From 18cbc7259ca396dea0c99ce9547e0e51370a347c Mon Sep 17 00:00:00 2001
From: Henry Gabryjelski <henrygab@users.noreply.github.com>
Date: Sun, 5 May 2024 16:00:16 -0700
Subject: [PATCH] prevent sending corrupt data to em4x70 tags

---
 armsrc/em4x70.c | 35 +++++++++++++++++++++++++++++++++++
 1 file changed, 35 insertions(+)

diff --git a/armsrc/em4x70.c b/armsrc/em4x70.c
index 05f08d6bc..d372efe77 100644
--- a/armsrc/em4x70.c
+++ b/armsrc/em4x70.c
@@ -744,6 +744,13 @@ void em4x70_write(const em4x70_data_t *etd, bool ledcontrol) {
 
     command_parity = etd->parity;
 
+    // Disable to prevent sending corrupted data to the tag.
+    if (command_parity) {
+        Dbprintf("Use of `--par` option with `lf em 4x70 write` is disabled to prevent corrupting tag data");
+        reply_ng(CMD_LF_EM4X70_WRITE, PM3_ENOTIMPL, NULL, 0);
+        return;
+    }
+
     init_tag();
     em4x70_setup_read();
 
@@ -808,6 +815,13 @@ void em4x70_auth(const em4x70_data_t *etd, bool ledcontrol) {
 
     command_parity = etd->parity;
 
+    // Disable to prevent sending corrupted data to the tag.
+    if (command_parity) {
+        Dbprintf("Use of `--par` option with `lf em 4x70 auth` is disabled to prevent corrupting tag data");
+        reply_ng(CMD_LF_EM4X70_WRITE, PM3_ENOTIMPL, NULL, 0);
+        return;
+    }
+
     init_tag();
     em4x70_setup_read();
 
@@ -829,6 +843,13 @@ void em4x70_brute(const em4x70_data_t *etd, bool ledcontrol) {
 
     command_parity = etd->parity;
 
+    // Disable to prevent sending corrupted data to the tag.
+    if (command_parity) {
+        Dbprintf("Use of `--par` option with `lf em 4x70 brute` is disabled to prevent corrupting tag data");
+        reply_ng(CMD_LF_EM4X70_WRITE, PM3_ENOTIMPL, NULL, 0);
+        return;
+    }
+
     init_tag();
     em4x70_setup_read();
 
@@ -850,6 +871,13 @@ void em4x70_write_pin(const em4x70_data_t *etd, bool ledcontrol) {
 
     command_parity = etd->parity;
 
+    // Disable to prevent sending corrupted data to the tag.
+    if (command_parity) {
+        Dbprintf("Use of `--par` option with `lf em 4x70 setpin` is disabled to prevent corrupting tag data");
+        reply_ng(CMD_LF_EM4X70_WRITE, PM3_ENOTIMPL, NULL, 0);
+        return;
+    }
+
     init_tag();
     em4x70_setup_read();
 
@@ -892,6 +920,13 @@ void em4x70_write_key(const em4x70_data_t *etd, bool ledcontrol) {
 
     command_parity = etd->parity;
 
+    // Disable to prevent sending corrupted data to the tag.
+    if (command_parity) {
+        Dbprintf("Use of `--par` option with `lf em 4x70 setkey` is disabled to prevent corrupting tag data");
+        reply_ng(CMD_LF_EM4X70_WRITE, PM3_ENOTIMPL, NULL, 0);
+        return;
+    }
+
     init_tag();
     em4x70_setup_read();