WIP OFW PR 2825: NFC: Improved MFC emulation on some readers

Not finished yet, added in current condition for more tests
by AloneLiberty

lib/nfc/nfc_worker.c

@@ -1107,7 +1107,9 @@ void nfc_worker_emulate_mf_classic(NfcWorker* nfc_worker) {
     furi_hal_nfc_listen_start(nfc_data);
     while(nfc_worker->state == NfcWorkerStateMfClassicEmulate) { //-V1044
         if(furi_hal_nfc_listen_rx(&tx_rx, 300)) {
-            mf_classic_emulator(&emulator, &tx_rx, false);
+            if(!mf_classic_emulator(&emulator, &tx_rx, false)) {
+                furi_hal_nfc_listen_start(nfc_data);
+            }
         }
     }
     if(emulator.data_changed) {
@@ -1382,8 +1384,6 @@ void nfc_worker_analyze_reader(NfcWorker* nfc_worker) {
     bool reader_no_data_notified = true;
 
     while(nfc_worker->state == NfcWorkerStateAnalyzeReader) {
-        furi_hal_nfc_stop_cmd();
-        furi_delay_ms(5);
         furi_hal_nfc_listen_start(nfc_data);
         if(furi_hal_nfc_listen_rx(&tx_rx, 300)) {
             if(reader_no_data_notified) {
@@ -1394,7 +1394,9 @@ void nfc_worker_analyze_reader(NfcWorker* nfc_worker) {
             NfcProtocol protocol =
                 reader_analyzer_guess_protocol(reader_analyzer, tx_rx.rx_data, tx_rx.rx_bits / 8);
             if(protocol == NfcDeviceProtocolMifareClassic) {
-                mf_classic_emulator(&emulator, &tx_rx, true);
+                if(!mf_classic_emulator(&emulator, &tx_rx, true)) {
+                    furi_hal_nfc_listen_start(nfc_data);
+                }
             }
         } else {
             reader_no_data_received_cnt++;
@@ -1406,6 +1408,7 @@ void nfc_worker_analyze_reader(NfcWorker* nfc_worker) {
             FURI_LOG_D(TAG, "No data from reader");
             continue;
         }
+        furi_delay_ms(1);
     }
 
     rfal_platform_spi_release();

lib/nfc/protocols/mifare_classic.c

@@ -883,12 +883,17 @@ bool mf_classic_emulator(
             break;
         }
 
-        if(cmd == 0x50 && plain_data[1] == 0x00) {
+        if(cmd == NFCA_CMD_HALT && plain_data[1] == 0x00) {
             FURI_LOG_T(TAG, "Halt received");
-            furi_hal_nfc_listen_sleep();
+            return false;
-            command_processed = true;
+        }
+
+        if(cmd == NFCA_CMD_RATS && !is_encrypted) {
+            // Mifare Classic doesn't support ATS, NACK it and start listening again
+            FURI_LOG_T(TAG, "RATS received");
             break;
         }
+
         if(cmd == MF_CLASSIC_AUTH_KEY_A_CMD || cmd == MF_CLASSIC_AUTH_KEY_B_CMD) {
             uint8_t block = plain_data[1];
             uint64_t key = 0;
@@ -903,8 +908,7 @@ bool mf_classic_emulator(
                     access_key = MfClassicKeyA;
                 } else {
                     FURI_LOG_D(TAG, "Key not known");
-                    command_processed = true;
+                    return false;
-                    break;
                 }
             } else {
                 if(mf_classic_is_key_found(
@@ -914,8 +918,7 @@ bool mf_classic_emulator(
                     access_key = MfClassicKeyB;
                 } else {
                     FURI_LOG_D(TAG, "Key not known");
-                    command_processed = true;
+                    return false;
-                    break;
                 }
             }
 
