refactor: code cleanup, stricter config validation (#155)

lib/config.go

@@ -0,0 +1,153 @@
+package lib
+
+import (
+	"errors"
+	"fmt"
+	"path/filepath"
+	"strings"
+
+	"github.com/spf13/pflag"
+	"github.com/spf13/viper"
+)
+
+type Config struct {
+	Permissions `mapstructure:",squash"`
+	Debug       bool
+	Address     string
+	Port        int
+	TLS         bool
+	Cert        string
+	Key         string
+	Prefix      string
+	NoSniff     bool
+	LogFormat   string
+	Auth        bool
+	CORS        CORS
+	Users       []User
+}
+
+func ParseConfig(filename string, flags *pflag.FlagSet) (*Config, error) {
+	v := viper.New()
+
+	// Configure flags bindings
+	if flags != nil {
+		err := v.BindPFlags(flags)
+		if err != nil {
+			return nil, err
+		}
+
+		err = v.BindPFlag("LogFormat", flags.Lookup("log_format"))
+		if err != nil {
+			return nil, err
+		}
+	}
+
+	// Configuration file settings
+	v.AddConfigPath(".")
+	v.AddConfigPath("/etc/webdav/")
+	v.SetConfigName("config")
+	if filename != "" {
+		v.SetConfigFile(filename)
+	}
+
+	// Environment settings
+	v.SetEnvPrefix("wd")
+	v.SetEnvKeyReplacer(strings.NewReplacer(".", "_"))
+	v.AutomaticEnv()
+
+	// Defaults
+	v.SetDefault("CORS.AllowedHeaders", []string{"*"})
+	v.SetDefault("CORS.AllowedHosts", []string{"*"})
+	v.SetDefault("CORS.AllowedMethods", []string{"*"})
+
+	// Read and unmarshal configuration
+	err := v.ReadInConfig()
+	if err != nil {
+		if _, ok := err.(viper.ConfigFileNotFoundError); !ok {
+			return nil, err
+		}
+	}
+
+	cfg := &Config{}
+	err = v.Unmarshal(cfg)
+	if err != nil {
+		return nil, err
+	}
+
+	// Cascade user settings
+	for i := range cfg.Users {
+		if !v.IsSet(fmt.Sprintf("Users.%d.Scope", i)) {
+			cfg.Users[i].Scope = cfg.Scope
+		}
+
+		if !v.IsSet(fmt.Sprintf("Users.%d.Modify", i)) {
+			cfg.Users[i].Modify = cfg.Modify
+		}
+
+		if !v.IsSet(fmt.Sprintf("Users.%d.Rules", i)) {
+			cfg.Users[i].Rules = cfg.Rules
+		}
+	}
+
+	err = cfg.Validate()
+	if err != nil {
+		return nil, err
+	}
+
+	return cfg, nil
+}
+
+func (c *Config) Validate() error {
+	var err error
+
+	if c.Auth && len(c.Users) == 0 {
+		return errors.New("invalid config: auth cannot be enabled without users")
+	}
+
+	if !c.Auth && len(c.Users) != 0 {
+		return errors.New("invalid config: auth cannot be disabled with users defined")
+	}
+
+	if c.TLS {
+		if c.Cert == "" {
+			return errors.New("invalid config: Cert must be defined if TLS is activated")
+		}
+
+		if c.Key == "" {
+			return errors.New("invalid config: Key must be defined if TLS is activated")
+		}
+
+		c.Cert, err = filepath.Abs(c.Cert)
+		if err != nil {
+			return fmt.Errorf("invalid config: %w", err)
+		}
+
+		c.Key, err = filepath.Abs(c.Key)
+		if err != nil {
+			return fmt.Errorf("invalid config: %w", err)
+		}
+	}
+
+	err = c.Permissions.Validate()
+	if err != nil {
+		return fmt.Errorf("invalid config: %w", err)
+	}
+
+	for _, u := range c.Users {
+		err := u.Validate()
+		if err != nil {
+			return fmt.Errorf("invalid config: %w", err)
+		}
+	}
+
+	return nil
+}
+
+type CORS struct {
+	Enabled        bool
+	Credentials    bool
+	AllowedHeaders []string
+	AllowedHosts   []string
+	AllowedMethods []string
+	ExposedHeaders []string
+}