diff --git a/CHANGELOG.md b/CHANGELOG.md
index 82af9ead6..c660d2011 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -3,6 +3,9 @@ All notable changes to this project will be documented in this file.
 This project uses the changelog in accordance with [keepchangelog](http://keepachangelog.com/). Please use this to write notable changes, which is not the same as git commit log...
 
 ## [unreleased][unreleased]
+ - Changed `data num` - now can print reversed and inverse (@iceman1001)
+ - Fixed `hf mf sim -ix` never returning console (@datatags)
+ - Added standalone mode `hf_unisniff` combining 14a/14b/15 sniffing with extra flash save options (@hazardousvoltage)
  - Added encryption and other SL3 functions for Mifare Plus - more to come (@team-orangeBlue)
  - Fixed the corrupted data in real-time sampling (@wh201906)
  - Added a slider in the plot window for navigation (@wh201906)
@@ -12,8 +15,6 @@ This project uses the changelog in accordance with [keepchangelog](http://keepac
  - Changed `hf 14a info` - now reads and prints QL88 sigantures (@iceman1001)
  - Fixed `hf iclass dump` truncating AA2 blocks and improve reliability (@nvx)
  - Added some info about UMC in "doc/magic_cards_notes.md" (@temskiy)
- - Added standalone mode `hf_unisniff` combining 14a/14b/15 sniffing with extra flash save options (@hazardousvoltage)
- - Fixed `hf mf sim -ix` never returning console (@datatags)
 
 ## [Faraday.4.17511][2023-11-13]
  - Fixed Python support of `experimental_client_with_swig` (@doegox)
diff --git a/armsrc/hitag2crack.c b/armsrc/hitag2crack.c
index bd5fc2a94..138fdf451 100644
--- a/armsrc/hitag2crack.c
+++ b/armsrc/hitag2crack.c
@@ -339,7 +339,7 @@ bool hitag2crack_read_page(uint8_t *responsestr, uint8_t pagenum, uint8_t *nrar,
             // decrypt response
             hitag2crack_xor(response, e_response, keybits + 10, 32);
             // convert to hexstring
-            binarraytohex(responsestr, response, 32);
+            binarray_2_hex(responsestr, response, 32);
             return true;
         } else {
             UserMessage("hitag2crack_read_page:\r\n hitag2crack_send_e_cmd returned ERROR_RESPONSE\r\n");
@@ -424,7 +424,7 @@ bool hitag2crack_tx_rx(uint8_t *responsestr, uint8_t *msg, int len, int state, b
         }
 
         // convert response to hexstring
-        binarraytohex(responsestr, tmp + 5, 32);
+        binarray_2_hex(responsestr, tmp + 5, 32);
         return true;
     } else {
 #ifdef RFIDLER_DEBUG
@@ -506,8 +506,8 @@ bool hitag2crack_decrypt_hex(uint8_t *response, uint8_t *hex) {
     binulong = hextoulong(hex);
 
     ulongtobinarray(bin, hitag2_crypt(binulong, 32), 32);
-    binarraytobinstring(binstr, bin, 32);
-    binarraytohex(binhex, bin, 32);
+    binarray_2_binstr(binstr, bin, 32);
+    binarray_2_hex(binhex, bin, 32);
 //    UserMessage("ar = %s\r\n", binstr);
 //    UserMessage("arhex = %s\r\n", binhex);
 
@@ -532,7 +532,7 @@ bool hitag2crack_decrypt_bin(uint8_t *response, uint8_t *e_binstr) {
     binulong = binarraytoulong(e_bin, len);
 
     ulongtobinarray(bin, hitag2_crypt(binulong, len), len);
-    binarraytobinstring(binstr, bin, len);
+    binarray_2_binstr(binstr, bin, len);
     strcpy(response, binstr);
     return true;
 }
@@ -646,7 +646,7 @@ bool hitag2_keystream(uint8_t *response, uint8_t *nrarhex) {
     }
 
     for (i = 0; i < 2048; i += 256) {
-        binarraytohex(keybitshex, keybits + i, 256);
+        binarray_2_hex(keybitshex, keybits + i, 256);
         UserMessage("%s\r\n", keybitshex);
     }
 
