mirror of
https://github.com/octoleo/syncthing.git
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282 lines
6.8 KiB
Go
282 lines
6.8 KiB
Go
// Copyright 2016 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// +build darwin dragonfly freebsd netbsd openbsd
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package route
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import "runtime"
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// An Addr represents an address associated with packet routing.
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type Addr interface {
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// Family returns an address family.
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Family() int
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}
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// A LinkAddr represents a link-layer address.
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type LinkAddr struct {
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Index int // interface index when attached
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Name string // interface name when attached
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Addr []byte // link-layer address when attached
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}
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// Family implements the Family method of Addr interface.
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func (a *LinkAddr) Family() int { return sysAF_LINK }
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func parseLinkAddr(b []byte) (Addr, error) {
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if len(b) < 8 {
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return nil, errInvalidAddr
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}
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_, a, err := parseKernelLinkAddr(sysAF_LINK, b[4:])
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if err != nil {
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return nil, err
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}
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a.(*LinkAddr).Index = int(nativeEndian.Uint16(b[2:4]))
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return a, nil
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}
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// parseKernelLinkAddr parses b as a link-layer address in
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// conventional BSD kernel form.
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func parseKernelLinkAddr(_ int, b []byte) (int, Addr, error) {
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// The encoding looks like the following:
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// +----------------------------+
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// | Type (1 octet) |
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// +----------------------------+
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// | Name length (1 octet) |
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// +----------------------------+
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// | Address length (1 octet) |
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// +----------------------------+
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// | Selector length (1 octet) |
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// +----------------------------+
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// | Data (variable) |
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// +----------------------------+
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//
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// On some platforms, all-bit-one of length field means "don't
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// care".
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nlen, alen, slen := int(b[1]), int(b[2]), int(b[3])
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if nlen == 0xff {
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nlen = 0
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}
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if alen == 0xff {
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alen = 0
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}
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if slen == 0xff {
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slen = 0
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}
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l := 4 + nlen + alen + slen
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if len(b) < l {
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return 0, nil, errInvalidAddr
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}
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data := b[4:]
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var name string
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var addr []byte
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if nlen > 0 {
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name = string(data[:nlen])
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data = data[nlen:]
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}
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if alen > 0 {
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addr = data[:alen]
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data = data[alen:]
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}
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return l, &LinkAddr{Name: name, Addr: addr}, nil
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}
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// An Inet4Addr represents an internet address for IPv4.
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type Inet4Addr struct {
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IP [4]byte // IP address
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}
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// Family implements the Family method of Addr interface.
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func (a *Inet4Addr) Family() int { return sysAF_INET }
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// An Inet6Addr represents an internet address for IPv6.
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type Inet6Addr struct {
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IP [16]byte // IP address
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ZoneID int // zone identifier
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}
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// Family implements the Family method of Addr interface.
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func (a *Inet6Addr) Family() int { return sysAF_INET6 }
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// parseInetAddr parses b as an internet address for IPv4 or IPv6.
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func parseInetAddr(af int, b []byte) (Addr, error) {
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switch af {
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case sysAF_INET:
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if len(b) < 16 {
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return nil, errInvalidAddr
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}
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a := &Inet4Addr{}
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copy(a.IP[:], b[4:8])
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return a, nil
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case sysAF_INET6:
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if len(b) < 28 {
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return nil, errInvalidAddr
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}
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a := &Inet6Addr{ZoneID: int(nativeEndian.Uint32(b[24:28]))}
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copy(a.IP[:], b[8:24])
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if a.IP[0] == 0xfe && a.IP[1]&0xc0 == 0x80 || a.IP[0] == 0xff && (a.IP[1]&0x0f == 0x01 || a.IP[1]&0x0f == 0x02) {
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// KAME based IPv6 protocol stack usually
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// embeds the interface index in the
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// interface-local or link-local address as
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// the kernel-internal form.
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id := int(bigEndian.Uint16(a.IP[2:4]))
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if id != 0 {
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a.ZoneID = id
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a.IP[2], a.IP[3] = 0, 0
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}
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}
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return a, nil
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default:
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return nil, errInvalidAddr
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}
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}
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// parseKernelInetAddr parses b as an internet address in conventional
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// BSD kernel form.
