From 441379e7a8b1b7468cbd37c15c5174b4c0faa9a4 Mon Sep 17 00:00:00 2001
From: Akhil Narang <me@akhilnarang.dev>
Date: Fri, 19 Apr 2024 17:36:30 +0530
Subject: [PATCH] refactor: don't modify email library's dictionary

Keep our own map of alternative character sets

Signed-off-by: Akhil Narang <me@akhilnarang.dev>
---
 frappe/__init__.py      | 15 ++++++++++++++-
 frappe/email/receive.py | 26 ++++++++++++--------------
 2 files changed, 26 insertions(+), 15 deletions(-)

diff --git a/frappe/__init__.py b/frappe/__init__.py
index 77b840412e..9c37d47d0c 100644
--- a/frappe/__init__.py
+++ b/frappe/__init__.py
@@ -2501,9 +2501,22 @@ def safe_encode(param, encoding="utf-8"):
 	return param
 
 
-def safe_decode(param, encoding="utf-8"):
+def safe_decode(param, encoding="utf-8", fallback_map: dict | None = None):
+	"""
+	Method to safely decode data into a string
+
+	:param param: The data to be decoded
+	:param encoding: The encoding to decode into
+	:param fallback_map: A fallback map to reference in case of a LookupError
+	:return:
+	"""
 	try:
 		param = param.decode(encoding)
+	except LookupError:
+		try:
+			param = param.decode((fallback_map or {}).get(encoding, "utf-8"))
+		except Exception:
+			pass
 	except Exception:
 		pass
 	return param
diff --git a/frappe/email/receive.py b/frappe/email/receive.py
index 82cc2c25a2..4d23a4d4b3 100644
--- a/frappe/email/receive.py
+++ b/frappe/email/receive.py
@@ -3,7 +3,6 @@
 
 import datetime
 import email
-import email.charset
 import email.utils
 import imaplib
 import json
@@ -39,19 +38,16 @@ from frappe.utils import (
 from frappe.utils.html_utils import clean_email_html
 from frappe.utils.user import is_system_user
 
-# use alias charset for python unknown charset
-email.charset.ALIASES.update(
-	{
-		"windows-874": "cp874",
-	}
-)
-
 # fix due to a python bug in poplib that limits it to 2048
 poplib._MAXLINE = 1_00_000
 
 THREAD_ID_PATTERN = re.compile(r"(?<=\[)[\w/-]+")
 WORDS_PATTERN = re.compile(r"\w+")
 
+ALTERNATE_CHARSET_MAP = {
+	"windows-874": "cp874",
+}
+
 
 class EmailSizeExceededError(frappe.ValidationError):
 	pass
@@ -413,12 +409,10 @@ class Email:
 		"""Parse and decode `Subject` header."""
 		_subject = decode_header(self.mail.get("Subject", "No Subject"))
 		self.subject = _subject[0][0] or ""
-		charset = _subject[0][1]
 
-		if charset:
+		if charset := _subject[0][1]:
 			# Encoding is known by decode_header (might also be unknown-8bit)
-			charset = email.charset.ALIASES.get(charset, charset)
-			self.subject = safe_decode(self.subject, charset)
+			self.subject = safe_decode(self.subject, charset, ALTERNATE_CHARSET_MAP)
 
 		if isinstance(self.subject, bytes):
 			# Fall back to utf-8 if the charset is unknown or decoding fails
@@ -512,11 +506,15 @@ class Email:
 
 	def get_payload(self, part):
 		charset = self.get_charset(part)
-		charset = email.charset.ALIASES.get(charset, charset)
 		try:
 			return str(part.get_payload(decode=True), str(charset), "ignore")
 		except LookupError:
-			return part.get_payload()
+			try:
+				return str(
+					part.get_payload(decode=True), ALTERNATE_CHARSET_MAP.get(charset, "utf-8"), "ignore"
+				)
+			except Exception:
+				return part.get_payload()
 
 	def get_attachment(self, part):
 		# charset = self.get_charset(part)