Fixed quoted-printable encoding for Japanese

config/mail/encoding.ts

@@ -41,16 +41,20 @@ export function quotedPrintableEncode(data: string, encLB = false) {
   const lines = Math.ceil(encodedData.length / 74) - 1;
 
   let offset = 0;
+  let offsetWrapChars = "";
   for (let i = 0; i < lines; i++) {
     let old = encodedData.slice(i * 74 + offset, (i + 1) * 74);
     offset = 0;
+    offsetWrapChars = "";
 
     if (old.at(-1) === "=") {
+      offsetWrapChars = old.slice(old.length - 1, old.length);
       old = old.slice(0, old.length - 1);
       offset = -1;
     }
 
     if (old.at(-2) === "=") {
+      offsetWrapChars = old.slice(old.length - 2, old.length);
       old = old.slice(0, old.length - 2);
       offset = -2;
     }
@@ -62,8 +66,12 @@ export function quotedPrintableEncode(data: string, encLB = false) {
     }
   }
 
+  if(offsetWrapChars !== "" && !offsetWrapChars.startsWith("=")) {
+    offsetWrapChars = "=" + offsetWrapChars;
+  }
+
   // Add rest with no new line
-  ret += encodedData.slice(lines * 74);
+  ret += offsetWrapChars + encodedData.slice(lines * 74);
 
   return ret;
 }
@@ -74,9 +82,18 @@ function hasNonAsciiCharacters(str: string) {
 }
 
 export function quotedPrintableEncodeInline(data: string) {
-  if (hasNonAsciiCharacters(data) || data.startsWith("=?")) {
+  if (data.startsWith("=?")) {
     return `=?utf-8?Q?${quotedPrintableEncode(data)}?=`;
   }
+  if(hasNonAsciiCharacters(data)){
+    data = quotedPrintableEncode(data).split("\r\n").map((l, i) => {
+	    if(l.endsWith("=")){
+		    // strip "=" that was appended by quotedPrintableEncode, but don't need for single line's =??= encoding
+        	l = l.substring(0, l.length - 1);
+	    }
+		return `${i>0?" ":""}=?utf-8?Q?${l}?=`;
+    }).join("\r\n");
+  }
 
   return data;
 }

test/encoding/quotedprintable.test.ts

@@ -0,0 +1,63 @@
+import { assertEquals } from "https://deno.land/[email protected]/testing/asserts.ts";
+import {quotedPrintableEncode, quotedPrintableEncodeInline} from "../../config/mail/encoding.ts";
+
+Deno.test("test quoted-printable encode ascii", () => {
+  const encodedString = quotedPrintableEncode("test");
+  assertEquals(encodedString, "test");
+});
+
+Deno.test("test quoted-printable encode multibyte('test' meaning in Japanese)", () => {
+  const encodedString = quotedPrintableEncode("テスト");
+  assertEquals(encodedString, "=e3=83=86=e3=82=b9=e3=83=88");
+});
+
+Deno.test("test quoted-printable encode multibyte('mail' meaning in Japanese)", () => {
+  const encodedString = quotedPrintableEncode("メール");
+  assertEquals(encodedString, "=e3=83=a1=e3=83=bc=e3=83=ab");
+});
+
+Deno.test("test quoted-printable encode multibyte [email protected]", () => {
+  const encodedString = quotedPrintableEncode("これは日本語のメールだよ");
+  assertEquals(encodedString, "=e3=81=93=e3=82=8c=e3=81=af=e6=97=a5=e6=9c=ac=e8=aa=9e=e3=81=ae=e3=83=a1=\r\n=e3=83=bc=e3=83=ab=e3=81=a0=e3=82=88");
+});
+
+Deno.test("test quoted-printable encode multibyte offset check +1 [email protected]", () => {
+  const encodedString = quotedPrintableEncode("1これは日本語のメールだよ");
+  assertEquals(encodedString, "1=e3=81=93=e3=82=8c=e3=81=af=e6=97=a5=e6=9c=ac=e8=aa=9e=e3=81=ae=e3=83=a1=\r\n=e3=83=bc=e3=83=ab=e3=81=a0=e3=82=88");
+});
+
+Deno.test("test quoted-printable encode multibyte offset check +2 [email protected]", () => {
+  const encodedString = quotedPrintableEncode("12これは日本語のメールだよ");
+  assertEquals(encodedString, "12=e3=81=93=e3=82=8c=e3=81=af=e6=97=a5=e6=9c=ac=e8=aa=9e=e3=81=ae=e3=83=a1=\r\n=e3=83=bc=e3=83=ab=e3=81=a0=e3=82=88");
+});
+
+Deno.test("test quoted-printable encode multibyte offset check +3 [email protected]", () => {
+  const encodedString = quotedPrintableEncode("123これは日本語のメールだよ");
+  assertEquals(encodedString, "123=e3=81=93=e3=82=8c=e3=81=af=e6=97=a5=e6=9c=ac=e8=aa=9e=e3=81=ae=e3=83=\r\n=a1=e3=83=bc=e3=83=ab=e3=81=a0=e3=82=88");
+});
+
+Deno.test("test quoted-printable encode multibyte [email protected] multi lines", () => {
+  const encodedString = quotedPrintableEncode("これは日本語のメールだよ。QP対象のMultiByteが問題になっていたので日本語以外も同様のはず。");
+  assertEquals(encodedString, "=e3=81=93=e3=82=8c=e3=81=af=e6=97=a5=e6=9c=ac=e8=aa=9e=e3=81=ae=e3=83=a1=\r\n"
+      + "=e3=83=bc=e3=83=ab=e3=81=a0=e3=82=88=e3=80=82QP=e5=af=be=e8=b1=a1=e3=81=aeMu=\r\n"
+      + "ltiByte=e3=81=8c=e5=95=8f=e9=a1=8c=e3=81=ab=e3=81=aa=e3=81=a3=e3=81=a6=e3=\r\n"
+      + "=81=84=e3=81=9f=e3=81=ae=e3=81=a7=e6=97=a5=e6=9c=ac=e8=aa=9e=e4=bb=a5=e5=a4=\r\n"
+      + "=96=e3=82=82=e5=90=8c=e6=a7=98=e3=81=ae=e3=81=af=e3=81=9a=e3=80=82");
+
+});
+
+Deno.test("test quoted-printable encode inline", () => {
+  const encodedString = quotedPrintableEncodeInline("test");
+  assertEquals(encodedString, "test");
+});
+
+Deno.test("test quoted-printable encode inline multibytes", () => {
+  const encodedString = quotedPrintableEncodeInline("テスト");
+  assertEquals(encodedString, "=?utf-8?Q?=e3=83=86=e3=82=b9=e3=83=88?=");
+});
+
+Deno.test("test quoted-printable encode inline multibytes and multi lines", () => {
+  const encodedString = quotedPrintableEncodeInline("これは日本語のメールだよ");
+  assertEquals(encodedString, "=?utf-8?Q?=e3=81=93=e3=82=8c=e3=81=af=e6=97=a5=e6=9c=ac=e8=aa=9e=e3=81=ae=e3=83=a1?=\r\n" +
+      " =?utf-8?Q?=e3=83=bc=e3=83=ab=e3=81=a0=e3=82=88?=");
+});