openapi3filter: guard BodyEncoder registration behind a RW lock (#934)

* openapi3filter: guard BodyEncoder registration behind a RW lock

Signed-off-by: Pierre Fenoll <[email protected]>

* docs.sh

Signed-off-by: Pierre Fenoll <[email protected]>

---------

Signed-off-by: Pierre Fenoll <[email protected]>

Author: fenollp

.github/docs/openapi3filter.txt

@@ -69,6 +69,8 @@ func RegisterBodyDecoder(contentType string, decoder BodyDecoder)
     body decoders should not be created/destroyed by multiple goroutines.
 
 func RegisterBodyEncoder(contentType string, encoder BodyEncoder)
+    RegisterBodyEncoder enables package-wide decoding of contentType values
+
 func TrimJSONPrefix(data []byte) []byte
     TrimJSONPrefix trims one of the possible prefixes
 
@@ -80,8 +82,7 @@ func UnregisterBodyDecoder(contentType string)
     goroutines.
 
 func UnregisterBodyEncoder(contentType string)
-    This call is not thread-safe: body encoders should not be created/destroyed
-    by multiple goroutines.
+    UnregisterBodyEncoder disables package-wide decoding of contentType values
 
 func ValidateParameter(ctx context.Context, input *RequestValidationInput, parameter *openapi3.Parameter) error
     ValidateParameter validates a parameter's value by JSON schema. The function
@@ -152,14 +153,13 @@ func RegisteredBodyDecoder(contentType string) BodyDecoder
     by multiple goroutines.
 
 type BodyEncoder func(body interface{}) ([]byte, error)
+    BodyEncoder really is an (encoding/json).Marshaler
 
 func RegisteredBodyEncoder(contentType string) BodyEncoder
     RegisteredBodyEncoder returns the registered body encoder for the given
     content type.
 
     If no encoder was registered for the given content type, nil is returned.
-    This call is not thread-safe: body encoders should not be created/destroyed
-    by multiple goroutines.
 
 type ContentParameterDecoder func(param *openapi3.Parameter, values []string) (interface{}, *openapi3.Schema, error)
     A ContentParameterDecoder takes a parameter definition from the OpenAPI

openapi3filter/req_resp_encoder.go

@@ -3,47 +3,56 @@ package openapi3filter
 import (
 	"encoding/json"
 	"fmt"
+	"sync"
 )
 
 func encodeBody(body interface{}, mediaType string) ([]byte, error) {
-	encoder, ok := bodyEncoders[mediaType]
-	if !ok {
-		return nil, &ParseError{
-			Kind:   KindUnsupportedFormat,
-			Reason: fmt.Sprintf("%s %q", prefixUnsupportedCT, mediaType),
-		}
+	if encoder := RegisteredBodyEncoder(mediaType); encoder != nil {
+		return encoder(body)
+	}
+	return nil, &ParseError{
+		Kind:   KindUnsupportedFormat,
+		Reason: fmt.Sprintf("%s %q", prefixUnsupportedCT, mediaType),
 	}
-	return encoder(body)
 }
 
+// BodyEncoder really is an (encoding/json).Marshaler
 type BodyEncoder func(body interface{}) ([]byte, error)
 
+var bodyEncodersM sync.RWMutex
 var bodyEncoders = map[string]BodyEncoder{
 	"application/json": json.Marshal,
 }
 
+// RegisterBodyEncoder enables package-wide decoding of contentType values
 func RegisterBodyEncoder(contentType string, encoder BodyEncoder) {
 	if contentType == "" {
 		panic("contentType is empty")
 	}
 	if encoder == nil {
 		panic("encoder is not defined")
 	}
+	bodyEncodersM.Lock()
 	bodyEncoders[contentType] = encoder
+	bodyEncodersM.Unlock()
 }
 
-// This call is not thread-safe: body encoders should not be created/destroyed by multiple goroutines.
+// UnregisterBodyEncoder disables package-wide decoding of contentType values
 func UnregisterBodyEncoder(contentType string) {
 	if contentType == "" {
 		panic("contentType is empty")
 	}
+	bodyEncodersM.Lock()
 	delete(bodyEncoders, contentType)
+	bodyEncodersM.Unlock()
 }
 
 // RegisteredBodyEncoder returns the registered body encoder for the given content type.
 //
 // If no encoder was registered for the given content type, nil is returned.
-// This call is not thread-safe: body encoders should not be created/destroyed by multiple goroutines.
 func RegisteredBodyEncoder(contentType string) BodyEncoder {
-	return bodyEncoders[contentType]
+	bodyEncodersM.RLock()
+	mayBE := bodyEncoders[contentType]
+	bodyEncodersM.RUnlock()
+	return mayBE
 }