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packet.go
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packet.go
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package direct
import (
"context"
"fmt"
"net/netip"
"github.com/database64128/shadowsocks-go/conn"
"github.com/database64128/shadowsocks-go/socks5"
"github.com/database64128/shadowsocks-go/zerocopy"
)
// DirectPacketClientPacker packs packets for direct connection.
//
// DirectPacketClientPacker implements the zerocopy ClientPacker interface.
type DirectPacketClientPacker struct {
// cachedDomain caches the last used domain target to avoid excessive DNS lookups.
cachedDomain string
// cachedDomainIP is the last used domain target's resolved IP address.
cachedDomainIP netip.Addr
// network controls the address family of a domain target's resolved IP address.
network string
// mtu is used in the PackInPlace method to determine whether the payload is too big.
mtu int
}
// NewDirectPacketClientPacker creates a packet packer for direct connection.
func NewDirectPacketClientPacker(network string, mtu int) *DirectPacketClientPacker {
return &DirectPacketClientPacker{
network: network,
mtu: mtu,
}
}
// ClientPackerInfo implements the zerocopy.ClientPacker ClientPackerInfo method.
func (DirectPacketClientPacker) ClientPackerInfo() zerocopy.ClientPackerInfo {
return zerocopy.ClientPackerInfo{}
}
func (p *DirectPacketClientPacker) updateDomainIPCache(ctx context.Context, targetAddr conn.Addr) error {
if p.cachedDomain != targetAddr.Domain() {
ip, err := targetAddr.ResolveIP(ctx, p.network)
if err != nil {
return err
}
p.cachedDomain = targetAddr.Domain()
p.cachedDomainIP = ip
}
return nil
}
// PackInPlace implements the zerocopy.ClientPacker PackInPlace method.
func (p *DirectPacketClientPacker) PackInPlace(ctx context.Context, b []byte, targetAddr conn.Addr, payloadStart, payloadLen int) (destAddrPort netip.AddrPort, packetStart, packetLen int, err error) {
if targetAddr.IsIP() {
destAddrPort = targetAddr.IPPort()
} else {
err = p.updateDomainIPCache(ctx, targetAddr)
if err != nil {
return
}
destAddrPort = netip.AddrPortFrom(p.cachedDomainIP, targetAddr.Port())
}
packetStart = payloadStart
packetLen = payloadLen
maxPacketLen := zerocopy.MaxPacketSizeForAddr(p.mtu, destAddrPort.Addr())
if packetLen > maxPacketLen {
err = zerocopy.ErrPayloadTooBig
}
return
}
// DirectPacketClientUnpacker unpacks packets from direct connection.
//
// DirectPacketClientUnpacker implements the zerocopy ClientUnpacker interface.
type DirectPacketClientUnpacker struct{}
// ClientUnpackerInfo implements the zerocopy.ClientUnpacker ClientUnpackerInfo method.
func (DirectPacketClientUnpacker) ClientUnpackerInfo() zerocopy.ClientUnpackerInfo {
return zerocopy.ClientUnpackerInfo{}
}
// UnpackInPlace implements the zerocopy.ClientUnpacker UnpackInPlace method.
func (DirectPacketClientUnpacker) UnpackInPlace(b []byte, packetSourceAddrPort netip.AddrPort, packetStart, packetLen int) (payloadSourceAddr netip.AddrPort, payloadStart, payloadLen int, err error) {
payloadSourceAddr = packetSourceAddrPort
payloadStart = packetStart
payloadLen = packetLen
return
}
type DirectPacketServerPackUnpacker struct {
// targetAddr is the address to which packets are forwarded by the direct server.
targetAddr conn.Addr
// targetAddrOnly controls whether to discard packets from non-target sources.
targetAddrOnly bool
}
// NewDirectPacketServerPackUnpacker creates a zerocopy.ServerPackUnpacker that forwards packets to the specified target address.
