feat: improve error handling with ERR_NSCM and data hints

Add ERR_NSCM (0xC0) error code to distinguish unrecognized commands
from packet errors. Update ERR_PCKT description to clarify that the
command was recognized but requires additional data.

The raw command now provides helpful hints when ERR_PCKT is returned,
showing the required data format and example usage for known commands.

Error distinction:
  0xC0 (ERR_NSCM) = command not recognized by bootloader
  0xC1 (ERR_PCKT) = command recognized but data missing/invalid

Signed-off-by: Vincent Jardin <vjardin@free.fr>

Author: vjardin

src/radfu.c

@@ -2705,6 +2705,59 @@ ra_raw_cmd(ra_device_t *dev, uint8_t cmd, const uint8_t *data, size_t data_len)
   /* Check if response indicates error */
   if (n >= 4 && (resp[3] & 0x80)) {
     printf("\n*** Response indicates ERROR ***\n");
+
+    /* Provide hints for ERR_PCKT (command recognized but needs data) */
+    if (n >= 5 && resp[4] == ERR_PCKT) {
+      uint8_t orig_cmd = resp[3] & 0x7F;
+      printf("\nHint: Command 0x%02X is recognized but requires data.\n", orig_cmd);
+      switch (orig_cmd) {
+      case 0x12: /* ERA */
+      case 0x13: /* WRI */
+      case 0x15: /* REA */
+      case 0x18: /* CRC */
+        printf("      Required: SAD[4] + EAD[4] (8 bytes, big-endian addresses)\n");
+        printf("      Example: radfu raw 0x%02X 00 00 00 00 00 00 00 FF\n", orig_cmd);
+        break;
+      case 0x34: /* BAU */
+        printf("      Required: BRT[4] (4 bytes, big-endian baud rate)\n");
+        printf("      Example: radfu raw 0x34 00 01 C2 00  (115200 bps)\n");
+        break;
+      case 0x3B: /* ARE */
+        printf("      Required: NUM[1] (1 byte, area number 0-3)\n");
+        printf("      Example: radfu raw 0x3B 00\n");
+        break;
+      case 0x30: /* AUTH/IDA */
+        printf("      Required: ID code (16 bytes) or SDLM+DDLM+CHCT (3 bytes)\n");
+        break;
+      case 0x4E: /* BND_SET */
+        printf("      Required: CFS1[2]+CFS2[2]+DFS[2]+SRS1[2]+SRS2[2] (10 bytes)\n");
+        break;
+      case 0x50: /* INI */
+        printf("      Required: SDLM[1]+DDLM[1] (2 bytes)\n");
+        break;
+      case 0x51: /* PRM_SET */
+        printf("      Required: PMID[1]+PMDT[1] (2 bytes)\n");
+        break;
+      case 0x52: /* PRM */
+        printf("      Required: PMID[1] (1 byte, parameter ID)\n");
+        printf("      Example: radfu raw 0x52 01\n");
+        break;
+      case 0x71: /* DLM_TRANSIT */
+        printf("      Required: SDLM[1]+DDLM[1] (2 bytes)\n");
+        break;
+      case 0x28: /* KEY */
+        printf("      Required: KYTY[1]+wrapped_key (1+80 bytes)\n");
+        break;
+      case 0x29: /* KEY_VFY */
+      case 0x2B: /* UKEY_VFY */
+        printf("      Required: KYID[1] (1 byte, key index)\n");
+        printf("      Example: radfu raw 0x%02X 01\n", orig_cmd);
+        break;
+      default:
+        printf("      Check protocol documentation for required data format.\n");
+        break;
+      }
+    }
     return -1;
   }
 

src/rapacker.c

@@ -16,8 +16,9 @@ static const struct {
   const char *name;
   const char *desc;
 } error_codes[] = {
-  { ERR_UNSU, "ERR_UNSU", "unsupported command"                },
-  { ERR_PCKT, "ERR_PCKT", "packet error (length/ETX)"          },
+  { ERR_UNSU, "ERR_UNSU", "unsupported command"                         },
+  { ERR_NSCM, "ERR_NSCM", "unrecognized command"                        },
+  { ERR_PCKT, "ERR_PCKT", "packet error (command recognized, need data)" },
   { ERR_CHKS, "ERR_CHKS", "checksum mismatch"                  },
   { ERR_FLOW, "ERR_FLOW", "command flow error"                 },
   { ERR_ADDR, "ERR_ADDR", "invalid address"                    },

src/rapacker.h

@@ -40,7 +40,8 @@
 
 /* MCU error codes */
 #define ERR_UNSU 0x0C /* Unsupported command */
-#define ERR_PCKT 0xC1 /* Packet error (length/ETX) */
+#define ERR_NSCM 0xC0 /* Unrecognized command (not supported by bootloader) */
+#define ERR_PCKT 0xC1 /* Packet error (command recognized, data missing/invalid) */
 #define ERR_CHKS 0xC2 /* Checksum mismatch */
 #define ERR_FLOW 0xC3 /* Command flow error */
 #define ERR_ADDR 0xD0 /* Invalid address */

tests/test_rapacker.c

@@ -241,7 +241,8 @@ test_strdesc(void **state) {
 
   /* Test error descriptions */
   assert_string_equal(ra_strdesc(ERR_UNSU), "unsupported command");
-  assert_string_equal(ra_strdesc(ERR_PCKT), "packet error (length/ETX)");
+  assert_string_equal(ra_strdesc(ERR_NSCM), "unrecognized command");
+  assert_string_equal(ra_strdesc(ERR_PCKT), "packet error (command recognized, need data)");
   assert_string_equal(ra_strdesc(ERR_CHKS), "checksum mismatch");
   assert_string_equal(ra_strdesc(ERR_FLOW), "command flow error");
   assert_string_equal(ra_strdesc(ERR_ADDR), "invalid address");