From efad96aa36a6fc4d9f492c5594ce7c49e1dbeed5 Mon Sep 17 00:00:00 2001
From: Bel LaPointe <breel@qualtrics.com>
Date: Wed, 7 Oct 2020 21:41:03 -0600
Subject: [PATCH] basic bitch

---
 config.go | 31 +++++++++++++++++++
 main.go   | 16 ++++++++++
 server.go | 89 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 136 insertions(+)
 create mode 100644 config.go
 create mode 100644 main.go
 create mode 100644 server.go

diff --git a/config.go b/config.go
new file mode 100644
index 0000000..5e21e69
--- /dev/null
+++ b/config.go
@@ -0,0 +1,31 @@
+package main
+
+import (
+	"fmt"
+	"local/args"
+	"time"
+)
+
+type Config struct {
+	Listen      string
+	Timeout     time.Duration
+	TLSInsecure bool
+}
+
+func NewConfig() *Config {
+	as := args.NewArgSet()
+
+	as.Append(args.INT, "p", "port to listen on", 61113)
+	as.Append(args.BOOL, "tls-insecure", "permit tls insecure", false)
+	as.Append(args.DURATION, "t", "timeout", time.Minute)
+
+	if err := as.Parse(); err != nil {
+		panic(err)
+	}
+
+	return &Config{
+		Listen:      fmt.Sprintf(":%v", as.GetInt("p")),
+		Timeout:     as.GetDuration("t"),
+		TLSInsecure: as.GetBool("tls-insecure"),
+	}
+}
diff --git a/main.go b/main.go
new file mode 100644
index 0000000..25fa252
--- /dev/null
+++ b/main.go
@@ -0,0 +1,16 @@
+package main
+
+import (
+	"log"
+	"net/http"
+)
+
+func main() {
+	config := NewConfig()
+	server := NewServer(config)
+
+	log.Printf("config: %+v", *config)
+	if err := http.ListenAndServe(config.Listen, server); err != nil {
+		panic(err)
+	}
+}
diff --git a/server.go b/server.go
new file mode 100644
index 0000000..cda5104
--- /dev/null
+++ b/server.go
@@ -0,0 +1,89 @@
+package main
+
+import (
+	"crypto/tls"
+	"errors"
+	"io"
+	"log"
+	"net"
+	"net/http"
+	"time"
+)
+
+type Server struct {
+	Transport http.RoundTripper
+	Timeout   time.Duration
+}
+
+func NewServer(c *Config) *Server {
+	transport := &http.Transport{}
+	transport.TLSClientConfig = &tls.Config{
+		InsecureSkipVerify: c.TLSInsecure,
+	}
+	return &Server{
+		Transport: transport,
+		Timeout:   c.Timeout,
+	}
+}
+
+func (s *Server) ServeHTTP(w http.ResponseWriter, r *http.Request) {
+	switch r.Method {
+	case http.MethodConnect:
+		s.Connect(w, r)
+	default:
+		s.Serve(w, r)
+	}
+}
+
+func (s *Server) Error(w http.ResponseWriter, err error) {
+	log.Println(err)
+	http.Error(w, err.Error(), http.StatusServiceUnavailable)
+	return
+}
+
+func (s *Server) Connect(w http.ResponseWriter, r *http.Request) {
+	dest, err := net.DialTimeout("tcp", r.Host, 30*time.Second)
+	if err != nil {
+		s.Error(w, err)
+		return
+	}
+
+	w.WriteHeader(http.StatusOK)
+	hijacker, ok := w.(http.Hijacker)
+	if !ok {
+		s.Error(w, errors.New("hijack not available"))
+		return
+	}
+
+	client, _, err := hijacker.Hijack()
+	if err != nil {
+		s.Error(w, err)
+		return
+	}
+
+	xfer := func(dst io.WriteCloser, src io.ReadCloser) {
+		defer dst.Close()
+		defer src.Close()
+		io.Copy(dst, src)
+	}
+
+	go xfer(dest, client)
+	go xfer(client, dest)
+}
+
+func (s *Server) Serve(w http.ResponseWriter, r *http.Request) {
+	resp, err := s.Transport.RoundTrip(r)
+	if err != nil {
+		s.Error(w, err)
+		return
+	}
+	defer resp.Body.Close()
+
+	w.WriteHeader(resp.StatusCode)
+	for k, v := range resp.Header {
+		for _, s := range v {
+			w.Header().Add(k, s)
+		}
+	}
+	io.Copy(w, resp.Body)
+}