From 4d38f3328f0a2e551fd7f19a1a1ead288cc27207 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Sven=20M=C3=A4der?= <maeder@phys.ethz.ch>
Date: Wed, 30 Mar 2022 16:11:13 +0200
Subject: [PATCH] Add address search in Received headers

---
 config/default.yaml   |  4 ++++
 src/EmailProcessor.ts | 11 ++++++++++-
 src/config.ts         |  1 +
 src/configUtils.ts    |  3 ++-
 4 files changed, 17 insertions(+), 2 deletions(-)

diff --git a/config/default.yaml b/config/default.yaml
index 7afa8a2..27b592f 100644
--- a/config/default.yaml
+++ b/config/default.yaml
@@ -75,6 +75,10 @@ defaultRoomConfig:
   # If true, the To header will be searched for valid targets (rooms).
   useToAsTarget: true
 
+  # If true, the Received header will be searched for valid targets (rooms).
+  # Useful for redirected emails (as used by sieve or mailman).
+  useEnvelopeToAsTarget: false
+
   # If true, the bot won't post an HTML message to the Matrix room, instead posting a plain
   # text message. It is recommended to use $text_body in your formatting to avoid HTML tags
   # being posted in the rough to the room.
diff --git a/src/EmailProcessor.ts b/src/EmailProcessor.ts
index e191c16..9dc0258 100644
--- a/src/EmailProcessor.ts
+++ b/src/EmailProcessor.ts
@@ -9,7 +9,7 @@ import { MessageType } from "./MessageType";
 interface IEmailTarget {
     address: string;
     name: string;
-    source: "to" | "cc" | "bcc";
+    source: "to" | "cc" | "bcc" | "envelope";
 }
 
 export class EmailProcessor {
@@ -36,6 +36,15 @@ export class EmailProcessor {
         for (const email of (message.to || [])) targets.push({address: email.address, name: email.name, source: 'to'});
         for (const email of (message.cc || [])) targets.push({address: email.address, name: email.name, source: 'cc'});
         for (const email of (message.bcc || [])) targets.push({address: email.address, name: email.name, source: 'bcc'});
+        for (const header of (message.headerLines || [])) {
+            if (header.key == 'received') {
+                const regex = /for <(.*)>/;
+                const email = header.line.match(regex);
+                if (email) {
+                    targets.push({address: email[1], name: '', source: 'envelope'});
+                }
+            }
+        }
 
         const primaryFrom = message.from[0];
 
diff --git a/src/config.ts b/src/config.ts
index b961544..9efaab7 100644
--- a/src/config.ts
+++ b/src/config.ts
@@ -8,6 +8,7 @@ export interface IRoomConfig {
     useCcAsTarget: boolean;
     useBccAsTarget: boolean;
     useToAsTarget: boolean;
+    useEnvelopeToAsTarget: boolean;
     plaintextOnly: boolean;
     attachments: {
         post: boolean;
diff --git a/src/configUtils.ts b/src/configUtils.ts
index 7fa5c5a..545fc93 100644
--- a/src/configUtils.ts
+++ b/src/configUtils.ts
@@ -13,7 +13,7 @@ export function getRoomConfig(roomId: string): IAnnotatedRoomConfig {
     return Object.assign({}, {roomId}, defaults, overrides) as IAnnotatedRoomConfig;
 }
 
-export function getRoomConfigsForTarget(emailAddress: string, source: "cc" | "bcc" | "to"): IAnnotatedRoomConfig[] {
+export function getRoomConfigsForTarget(emailAddress: string, source: "cc" | "bcc" | "to" | "envelope"): IAnnotatedRoomConfig[] {
     const configs: IAnnotatedRoomConfig[] = [];
     const customMapping = config.customMailTargets[emailAddress];
     if (!customMapping) {
@@ -41,6 +41,7 @@ export function getRoomConfigsForTarget(emailAddress: string, source: "cc" | "bc
         if (source === "cc" && !roomConfig.useCcAsTarget) continue;
         if (source === "bcc" && !roomConfig.useBccAsTarget) continue;
         if (source === "to" && !roomConfig.useToAsTarget) continue;
+        if (source === "envelope" && !roomConfig.useEnvelopeToAsTarget) continue;
         freshConfigs.push(roomConfig);
     }