mirror of
https://github.com/Luzifer/elastic_cron.git
synced 2024-12-23 10:51:21 +00:00
61 lines
1.7 KiB
Go
61 lines
1.7 KiB
Go
// Copyright 2014 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 (
|
|
"encoding/binary"
|
|
"net"
|
|
"runtime"
|
|
|
|
"golang.org/x/net/internal/socket"
|
|
"golang.org/x/net/ipv4"
|
|
)
|
|
|
|
// freebsdVersion is set in sys_freebsd.go.
|
|
// See http://www.freebsd.org/doc/en/books/porters-handbook/freebsd-versions.html.
|
|
var freebsdVersion uint32
|
|
|
|
// ParseIPv4Header parses b as an IPv4 header of ICMP error message
|
|
// invoking packet, which is contained in ICMP error message.
|
|
func ParseIPv4Header(b []byte) (*ipv4.Header, error) {
|
|
if len(b) < ipv4.HeaderLen {
|
|
return nil, errHeaderTooShort
|
|
}
|
|
hdrlen := int(b[0]&0x0f) << 2
|
|
if hdrlen > len(b) {
|
|
return nil, errBufferTooShort
|
|
}
|
|
h := &ipv4.Header{
|
|
Version: int(b[0] >> 4),
|
|
Len: hdrlen,
|
|
TOS: int(b[1]),
|
|
ID: int(binary.BigEndian.Uint16(b[4:6])),
|
|
FragOff: int(binary.BigEndian.Uint16(b[6:8])),
|
|
TTL: int(b[8]),
|
|
Protocol: int(b[9]),
|
|
Checksum: int(binary.BigEndian.Uint16(b[10:12])),
|
|
Src: net.IPv4(b[12], b[13], b[14], b[15]),
|
|
Dst: net.IPv4(b[16], b[17], b[18], b[19]),
|
|
}
|
|
switch runtime.GOOS {
|
|
case "darwin":
|
|
h.TotalLen = int(socket.NativeEndian.Uint16(b[2:4]))
|
|
case "freebsd":
|
|
if freebsdVersion >= 1000000 {
|
|
h.TotalLen = int(binary.BigEndian.Uint16(b[2:4]))
|
|
} else {
|
|
h.TotalLen = int(socket.NativeEndian.Uint16(b[2:4]))
|
|
}
|
|
default:
|
|
h.TotalLen = int(binary.BigEndian.Uint16(b[2:4]))
|
|
}
|
|
h.Flags = ipv4.HeaderFlags(h.FragOff&0xe000) >> 13
|
|
h.FragOff = h.FragOff & 0x1fff
|
|
if hdrlen-ipv4.HeaderLen > 0 {
|
|
h.Options = make([]byte, hdrlen-ipv4.HeaderLen)
|
|
copy(h.Options, b[ipv4.HeaderLen:])
|
|
}
|
|
return h, nil
|
|
}
|