diff --git a/unum/vendor/golang.org/x/net/icmp/messagebody.go b/unum/vendor/golang.org/x/net/icmp/messagebody.go
new file mode 100644
index 0000000..2463730
--- /dev/null
+++ b/unum/vendor/golang.org/x/net/icmp/messagebody.go
@@ -0,0 +1,41 @@
+// Copyright 2012 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package icmp
+
+// A MessageBody represents an ICMP message body.
+type MessageBody interface {
+	// Len returns the length of ICMP message body.
+	// Proto must be either the ICMPv4 or ICMPv6 protocol number.
+	Len(proto int) int
+
+	// Marshal returns the binary encoding of ICMP message body.
+	// Proto must be either the ICMPv4 or ICMPv6 protocol number.
+	Marshal(proto int) ([]byte, error)
+}
+
+// A DefaultMessageBody represents the default message body.
+type DefaultMessageBody struct {
+	Data []byte // data
+}
+
+// Len implements the Len method of MessageBody interface.
+func (p *DefaultMessageBody) Len(proto int) int {
+	if p == nil {
+		return 0
+	}
+	return len(p.Data)
+}
+
+// Marshal implements the Marshal method of MessageBody interface.
+func (p *DefaultMessageBody) Marshal(proto int) ([]byte, error) {
+	return p.Data, nil
+}
+
+// parseDefaultMessageBody parses b as an ICMP message body.
+func parseDefaultMessageBody(proto int, b []byte) (MessageBody, error) {
+	p := &DefaultMessageBody{Data: make([]byte, len(b))}
+	copy(p.Data, b)
+	return p, nil
+}