refactor

cmd/spoof-dpi/main.go

@@ -1,12 +1,22 @@
 package main
 
 import (
-	"fmt"
+	"flag"
+	"os"
 
-	"github.com/itworksnow/SpoofDPI/hello"
+	"github.com/xvzc/SpoofDPI/proxy"
 )
 
 func main() {
-    fmt.Print("hello")
-    hello.SayHello()
+    src := flag.String("src", "localhost:8080", "source-ip:source-port")
+    dns := flag.String("dns", "8.8.8.8", "DNS server")
+    debug := flag.Bool("debug", false, "true | false")
+    mtu := flag.Int("mtu", 100, "int")
+
+    err := proxy.InitConfig(*src, *dns, *mtu, *debug)
+    if err != nil {
+        os.Exit(1)
+    }
+
+    proxy.Start()
 }

go.mod

@@ -1,3 +1,5 @@
-module SpoofDPI
+module github.com/xvzc/SpoofDPI
 
 go 1.17
+
+require github.com/babolivier/go-doh-client v0.0.0-20201028162107-a76cff4cb8b6

go.sum

@@ -0,0 +1,2 @@
+github.com/babolivier/go-doh-client v0.0.0-20201028162107-a76cff4cb8b6 h1:4NNbNM2Iq/k57qEu7WfL67UrbPq1uFWxW4qODCohi+0=
+github.com/babolivier/go-doh-client v0.0.0-20201028162107-a76cff4cb8b6/go.mod h1:J29hk+f9lJrblVIfiJOtTFk+OblBawmib4uz/VdKzlg=

hello/hello.go

@@ -1,9 +0,0 @@
-package hello
-
-import (
-    "fmt"
-)
-
-func SayHello() {
-    fmt.Print("from module hello: Hello")
-}

proxy/config.go

@@ -0,0 +1,69 @@
+package proxy
+
+import (
+	"errors"
+	"log"
+	"strings"
+    "fmt"
+    "sync"
+)
+
+type Config struct {
+    SrcIp string
+    SrcPort string
+    DNS string
+    MTU int
+    Debug bool
+}
+
+var config *Config
+var once sync.Once
+var err error
+
+func tokenizeAddress(srcAddress string) (string, string, error) {
+    tokens := strings.Split(srcAddress, ":")
+    if len(tokens) < 2 {
+        return "", "", errors.New("Error while parsing source address: invalid format.")
+    }
+
+    ip := tokens[0]
+    port := tokens[1]
+
+    return ip, port, nil
+}
+
+func InitConfig(srcAddress string, dns string, mtu int, debug bool) error {
+    err = nil
+
+    once.Do(func() {
+        ip, port, err := tokenizeAddress(srcAddress)
+        if err != nil {
+            log.Fatal(err)
+            return
+        }
+
+        config = &Config{
+            SrcIp : ip,
+            SrcPort : port,
+            DNS : dns,
+            MTU : mtu,
+            Debug : debug,
+        }
+    })
+
+    log.Println("source ip   : " + config.SrcIp)
+    log.Println("source port : " + config.SrcPort)
+    log.Println("dns         : " + config.DNS)
+    log.Println("mtu         : " + fmt.Sprint(config.MTU))
+    if config.Debug {
+        log.Println("debug       : true")
+    } else {
+        log.Println("debug       : false")
+    }
+
+    return err
+}
+
+func getConfig() (*Config) {
+    return config
+}

proxy/http.go

@@ -0,0 +1,45 @@
+package proxy
+
+import (
+	"fmt"
+	"log"
+	"net"
+
+	"github.com/xvzc/SpoofDPI/util"
+)
+
+func HandleHttp(clientConn net.Conn, ip string, message []byte)  {
+    remoteConn, err := net.Dial("tcp", ip+":80") // create connection to server
+    if err != nil {
+        log.Fatal(err)
+        return
+    }
+    defer remoteConn.Close()
+
+    _, write_err := remoteConn.Write(message)
+    if write_err != nil {
+        log.Fatal("failed:", write_err)
+        return
+    }
+    defer remoteConn.(*net.TCPConn).CloseWrite()
+
+    buf, err := util.ReadMessage(remoteConn)
+    if err != nil {
+        log.Fatal("failed:", err)
+        return
+    }
+
+    fmt.Println()
+    log.Println()
+    fmt.Println("##### Response from the server: ")
+    fmt.Println(string(buf))
+
+    // Write to client
+    _, write_err = clientConn.Write(buf)
+    if write_err != nil {
+        log.Fatal("failed:", write_err)
+        return
+    }
+    defer clientConn.(*net.TCPConn).CloseWrite()
+}
+