func NewDirectPacketServerPackUnpacker(targetAddr conn.Addr, targetAddrOnly bool) *DirectPacketServerPackUnpacker {
return &DirectPacketServerPackUnpacker{
targetAddr: targetAddr,
targetAddrOnly: targetAddrOnly,
}
}
// ServerPackerInfo implements the zerocopy.ServerPacker ServerPackerInfo method.
func (DirectPacketServerPackUnpacker) ServerPackerInfo() zerocopy.ServerPackerInfo {
return zerocopy.ServerPackerInfo{}
}
// PackInPlace implements the zerocopy.ServerPacker PackInPlace method.
func (p *DirectPacketServerPackUnpacker) PackInPlace(b []byte, sourceAddrPort netip.AddrPort, payloadStart, payloadLen, maxPacketLen int) (packetStart, packetLen int, err error) {
packetStart = payloadStart
packetLen = payloadLen
if packetLen > maxPacketLen {
err = zerocopy.ErrPayloadTooBig
}
if p.targetAddrOnly && !conn.AddrPortMappedEqual(sourceAddrPort, p.targetAddr.IPPort()) {
err = fmt.Errorf("dropped packet from non-target source %s", sourceAddrPort)
}
return
}
// ServerUnpackerInfo implements the zerocopy.ServerUnpacker ServerUnpackerInfo method.
func (DirectPacketServerPackUnpacker) ServerUnpackerInfo() zerocopy.ServerUnpackerInfo {
return zerocopy.ServerUnpackerInfo{}
}
// UnpackInPlace implements the zerocopy.ServerUnpacker UnpackInPlace method.
func (p *DirectPacketServerPackUnpacker) UnpackInPlace(b []byte, sourceAddrPort netip.AddrPort, packetStart, packetLen int) (targetAddr conn.Addr, payloadStart, payloadLen int, err error) {
targetAddr = p.targetAddr
payloadStart = packetStart
payloadLen = packetLen
return
}
// NewPacker implements the zerocopy.ServerUnpacker NewPacker method.
func (p *DirectPacketServerPackUnpacker) NewPacker() (zerocopy.ServerPacker, error) {
return p, nil
}
// ShadowsocksNonePacketClientMessageHeadroom is the headroom required by a Shadowsocks none client message.
var ShadowsocksNonePacketClientMessageHeadroom = zerocopy.Headroom{
Front: socks5.MaxAddrLen,
Rear: 0,
}
// ShadowsocksNonePacketServerMessageHeadroom is the headroom required by a Shadowsocks none server message.
var ShadowsocksNonePacketServerMessageHeadroom = zerocopy.Headroom{
Front: socks5.IPv6AddrLen,
Rear: 0,
}
// ShadowsocksNonePacketClientPacker implements the zerocopy ClientPacker interface.
type ShadowsocksNonePacketClientPacker struct {
// serverAddrPort is the Shadowsocks none server's IP and port.
serverAddrPort netip.AddrPort
// maxPacketSize is the maximum allowed size of a packed packet.
// The value is calculated from MTU and server address family.
maxPacketSize int
}
// NewShadowsocksNonePacketClientPacker creates a Shadowsocks none packet client packer.
func NewShadowsocksNonePacketClientPacker(serverAddrPort netip.AddrPort, maxPacketSize int) *ShadowsocksNonePacketClientPacker {
return &ShadowsocksNonePacketClientPacker{
serverAddrPort: serverAddrPort,
maxPacketSize: maxPacketSize,
}
}
// ClientPackerInfo implements the zerocopy.ClientPacker ClientPackerInfo method.
func (ShadowsocksNonePacketClientPacker) ClientPackerInfo() zerocopy.ClientPackerInfo {
return zerocopy.ClientPackerInfo{
Headroom: ShadowsocksNonePacketClientMessageHeadroom,
}
}
// PackInPlace implements the zerocopy.ClientPacker PackInPlace method.
