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Disallow unknown fields (strict unmarshal) when loading modules

This makes it faster and easier to detect broken configurations, but
is a slight performance hit on config loads since we have to re-encode
the decoded struct back into JSON without the module name's key
This commit is contained in:
Matthew Holt 2019-05-22 14:32:12 -06:00
parent 869fbac632
commit f976451d19
2 changed files with 29 additions and 7 deletions

View file

@ -84,7 +84,7 @@ func (ctx Context) LoadModule(name string, rawMsg json.RawMessage) (interface{},
// fill in its config only if there is a config to fill in
if len(rawMsg) > 0 {
err := json.Unmarshal(rawMsg, &val)
err := strictUnmarshalJSON(rawMsg, &val)
if err != nil {
return nil, fmt.Errorf("decoding module config: %s: %v", mod.Name, err)
}
@ -127,7 +127,7 @@ func (ctx Context) LoadModule(name string, rawMsg json.RawMessage) (interface{},
// containing the module name is treated special/separate from all
// the other keys.
func (ctx Context) LoadModuleInline(moduleNameKey, moduleScope string, raw json.RawMessage) (interface{}, error) {
moduleName, err := getModuleNameInline(moduleNameKey, raw)
moduleName, raw, err := getModuleNameInline(moduleNameKey, raw)
if err != nil {
return nil, err
}

View file

@ -1,6 +1,7 @@
package caddy2
import (
"bytes"
"encoding/json"
"fmt"
"sort"
@ -120,20 +121,31 @@ func Modules() []string {
}
// getModuleNameInline loads the string value from raw of moduleNameKey,
// where raw must be a JSON encoding of a map.
func getModuleNameInline(moduleNameKey string, raw json.RawMessage) (string, error) {
// where raw must be a JSON encoding of a map. It returns that value,
// along with the result of removing that key from raw.
func getModuleNameInline(moduleNameKey string, raw json.RawMessage) (string, json.RawMessage, error) {
var tmp map[string]interface{}
err := json.Unmarshal(raw, &tmp)
if err != nil {
return "", err
return "", nil, err
}
moduleName, ok := tmp[moduleNameKey].(string)
if !ok || moduleName == "" {
return "", fmt.Errorf("module name not specified with key '%s' in %+v", moduleNameKey, tmp)
return "", nil, fmt.Errorf("module name not specified with key '%s' in %+v", moduleNameKey, tmp)
}
return moduleName, nil
// remove key from the object, otherwise decoding it later
// will yield an error because the struct won't recognize it
// (this is only needed because we strictly enforce that
// all keys are recognized when loading modules)
delete(tmp, moduleNameKey)
result, err := json.Marshal(tmp)
if err != nil {
return "", nil, fmt.Errorf("re-encoding module configuration: %v", err)
}
return moduleName, result, nil
}
// Provisioner is implemented by modules which may need to perform
@ -166,6 +178,16 @@ type CleanerUpper interface {
Cleanup() error
}
// strictUnmarshalJSON is like json.Unmarshal but returns an error
// if any of the fields are unrecognized. Useful when decoding
// module configurations, where you want to be more sure they're
// correct.
func strictUnmarshalJSON(data []byte, v interface{}) error {
dec := json.NewDecoder(bytes.NewReader(data))
dec.DisallowUnknownFields()
return dec.Decode(v)
}
var (
modules = make(map[string]Module)
modulesMu sync.Mutex