283 lines
7.5 KiB
Go
283 lines
7.5 KiB
Go
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// Copyright 2017 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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// Package socket provides a portable interface for socket system
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// calls.
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package socket // import "golang.org/x/net/internal/socket"
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import (
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"errors"
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"net"
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"unsafe"
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)
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// An Option represents a sticky socket option.
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type Option struct {
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Level int // level
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Name int // name; must be equal or greater than 1
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Len int // length of value in bytes; must be equal or greater than 1
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}
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// Get reads a value for the option from the kernel.
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// It returns the number of bytes written into b.
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func (o *Option) Get(c *Conn, b []byte) (int, error) {
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if o.Name < 1 || o.Len < 1 {
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return 0, errors.New("invalid option")
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}
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if len(b) < o.Len {
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return 0, errors.New("short buffer")
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}
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return o.get(c, b)
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}
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// GetInt returns an integer value for the option.
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//
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// The Len field of Option must be either 1 or 4.
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func (o *Option) GetInt(c *Conn) (int, error) {
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if o.Len != 1 && o.Len != 4 {
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return 0, errors.New("invalid option")
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}
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var b []byte
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var bb [4]byte
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if o.Len == 1 {
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b = bb[:1]
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} else {
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b = bb[:4]
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}
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n, err := o.get(c, b)
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if err != nil {
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return 0, err
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}
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if n != o.Len {
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return 0, errors.New("invalid option length")
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}
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if o.Len == 1 {
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return int(b[0]), nil
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}
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return int(NativeEndian.Uint32(b[:4])), nil
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}
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// Set writes the option and value to the kernel.
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func (o *Option) Set(c *Conn, b []byte) error {
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if o.Name < 1 || o.Len < 1 {
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return errors.New("invalid option")
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}
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if len(b) < o.Len {
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return errors.New("short buffer")
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}
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return o.set(c, b)
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}
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// SetInt writes the option and value to the kernel.
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//
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// The Len field of Option must be either 1 or 4.
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func (o *Option) SetInt(c *Conn, v int) error {
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if o.Len != 1 && o.Len != 4 {
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return errors.New("invalid option")
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}
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var b []byte
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if o.Len == 1 {
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b = []byte{byte(v)}
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} else {
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var bb [4]byte
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NativeEndian.PutUint32(bb[:o.Len], uint32(v))
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b = bb[:4]
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}
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return o.set(c, b)
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}
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func controlHeaderLen() int {
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return roundup(sizeofCmsghdr)
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}
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func controlMessageLen(dataLen int) int {
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return roundup(sizeofCmsghdr) + dataLen
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}
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// ControlMessageSpace returns the whole length of control message.
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func ControlMessageSpace(dataLen int) int {
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return roundup(sizeofCmsghdr) + roundup(dataLen)
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}
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// A ControlMessage represents the head message in a stream of control
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// messages.
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//
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// A control message comprises of a header, data and a few padding
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// fields to conform to the interface to the kernel.
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//
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// See RFC 3542 for further information.
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type ControlMessage []byte
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// Data returns the data field of the control message at the head on
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// w.
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func (m ControlMessage) Data(dataLen int) []byte {
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l := controlHeaderLen()
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if len(m) < l || len(m) < l+dataLen {
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return nil
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}
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return m[l : l+dataLen]
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}
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// Next returns the control message at the next on w.
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//
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// Next works only for standard control messages.
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func (m ControlMessage) Next(dataLen int) ControlMessage {
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l := ControlMessageSpace(dataLen)
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if len(m) < l {
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return nil
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}
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return m[l:]
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}
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// MarshalHeader marshals the header fields of the control message at
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// the head on w.
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func (m ControlMessage) MarshalHeader(lvl, typ, dataLen int) error {
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if len(m) < controlHeaderLen() {
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return errors.New("short message")
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}
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h := (*cmsghdr)(unsafe.Pointer(&m[0]))
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h.set(controlMessageLen(dataLen), lvl, typ)
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return nil
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}
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// ParseHeader parses and returns the header fields of the control
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// message at the head on w.
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func (m ControlMessage) ParseHeader() (lvl, typ, dataLen int, err error) {
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l := controlHeaderLen()
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if len(m) < l {
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return 0, 0, 0, errors.New("short message")
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}
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h := (*cmsghdr)(unsafe.Pointer(&m[0]))
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return h.lvl(), h.typ(), int(uint64(h.len()) - uint64(l)), nil
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}
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// Marshal marshals the control message at the head on w, and returns
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// the next control message.
