lib/http: Add authentication middleware with basic auth implementation

lib/http/auth/auth.go

@@ -0,0 +1,77 @@
+package auth
+
+import (
+	"github.com/rclone/rclone/fs/config/flags"
+	"github.com/rclone/rclone/lib/http"
+	"github.com/spf13/pflag"
+)
+
+// Help contains text describing the http authentication to add to the command
+// help.
+var Help = `
+#### Authentication
+
+By default this will serve files without needing a login.
+
+You can either use an htpasswd file which can take lots of users, or
+set a single username and password with the --user and --pass flags.
+
+Use --htpasswd /path/to/htpasswd to provide an htpasswd file.  This is
+in standard apache format and supports MD5, SHA1 and BCrypt for basic
+authentication.  Bcrypt is recommended.
+
+To create an htpasswd file:
+
+    touch htpasswd
+    htpasswd -B htpasswd user
+    htpasswd -B htpasswd anotherUser
+
+The password file can be updated while rclone is running.
+
+Use --realm to set the authentication realm.
+`
+
+// CustomAuthFn if used will be used to authenticate user, pass. If an error
+// is returned then the user is not authenticated.
+//
+// If a non nil value is returned then it is added to the context under the key
+type CustomAuthFn func(user, pass string) (value interface{}, err error)
+
+// Options contains options for the http authentication
+type Options struct {
+	HtPasswd  string       // htpasswd file - if not provided no authentication is done
+	Realm     string       // realm for authentication
+	BasicUser string       // single username for basic auth if not using Htpasswd
+	BasicPass string       // password for BasicUser
+	Auth      CustomAuthFn `json:"-"` // custom Auth (not set by command line flags)
+}
+
+// Auth instantiates middleware that authenticates users based on the configuration
+func Auth(opt Options) http.Middleware {
+	if opt.Auth != nil {
+		return CustomAuth(opt.Auth, opt.Realm)
+	} else if opt.HtPasswd != "" {
+		return HtPasswdAuth(opt.HtPasswd, opt.Realm)
+	} else if opt.BasicUser != "" {
+		return SingleAuth(opt.BasicUser, opt.BasicPass, opt.Realm)
+	}
+	return nil
+}
+
+// Options set by command line flags
+var (
+	Opt = Options{}
+)
+
+// AddFlagsPrefix adds flags for http/auth
+func AddFlagsPrefix(flagSet *pflag.FlagSet, prefix string, Opt *Options) {
+	flags.StringVarP(flagSet, &Opt.HtPasswd, prefix+"htpasswd", "", Opt.HtPasswd, "htpasswd file - if not provided no authentication is done")
+	flags.StringVarP(flagSet, &Opt.Realm, prefix+"realm", "", Opt.Realm, "realm for authentication")
+	flags.StringVarP(flagSet, &Opt.BasicUser, prefix+"user", "", Opt.BasicUser, "User name for authentication.")
+	flags.StringVarP(flagSet, &Opt.BasicPass, prefix+"pass", "", Opt.BasicPass, "Password for authentication.")
+}
+
+// AddFlags adds flags for the http/auth
+func AddFlags(flagSet *pflag.FlagSet) {
+	AddFlagsPrefix(flagSet, "", &Opt)
+}