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Support TCP connection to the backend

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This commit is contained in:
Frank Denis 2018-01-09 19:47:24 +01:00
parent 888db6a8fb
commit 1a59d93192
2 changed files with 85 additions and 32 deletions
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35
dnscrypt-proxy/common.go
View file

@ -1,6 +1,9 @@
package main
import (
"encoding/binary"
"errors"
"net"
"time"
)
@ -28,6 +31,38 @@ func HasTCFlag(packet []byte) bool {
return packet[2]&2 == 2
}
func PrefixWithSize(packet []byte) ([]byte, error) {
packet_len := len(packet)
if packet_len > 0xffff {
return packet, errors.New("Packet too large")
}
packet = append(append(packet, 0), 0)
copy(packet[2:], packet[:len(packet)-2])
binary.BigEndian.PutUint16(packet[0:2], uint16(len(packet)-2))
return packet, nil
}
func ReadPrefixed(conn *net.TCPConn) ([]byte, error) {
buf := make([]byte, 2+MaxDNSPacketSize)
packetLength, pos := -1, 0
for {
readnb, err := (*conn).Read(buf[pos:])
if err != nil {
return buf, err
}
pos += readnb
if pos >= 2 && packetLength < 0 {
packetLength = int(binary.BigEndian.Uint16(buf[0:2]))
if packetLength > MaxDNSPacketSize-1 {
return buf, errors.New("Packet too large")
}
}
if pos >= 2+packetLength {
return buf[2:pos], nil
}
}
}
func Min(a, b int) int {
if a < b {
return a

82
dnscrypt-proxy/main.go
View file

@ -2,7 +2,6 @@ package main
import (
"crypto/rand"
"encoding/binary"
"fmt"
"log"
"net"
@ -68,7 +67,7 @@ func (proxy *Proxy) udpListener(listenAddr *net.UDPAddr) error {
}
packet := buffer[:length]
go func() {
proxy.processIncomingQuery(proxy.serversInfo.getOne(), packet, &clientAddr, clientPc)
proxy.processIncomingQuery(proxy.serversInfo.getOne(), "udp", packet, &clientAddr, clientPc)
}()
}
}
@ -88,53 +87,72 @@ func (proxy *Proxy) tcpListener(listenAddr *net.TCPAddr) error {
go func() {
defer clientPc.Close()
clientPc.SetDeadline(time.Now().Add(proxy.timeout))
buffer := make([]byte, 2+MaxDNSPacketSize-1)
length, err := clientPc.Read(buffer)
if err != nil {
packet, err := ReadPrefixed(clientPc.(*net.TCPConn))
if err != nil || len(packet) < MinDNSPacketSize {
return
}
innerLength := binary.BigEndian.Uint16(buffer[0:2])
if int(innerLength) > length-2 {
return
}
packet := buffer[2:length]
proxy.processIncomingQuery(proxy.serversInfo.getOne(), packet, nil, clientPc)
proxy.processIncomingQuery(proxy.serversInfo.getOne(), "tcp", packet, nil, clientPc)
}()
}
}
func (proxy *Proxy) processIncomingQuery(serverInfo *ServerInfo, packet []byte, clientAddr *net.Addr, clientPc net.Conn) {
func (proxy *Proxy) processIncomingQuery(serverInfo *ServerInfo, serverProto string, packet []byte, clientAddr *net.Addr, clientPc net.Conn) {
if len(packet) < MinDNSPacketSize {
return
}
encrypted, clientNonce, err := proxy.Encrypt(serverInfo, packet, "udp")
encrypted, clientNonce, err := proxy.Encrypt(serverInfo, packet, serverProto)
if err != nil {
return
}
pc, err := net.DialUDP("udp", nil, serverInfo.UDPAddr)
if err != nil {
return
}
pc.SetDeadline(time.Now().Add(serverInfo.Timeout))
pc.Write(encrypted)
if serverProto == "udp" {
pc, err := net.DialUDP(serverProto, nil, serverInfo.UDPAddr)
if err != nil {
return
}
pc.SetDeadline(time.Now().Add(serverInfo.Timeout))
pc.Write(encrypted)
encrypted = make([]byte, MaxDNSPacketSize)
length, err := pc.Read(encrypted)
pc.Close()
if err != nil {
return
}
encrypted = encrypted[:length]
packet, err = proxy.Decrypt(serverInfo, encrypted, clientNonce)
if err != nil {
return
encrypted = make([]byte, MaxDNSPacketSize)
length, err := pc.Read(encrypted)
pc.Close()
if err != nil {
return
}
encrypted = encrypted[:length]
packet, err = proxy.Decrypt(serverInfo, encrypted, clientNonce)
if err != nil {
return
}
} else {
pc, err := net.DialTCP(serverProto, nil, serverInfo.TCPAddr)
if err != nil {
return
}
pc.SetDeadline(time.Now().Add(serverInfo.Timeout))
encrypted, err = PrefixWithSize(encrypted)
if err != nil {
return
}
pc.Write(encrypted)
encrypted, err := ReadPrefixed(pc)
pc.Close()
if err != nil {
return
}
packet, err = proxy.Decrypt(serverInfo, encrypted, clientNonce)
if err != nil {
return
}
}
if clientAddr != nil {
clientPc.(net.PacketConn).WriteTo(packet, *clientAddr)
} else {
packet = append(append(packet, 0), 0)
copy(packet[2:], packet[:len(packet)-2])
binary.BigEndian.PutUint16(packet[0:2], uint16(len(packet)-2))
packet, err = PrefixWithSize(packet)
if err != nil {
return
}
clientPc.Write(packet)
}
if HasTCFlag(packet) {