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package main
import (
"bufio"
"bytes"
"context"
"flag"
"fmt"
"log"
"net"
"net/http"
"net/url"
"regexp"
"github.com/elazarl/goproxy"
"github.com/inconshreveable/go-vhost"
)
func orPanic(err error) {
if err != nil {
panic(err)
}
}
func main() {
verbose := flag.Bool("v", true, "should every proxy request be logged to stdout")
http_addr := flag.String("httpaddr", ":3129", "proxy http listen address")
https_addr := flag.String("httpsaddr", ":3128", "proxy https listen address")
flag.Parse()
proxy := goproxy.NewProxyHttpServer()
proxy.Verbose = *verbose
if proxy.Verbose {
log.Printf("Server starting up! - configured to listen on http interface %s and https interface %s", *http_addr, *https_addr)
}
proxy.NonproxyHandler = http.HandlerFunc(func(w http.ResponseWriter, req *http.Request) {
if req.Host == "" {
fmt.Fprintln(w, "Cannot handle requests without Host header, e.g., HTTP 1.0")
return
}
req.URL.Scheme = "http"
req.URL.Host = req.Host
proxy.ServeHTTP(w, req)
})
proxy.OnRequest(goproxy.ReqHostMatches(regexp.MustCompile("^.*$"))).
HandleConnect(goproxy.AlwaysMitm)
proxy.OnRequest(goproxy.ReqHostMatches(regexp.MustCompile("^.*:80$"))).
HijackConnect(func(req *http.Request, client net.Conn, ctx *goproxy.ProxyCtx) {
defer func() {
if e := recover(); e != nil {
ctx.Logf("error connecting to remote: %v", e)
client.Write([]byte("HTTP/1.1 500 Cannot reach destination\r\n\r\n"))
}
client.Close()
}()
clientBuf := bufio.NewReadWriter(bufio.NewReader(client), bufio.NewWriter(client))
remote, err := connectDial(req.Context(), proxy, "tcp", req.URL.Host)
orPanic(err)
remoteBuf := bufio.NewReadWriter(bufio.NewReader(remote), bufio.NewWriter(remote))
for {
req, err := http.ReadRequest(clientBuf.Reader)
orPanic(err)
orPanic(req.Write(remoteBuf))
orPanic(remoteBuf.Flush())
resp, err := http.ReadResponse(remoteBuf.Reader, req)
orPanic(err)
orPanic(resp.Write(clientBuf.Writer))
orPanic(clientBuf.Flush())
}
})
go func() {
log.Fatalln(http.ListenAndServe(*http_addr, proxy))
}()
// listen to the TLS ClientHello but make it a CONNECT request instead
ln, err := net.Listen("tcp", *https_addr)
if err != nil {
log.Fatalf("Error listening for https connections - %v", err)
}
for {
c, err := ln.Accept()
if err != nil {
log.Printf("Error accepting new connection - %v", err)
continue
}
go func(c net.Conn) {
tlsConn, err := vhost.TLS(c)
if err != nil {
log.Printf("Error accepting new connection - %v", err)
}
if tlsConn.Host() == "" {
log.Printf("Cannot support non-SNI enabled clients")
return
}
connectReq := &http.Request{
Method: "CONNECT",
URL: &url.URL{
Opaque: tlsConn.Host(),
Host: net.JoinHostPort(tlsConn.Host(), "443"),
},
Host: tlsConn.Host(),
Header: make(http.Header),
RemoteAddr: c.RemoteAddr().String(),
}
resp := dumbResponseWriter{tlsConn}
proxy.ServeHTTP(resp, connectReq)
}(c)
}
}
// copied/converted from https.go
func dial(ctx context.Context, proxy *goproxy.ProxyHttpServer, network, addr string) (c net.Conn, err error) {
if proxy.Tr.DialContext != nil {
return proxy.Tr.DialContext(ctx, network, addr)
}
var d net.Dialer
return d.DialContext(ctx, network, addr)
}
// copied/converted from https.go
func connectDial(ctx context.Context, proxy *goproxy.ProxyHttpServer, network, addr string) (c net.Conn, err error) {
if proxy.ConnectDial == nil {
return dial(ctx, proxy, network, addr)
}
return proxy.ConnectDial(network, addr)
}
type dumbResponseWriter struct {
net.Conn
}
func (dumb dumbResponseWriter) Header() http.Header {
panic("Header() should not be called on this ResponseWriter")
}
func (dumb dumbResponseWriter) Write(buf []byte) (int, error) {
if bytes.Equal(buf, []byte("HTTP/1.0 200 OK\r\n\r\n")) {
return len(buf), nil // throw away the HTTP OK response from the faux CONNECT request
}
return dumb.Conn.Write(buf)
}
func (dumb dumbResponseWriter) WriteHeader(code int) {
panic("WriteHeader() should not be called on this ResponseWriter")
}
func (dumb dumbResponseWriter) Hijack() (net.Conn, *bufio.ReadWriter, error) {
return dumb, bufio.NewReadWriter(bufio.NewReader(dumb), bufio.NewWriter(dumb)), nil
}
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