feat: |Worker| add REMOVE_ALL_ATTACHMENT and REMOVE_EXCEED_SIZE_ATTAC… (#562)

feat: |Worker| add REMOVE_ALL_ATTACHMENT and REMOVE_EXCEED_SIZE_ATTACHMENT

worker/src/email/check_attachment.ts

@@ -0,0 +1,48 @@
+import { Bindings, ParsedEmailContext } from "../types";
+import { getBooleanValue } from "../utils";
+import { commonParseMail } from "../common";
+import { createMimeMessage } from "mimetext";
+
+export const remove_attachment_if_need = async (
+    env: Bindings,
+    parsedEmailContext: ParsedEmailContext,
+    from_address: string,
+    to_address: string,
+    size: number
+): Promise<void> => {
+    // if configured, remove all attachment
+    const removeAllAttachment = getBooleanValue(env.REMOVE_ALL_ATTACHMENT);
+    // if attachment size > 2MB, remove attachment
+    const removeExceedSizeAttachment = getBooleanValue(env.REMOVE_EXCEED_SIZE_ATTACHMENT) && size >= 2 * 1024 * 1024;
+    const shouldRemoveAttachment = removeAllAttachment || removeExceedSizeAttachment;
+    if (!shouldRemoveAttachment) return;
+
+    const parsedEmail = await commonParseMail(parsedEmailContext);
+    if (!parsedEmail) return;
+
+    const msg = createMimeMessage();
+    if (parsedEmail?.headers) {
+        for (const header of parsedEmail.headers) {
+            msg.setHeader(header["key"], header["value"]);
+        }
+    }
+    msg.setSender({
+        name: parsedEmail?.sender || from_address,
+        addr: from_address
+    });
+    msg.setRecipient(to_address);
+    msg.setSubject(parsedEmail?.subject || "Failed to parse email subject");
+    if (parsedEmail?.html) {
+        msg.addMessage({
+            contentType: 'text/html',
+            data: parsedEmail.html
+        });
+    }
+    if (parsedEmail?.text) {
+        msg.addMessage({
+            contentType: 'text/plain',
+            data: parsedEmail.text
+        });
+    }
+    parsedEmailContext.rawEmail = msg.asRaw();
+}

worker/src/email/index.ts

@@ -7,6 +7,7 @@ import { auto_reply } from "./auto_reply";
 import { isBlocked } from "./black_list";
 import { triggerWebhook, triggerAnotherWorker, commonParseMail } from "../common";
 import { check_if_junk_mail } from "./check_junk";
+import { remove_attachment_if_need } from "./check_attachment";
 
 
 async function email(message: ForwardableEmailMessage, env: Bindings, ctx: ExecutionContext) {
@@ -32,13 +33,20 @@ async function email(message: ForwardableEmailMessage, env: Bindings, ctx: Execu
         console.log("check junk mail error", error);
     }
 
+    // remove attachment if configured or size > 2MB
+    try {
+        await remove_attachment_if_need(env, parsedEmailContext, message.from, message.to, message.rawSize);
+    } catch (error) {
+        console.log("remove attachment error", error);
+    }
+
     const message_id = message.headers.get("Message-ID");
     // save email
     try {
         const { success } = await env.DB.prepare(
             `INSERT INTO raw_mails (source, address, raw, message_id) VALUES (?, ?, ?, ?)`
         ).bind(
-            message.from, message.to, rawEmail, message_id
+            message.from, message.to, parsedEmailContext.rawEmail, message_id
         ).run();
         if (!success) {
             message.setReject(`Failed save message to ${message.to}`);