From 650f1902f8dcec35bb98f6dc9d9ff6e86065f217 Mon Sep 17 00:00:00 2001
From: The MMGen Project <mmgen@tuta.io>
Date: Wed, 9 Sep 2026 18:33:59 +0000
Subject: [PATCH] tx.completed: new `legacy_fmt_chk()` method

See dd714815, 852cdeda

Reject Ethereum transaction files with double-encoded serialized data as well.
---
 mmgen/autosign/__init__.py                  |  4 +++-
 mmgen/exception.py                          |  2 +-
 mmgen/proto/eth/tx/unsigned.py              |  1 +
 mmgen/tx/completed.py                       | 17 +++++++++++++++++
 mmgen/tx/file.py                            |  8 +-------
 test/cmdtest_d/autosign.py                  |  2 +-
 test/overlay/fakemods/mmgen/tx/completed.py |  9 +++++++++
 7 files changed, 33 insertions(+), 10 deletions(-)
 create mode 100644 test/overlay/fakemods/mmgen/tx/completed.py

diff --git a/mmgen/autosign/__init__.py b/mmgen/autosign/__init__.py
index dbb3dbda..9bbf2838 100755
--- a/mmgen/autosign/__init__.py
+++ b/mmgen/autosign/__init__.py
@@ -272,7 +272,9 @@ class Autosign:
 				except Exception as e:
 					ymsg('An error occurred with {} ‘{}’:\n    {}: ‘{}’'.format(
 						target.desc, f.name, type(e).__name__, e))
-					if type(e).__name__ == 'LegacyTxSignRequestError':
+					if type(e).__name__ == 'TxFileVersionError':
+						self.do_umount()
+						self.led.set('on')
 						raise
 				except:
 					ymsg('An error occurred with {} ‘{}’'.format(target.desc, f.name))
diff --git a/mmgen/exception.py b/mmgen/exception.py
index a409c795..8506e6c3 100755
--- a/mmgen/exception.py
+++ b/mmgen/exception.py
@@ -86,7 +86,7 @@ class WalletFileError(Exception):         mmcode = 3
 class HexadecimalStringError(Exception):  mmcode = 3
 class SeedLengthError(Exception):         mmcode = 3
 class PrivateKeyError(Exception):         mmcode = 3
-class LegacyTxSignRequestError(Exception):mmcode = 3
+class TxFileVersionError(Exception):      mmcode = 3
 class MMGenCalledProcessError(Exception): mmcode = 3
 class TestSuiteFatalException(Exception): mmcode = 3
 
diff --git a/mmgen/proto/eth/tx/unsigned.py b/mmgen/proto/eth/tx/unsigned.py
index e2d1969c..46f4e6d8 100755
--- a/mmgen/proto/eth/tx/unsigned.py
+++ b/mmgen/proto/eth/tx/unsigned.py
@@ -30,6 +30,7 @@ class Unsigned(VmUnsigned, Completed, TxBase.Unsigned):
 		if isinstance(self.serialized, dict):
 			d = self.serialized
 		else:
+			self.legacy_fmt_chk('double-encoded serialized data')
 			d = json.loads(self.serialized)
 
 		o = {
diff --git a/mmgen/tx/completed.py b/mmgen/tx/completed.py
index 0b15a4db..0c6a1127 100755
--- a/mmgen/tx/completed.py
+++ b/mmgen/tx/completed.py
@@ -12,6 +12,7 @@
 tx.completed: completed transaction class
 """
 
+from ..cfg import gc
 from ..util import msg, ymsg, die
 from .base import Base
 
@@ -102,9 +103,25 @@ class Completed(Base):
 		if self.is_swap:
 			raise ValueError('missing or invalid memo in swap transaction')
 
+	def die_on_version_error(self, errmsg): # overridden by test.overlay.fakemods
+		die('TxFileVersionError', errmsg)
+
+	def legacy_fmt_chk(self, desc):
+		if 'sign' in gc.prog_name:
+			a, b = ('sign', 'Has your online installation been compromised?')
+		elif 'send' in gc.prog_name:
+			a, b = ('send', 'Is your offline installation out of date?')
+		else:
+			return
+		fs = f'Request to {{}} legacy-format transaction ({desc}). {{}}'
+		self.die_on_version_error(fs.format(a, b))
+
 class DummyCompleted: # required by MMGenTxFile.get_proto()
 
 	desc = 'dummy transaction'
 
 	def __init__(self, cfg):
 		self.cfg = cfg
+
+	die_on_version_error = Completed.die_on_version_error
+	legacy_fmt_chk = Completed.legacy_fmt_chk
diff --git a/mmgen/tx/file.py b/mmgen/tx/file.py
index 0ceec6b1..8e8421c1 100755
--- a/mmgen/tx/file.py
+++ b/mmgen/tx/file.py
@@ -22,7 +22,6 @@ tx.file: Transaction file operations for the MMGen suite
 
 import os, json
 
-from ..cfg import gc
 from ..util import ymsg, make_chksum_6, die
 from ..obj import MMGenObject, HexStr, MMGenTxID, CoinTxID, MMGenTxComment
 
@@ -134,12 +133,7 @@ class MMGenTxFile(MMGenObject):
 		tx = self.tx
 		tx.file_format = 'legacy'
 
-		if 'sign' in gc.prog_name:
-			m = 'Request to sign legacy-format transaction. Has your online installation been compromised?'
-			if tx.cfg.test_suite:
-				ymsg(m)
-			else:
-				die('LegacyTxSignRequestError', m)
+		tx.legacy_fmt_chk('non-JSON')
 
 		def deserialize(raw_data, *, desc):
 			from ast import literal_eval
diff --git a/test/cmdtest_d/autosign.py b/test/cmdtest_d/autosign.py
index da802602..990c5ded 100755
--- a/test/cmdtest_d/autosign.py
+++ b/test/cmdtest_d/autosign.py
@@ -930,7 +930,7 @@ class CmdTestAutosign(CmdTestAutosignBase):
 		if exc_exit_val:
 			return do_return()
 
-		t.expect('compromised')
+		t.expect('legacy-format')
 
 		t.expect(
 			f'{self.tx_count} {tx_desc}{suf(self.tx_count)} signed' if self.tx_count else
diff --git a/test/overlay/fakemods/mmgen/tx/completed.py b/test/overlay/fakemods/mmgen/tx/completed.py
new file mode 100644
index 00000000..30e5e2af
--- /dev/null
+++ b/test/overlay/fakemods/mmgen/tx/completed.py
@@ -0,0 +1,9 @@
+from .completed_orig import *
+
+class overlay_fake_Completed(Completed):
+
+	def die_on_version_error(self, errmsg):
+		ymsg(errmsg)
+
+Completed.die_on_version_error = overlay_fake_Completed.die_on_version_error
+DummyCompleted.die_on_version_error = overlay_fake_Completed.die_on_version_error