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// Copyright 2010 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.
// (Raw) IP sockets
package net
import (
"os"
"sync"
"syscall"
)
var onceReadProtocols sync.Once
func sockaddrToIP(sa syscall.Sockaddr) Addr {
switch sa := sa.(type) {
case *syscall.SockaddrInet4:
return &IPAddr{sa.Addr[0:]}
case *syscall.SockaddrInet6:
return &IPAddr{sa.Addr[0:]}
}
return nil
}
// IPAddr represents the address of a IP end point.
type IPAddr struct {
IP IP
}
// Network returns the address's network name, "ip".
func (a *IPAddr) Network() string { return "ip" }
func (a *IPAddr) String() string {
if a == nil {
return "<nil>"
}
return a.IP.String()
}
func (a *IPAddr) family() int {
if a == nil || len(a.IP) <= 4 {
return syscall.AF_INET
}
if a.IP.To4() != nil {
return syscall.AF_INET
}
return syscall.AF_INET6
}
func (a *IPAddr) sockaddr(family int) (syscall.Sockaddr, os.Error) {
return ipToSockaddr(family, a.IP, 0)
}
func (a *IPAddr) toAddr() sockaddr {
if a == nil { // nil *IPAddr
return nil // nil interface
}
return a
}
// ResolveIPAddr parses addr as a IP address and resolves domain
// names to numeric addresses on the network net, which must be
// "ip", "ip4" or "ip6". A literal IPv6 host address must be
// enclosed in square brackets, as in "[::]".
func ResolveIPAddr(net, addr string) (*IPAddr, os.Error) {
ip, err := hostToIP(net, addr)
if err != nil {
return nil, err
}
return &IPAddr{ip}, nil
}
// IPConn is the implementation of the Conn and PacketConn
// interfaces for IP network connections.
type IPConn struct {
fd *netFD
}
func newIPConn(fd *netFD) *IPConn { return &IPConn{fd} }
func (c *IPConn) ok() bool { return c != nil && c.fd != nil }
// Implementation of the Conn interface - see Conn for documentation.
// Read implements the net.Conn Read method.
func (c *IPConn) Read(b []byte) (n int, err os.Error) {
n, _, err = c.ReadFrom(b)
return
}
// Write implements the net.Conn Write method.
func (c *IPConn) Write(b []byte) (n int, err os.Error) {
if !c.ok() {
return 0, os.EINVAL
}
return c.fd.Write(b)
}
// Close closes the IP connection.
func (c *IPConn) Close() os.Error {
if !c.ok() {
return os.EINVAL
}
err := c.fd.Close()
c.fd = nil
return err
}
// LocalAddr returns the local network address.
func (c *IPConn) LocalAddr() Addr {
if !c.ok() {
return nil
}
return c.fd.laddr
}
// RemoteAddr returns the remote network address, a *IPAddr.
func (c *IPConn) RemoteAddr() Addr {
if !c.ok() {
return nil
}
return c.fd.raddr
}
// SetTimeout implements the net.Conn SetTimeout method.
func (c *IPConn) SetTimeout(nsec int64) os.Error {
if !c.ok() {
return os.EINVAL
}
return setTimeout(c.fd, nsec)
}
// SetReadTimeout implements the net.Conn SetReadTimeout method.
func (c *IPConn) SetReadTimeout(nsec int64) os.Error {
if !c.ok() {
return os.EINVAL
}
return setReadTimeout(c.fd, nsec)
}
// SetWriteTimeout implements the net.Conn SetWriteTimeout method.
func (c *IPConn) SetWriteTimeout(nsec int64) os.Error {
if !c.ok() {
return os.EINVAL
}
return setWriteTimeout(c.fd, nsec)
}
// SetReadBuffer sets the size of the operating system's
// receive buffer associated with the connection.
func (c *IPConn) SetReadBuffer(bytes int) os.Error {
if !c.ok() {
return os.EINVAL
}
return setReadBuffer(c.fd, bytes)
}
// SetWriteBuffer sets the size of the operating system's
// transmit buffer associated with the connection.
func (c *IPConn) SetWriteBuffer(bytes int) os.Error {
if !c.ok() {
return os.EINVAL
}
return setWriteBuffer(c.fd, bytes)
}
// IP-specific methods.
// ReadFromIP reads a IP packet from c, copying the payload into b.
// It returns the number of bytes copied into b and the return address
// that was on the packet.
//
// ReadFromIP can be made to time out and return an error with
// Timeout() == true after a fixed time limit; see SetTimeout and
// SetReadTimeout.
func (c *IPConn) ReadFromIP(b []byte) (n int, addr *IPAddr, err os.Error) {
if !c.ok() {
return 0, nil, os.EINVAL
}
// TODO(cw,rsc): consider using readv if we know the family
// type to avoid the header trim/copy
n, sa, err := c.fd.ReadFrom(b)
switch sa := sa.(type) {
case *syscall.SockaddrInet4:
addr = &IPAddr{sa.Addr[0:]}
if len(b) >= 4 { // discard ipv4 header
hsize := (int(b[0]) & 0xf) * 4
copy(b, b[hsize:])
n -= hsize
}
case *syscall.SockaddrInet6:
addr = &IPAddr{sa.Addr[0:]}
}
return
}
// ReadFrom implements the net.PacketConn ReadFrom method.
func (c *IPConn) ReadFrom(b []byte) (n int, addr Addr, err os.Error) {
if !c.ok() {
return 0, nil, os.EINVAL
}
n, uaddr, err := c.ReadFromIP(b)
return n, uaddr.toAddr(), err
}
// WriteToIP writes a IP packet to addr via c, copying the payload from b.
