mirror of
https://github.com/Luzifer/repo-template.git
synced 2024-12-23 20:51:19 +00:00
109 lines
3 KiB
Go
109 lines
3 KiB
Go
// Copyright 2015 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
|
|
|
|
import "golang.org/x/net/internal/iana"
|
|
|
|
// multipartMessageBodyDataLen takes b as an original datagram and
|
|
// exts as extensions, and returns a required length for message body
|
|
// and a required length for a padded original datagram in wire
|
|
// format.
|
|
func multipartMessageBodyDataLen(proto int, b []byte, exts []Extension) (bodyLen, dataLen int) {
|
|
for _, ext := range exts {
|
|
bodyLen += ext.Len(proto)
|
|
}
|
|
if bodyLen > 0 {
|
|
dataLen = multipartMessageOrigDatagramLen(proto, b)
|
|
bodyLen += 4 // length of extension header
|
|
} else {
|
|
dataLen = len(b)
|
|
}
|
|
bodyLen += dataLen
|
|
return bodyLen, dataLen
|
|
}
|
|
|
|
// multipartMessageOrigDatagramLen takes b as an original datagram,
|
|
// and returns a required length for a padded orignal datagram in wire
|
|
// format.
|
|
func multipartMessageOrigDatagramLen(proto int, b []byte) int {
|
|
roundup := func(b []byte, align int) int {
|
|
// According to RFC 4884, the padded original datagram
|
|
// field must contain at least 128 octets.
|
|
if len(b) < 128 {
|
|
return 128
|
|
}
|
|
r := len(b)
|
|
return (r + align - 1) & ^(align - 1)
|
|
}
|
|
switch proto {
|
|
case iana.ProtocolICMP:
|
|
return roundup(b, 4)
|
|
case iana.ProtocolIPv6ICMP:
|
|
return roundup(b, 8)
|
|
default:
|
|
return len(b)
|
|
}
|
|
}
|
|
|
|
// marshalMultipartMessageBody takes data as an original datagram and
|
|
// exts as extesnsions, and returns a binary encoding of message body.
|
|
// It can be used for non-multipart message bodies when exts is nil.
|
|
func marshalMultipartMessageBody(proto int, data []byte, exts []Extension) ([]byte, error) {
|
|
bodyLen, dataLen := multipartMessageBodyDataLen(proto, data, exts)
|
|
b := make([]byte, 4+bodyLen)
|
|
copy(b[4:], data)
|
|
off := dataLen + 4
|
|
if len(exts) > 0 {
|
|
b[dataLen+4] = byte(extensionVersion << 4)
|
|
off += 4 // length of object header
|
|
for _, ext := range exts {
|
|
switch ext := ext.(type) {
|
|
case *MPLSLabelStack:
|
|
if err := ext.marshal(proto, b[off:]); err != nil {
|
|
return nil, err
|
|
}
|
|
off += ext.Len(proto)
|
|
case *InterfaceInfo:
|
|
attrs, l := ext.attrsAndLen(proto)
|
|
if err := ext.marshal(proto, b[off:], attrs, l); err != nil {
|
|
return nil, err
|
|
}
|
|
off += ext.Len(proto)
|
|
}
|
|
}
|
|
s := checksum(b[dataLen+4:])
|
|
b[dataLen+4+2] ^= byte(s)
|
|
b[dataLen+4+3] ^= byte(s >> 8)
|
|
switch proto {
|
|
case iana.ProtocolICMP:
|
|
b[1] = byte(dataLen / 4)
|
|
case iana.ProtocolIPv6ICMP:
|
|
b[0] = byte(dataLen / 8)
|
|
}
|
|
}
|
|
return b, nil
|
|
}
|
|
|
|
// parseMultipartMessageBody parses b as either a non-multipart
|
|
// message body or a multipart message body.
|
|
func parseMultipartMessageBody(proto int, b []byte) ([]byte, []Extension, error) {
|
|
var l int
|
|
switch proto {
|
|
case iana.ProtocolICMP:
|
|
l = 4 * int(b[1])
|
|
case iana.ProtocolIPv6ICMP:
|
|
l = 8 * int(b[0])
|
|
}
|
|
if len(b) == 4 {
|
|
return nil, nil, nil
|
|
}
|
|
exts, l, err := parseExtensions(b[4:], l)
|
|
if err != nil {
|
|
l = len(b) - 4
|
|
}
|
|
data := make([]byte, l)
|
|
copy(data, b[4:])
|
|
return data, exts, nil
|
|
}
|