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func parseKernelInetAddr(af int, b []byte) (int, Addr, error) {
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// The encoding looks similar to the NLRI encoding.
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// +----------------------------+
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// | Length (1 octet) |
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// +----------------------------+
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// | Address prefix (variable) |
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// +----------------------------+
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//
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// The differences between the kernel form and the NLRI
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// encoding are:
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//
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// - The length field of the kernel form indicates the prefix
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// length in bytes, not in bits
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//
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// - In the kernel form, zero value of the length field
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// doesn't mean 0.0.0.0/0 or ::/0
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//
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// - The kernel form appends leading bytes to the prefix field
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// to make the <length, prefix> tuple to be conformed with
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// the routing message boundary
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l := int(b[0])
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if runtime.GOOS == "darwin" {
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// On Darwn, an address in the kernel form is also
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// used as a message filler.
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if l == 0 || len(b) > roundup(l) {
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l = roundup(l)
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}
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} else {
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l = roundup(l)
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}
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if len(b) < l {
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return 0, nil, errInvalidAddr
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}
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// Don't reorder case expressions.
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// The case expressions for IPv6 must come first.
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const (
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off4 = 4 // offset of in_addr
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off6 = 8 // offset of in6_addr
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)
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switch {
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case b[0] == 28: // size of sockaddr_in6
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a := &Inet6Addr{}
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copy(a.IP[:], b[off6:off6+16])
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return int(b[0]), a, nil
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case af == sysAF_INET6:
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a := &Inet6Addr{}
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if l-1 < off6 {
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copy(a.IP[:], b[1:l])
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} else {
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copy(a.IP[:], b[l-off6:l])
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}
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return int(b[0]), a, nil
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case b[0] == 16: // size of sockaddr_in
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a := &Inet4Addr{}
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copy(a.IP[:], b[off4:off4+4])
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return int(b[0]), a, nil
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default: // an old fashion, AF_UNSPEC or unknown means AF_INET
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a := &Inet4Addr{}
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if l-1 < off4 {
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copy(a.IP[:], b[1:l])
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} else {
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copy(a.IP[:], b[l-off4:l])
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}
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return int(b[0]), a, nil
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}
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}
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// A DefaultAddr represents an address of various operating
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// system-specific features.
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type DefaultAddr struct {
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af int
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Raw []byte // raw format of address
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}
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// Family implements the Family method of Addr interface.
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func (a *DefaultAddr) Family() int { return a.af }
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func parseDefaultAddr(b []byte) (Addr, error) {
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if len(b) < 2 || len(b) < int(b[0]) {
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return nil, errInvalidAddr
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}
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a := &DefaultAddr{af: int(b[1]), Raw: b[:b[0]]}
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return a, nil
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}
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func parseAddrs(attrs uint, fn func(int, []byte) (int, Addr, error), b []byte) ([]Addr, error) {
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var as [sysRTAX_MAX]Addr
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af := int(sysAF_UNSPEC)
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for i := uint(0); i < sysRTAX_MAX && len(b) >= roundup(0); i++ {
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if attrs&(1<<i) == 0 {
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continue
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}
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if i <= sysRTAX_BRD {
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switch b[1] {
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case sysAF_LINK:
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a, err := parseLinkAddr(b)
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if err != nil {
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return nil, err
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}
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as[i] = a
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l := roundup(int(b[0]))
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if len(b) < l {
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return nil, errMessageTooShort
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}
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b = b[l:]
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case sysAF_INET, sysAF_INET6:
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af = int(b[1])
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a, err := parseInetAddr(af, b)
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if err != nil {
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return nil, err
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}
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as[i] = a
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l := roundup(int(b[0]))
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if len(b) < l {
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return nil, errMessageTooShort
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}
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b = b[l:]
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default:
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l, a, err := fn(af, b)
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if err != nil {
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return nil, err
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}
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as[i] = a
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ll := roundup(l)
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if len(b) < ll {
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b = b[l:]
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} else {
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b = b[ll:]
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}
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}
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} else {
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a, err := parseDefaultAddr(b)
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if err != nil {
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return nil, err
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}
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as[i] = a
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l := roundup(int(b[0]))
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if len(b) < l {
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return nil, errMessageTooShort
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}
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b = b[l:]
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}
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}
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return as[:], nil
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}
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