func (p *ShadowsocksNonePacketClientPacker) PackInPlace(ctx context.Context, b []byte, targetAddr conn.Addr, payloadStart, payloadLen int) (destAddrPort netip.AddrPort, packetStart, packetLen int, err error) {
targetAddrLen := socks5.LengthOfAddrFromConnAddr(targetAddr)
destAddrPort = p.serverAddrPort
packetStart = payloadStart - targetAddrLen
packetLen = payloadLen + targetAddrLen
if packetLen > p.maxPacketSize {
err = zerocopy.ErrPayloadTooBig
}
socks5.WriteAddrFromConnAddr(b[packetStart:], targetAddr)
return
}
// ShadowsocksNonePacketClientUnpacker implements the zerocopy ClientUnpacker interface.
type ShadowsocksNonePacketClientUnpacker struct {
// serverAddrPort is the Shadowsocks none server's IP and port.
serverAddrPort netip.AddrPort
}
// NewShadowsocksNonePacketClientUnpacker creates a Shadowsocks none packet client unpacker.
func NewShadowsocksNonePacketClientUnpacker(serverAddrPort netip.AddrPort) *ShadowsocksNonePacketClientUnpacker {
return &ShadowsocksNonePacketClientUnpacker{
serverAddrPort: serverAddrPort,
}
}
// ClientUnpackerInfo implements the zerocopy.ClientUnpacker ClientUnpackerInfo method.
func (ShadowsocksNonePacketClientUnpacker) ClientUnpackerInfo() zerocopy.ClientUnpackerInfo {
return zerocopy.ClientUnpackerInfo{
Headroom: ShadowsocksNonePacketServerMessageHeadroom,
}
}
// UnpackInPlace implements the zerocopy.ClientUnpacker UnpackInPlace method.
func (p *ShadowsocksNonePacketClientUnpacker) UnpackInPlace(b []byte, packetSourceAddrPort netip.AddrPort, packetStart, packetLen int) (payloadSourceAddrPort netip.AddrPort, payloadStart, payloadLen int, err error) {
if !conn.AddrPortMappedEqual(packetSourceAddrPort, p.serverAddrPort) {
err = fmt.Errorf("dropped packet from non-server source %s", packetSourceAddrPort)
return
}
var payloadSourceAddrLen int
payloadSourceAddrPort, payloadSourceAddrLen, err = socks5.AddrPortFromSlice(b[packetStart : packetStart+packetLen])
payloadStart = packetStart + payloadSourceAddrLen
payloadLen = packetLen - payloadSourceAddrLen
return
}
// ShadowsocksNonePacketServerPacker implements the zerocopy ServerPacker interface.
type ShadowsocksNonePacketServerPacker struct{}
// ServerPackerInfo implements the zerocopy.ServerPacker ServerPackerInfo method.
func (ShadowsocksNonePacketServerPacker) ServerPackerInfo() zerocopy.ServerPackerInfo {
return zerocopy.ServerPackerInfo{
Headroom: ShadowsocksNonePacketServerMessageHeadroom,
}
}
// PackInPlace implements the zerocopy.ServerPacker PackInPlace method.
func (ShadowsocksNonePacketServerPacker) PackInPlace(b []byte, sourceAddrPort netip.AddrPort, payloadStart, payloadLen, maxPacketLen int) (packetStart, packetLen int, err error) {
targetAddrLen := socks5.LengthOfAddrFromAddrPort(sourceAddrPort)
packetStart = payloadStart - targetAddrLen
packetLen = payloadLen + targetAddrLen
if packetLen > maxPacketLen {
err = zerocopy.ErrPayloadTooBig
}
socks5.WriteAddrFromAddrPort(b[packetStart:], sourceAddrPort)
return
}
// ShadowsocksNonePacketServerUnpacker implements the zerocopy Unpacker interface.
type ShadowsocksNonePacketServerUnpacker struct {
// cachedDomain caches the last used domain target to avoid allocating new strings.
cachedDomain string
}
// ServerUnpackerInfo implements the zerocopy.ServerUnpacker ServerUnpackerInfo method.
func (ShadowsocksNonePacketServerUnpacker) ServerUnpackerInfo() zerocopy.ServerUnpackerInfo {
return zerocopy.ServerUnpackerInfo{
Headroom: ShadowsocksNonePacketClientMessageHeadroom,
}
}
// UnpackInPlace implements the zerocopy.ServerUnpacker UnpackInPlace method.
