[#369] Enhanced http requests logging

Signed-off-by: Nikita Zinkevich <n.zinkevich@yadro.com>

pkg/xmlutils/xmlutils.go

@@ -0,0 +1,48 @@
+package xmlutils
+
+import (
+	"bytes"
+	"encoding/base64"
+	"encoding/xml"
+	"io"
+)
+
+type nopCloseWriter struct {
+	io.Writer
+}
+
+func (b nopCloseWriter) Close() error {
+	return nil
+}
+
+const (
+	nonXML  = "nonXML"
+	typeXML = "application/xml"
+)
+
+func DetectXML(data []byte) string {
+	token, err := xml.NewDecoder(bytes.NewReader(data)).RawToken()
+	if err != nil {
+		return nonXML
+	}
+
+	switch token.(type) {
+	case xml.StartElement, xml.ProcInst:
+		return typeXML
+	}
+	return nonXML
+}
+
+func ChooseWriter(dataType string, bodyWriter io.Writer) io.WriteCloser {
+	if dataType == typeXML {
+		return nopCloseWriter{bodyWriter}
+	}
+	return base64.NewEncoder(base64.StdEncoding, bodyWriter)
+}
+
+func ChooseReader(dataType string, bodyReader io.Reader) io.Reader {
+	if dataType == typeXML {
+		return bodyReader
+	}
+	return base64.NewDecoder(base64.StdEncoding, bodyReader)
+}