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// +build !confonly
package dns
import (
"context"
"io"
"sync"
"golang.org/x/net/dns/dnsmessage"
"v2ray.com/core"
"v2ray.com/core/common"
"v2ray.com/core/common/buf"
"v2ray.com/core/common/net"
dns_proto "v2ray.com/core/common/protocol/dns"
"v2ray.com/core/common/session"
"v2ray.com/core/common/task"
"v2ray.com/core/features/dns"
"v2ray.com/core/transport"
"v2ray.com/core/transport/internet"
)
func init() {
common.Must(common.RegisterConfig((*Config)(nil), func(ctx context.Context, config interface{}) (interface{}, error) {
h := new(Handler)
if err := core.RequireFeatures(ctx, func(dnsClient dns.Client) error {
return h.Init(config.(*Config), dnsClient)
}); err != nil {
return nil, err
}
return h, nil
}))
}
type ownLinkVerifier interface {
IsOwnLink(ctx context.Context) bool
}
type Handler struct {
ipv4Lookup dns.IPv4Lookup
ipv6Lookup dns.IPv6Lookup
ownLinkVerifier ownLinkVerifier
server net.Destination
}
func (h *Handler) Init(config *Config, dnsClient dns.Client) error {
ipv4lookup, ok := dnsClient.(dns.IPv4Lookup)
if !ok {
return newError("dns.Client doesn't implement IPv4Lookup")
}
h.ipv4Lookup = ipv4lookup
ipv6lookup, ok := dnsClient.(dns.IPv6Lookup)
if !ok {
return newError("dns.Client doesn't implement IPv6Lookup")
}
h.ipv6Lookup = ipv6lookup
if v, ok := dnsClient.(ownLinkVerifier); ok {
h.ownLinkVerifier = v
}
if config.Server != nil {
h.server = config.Server.AsDestination()
}
return nil
}
func (h *Handler) isOwnLink(ctx context.Context) bool {
return h.ownLinkVerifier != nil && h.ownLinkVerifier.IsOwnLink(ctx)
}
func parseIPQuery(b []byte) (r bool, domain string, id uint16, qType dnsmessage.Type) {
var parser dnsmessage.Parser
header, err := parser.Start(b)
if err != nil {
newError("parser start").Base(err).WriteToLog()
return
}
id = header.ID
q, err := parser.Question()
if err != nil {
newError("question").Base(err).WriteToLog()
return
}
qType = q.Type
if qType != dnsmessage.TypeA && qType != dnsmessage.TypeAAAA {
return
}
domain = q.Name.String()
r = true
return
}
// Process implements proxy.Outbound.
func (h *Handler) Process(ctx context.Context, link *transport.Link, d internet.Dialer) error {
outbound := session.OutboundFromContext(ctx)
if outbound == nil || !outbound.Target.IsValid() {
return newError("invalid outbound")
}
srcNetwork := outbound.Target.Network
dest := outbound.Target
if h.server.Network != net.Network_Unknown {
dest.Network = h.server.Network
}
if h.server.Address != nil {
dest.Address = h.server.Address
}
if h.server.Port != 0 {
dest.Port = h.server.Port
}
newError("handling DNS traffic to ", dest).WriteToLog(session.ExportIDToError(ctx))
conn := &outboundConn{
dialer: func() (internet.Connection, error) {
return d.Dial(ctx, dest)
},
connReady: make(chan struct{}, 1),
}
var reader dns_proto.MessageReader
var writer dns_proto.MessageWriter
if srcNetwork == net.Network_TCP {
reader = dns_proto.NewTCPReader(link.Reader)
writer = &dns_proto.TCPWriter{
Writer: link.Writer,
}
} else {
reader = &dns_proto.UDPReader{
Reader: link.Reader,
}
writer = &dns_proto.UDPWriter{
Writer: link.Writer,
}
}
var connReader dns_proto.MessageReader
var connWriter dns_proto.MessageWriter
if dest.Network == net.Network_TCP {
connReader = dns_proto.NewTCPReader(buf.NewReader(conn))
connWriter = &dns_proto.TCPWriter{
Writer: buf.NewWriter(conn),