func (p *ShadowsocksNonePacketServerUnpacker) UnpackInPlace(b []byte, sourceAddrPort netip.AddrPort, packetStart, packetLen int) (targetAddr conn.Addr, payloadStart, payloadLen int, err error) {
var targetAddrLen int
targetAddr, targetAddrLen, p.cachedDomain, err = socks5.ConnAddrFromSliceWithDomainCache(b[packetStart:packetStart+packetLen], p.cachedDomain)
payloadStart = packetStart + targetAddrLen
payloadLen = packetLen - targetAddrLen
return
}
// NewPacker implements the zerocopy.ServerUnpacker NewPacker method.
func (ShadowsocksNonePacketServerUnpacker) NewPacker() (zerocopy.ServerPacker, error) {
return ShadowsocksNonePacketServerPacker{}, nil
}
// Socks5PacketClientMessageHeadroom is the headroom required by a SOCKS5 client message.
var Socks5PacketClientMessageHeadroom = zerocopy.Headroom{
Front: 3 + socks5.MaxAddrLen,
Rear: 0,
}
// Socks5PacketServerMessageHeadroom is the headroom required by a SOCKS5 server message.
var Socks5PacketServerMessageHeadroom = zerocopy.Headroom{
Front: 3 + socks5.IPv6AddrLen,
Rear: 0,
}
// Socks5PacketClientPacker implements the zerocopy ClientPacker interface.
type Socks5PacketClientPacker struct {
// serverAddrPort is the SOCKS5 server's IP and port.
serverAddrPort netip.AddrPort
// maxPacketSize is the maximum allowed size of a packed packet.
// The value is calculated from MTU and server address family.
maxPacketSize int
}
// NewSocks5PacketClientPacker creates a SOCKS5 packet client packer.
func NewSocks5PacketClientPacker(serverAddrPort netip.AddrPort, maxPacketSize int) *Socks5PacketClientPacker {
return &Socks5PacketClientPacker{
serverAddrPort: serverAddrPort,
maxPacketSize: maxPacketSize,
}
}
// ClientPackerInfo implements the zerocopy.ClientPacker ClientPackerInfo method.
func (Socks5PacketClientPacker) ClientPackerInfo() zerocopy.ClientPackerInfo {
return zerocopy.ClientPackerInfo{
Headroom: Socks5PacketClientMessageHeadroom,
}
}
// PackInPlace implements the zerocopy.ClientPacker PackInPlace method.
func (p *Socks5PacketClientPacker) PackInPlace(ctx context.Context, b []byte, targetAddr conn.Addr, payloadStart, payloadLen int) (destAddrPort netip.AddrPort, packetStart, packetLen int, err error) {
targetAddrLen := socks5.LengthOfAddrFromConnAddr(targetAddr)
destAddrPort = p.serverAddrPort
packetStart = payloadStart - targetAddrLen - 3
packetLen = payloadLen + targetAddrLen + 3
if packetLen > p.maxPacketSize {
err = zerocopy.ErrPayloadTooBig
}
socks5.WritePacketHeader(b[packetStart:])
socks5.WriteAddrFromConnAddr(b[packetStart+3:], targetAddr)
return
}
// Socks5PacketClientUnpacker implements the zerocopy Unpacker interface.
type Socks5PacketClientUnpacker struct {
// serverAddrPort is the SOCKS5 server's IP and port.
serverAddrPort netip.AddrPort
}
// NewSocks5PacketClientUnpacker creates a SOCKS5 packet client unpacker.
func NewSocks5PacketClientUnpacker(serverAddrPort netip.AddrPort) *Socks5PacketClientUnpacker {
return &Socks5PacketClientUnpacker{
serverAddrPort: serverAddrPort,
}
}
// ClientUnpackerInfo implements the zerocopy.ClientUnpacker ClientUnpackerInfo method.
func (Socks5PacketClientUnpacker) ClientUnpackerInfo() zerocopy.ClientUnpackerInfo {
return zerocopy.ClientUnpackerInfo{
Headroom: Socks5PacketServerMessageHeadroom,
}
}
// UnpackInPlace implements the zerocopy.ClientUnpacker UnpackInPlace method.
