114 lines
2.8 KiB
Go
114 lines
2.8 KiB
Go
// Copyright 2009 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 net
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import (
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"context"
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"errors"
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"os"
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"syscall"
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)
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func (c *UDPConn) readFrom(b []byte) (n int, addr *UDPAddr, err error) {
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buf := make([]byte, udpHeaderSize+len(b))
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m, err := c.fd.Read(buf)
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if err != nil {
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return 0, nil, err
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}
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if m < udpHeaderSize {
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return 0, nil, errors.New("short read reading UDP header")
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}
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buf = buf[:m]
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h, buf := unmarshalUDPHeader(buf)
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n = copy(b, buf)
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return n, &UDPAddr{IP: h.raddr, Port: int(h.rport)}, nil
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}
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func (c *UDPConn) readMsg(b, oob []byte) (n, oobn, flags int, addr *UDPAddr, err error) {
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return 0, 0, 0, nil, syscall.EPLAN9
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}
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func (c *UDPConn) writeTo(b []byte, addr *UDPAddr) (int, error) {
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if addr == nil {
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return 0, errMissingAddress
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}
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h := new(udpHeader)
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h.raddr = addr.IP.To16()
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h.laddr = c.fd.laddr.(*UDPAddr).IP.To16()
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h.ifcaddr = IPv6zero // ignored (receive only)
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h.rport = uint16(addr.Port)
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h.lport = uint16(c.fd.laddr.(*UDPAddr).Port)
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buf := make([]byte, udpHeaderSize+len(b))
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i := copy(buf, h.Bytes())
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copy(buf[i:], b)
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if _, err := c.fd.Write(buf); err != nil {
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return 0, err
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}
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return len(b), nil
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}
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func (c *UDPConn) writeMsg(b, oob []byte, addr *UDPAddr) (n, oobn int, err error) {
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return 0, 0, syscall.EPLAN9
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}
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func dialUDP(ctx context.Context, net string, laddr, raddr *UDPAddr) (*UDPConn, error) {
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fd, err := dialPlan9(ctx, net, laddr, raddr)
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if err != nil {
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return nil, err
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}
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return newUDPConn(fd), nil
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}
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const udpHeaderSize = 16*3 + 2*2
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type udpHeader struct {
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raddr, laddr, ifcaddr IP
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rport, lport uint16
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}
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func (h *udpHeader) Bytes() []byte {
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b := make([]byte, udpHeaderSize)
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i := 0
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i += copy(b[i:i+16], h.raddr)
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i += copy(b[i:i+16], h.laddr)
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i += copy(b[i:i+16], h.ifcaddr)
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b[i], b[i+1], i = byte(h.rport>>8), byte(h.rport), i+2
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b[i], b[i+1], i = byte(h.lport>>8), byte(h.lport), i+2
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return b
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}
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func unmarshalUDPHeader(b []byte) (*udpHeader, []byte) {
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h := new(udpHeader)
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h.raddr, b = IP(b[:16]), b[16:]
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h.laddr, b = IP(b[:16]), b[16:]
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h.ifcaddr, b = IP(b[:16]), b[16:]
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h.rport, b = uint16(b[0])<<8|uint16(b[1]), b[2:]
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h.lport, b = uint16(b[0])<<8|uint16(b[1]), b[2:]
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return h, b
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}
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func listenUDP(ctx context.Context, network string, laddr *UDPAddr) (*UDPConn, error) {
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l, err := listenPlan9(ctx, network, laddr)
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if err != nil {
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return nil, err
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}
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_, err = l.ctl.WriteString("headers")
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if err != nil {
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return nil, err
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}
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l.data, err = os.OpenFile(l.dir+"/data", os.O_RDWR, 0)
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if err != nil {
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return nil, err
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}
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fd, err := l.netFD()
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return newUDPConn(fd), err
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}
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func listenMulticastUDP(ctx context.Context, network string, ifi *Interface, gaddr *UDPAddr) (*UDPConn, error) {
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return nil, syscall.EPLAN9
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}
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