1 // Copyright 2015 The Go Authors. All rights reserved.
2 // Use of this source code is governed by a BSD-style
3 // license that can be found in the LICENSE file.
7 import "golang.org/x/net/internal/iana"
9 // multipartMessageBodyDataLen takes b as an original datagram and
10 // exts as extensions, and returns a required length for message body
11 // and a required length for a padded original datagram in wire
13 func multipartMessageBodyDataLen(proto int, b []byte, exts []Extension) (bodyLen, dataLen int) {
14 for _, ext := range exts {
15 bodyLen += ext.Len(proto)
18 dataLen = multipartMessageOrigDatagramLen(proto, b)
19 bodyLen += 4 // length of extension header
24 return bodyLen, dataLen
27 // multipartMessageOrigDatagramLen takes b as an original datagram,
28 // and returns a required length for a padded orignal datagram in wire
30 func multipartMessageOrigDatagramLen(proto int, b []byte) int {
31 roundup := func(b []byte, align int) int {
32 // According to RFC 4884, the padded original datagram
33 // field must contain at least 128 octets.
38 return (r + align - 1) & ^(align - 1)
41 case iana.ProtocolICMP:
43 case iana.ProtocolIPv6ICMP:
50 // marshalMultipartMessageBody takes data as an original datagram and
51 // exts as extesnsions, and returns a binary encoding of message body.
52 // It can be used for non-multipart message bodies when exts is nil.
53 func marshalMultipartMessageBody(proto int, data []byte, exts []Extension) ([]byte, error) {
54 bodyLen, dataLen := multipartMessageBodyDataLen(proto, data, exts)
55 b := make([]byte, 4+bodyLen)
59 b[dataLen+4] = byte(extensionVersion << 4)
60 off += 4 // length of object header
61 for _, ext := range exts {
62 switch ext := ext.(type) {
64 if err := ext.marshal(proto, b[off:]); err != nil {
69 attrs, l := ext.attrsAndLen(proto)
70 if err := ext.marshal(proto, b[off:], attrs, l); err != nil {
76 s := checksum(b[dataLen+4:])
77 b[dataLen+4+2] ^= byte(s)
78 b[dataLen+4+3] ^= byte(s >> 8)
80 case iana.ProtocolICMP:
81 b[1] = byte(dataLen / 4)
82 case iana.ProtocolIPv6ICMP:
83 b[0] = byte(dataLen / 8)
89 // parseMultipartMessageBody parses b as either a non-multipart
90 // message body or a multipart message body.
91 func parseMultipartMessageBody(proto int, b []byte) ([]byte, []Extension, error) {
94 case iana.ProtocolICMP:
96 case iana.ProtocolIPv6ICMP:
102 exts, l, err := parseExtensions(b[4:], l)
106 data := make([]byte, l)
108 return data, exts, nil