commit 28a539e0a8754a0366b59a57b47f660d8960759a
Author: Bel LaPointe <breel@qualtrics.com>
Date:   Mon Dec 6 21:50:28 2021 -0700

    mvp

diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..5320254
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,2 @@
+**/*.sw*
+/mitm
diff --git a/main.go b/main.go
new file mode 100644
index 0000000..fd2ee11
--- /dev/null
+++ b/main.go
@@ -0,0 +1,155 @@
+package main
+
+import (
+	"bytes"
+	"errors"
+	"flag"
+	"io"
+	"io/ioutil"
+	"log"
+	"net"
+	"net/http"
+	"time"
+)
+
+type fproxy struct{}
+
+type peek struct {
+	buff  *bytes.Buffer
+	buff2 *bytes.Buffer
+}
+
+func newPeek() peek {
+	return peek{
+		buff:  bytes.NewBuffer(nil),
+		buff2: bytes.NewBuffer(nil),
+	}
+}
+
+func (peek peek) Read(b []byte) (int, error) {
+	n, err := peek.buff.Read(b)
+	peek.buff2.Write(b[:n])
+	log.Printf("read (%d): %s", n, b[:n])
+	return n, err
+}
+
+func (peek peek) Write(b []byte) (int, error) {
+	n, err := peek.buff.Write(b)
+	log.Printf("wrote %d): %s", n, b[:n])
+	return n, err
+}
+
+func (peek peek) Close() error {
+	//log.Printf("Close: %s", peek.buff2.Bytes())
+	return nil
+}
+
+func main() {
+	port := flag.String("p", ":9005", "addr to listen on")
+	flag.Parse()
+	log.Printf("listening on %s", *port)
+	if err := http.ListenAndServe(*port, fproxy{}); err != nil {
+		panic(err)
+	}
+}
+
+func (fproxy fproxy) ServeHTTP(w http.ResponseWriter, r *http.Request) {
+	if err := fproxy.serveHTTP(w, r); err != nil {
+		http.Error(w, err.Error(), http.StatusInternalServerError)
+	}
+}
+
+func (fproxy fproxy) serveHTTP(w http.ResponseWriter, r *http.Request) error {
+	if r.Method == http.MethodConnect {
+		return fproxy.passthrough(w, r)
+	}
+	return fproxy.proxy(w, r)
+}
+
+func (fproxy fproxy) proxy(w http.ResponseWriter, r *http.Request) error {
+	if r.URL.Scheme == "" {
+		r.URL.Scheme = "http"
+	}
+	b, err := ioutil.ReadAll(r.Body)
+	if err != nil {
+		return err
+	}
+	r.Body = ioutil.NopCloser(bytes.NewReader(b))
+	resp, err := (&http.Transport{}).RoundTrip(r)
+	if err != nil {
+		return err
+	}
+	defer resp.Body.Close()
+	for k, v := range resp.Header {
+		for i := range v {
+			w.Header().Add(k, v[i])
+		}
+	}
+	w.WriteHeader(resp.StatusCode)
+	peek := bytes.NewBuffer(nil)
+	forward := func(b []byte) {
+		peek.Write(b)
+		w.Write(b)
+	}
+	buff := make([]byte, 1024)
+	var n int
+	for n, err = resp.Body.Read(buff); err == nil; n, err = resp.Body.Read(buff) {
+		forward(buff[:n])
+	}
+	forward(buff[:n])
+	if err == io.EOF {
+		err = nil
+	}
+	log.Printf("%s: %+v: %s => %d: %+v: %s", r.Method, r.Header, b, resp.StatusCode, resp.Header, peek.Bytes())
+	//_, err = io.Copy(w, resp.Body)
+	return err
+}
+
+func (fproxy fproxy) passthrough(w http.ResponseWriter, r *http.Request) error {
+	log.Printf("passthrough")
+	defer log.Printf("/passthrough")
+
+	dest_conn, err := net.DialTimeout("tcp", r.Host, 30*time.Second)
+	if err != nil {
+		return err
+	}
+	w.WriteHeader(http.StatusOK)
+	hijacker, ok := w.(http.Hijacker)
+	if !ok {
+		return errors.New("Hijacking not supported")
+	}
+	client_conn, _, err := hijacker.Hijack()
+	if err != nil {
+		return err
+	}
+
+	transfer := func(destination io.WriteCloser, source io.ReadCloser) {
+		defer destination.Close()
+		defer source.Close()
+		io.Copy(destination, source)
+		return
+		/*
+			b := make([]byte, 1024)
+			for n, err := source.Read(b); err != io.EOF; n, err = source.Read(b) {
+				log.Printf("read %v/%v", n, err)
+				if err != nil {
+					xferErr = err
+					return
+				}
+				for n > 0 {
+					m, err := destination.Write(b[:n])
+					if err != nil {
+						xferErr = err
+						return
+					}
+					n -= m
+				}
+			}
+		*/
+	}
+
+	go transfer(dest_conn, client_conn)
+	go transfer(client_conn, dest_conn)
+
+	return nil
+}