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// Copyright 2017 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 socket provides a portable interface for socket system
// calls.
package socket // import "golang.org/x/net/internal/socket"
import (
"errors"
"net"
"runtime"
"unsafe"
)
var errNotImplemented = errors.New("not implemented on " + runtime.GOOS + "/" + runtime.GOARCH)
// An Option represents a sticky socket option.
type Option struct {
Level int // level
Name int // name; must be equal or greater than 1
Len int // length of value in bytes; must be equal or greater than 1
}
// Get reads a value for the option from the kernel.
// It returns the number of bytes written into b.
func (o *Option) Get(c *Conn, b []byte) (int, error) {
if o.Name < 1 || o.Len < 1 {
return 0, errors.New("invalid option")
}
if len(b) < o.Len {
return 0, errors.New("short buffer")
}
return o.get(c, b)
}
// GetInt returns an integer value for the option.
//
// The Len field of Option must be either 1 or 4.
func (o *Option) GetInt(c *Conn) (int, error) {
if o.Len != 1 && o.Len != 4 {
return 0, errors.New("invalid option")
}
var b []byte
var bb [4]byte
if o.Len == 1 {
b = bb[:1]
} else {
b = bb[:4]
}
n, err := o.get(c, b)
if err != nil {
return 0, err
}
if n != o.Len {
return 0, errors.New("invalid option length")
}
if o.Len == 1 {
return int(b[0]), nil
}
return int(NativeEndian.Uint32(b[:4])), nil
}
// Set writes the option and value to the kernel.
func (o *Option) Set(c *Conn, b []byte) error {
if o.Name < 1 || o.Len < 1 {
return errors.New("invalid option")
}
if len(b) < o.Len {
return errors.New("short buffer")
}
return o.set(c, b)
}
// SetInt writes the option and value to the kernel.
//
// The Len field of Option must be either 1 or 4.
func (o *Option) SetInt(c *Conn, v int) error {
if o.Len != 1 && o.Len != 4 {
return errors.New("invalid option")
}
var b []byte
if o.Len == 1 {
b = []byte{byte(v)}
} else {
var bb [4]byte
NativeEndian.PutUint32(bb[:o.Len], uint32(v))
b = bb[:4]
}
return o.set(c, b)
}
func controlHeaderLen() int {
return roundup(sizeofCmsghdr)
}
func controlMessageLen(dataLen int) int {
return roundup(sizeofCmsghdr) + dataLen
}
// ControlMessageSpace returns the whole length of control message.
func ControlMessageSpace(dataLen int) int {
return roundup(sizeofCmsghdr) + roundup(dataLen)
}
// A ControlMessage represents the head message in a stream of control
// messages.
//
// A control message comprises of a header, data and a few padding
// fields to conform to the interface to the kernel.
//
// See RFC 3542 for further information.
type ControlMessage []byte
// Data returns the data field of the control message at the head on
// m.
func (m ControlMessage) Data(dataLen int) []byte {
l := controlHeaderLen()
if len(m) < l || len(m) < l+dataLen {
return nil
}
return m[l : l+dataLen]
}
// Next returns the control message at the next on m.
//
// Next works only for standard control messages.
func (m ControlMessage) Next(dataLen int) ControlMessage {
l := ControlMessageSpace(dataLen)
if len(m) < l {
return nil
}
return m[l:]
}
// MarshalHeader marshals the header fields of the control message at
// the head on m.
func (m ControlMessage) MarshalHeader(lvl, typ, dataLen int) error {
if len(m) < controlHeaderLen() {
return errors.New("short message")
}
h := (*cmsghdr)(unsafe.Pointer(&m[0]))
h.set(controlMessageLen(dataLen), lvl, typ)
return nil
}
// ParseHeader parses and returns the header fields of the control
// message at the head on m.
func (m ControlMessage) ParseHeader() (lvl, typ, dataLen int, err error) {
l := controlHeaderLen()
if len(m) < l {
return 0, 0, 0, errors.New("short message")
}
h := (*cmsghdr)(unsafe.Pointer(&m[0]))
return h.lvl(), h.typ(), int(uint64(h.len()) - uint64(l)), nil
}
// Marshal marshals the control message at the head on m, and returns
// the next control message.
