string `toml:"listen_doh"`
+}
+
+type CacheConfig struct {
+	MaxEntries int    `toml:"max_entries"`
+	DBPath     string `toml:"db_path"`
+}
+
+type ResolverConfig struct {
+	Timeout        string `toml:"timeout"`
+	MaxDelegations int    `toml:"max_delegations"`
+}
+
+type BlocklistConfig struct {
+	Response string   `toml:"response"`
+	Files    []string `toml:"files"`
+	URLs     []string `toml:"urls"`
+}
+
+type LogConfig struct {
+	Level string `toml:"level"`
+}
+
+type CLIFlags struct {
+	Config string
+	LogLevel string
+	ListenUDP string
+	ListenTCP string
+	ListenDOH string
+}
+
+func ParseFlags() CLIFlags {
+	var f CLIFlags
+	flag.StringVar(&f.Config, "config", "linum.toml", "path to config file")
+	flag.StringVar(&f.LogLevel, "loglevel", "", "log level (debug|info|warn|error)")
+	flag.StringVar(&f.ListenUDP, "udp", "", "UDP listen address")
+	flag.StringVar(&f.ListenTCP, "tcp", "", "TCP listen address")
+	flag.StringVar(&f.ListenDOH, "doh", "", "DoH listen address")
+	flag.Parse()
+	return f
+}
+
+func Default() Config{
+	return Config{
+		Server: ServerConfig{
+			ListenUDP: ":5353",
+			ListenTCP: ":5353",
+			ListenDOH: ":8443",
+		},
+		Cache: CacheConfig{
+			MaxEntries: 100000,
+		},
+		Resolver: ResolverConfig{
+			Timeout: "2s",
+			MaxDelegations: 30,
+		},
+		Blocklist: BlocklistConfig{
+			Response: "zero_ip",
+		},
+		Log: LogConfig{
+			Level: "info",
+		},
+	}
+}
+
+func LoadFile(path string) (Config, error) {
+	var cfg Config
+	_, err := toml.DecodeFile(path, &cfg)
+	return cfg, err
+}
+
+func Merge(dst, src Config) Config {
+	if src.Server.ListenUDP != "" {
+		dst.Server.ListenUDP = src.Server.ListenUDP
+	}
+	if src.Server.ListenTCP != "" {
+		dst.Server.ListenTCP = src.Server.ListenTCP
+	}
+	if src.Server.ListenDOH != "" {
+		dst.Server.ListenDOH = src.Server.ListenDOH
+	}
+	if src.Cache.MaxEntries > 0 {
+		dst.Cache.MaxEntries = src.Cache.MaxEntries
+	}
+	if src.Cache.DBPath != "" {
+		dst.Cache.DBPath = src.Cache.DBPath
+	}
+	if src.Resolver.Timeout != "" {
+		dst.Resolver.Timeout = src.Resolver.Timeout
+	}
+	if src.Resolver.MaxDelegations > 0 {
+		dst.Resolver.MaxDelegations = src.Resolver.MaxDelegations
+	}
+	if src.Blocklist.Response != "" {
+		dst.Blocklist.Response = src.Blocklist.Response
+	}
+	if len(src.Blocklist.Files) > 0 {
+		dst.Blocklist.Files = src.Blocklist.Files
+	}
+	if len(src.Blocklist.URLs) > 0 {
+		dst.Blocklist.URLs = src.Blocklist.URLs
+	}
+	if src.Log.Level != "" {
+		dst.Log.Level = src.Log.Level
+	}
+	return dst
+}
+
+func (f CLIFlags) Apply(cfg Config) Config {
+	if f.ListenUDP != "" {
+		cfg.Server.ListenUDP = f.ListenUDP
+	}
+	if f.ListenTCP != "" {
+		cfg.Server.ListenTCP = f.ListenTCP
+	}
+	if f.ListenDOH != "" {
+		cfg.Server.ListenDOH = f.ListenDOH
+	}
+	if f.LogLevel != "" {
+		cfg.Log.Level = f.LogLevel
+	}
+	return cfg
+}
+
+func (c Config) Validate() error {
+	switch c.Blocklist.Response {
+	case "zero_ip", "nxdomain", "":
+	default:
+		return fmt.Errorf("invalid blocklist response %q (want zero_ip or nxdomain)", c.Blocklist.Response)
+	}
+	return nil
+}