proxy/proxy.go

@@ -0,0 +1,58 @@
+package proxy
+
+import (
+	"log"
+    "fmt"
+	"net"
+	"os"
+    "github.com/xvzc/SpoofDPI/util"
+)
+
+func Start() {
+    listener, err := net.Listen("tcp", ":" + config.SrcPort)
+	if err != nil {
+        log.Fatal("Error creating listener: ", err)
+        os.Exit(1)
+	}
+
+    log.Println("Created a listener")
+
+    for {
+		clientConn, err := listener.Accept()
+		if err != nil {
+            log.Fatal("Error accepting connection: ", err)
+			continue
+		}
+
+        log.Println("Accepted a new connection.", clientConn.RemoteAddr())
+
+        go func() {
+            defer clientConn.Close()
+
+            message , err := util.ReadMessage(clientConn)
+            if err != nil {
+                return
+            }
+
+            fmt.Println()
+            log.Println()
+            fmt.Println("##### Request from client : ")
+            fmt.Println(string(message))
+
+            domain := util.ExtractDomain(&message)
+
+            ip, err := util.DnsLookupOverHttps(getConfig().DNS, domain) // Dns lookup over https
+            if err != nil {
+                return
+            }
+
+            log.Println("ip: "+ ip)
+
+            if util.ExtractMethod(&message) == "CONNECT" {
+                fmt.Println("got a HTTPS Request")
+            }else {
+                HandleHttp(clientConn, ip, message)
+            }
+        }()
+    }
+}

util/util.go

@@ -0,0 +1,92 @@
+package util
+
+import (
+    "net"
+    "log"
+    "io"
+    "strings"
+    "github.com/babolivier/go-doh-client"
+)
+
+
+func ReadMessage(conn net.Conn)([]byte, error) {
+    buf := make([]byte, 0, 4096) // big buffer
+    tmp := make([]byte, 1024)     // using small tmo buffer for demonstrating
+    for {
+        n, err := conn.Read(tmp)
+        if err != nil {
+            if err != io.EOF {
+                log.Fatal("ReadRequest error:", err)
+            }
+            return nil, err
+        }
+        buf = append(buf, tmp[:n]...)
+
+        if n < 1024 {
+            break
+        }
+    }
+
+    return buf, nil
+}
+
+func ExtractDomain(message *[]byte) (string) {
+    i := 0
+    for ; i < len(*message); i++ {
+        if (*message)[i] == '\n' {
+            i++
+            break;
+        }
+    }
+
+    for ; i < len(*message); i++ {
+        if (*message)[i] == ' ' {
+            i++
+            break;
+        }
+    }
+
+    j := i
+    for ; j < len(*message); j++ {
+        if (*message)[j] == '\n' {
+            break;
+        }
+    }
+
+    domain := strings.Split(string((*message)[i:j]), ":")[0]
+
+    return strings.TrimSpace(domain)
+}
+
+func DnsLookupOverHttps(dns string, domain string)(string, error) {
+    // Perform a A lookup on example.com
+    resolver := doh.Resolver{
+        Host:  dns, // Change this with your favourite DoH-compliant resolver.
+        Class: doh.IN,
+    }
+
+    log.Println(domain)
+    a, _, err := resolver.LookupA(domain)
+    if err != nil {
+        log.Fatal("Error looking up dns. ", err)
+        return "", err
+    }
+
+    ip := a[0].IP4 
+
+    return ip, nil
+}
+
+func ExtractMethod(message *[]byte) (string) {
+    i := 0
+    for ; i < len(*message); i++ {
+        if (*message)[i] == ' ' {
+            break;
+        }
+    }
+
+    method := strings.TrimSpace(string((*message)[:i]))
+    log.Println(method)
+
+    return strings.ToUpper(method)
+}