func (m ControlMessage) Marshal(lvl, typ int, data []byte) (ControlMessage, error) {
l := len(data)
if len(m) < ControlMessageSpace(l) {
return nil, errors.New("short message")
}
h := (*cmsghdr)(unsafe.Pointer(&m[0]))
h.set(controlMessageLen(l), lvl, typ)
if l > 0 {
copy(m.Data(l), data)
}
return m.Next(l), nil
}
// Parse parses m as a single or multiple control messages.
//
// Parse works for both standard and compatible messages.
func (m ControlMessage) Parse() ([]ControlMessage, error) {
var ms []ControlMessage
for len(m) >= controlHeaderLen() {
h := (*cmsghdr)(unsafe.Pointer(&m[0]))
l := h.len()
if l <= 0 {
return nil, errors.New("invalid header length")
}
if uint64(l) < uint64(controlHeaderLen()) {
return nil, errors.New("invalid message length")
}
if uint64(l) > uint64(len(m)) {
return nil, errors.New("short buffer")
}
// On message reception:
//
// |<- ControlMessageSpace --------------->|
// |<- controlMessageLen ---------->| |
// |<- controlHeaderLen ->| | |
// +---------------+------+---------+------+
// | Header | PadH | Data | PadD |
// +---------------+------+---------+------+
//
// On compatible message reception:
//
// | ... |<- controlMessageLen ----------->|
// | ... |<- controlHeaderLen ->| |
// +-----+---------------+------+----------+
// | ... | Header | PadH | Data |
// +-----+---------------+------+----------+
ms = append(ms, ControlMessage(m[:l]))
ll := l - controlHeaderLen()
if len(m) >= ControlMessageSpace(ll) {
m = m[ControlMessageSpace(ll):]
} else {
m = m[controlMessageLen(ll):]
}
}
return ms, nil
}
// NewControlMessage returns a new stream of control messages.
func NewControlMessage(dataLen []int) ControlMessage {
var l int
for i := range dataLen {
l += ControlMessageSpace(dataLen[i])
}
return make([]byte, l)
}
// A Message represents an IO message.
type Message struct {
// When writing, the Buffers field must contain at least one
// byte to write.
// When reading, the Buffers field will always contain a byte
// to read.
Buffers [][]byte
// OOB contains protocol-specific control or miscellaneous
// ancillary data known as out-of-band data.
OOB []byte
// Addr specifies a destination address when writing.
// It can be nil when the underlying protocol of the raw
// connection uses connection-oriented communication.
// After a successful read, it may contain the source address
// on the received packet.
Addr net.Addr
N int // # of bytes read or written from/to Buffers
NN int // # of bytes read or written from/to OOB
Flags int // protocol-specific information on the received message
}
// RecvMsg wraps recvmsg system call.
//
// The provided flags is a set of platform-dependent flags, such as
// syscall.MSG_PEEK.
func (c *Conn) RecvMsg(m *Message, flags int) error {
return c.recvMsg(m, flags)
}
// SendMsg wraps sendmsg system call.
//
// The provided flags is a set of platform-dependent flags, such as
// syscall.MSG_DONTROUTE.
func (c *Conn) SendMsg(m *Message, flags int) error {
return c.sendMsg(m, flags)
}
// RecvMsgs wraps recvmmsg system call.
//
// It returns the number of processed messages.
//
// The provided flags is a set of platform-dependent flags, such as
// syscall.MSG_PEEK.
//
// Only Linux supports this.
func (c *Conn) RecvMsgs(ms []Message, flags int) (int, error) {
return c.recvMsgs(ms, flags)
}
// SendMsgs wraps sendmmsg system call.
//
// It returns the number of processed messages.
//
// The provided flags is a set of platform-dependent flags, such as
// syscall.MSG_DONTROUTE.
//
// Only Linux supports this.
func (c *Conn) SendMsgs(ms []Message, flags int) (int, error) {
return c.sendMsgs(ms, flags)
}