func (p *Socks5PacketClientUnpacker) UnpackInPlace(b []byte, packetSourceAddrPort netip.AddrPort, packetStart, packetLen int) (payloadSourceAddrPort netip.AddrPort, payloadStart, payloadLen int, err error) {
if !conn.AddrPortMappedEqual(packetSourceAddrPort, p.serverAddrPort) {
err = fmt.Errorf("dropped packet from non-server source %s", packetSourceAddrPort)
return
}
if packetLen < 3 {
err = fmt.Errorf("%w: %d", zerocopy.ErrPacketTooSmall, packetLen)
return
}
pkt := b[packetStart : packetStart+packetLen]
err = socks5.ValidatePacketHeader(pkt)
if err != nil {
return
}
var payloadSourceAddrLen int
payloadSourceAddrPort, payloadSourceAddrLen, err = socks5.AddrPortFromSlice(pkt[3:])
payloadStart = packetStart + payloadSourceAddrLen + 3
payloadLen = packetLen - payloadSourceAddrLen - 3
return
}
// Socks5PacketServerPacker implements the zerocopy ServerPacker interface.
type Socks5PacketServerPacker struct{}
// ServerPackerInfo implements the zerocopy.ServerPacker ServerPackerInfo method.
func (Socks5PacketServerPacker) ServerPackerInfo() zerocopy.ServerPackerInfo {
return zerocopy.ServerPackerInfo{
Headroom: Socks5PacketServerMessageHeadroom,
}
}
// PackInPlace implements the zerocopy.ServerPacker PackInPlace method.
func (Socks5PacketServerPacker) PackInPlace(b []byte, sourceAddrPort netip.AddrPort, payloadStart, payloadLen, maxPacketLen int) (packetStart, packetLen int, err error) {
targetAddrLen := socks5.LengthOfAddrFromAddrPort(sourceAddrPort)
packetStart = payloadStart - targetAddrLen - 3
packetLen = payloadLen + targetAddrLen + 3
if packetLen > maxPacketLen {
err = zerocopy.ErrPayloadTooBig
}
socks5.WritePacketHeader(b[packetStart:])
socks5.WriteAddrFromAddrPort(b[packetStart+3:], sourceAddrPort)
return
}
// Socks5PacketServerUnpacker implements the zerocopy Unpacker interface.
type Socks5PacketServerUnpacker struct {
// cachedDomain caches the last used domain target to avoid allocating new strings.
cachedDomain string
}
// ServerUnpackerInfo implements the zerocopy.ServerUnpacker ServerUnpackerInfo method.
func (Socks5PacketServerUnpacker) ServerUnpackerInfo() zerocopy.ServerUnpackerInfo {
return zerocopy.ServerUnpackerInfo{
Headroom: Socks5PacketClientMessageHeadroom,
}
}
// UnpackInPlace implements the zerocopy.ServerUnpacker UnpackInPlace method.
func (p *Socks5PacketServerUnpacker) UnpackInPlace(b []byte, sourceAddrPort netip.AddrPort, packetStart, packetLen int) (targetAddr conn.Addr, payloadStart, payloadLen int, err error) {
if packetLen < 3 {
err = fmt.Errorf("%w: %d", zerocopy.ErrPacketTooSmall, packetLen)
return
}
pkt := b[packetStart : packetStart+packetLen]
err = socks5.ValidatePacketHeader(pkt)
if err != nil {
return
}
var targetAddrLen int
targetAddr, targetAddrLen, p.cachedDomain, err = socks5.ConnAddrFromSliceWithDomainCache(pkt[3:], p.cachedDomain)
payloadStart = packetStart + targetAddrLen + 3
payloadLen = packetLen - targetAddrLen - 3
return
}
// NewPacker implements the zerocopy.ServerUnpacker NewPacker method.
func (Socks5PacketServerUnpacker) NewPacker() (zerocopy.ServerPacker, error) {
return Socks5PacketServerPacker{}, nil
}