Fix if more than one library replaces request.Body

httpcontext.go

@@ -3,6 +3,7 @@ package httpcontext
 import (
 	"io"
 	"net/http"
+	"reflect"
 )
 
 // Set sets a context value on req.
@@ -79,7 +80,7 @@ func (crc *contextReadCloser) Context() map[interface{}]interface{} {
 }
 
 func getContextReadCloser(req *http.Request) ContextReadCloser {
-	crc, ok := req.Body.(ContextReadCloser)
+	crc, ok := findContextReadCloser(req.Body)
 	if !ok {
 		crc = &contextReadCloser{
 			ReadCloser: req.Body,
@@ -89,3 +90,51 @@ func getContextReadCloser(req *http.Request) ContextReadCloser {
 	}
 	return crc
 }
+
+func findContextReadCloser(rc io.ReadCloser) (ContextReadCloser, bool) {
+	for {
+		if a, ok := rc.(ContextReadCloser); ok {
+			return a, true
+		}
+		rc = findNestedReadCloser(rc)
+		if rc == nil {
+			return nil, false
+		}
+	}
+}
+
+func findNestedReadCloser(rc io.ReadCloser) io.ReadCloser {
+	if s := findStruct(rc); s != nil {
+		// try a struct field called ReadCloser first
+		if maybeRC := (*s).FieldByName("ReadCloser"); (maybeRC != reflect.Value{}) && maybeRC.CanInterface() {
+			if rc, ok := maybeRC.Interface().(io.ReadCloser); ok {
+				return rc
+			}
+		}
+
+		// try all fields and see if we can find a ReadCloser
+		for i := 0; i < (*s).Type().NumField(); i++ {
+			if maybeRC := (*s).Field(i); maybeRC.CanInterface() {
+				if rc, ok := maybeRC.Interface().(io.ReadCloser); ok {
+					return rc
+				}
+			}
+		}
+	}
+	return nil
+}
+
+func findStruct(rc io.ReadCloser) *reflect.Value {
+	maybeStruct := reflect.ValueOf(rc)
+	for {
+		switch maybeStruct.Kind() {
+		case reflect.Struct:
+			return &maybeStruct
+		case reflect.Ptr:
+			maybeStruct = reflect.Indirect(maybeStruct)
+		default:
+			return nil
+		}
+	}
+}
+