@@ -943,16 +946,14 @@ bool mf_classic_emulator(
                 tx_rx->tx_bits = sizeof(nt) * 8;
                 tx_rx->tx_rx_type = FuriHalNfcTxRxTransparent;
             }
+
             if(!furi_hal_nfc_tx_rx(tx_rx, 500)) {
                 FURI_LOG_E(TAG, "Error in NT exchange");
-                command_processed = true;
+                return false;
-                break;
             }
 
             if(tx_rx->rx_bits != 64) {
-                FURI_LOG_W(TAG, "Incorrect nr + ar length: %d", tx_rx->rx_bits);
+                return false;
-                command_processed = true;
-                break;
             }
 
             uint32_t nr = nfc_util_bytes2num(tx_rx->rx_data, 4);
@@ -963,8 +964,7 @@ bool mf_classic_emulator(
             if(cardRr != prng_successor(nonce, 64)) {
                 FURI_LOG_T(TAG, "Wrong AUTH! %08lX != %08lX", cardRr, prng_successor(nonce, 64));
                 // Don't send NACK, as the tag doesn't send it
-                command_processed = true;
+                return false;
-                break;
             }
 
             uint32_t ans = prng_successor(nonce, 96);
@@ -1156,6 +1156,7 @@ bool mf_classic_emulator(
         tx_rx->tx_rx_type = FuriHalNfcTxRxTransparent;
         tx_rx->tx_bits = 4;
         furi_hal_nfc_tx_rx(tx_rx, 300);
+        return false;
     }
 
     return true;
@@ -1164,7 +1165,7 @@ bool mf_classic_emulator(
 void mf_classic_halt(FuriHalNfcTxRxContext* tx_rx, Crypto1* crypto) {
     furi_assert(tx_rx);
 
-    uint8_t plain_data[4] = {0x50, 0x00, 0x00, 0x00};
+    uint8_t plain_data[4] = {NFCA_CMD_HALT, 0x00, 0x00, 0x00};
 
     nfca_append_crc16(plain_data, 2);
     if(crypto) {

lib/nfc/protocols/nfca.c

@@ -3,8 +3,6 @@
 #include <stdio.h>
 #include <furi.h>
 
-#define NFCA_CMD_RATS (0xE0U)
-
 #define NFCA_CRC_INIT (0x6363)
 
 #define NFCA_F_SIG (13560000.0)
@@ -22,7 +20,7 @@ typedef struct {
 
 static uint8_t nfca_default_ats[] = {0x05, 0x78, 0x80, 0x80, 0x00};
 
-static uint8_t nfca_sleep_req[] = {0x50, 0x00};
+static uint8_t nfca_halt_req[] = {NFCA_CMD_HALT, 0x00};
 
 uint16_t nfca_get_crc16(uint8_t* buff, uint16_t len) {
     uint16_t crc = NFCA_CRC_INIT;
@@ -50,17 +48,17 @@ bool nfca_emulation_handler(
     uint16_t buff_rx_len,
     uint8_t* buff_tx,
     uint16_t* buff_tx_len) {
-    bool sleep = false;
+    bool halt = false;
     uint8_t rx_bytes = buff_rx_len / 8;
 
-    if(rx_bytes == sizeof(nfca_sleep_req) && !memcmp(buff_rx, nfca_sleep_req, rx_bytes)) {
+    if(rx_bytes == sizeof(nfca_halt_req) && !memcmp(buff_rx, nfca_halt_req, rx_bytes)) {
-        sleep = true;
+        halt = true;
     } else if(rx_bytes == sizeof(nfca_cmd_rats) && buff_rx[0] == NFCA_CMD_RATS) {
         memcpy(buff_tx, nfca_default_ats, sizeof(nfca_default_ats));
         *buff_tx_len = sizeof(nfca_default_ats) * 8;
     }
 
-    return sleep;
+    return halt;
 }
 
 static void nfca_add_bit(DigitalSignal* signal, bool bit) {

lib/nfc/protocols/nfca.h

@@ -5,6 +5,9 @@
 
 #include <lib/digital_signal/digital_signal.h>
 
+#define NFCA_CMD_RATS (0xE0U)
+#define NFCA_CMD_HALT (0x50U)
+
 typedef struct {
     DigitalSignal* one;
     DigitalSignal* zero;