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tailscale/ipn/conffile/conffile.go

101 lines
2.8 KiB
Go

// Copyright (c) Tailscale Inc & AUTHORS
// SPDX-License-Identifier: BSD-3-Clause
// Package conffile contains code to load, manipulate, and access config file
// settings.
package conffile
import (
"bytes"
"encoding/json"
"errors"
"fmt"
"os"
"runtime"
"tailscale.com/ipn"
)
// Config describes a config file.
type Config struct {
Path string // disk path of HuJSON, or VMUserDataPath
Raw []byte // raw bytes from disk, in HuJSON form
Std []byte // standardized JSON form
Version string // "alpha0" for now
// Parsed is the parsed config, converted from its on-disk version to the
// latest known format.
//
// As of 2023-10-15 there is exactly one format ("alpha0") so this is both
// the on-disk format and the in-memory upgraded format.
Parsed ipn.ConfigVAlpha
}
// WantRunning reports whether c is non-nil and it's configured to be running.
func (c *Config) WantRunning() bool {
return c != nil && !c.Parsed.Enabled.EqualBool(false)
}
// VMUserDataPath is a sentinel value for Load to use to get the data
// from the VM's metadata service's user-data field.
const VMUserDataPath = "vm:user-data"
// hujsonStandardize is set to hujson.Standardize by conffile_hujson.go on
// platforms that support config files.
var hujsonStandardize func([]byte) ([]byte, error)
// Load reads and parses the config file at the provided path on disk.
func Load(path string) (*Config, error) {
switch runtime.GOOS {
case "ios", "android":
// compile-time for deadcode elimination
return nil, fmt.Errorf("config file loading not supported on %q", runtime.GOOS)
}
if hujsonStandardize == nil {
// Build tags are wrong in conffile_hujson.go
return nil, errors.New("[unexpected] config file loading not wired up")
}
var c Config
c.Path = path
var err error
switch path {
case VMUserDataPath:
c.Raw, err = readVMUserData()
default:
c.Raw, err = os.ReadFile(path)
}
if err != nil {
return nil, err
}
c.Std, err = hujsonStandardize(c.Raw)
if err != nil {
return nil, fmt.Errorf("error parsing config file %s HuJSON/JSON: %w", path, err)
}
var ver struct {
Version string `json:"version"`
}
if err := json.Unmarshal(c.Std, &ver); err != nil {
return nil, fmt.Errorf("error parsing config file %s: %w", path, err)
}
switch ver.Version {
case "":
return nil, fmt.Errorf("error parsing config file %s: no \"version\" field defined", path)
case "alpha0":
default:
return nil, fmt.Errorf("error parsing config file %s: unsupported \"version\" value %q; want \"alpha0\" for now", path, ver.Version)
}
c.Version = ver.Version
jd := json.NewDecoder(bytes.NewReader(c.Std))
jd.DisallowUnknownFields()
err = jd.Decode(&c.Parsed)
if err != nil {
return nil, fmt.Errorf("error parsing config file %s: %w", path, err)
}
if jd.More() {
return nil, fmt.Errorf("error parsing config file %s: trailing data after JSON object", path)
}
return &c, nil
}