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// Copyright 2009 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 net
import (
"context"
"errors"
"net/netip"
"os"
"syscall"
)
func (c *UDPConn) readFrom(b []byte, addr *UDPAddr) (int, *UDPAddr, error) {
buf := make([]byte, udpHeaderSize+len(b))
m, err := c.fd.Read(buf)
if err != nil {
return 0, nil, err
}
if m < udpHeaderSize {
return 0, nil, errors.New("short read reading UDP header")
}
buf = buf[:m]
h, buf := unmarshalUDPHeader(buf)
n := copy(b, buf)
*addr = UDPAddr{IP: h.raddr, Port: int(h.rport)}
return n, addr, nil
}
func (c *UDPConn) readFromAddrPort(b []byte) (int, netip.AddrPort, error) {
// TODO: optimize. The equivalent code on posix is alloc-free.
buf := make([]byte, udpHeaderSize+len(b))
m, err := c.fd.Read(buf)
if err != nil {
return 0, netip.AddrPort{}, err
}
if m < udpHeaderSize {
return 0, netip.AddrPort{}, errors.New("short read reading UDP header")
}
buf = buf[:m]
h, buf := unmarshalUDPHeader(buf)
n := copy(b, buf)
ip, _ := netip.AddrFromSlice(h.raddr)
addr := netip.AddrPortFrom(ip, h.rport)
return n, addr, nil
}
func (c *UDPConn) readMsg(b, oob []byte) (n, oobn, flags int, addr netip.AddrPort, err error) {
return 0, 0, 0, netip.AddrPort{}, syscall.EPLAN9
}
func (c *UDPConn) writeTo(b []byte, addr *UDPAddr) (int, error) {
if addr == nil {
return 0, errMissingAddress
}
h := new(udpHeader)
h.raddr = addr.IP.To16()
h.laddr = c.fd.laddr.(*UDPAddr).IP.To16()
h.ifcaddr = IPv6zero // ignored (receive only)
h.rport = uint16(addr.Port)
h.lport = uint16(c.fd.laddr.(*UDPAddr).Port)
buf := make([]byte, udpHeaderSize+len(b))
i := copy(buf, h.Bytes())
copy(buf[i:], b)
if _, err := c.fd.Write(buf); err != nil {
return 0, err
}
return len(b), nil
}
func (c *UDPConn) writeToAddrPort(b []byte, addr netip.AddrPort) (int, error) {
return c.writeTo(b, UDPAddrFromAddrPort(addr)) // TODO: optimize instead of allocating
}
func (c *UDPConn) writeMsg(b, oob []byte, addr *UDPAddr) (n, oobn int, err error) {
return 0, 0, syscall.EPLAN9
}
func (c *UDPConn) writeMsgAddrPort(b, oob []byte, addr netip.AddrPort) (n, oobn int, err error) {
return 0, 0, syscall.EPLAN9
}
func (sd *sysDialer) dialUDP(ctx context.Context, laddr, raddr *UDPAddr) (*UDPConn, error) {
fd, err := dialPlan9(ctx, sd.network, laddr, raddr)
if err != nil {
return nil, err
}
return newUDPConn(fd), nil
}
const udpHeaderSize = 16*3 + 2*2
type udpHeader struct {
raddr, laddr, ifcaddr IP
rport, lport uint16
}
func (h *udpHeader) Bytes() []byte {
b := make([]byte, udpHeaderSize)
i := 0
i += copy(b[i:i+16], h.raddr)
i += copy(b[i:i+16], h.laddr)
i += copy(b[i:i+16], h.ifcaddr)
b[i], b[i+1], i = byte(h.rport>>8), byte(h.rport), i+2
b[i], b[i+1], i = byte(h.lport>>8), byte(h.lport), i+2
return b
}
func unmarshalUDPHeader(b []byte) (*udpHeader, []byte) {
h := new(udpHeader)
h.raddr, b = IP(b[:16]), b[16:]
h.laddr, b = IP(b[:16]), b[16:]
h.ifcaddr, b = IP(b[:16]), b[16:]
h.rport, b = uint16(b[0])<<8|uint16(b[1]), b[2:]
h.lport, b = uint16(b[0])<<8|uint16(b[1]), b[2:]
return h, b
}
func (sl *sysListener) listenUDP(ctx context.Context, laddr *UDPAddr) (*UDPConn, error) {
l, err := listenPlan9(ctx, sl.network, laddr)
if err != nil {
return nil, err
}
_, err = l.ctl.WriteString("headers")
if err != nil {
return nil, err
}
l.data, err = os.OpenFile(l.dir+"/data", os.O_RDWR, 0)
if err != nil {
return nil, err
}
fd, err := l.netFD()
return newUDPConn(fd), err
}
func (sl *sysListener) listenMulticastUDP(ctx context.Context, ifi *Interface, gaddr *UDPAddr) (*UDPConn, error) {
// Plan 9 does not like announce command with a multicast address,
// so do not specify an IP address when listening.
l, err := listenPlan9(ctx, sl.network, &UDPAddr{IP: nil, Port: gaddr.Port, Zone: gaddr.Zone})
if err != nil {
return nil, err
}
_, err = l.ctl.WriteString("headers")
if err != nil {
return nil, err
}
var addrs []Addr
if ifi != nil {
addrs, err = ifi.Addrs()
if err != nil {
return nil, err
}
} else {
addrs, err = InterfaceAddrs()
if err != nil {
return nil, err
}
}
have4 := gaddr.IP.To4() != nil
for _, addr := range addrs {
if ipnet, ok := addr.(*IPNet); ok && (ipnet.IP.To4() != nil) == have4 {
_, err = l.ctl.WriteString("addmulti " + ipnet.IP.String() + " " + gaddr.IP.String())
if err != nil {
return nil, &OpError{Op: "addmulti", Net: "", Source: nil, Addr: ipnet, Err: err}
}
}
}
l.data, err = os.OpenFile(l.dir+"/data", os.O_RDWR, 0)
if err != nil {
return nil, err
}
fd, err := l.netFD()
if err != nil {
return nil, err
}
return newUDPConn(fd), nil
}
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