chore: initial commit

internal/config/config.go

@@ -0,0 +1,76 @@
+package config
+
+import (
+	"fmt"
+	"io"
+	"net/netip"
+	"os"
+	"strings"
+
+	"gopkg.in/yaml.v3"
+)
+
+type Config struct {
+	Server struct {
+		TrustedProxies []string `yaml:"trusted_proxies"`
+		Listen         string   `yaml:"listen"`
+		PublicOrigin   string   `yaml:"public_origin"`
+	} `yaml:"server"`
+	Admin struct {
+		Password string `yaml:"password"`
+	} `yaml:"admin"`
+	Storage struct {
+		LogRetentionDays int    `yaml:"log_retention_days"`
+		Path             string `yaml:"path"`
+	} `yaml:"storage"`
+	Limits struct {
+		RequestsPerMinute int `yaml:"requests_per_minute"`
+		PerKeyConcurrency int `yaml:"per_key_concurrency"`
+		GlobalConcurrency int `yaml:"global_concurrency"`
+	} `yaml:"limits"`
+}
+
+func Load(path string) (Config, error) {
+	var c Config
+	c.Limits.RequestsPerMinute = 120
+	c.Limits.PerKeyConcurrency = 8
+	c.Limits.GlobalConcurrency = 64
+	c.Server.Listen = "127.0.0.1:8080"
+	c.Storage.Path = "./data/router.db"
+	f, err := os.Open(path)
+	if err != nil {
+		return c, err
+	}
+	defer f.Close()
+	dec := yaml.NewDecoder(f)
+	dec.KnownFields(true)
+	if err = dec.Decode(&c); err != nil {
+		return c, fmt.Errorf("invalid config: %w", err)
+	}
+	var extra any
+	if err = dec.Decode(&extra); err != io.EOF {
+		return c, fmt.Errorf("config must contain exactly one YAML document")
+	}
+	if len(c.Admin.Password) < 12 || strings.HasPrefix(c.Admin.Password, "CHANGE-ME") {
+		return c, fmt.Errorf("admin.password must be a non-placeholder password of at least 12 characters")
+	}
+	if c.Server.Listen == "" || c.Storage.Path == "" {
+		return c, fmt.Errorf("server.listen and storage.path must not be empty")
+	}
+	if c.Limits.RequestsPerMinute <= 0 || c.Limits.PerKeyConcurrency <= 0 || c.Limits.GlobalConcurrency <= 0 {
+		return c, fmt.Errorf("limits must be positive integers")
+	}
+	if c.Storage.LogRetentionDays < 0 {
+		return c, fmt.Errorf("storage.log_retention_days must be nonnegative")
+	}
+	for _, cidr := range c.Server.TrustedProxies {
+		p, err := netip.ParsePrefix(cidr)
+		if err != nil {
+			return c, fmt.Errorf("invalid trusted proxy CIDR %q: %w", cidr, err)
+		}
+		if p.Bits() == 0 {
+			return c, fmt.Errorf("trusted proxy CIDR must not trust all addresses")
+		}
+	}
+	return c, nil
+}