From 544f1c956cd63e859828348a27ab0f2e585730fa Mon Sep 17 00:00:00 2001
From: valkyrie_pilot <valk@randomairborne.dev>
Date: Sun, 24 Jul 2022 19:24:03 -0600
Subject: [PATCH] Auto-Convert UTF-16 to UTF-8

---
 main.go | 36 +++++++++++++++++++++++++++++++++++-
 1 file changed, 35 insertions(+), 1 deletion(-)

diff --git a/main.go b/main.go
index 70e25de..da5c657 100644
--- a/main.go
+++ b/main.go
@@ -1,6 +1,7 @@
 package main
 
 import (
+	"bytes"
 	"fmt"
 	"html/template"
 	"io"
@@ -8,6 +9,8 @@ import (
 	"net/http"
 	"os"
 	"strings"
+	"unicode/utf16"
+	"unicode/utf8"
 )
 
 var contentTemplate *template.Template
@@ -40,7 +43,6 @@ func handleRequest(w http.ResponseWriter, r *http.Request) {
 	}
 
 	defer req.Body.Close()
-
 	w.Header().Set("Content-Type", "text/html; charset=utf-8")
 
 	if req.StatusCode != http.StatusOK {
@@ -53,6 +55,15 @@ func handleRequest(w http.ResponseWriter, r *http.Request) {
 		_, _ = fmt.Fprintln(w, "An error occurred reading the contents of the response")
 		return
 	}
+	ctype_encoding := strings.Split(req.Header.Get("Content-Type"), ";%20")
+	if strings.ToLower(ctype_encoding[len(ctype_encoding)-1]) == "charset=utf-16" {
+		contents, err = DecodeUTF16(contents)
+		if err != nil {
+			log.Println(err)
+			fmt.Fprintln(w, "An error occurred decoding the response")
+			return
+		}
+	}
 	escaped := template.HTMLEscapeString(string(contents))
 	corrected := strings.Replace(escaped, "\n", "<br>", -1)
 
@@ -63,3 +74,26 @@ func handleRequest(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 }
+
+func DecodeUTF16(b []byte) ([]byte, error) {
+
+	if len(b)%2 != 0 {
+		return make([]byte, 0), fmt.Errorf("Must have even length byte slice")
+	}
+
+	u16s := make([]uint16, 1)
+
+	ret := &bytes.Buffer{}
+
+	b8buf := make([]byte, 4)
+
+	lb := len(b)
+	for i := 0; i < lb; i += 2 {
+		u16s[0] = uint16(b[i]) + (uint16(b[i+1]) << 8)
+		r := utf16.Decode(u16s)
+		n := utf8.EncodeRune(b8buf, r[0])
+		ret.Write(b8buf[:n])
+	}
+
+	return ret.Bytes(), nil
+}
\ No newline at end of file