From 01b113f50820b64e550be3e09d1e29918c6185da Mon Sep 17 00:00:00 2001
From: Willy-JL <49810075+Willy-JL@users.noreply.github.com>
Date: Fri, 14 Mar 2025 23:00:59 +0000
Subject: [PATCH] Fix chunk sizes

---
 lib/nfc/protocols/type_4_tag/type_4_tag_i.h          |  5 ++++-
 lib/nfc/protocols/type_4_tag/type_4_tag_listener_i.c | 12 +++++++-----
 lib/nfc/protocols/type_4_tag/type_4_tag_poller_i.c   |  2 +-
 3 files changed, 12 insertions(+), 7 deletions(-)

diff --git a/lib/nfc/protocols/type_4_tag/type_4_tag_i.h b/lib/nfc/protocols/type_4_tag/type_4_tag_i.h
index d64efcc2c..b0e319ba9 100644
--- a/lib/nfc/protocols/type_4_tag/type_4_tag_i.h
+++ b/lib/nfc/protocols/type_4_tag/type_4_tag_i.h
@@ -33,8 +33,11 @@
 #define TYPE_4_TAG_T4T_CC_FILE_ID        0xE1, 0x03
 #define TYPE_4_TAG_T4T_CC_VNO            (0x20)
 
+// 4a layer adds 1..3 byte prefix, 3a layer adds 2 byte suffix and has 256 byte buffer
+#define TYPE_4_TAG_BUF_SIZE     (256U - 3U - 2U)
 // Read returns 2 byte status trailer, write sends 5 byte command header
-#define TYPE_4_TAG_BUF_SIZE (TYPE_4_TAG_ISO_RW_CHUNK_LEN + 5)
+#define TYPE_4_TAG_CHUNK_LEN    MIN(TYPE_4_TAG_BUF_SIZE - 5U, TYPE_4_TAG_ISO_RW_CHUNK_LEN)
+#define TYPE_4_TAG_DEFAULT_SIZE (2048U)
 
 // Capability Container parsing structures
 
diff --git a/lib/nfc/protocols/type_4_tag/type_4_tag_listener_i.c b/lib/nfc/protocols/type_4_tag/type_4_tag_listener_i.c
index a5557f95f..94e64788a 100644
--- a/lib/nfc/protocols/type_4_tag/type_4_tag_listener_i.c
+++ b/lib/nfc/protocols/type_4_tag/type_4_tag_listener_i.c
@@ -112,13 +112,15 @@ static Type4TagError type_4_tag_listener_iso_read(
         bit_lib_num_to_bytes_be(sizeof(cc_buf), sizeof(cc->len), (void*)&cc->len);
         cc->t4t_vno = TYPE_4_TAG_T4T_CC_VNO;
         bit_lib_num_to_bytes_be(
-            instance->data->is_tag_specific ? instance->data->chunk_max_read :
-                                              TYPE_4_TAG_ISO_RW_CHUNK_LEN,
+            instance->data->is_tag_specific ?
+                MIN(instance->data->chunk_max_read, TYPE_4_TAG_CHUNK_LEN) :
+                TYPE_4_TAG_CHUNK_LEN,
             sizeof(cc->mle),
             (void*)&cc->mle);
         bit_lib_num_to_bytes_be(
-            instance->data->is_tag_specific ? instance->data->chunk_max_write :
-                                              TYPE_4_TAG_ISO_RW_CHUNK_LEN,
+            instance->data->is_tag_specific ?
+                MIN(instance->data->chunk_max_write, TYPE_4_TAG_CHUNK_LEN) :
+                TYPE_4_TAG_CHUNK_LEN,
             sizeof(cc->mlc),
             (void*)&cc->mlc);
         cc->tlv[0].type = Type4TagCcTlvTypeNdefFileCtrl;
@@ -129,7 +131,7 @@ static Type4TagError type_4_tag_listener_iso_read(
             (void*)&cc->tlv[0].value.ndef_file_ctrl.file_id);
         bit_lib_num_to_bytes_be(
             instance->data->is_tag_specific ? instance->data->ndef_max_len :
-                                              TYPE_4_TAG_ISO_RW_CHUNK_LEN,
+                                              TYPE_4_TAG_DEFAULT_SIZE,
             sizeof(cc->tlv[0].value.ndef_file_ctrl.max_len),
             (void*)&cc->tlv[0].value.ndef_file_ctrl.max_len);
         cc->tlv[0].value.ndef_file_ctrl.read_perm =
diff --git a/lib/nfc/protocols/type_4_tag/type_4_tag_poller_i.c b/lib/nfc/protocols/type_4_tag/type_4_tag_poller_i.c
index 45a9da1fc..92caae7d7 100644
--- a/lib/nfc/protocols/type_4_tag/type_4_tag_poller_i.c
+++ b/lib/nfc/protocols/type_4_tag/type_4_tag_poller_i.c
@@ -198,7 +198,7 @@ Type4TagError type_4_tag_poller_read_ndef(Type4TagPoller* instance) {
             FURI_LOG_D(TAG, "NDEF file is empty");
             break;
         }
-        uint8_t chunk_max = MIN(instance->data->chunk_max_read, TYPE_4_TAG_ISO_RW_CHUNK_LEN);
+        uint8_t chunk_max = MIN(instance->data->chunk_max_read, TYPE_4_TAG_CHUNK_LEN);
         if(ndef_len > TYPE_4_TAG_ISO_READ_P_OFFSET_MAX + chunk_max - sizeof(ndef_len)) {
             FURI_LOG_E(TAG, "NDEF file too long: %zu bytes", ndef_len);
             error = Type4TagErrorNotSupported;