}
} else {
connReader = &dns_proto.UDPReader{
Reader: buf.NewPacketReader(conn),
}
connWriter = &dns_proto.UDPWriter{
Writer: buf.NewWriter(conn),
}
}
request := func() error {
defer conn.Close()
for {
b, err := reader.ReadMessage()
if err == io.EOF {
return nil
}
if err != nil {
return err
}
if !h.isOwnLink(ctx) {
isIPQuery, domain, id, qType := parseIPQuery(b.Bytes())
if isIPQuery {
go h.handleIPQuery(id, qType, domain, writer)
continue
}
}
if err := connWriter.WriteMessage(b); err != nil {
return err
}
}
}
response := func() error {
for {
b, err := connReader.ReadMessage()
if err == io.EOF {
return nil
}
if err != nil {
return err
}
if err := writer.WriteMessage(b); err != nil {
return err
}
}
}
if err := task.Run(ctx, request, response); err != nil {
return newError("connection ends").Base(err)
}
return nil
}
func (h *Handler) handleIPQuery(id uint16, qType dnsmessage.Type, domain string, writer dns_proto.MessageWriter) {
var ips []net.IP
var err error
switch qType {
case dnsmessage.TypeA:
ips, err = h.ipv4Lookup.LookupIPv4(domain)
case dnsmessage.TypeAAAA:
ips, err = h.ipv6Lookup.LookupIPv6(domain)
}
rcode := dns.RCodeFromError(err)
if rcode == 0 && len(ips) == 0 && err != dns.ErrEmptyResponse {
newError("ip query").Base(err).WriteToLog()
return
}
b := buf.New()
rawBytes := b.Extend(buf.Size)
builder := dnsmessage.NewBuilder(rawBytes[:0], dnsmessage.Header{
ID: id,
RCode: dnsmessage.RCode(rcode),
RecursionAvailable: true,
RecursionDesired: true,
Response: true,
Authoritative: true,
})
builder.EnableCompression()
common.Must(builder.StartQuestions())
common.Must(builder.Question(dnsmessage.Question{
Name: dnsmessage.MustNewName(domain),
Class: dnsmessage.ClassINET,
Type: qType,
}))
common.Must(builder.StartAnswers())
rHeader := dnsmessage.ResourceHeader{Name: dnsmessage.MustNewName(domain), Class: dnsmessage.ClassINET, TTL: 600}
for _, ip := range ips {
if len(ip) == net.IPv4len {
var r dnsmessage.AResource
copy(r.A[:], ip)
common.Must(builder.AResource(rHeader, r))
} else {
var r dnsmessage.AAAAResource
copy(r.AAAA[:], ip)
common.Must(builder.AAAAResource(rHeader, r))
}
}
msgBytes, err := builder.Finish()
if err != nil {
newError("pack message").Base(err).WriteToLog()
b.Release()
return
}
b.Resize(0, int32(len(msgBytes)))
if err := writer.WriteMessage(b); err != nil {
newError("write IP answer").Base(err).WriteToLog()
}
}
type outboundConn struct {
access sync.Mutex
dialer func() (internet.Connection, error)
conn net.Conn
connReady chan struct{}
}
func (c *outboundConn) dial() error {
conn, err := c.dialer()
if err != nil {
return err
}
c.conn = conn
c.connReady <- struct{}{}
return nil
}
func (c *outboundConn) Write(b []byte) (int, error) {
c.access.Lock()
if c.conn == nil {
if err := c.dial(); err != nil {
c.access.Unlock()
newError("failed to dial outbound connection").Base(err).AtWarning().WriteToLog()
return len(b), nil
}
}
c.access.Unlock()
return c.conn.Write(b)
}
func (c *outboundConn) Read(b []byte) (int, error) {
var conn net.Conn
c.access.Lock()
conn = c.conn
c.access.Unlock()
if conn == nil {
_, open := <-c.connReady
if !open {
return 0, io.EOF
}
conn = c.conn
}
return conn.Read(b)
}
func (c *outboundConn) Close() error {
c.access.Lock()
close(c.connReady)
if c.conn != nil {
c.conn.Close()
}
c.access.Unlock()
return nil
}
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