//
// WriteToIP can be made to time out and return
// an error with Timeout() == true after a fixed time limit;
// see SetTimeout and SetWriteTimeout.
// On packet-oriented connections, write timeouts are rare.
func (c *IPConn) WriteToIP(b []byte, addr *IPAddr) (n int, err os.Error) {
if !c.ok() {
return 0, os.EINVAL
}
sa, err1 := addr.sockaddr(c.fd.family)
if err1 != nil {
return 0, &OpError{Op: "write", Net: "ip", Addr: addr, Error: err1}
}
return c.fd.WriteTo(b, sa)
}
// WriteTo implements the net.PacketConn WriteTo method.
func (c *IPConn) WriteTo(b []byte, addr Addr) (n int, err os.Error) {
if !c.ok() {
return 0, os.EINVAL
}
a, ok := addr.(*IPAddr)
if !ok {
return 0, &OpError{"writeto", "ip", addr, os.EINVAL}
}
return c.WriteToIP(b, a)
}
// Convert "host" into IP address.
func hostToIP(net, host string) (ip IP, err os.Error) {
var addr IP
// Try as an IP address.
addr = ParseIP(host)
if addr == nil {
filter := anyaddr
if net != "" && net[len(net)-1] == '4' {
filter = ipv4only
}
if net != "" && net[len(net)-1] == '6' {
filter = ipv6only
}
// Not an IP address. Try as a DNS name.
addrs, err1 := LookupHost(host)
if err1 != nil {
err = err1
goto Error
}
addr = firstFavoriteAddr(filter, addrs)
if addr == nil {
// should not happen
err = &AddrError{"LookupHost returned no suitable address", addrs[0]}
goto Error
}
}
return addr, nil
Error:
return nil, err
}
var protocols map[string]int
func readProtocols() {
protocols = make(map[string]int)
if file, err := open("/etc/protocols"); err == nil {
for line, ok := file.readLine(); ok; line, ok = file.readLine() {
// tcp 6 TCP # transmission control protocol
if i := byteIndex(line, '#'); i >= 0 {
line = line[0:i]
}
f := getFields(line)
if len(f) < 2 {
continue
}
if proto, _, ok := dtoi(f[1], 0); ok {
protocols[f[0]] = proto
for _, alias := range f[2:] {
protocols[alias] = proto
}
}
}
file.close()
}
}
func splitNetProto(netProto string) (net string, proto int, err os.Error) {
onceReadProtocols.Do(readProtocols)
i := last(netProto, ':')
if i < 0 { // no colon
return "", 0, os.NewError("no IP protocol specified")
}
net = netProto[0:i]
protostr := netProto[i+1:]
proto, i, ok := dtoi(protostr, 0)
if !ok || i != len(protostr) {
// lookup by name
proto, ok = protocols[protostr]
if ok {
return
}
}
return
}
// DialIP connects to the remote address raddr on the network net,
// which must be "ip", "ip4", or "ip6".
func DialIP(netProto string, laddr, raddr *IPAddr) (c *IPConn, err os.Error) {
net, proto, err := splitNetProto(netProto)
if err != nil {
return
}
switch net {
case "ip", "ip4", "ip6":
default:
return nil, UnknownNetworkError(net)
}
if raddr == nil {
return nil, &OpError{"dial", "ip", nil, errMissingAddress}
}
fd, e := internetSocket(net, laddr.toAddr(), raddr.toAddr(), syscall.SOCK_RAW, proto, "dial", sockaddrToIP)
if e != nil {
return nil, e
}
return newIPConn(fd), nil
}
// ListenIP listens for incoming IP packets addressed to the
// local address laddr. The returned connection c's ReadFrom
// and WriteTo methods can be used to receive and send IP
// packets with per-packet addressing.
func ListenIP(netProto string, laddr *IPAddr) (c *IPConn, err os.Error) {
net, proto, err := splitNetProto(netProto)
if err != nil {
return
}
switch net {
case "ip", "ip4", "ip6":
default:
return nil, UnknownNetworkError(net)
}
fd, e := internetSocket(net, laddr.toAddr(), nil, syscall.SOCK_RAW, proto, "dial", sockaddrToIP)
if e != nil {
return nil, e
}
return newIPConn(fd), nil
}
// BindToDevice binds an IPConn to a network interface.
func (c *IPConn) BindToDevice(device string) os.Error {
if !c.ok() {
return os.EINVAL
}
c.fd.incref()
defer c.fd.decref()
return os.NewSyscallError("setsockopt", syscall.BindToDevice(c.fd.sysfd, device))
}