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func (m ControlMessage) Marshal(lvl, typ int, data []byte) (ControlMessage, error) {
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l := len(data)
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if len(m) < ControlMessageSpace(l) {
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return nil, errors.New("short message")
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}
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h := (*cmsghdr)(unsafe.Pointer(&m[0]))
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h.set(controlMessageLen(l), lvl, typ)
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if l > 0 {
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copy(m.Data(l), data)
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}
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return m.Next(l), nil
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}
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// Parse parses w as a single or multiple control messages.
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//
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// Parse works for both standard and compatible messages.
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func (m ControlMessage) Parse() ([]ControlMessage, error) {
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var ms []ControlMessage
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for len(m) >= controlHeaderLen() {
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h := (*cmsghdr)(unsafe.Pointer(&m[0]))
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l := h.len()
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if uint64(l) < uint64(controlHeaderLen()) {
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return nil, errors.New("invalid message length")
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}
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if uint64(l) > uint64(len(m)) {
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return nil, errors.New("short buffer")
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}
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// On message reception:
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//
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// |<- ControlMessageSpace --------------->|
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// |<- controlMessageLen ---------->| |
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// |<- controlHeaderLen ->| | |
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// +---------------+------+---------+------+
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// | Header | PadH | Data | PadD |
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// +---------------+------+---------+------+
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//
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// On compatible message reception:
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//
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// | ... |<- controlMessageLen ----------->|
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// | ... |<- controlHeaderLen ->| |
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// +-----+---------------+------+----------+
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// | ... | Header | PadH | Data |
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// +-----+---------------+------+----------+
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ms = append(ms, ControlMessage(m[:l]))
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ll := l - controlHeaderLen()
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if len(m) >= ControlMessageSpace(ll) {
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m = m[ControlMessageSpace(ll):]
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} else {
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m = m[controlMessageLen(ll):]
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}
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}
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return ms, nil
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}
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// NewControlMessage returns a new stream of control messages.
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func NewControlMessage(dataLen []int) ControlMessage {
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var l int
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for i := range dataLen {
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l += ControlMessageSpace(dataLen[i])
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}
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return make([]byte, l)
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}
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// A Message represents an IO message.
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type Message struct {
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// When writing, the Buffers field must contain at least one
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// byte to write.
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// When reading, the Buffers field will always contain a byte
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// to read.
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Buffers [][]byte
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// OOB contains protocol-specific control or miscellaneous
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// ancillary data known as out-of-band data.
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OOB []byte
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// Addr specifies a destination address when writing.
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// It can be nil when the underlying protocol of the raw
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// connection uses connection-oriented communication.
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// After a successful read, it may contain the source address
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// on the received packet.
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Addr net.Addr
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N int // # of bytes read or written from/to Buffers
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NN int // # of bytes read or written from/to OOB
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Flags int // protocol-specific information on the received message
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}
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// RecvMsg wraps recvmsg system call.
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//
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// The provided flags is a set of platform-dependent flags, such as
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// syscall.MSG_PEEK.
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func (c *Conn) RecvMsg(m *Message, flags int) error {
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return c.recvMsg(m, flags)
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}
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// SendMsg wraps sendmsg system call.
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//
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// The provided flags is a set of platform-dependent flags, such as
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// syscall.MSG_DONTROUTE.
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func (c *Conn) SendMsg(m *Message, flags int) error {
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return c.sendMsg(m, flags)
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}
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// RecvMsgs wraps recvmmsg system call.
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//
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// It returns the number of processed messages.
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//
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// The provided flags is a set of platform-dependent flags, such as
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// syscall.MSG_PEEK.
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//
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// Only Linux supports this.
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func (c *Conn) RecvMsgs(ms []Message, flags int) (int, error) {
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return c.recvMsgs(ms, flags)
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}
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// SendMsgs wraps sendmmsg system call.
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//
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// It returns the number of processed messages.
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//
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// The provided flags is a set of platform-dependent flags, such as
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// syscall.MSG_DONTROUTE.
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//
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// Only Linux supports this.
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func (c *Conn) SendMsgs(ms []Message, flags int) (int, error) {
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return c.sendMsgs(ms, flags)
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}
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