diff --git a/armsrc/optimized_cipher.c b/armsrc/optimized_cipher.c
index 68b36af85..c2ffa5da9 100644
--- a/armsrc/optimized_cipher.c
+++ b/armsrc/optimized_cipher.c
@@ -115,12 +115,12 @@ static void init_opt_select_LUT(void) {
     print_result("", opt_select_LUT, 256);
 }
 ***********************************************************************************/
-
+/*
 #define opt__select(x,y,r)  (4 & (((r & (r << 2)) >> 5) ^ ((r & ~(r << 2)) >> 4) ^ ( (r | r << 2) >> 3)))\
     |(2 & (((r | r << 2) >> 6) ^ ( (r | r << 2) >> 1) ^ (r >> 5) ^ r ^ ((x^y) << 1)))\
     |(1 & (((r & ~(r << 2)) >> 4) ^ ((r & (r << 2)) >> 3) ^ r ^ x))
 
-/*
+
  * Some background on the expression above can be found here...
 uint8_t xopt__select(bool x, bool y, uint8_t r)
 {
@@ -201,7 +201,9 @@ static void opt_suc(const uint8_t *k, State_t *s, const uint8_t *in, uint8_t len
     }
     //For tag MAC, an additional 32 zeroes
     if (add32Zeroes) {
-        for (int i = 0; i < 16; i++) {
+        for (int i = 0; i < 8; i++) {
+            opt_successor(k, s, 0);
+            opt_successor(k, s, 0);
             opt_successor(k, s, 0);
             opt_successor(k, s, 0);
         }
diff --git a/armsrc/optimized_cipherutils.c b/armsrc/optimized_cipherutils.c
index 3afba7164..66a618291 100644
--- a/armsrc/optimized_cipherutils.c
+++ b/armsrc/optimized_cipherutils.c
@@ -114,7 +114,7 @@ uint64_t x_bytes_to_num(uint8_t *src, size_t len) {
     return num;
 }
 
-uint8_t reversebytes(uint8_t b) {
+uint8_t reversebyte(uint8_t b) {
     b = (b & 0xF0) >> 4 | (b & 0x0F) << 4;
     b = (b & 0xCC) >> 2 | (b & 0x33) << 2;
     b = (b & 0xAA) >> 1 | (b & 0x55) << 1;
@@ -124,14 +124,14 @@ uint8_t reversebytes(uint8_t b) {
 void reverse_arraybytes(uint8_t *arr, size_t len) {
     size_t i;
     for (i = 0; i < len ; i++) {
-        arr[i] = reversebytes(arr[i]);
+        arr[i] = reversebyte(arr[i]);
     }
 }
 
 void reverse_arraycopy(uint8_t *arr, uint8_t *dest, size_t len) {
     size_t i;
     for (i = 0; i < len ; i++) {
-        dest[i] = reversebytes(arr[i]);
+        dest[i] = reversebyte(arr[i]);
     }
 }
 
diff --git a/armsrc/optimized_cipherutils.h b/armsrc/optimized_cipherutils.h
index 1bef017a2..8d8a75f8c 100644
--- a/armsrc/optimized_cipherutils.h
+++ b/armsrc/optimized_cipherutils.h
@@ -57,7 +57,7 @@ int bitsLeft(BitstreamIn_t *stream);
 void push6bits(BitstreamOut_t *stream, uint8_t bits);
 void x_num_to_bytes(uint64_t n, size_t len, uint8_t *dest);
 uint64_t x_bytes_to_num(uint8_t *src, size_t len);
-uint8_t reversebytes(uint8_t b);
+uint8_t reversebyte(uint8_t b);
 void reverse_arraybytes(uint8_t *arr, size_t len);
 void reverse_arraycopy(uint8_t *arr, uint8_t *dest, size_t len);
 #endif // CIPHERUTILS_H
diff --git a/client/src/cmddata.c b/client/src/cmddata.c
index 62b824304..74d6e3262 100644
--- a/client/src/cmddata.c
+++ b/client/src/cmddata.c
@@ -276,7 +276,7 @@ int printDemodBuff(uint8_t offset, bool strip_leading, bool invert, bool print_h
     if (print_hex) {
         p = (buf + offset);
         char hex[MAX_DEMODULATION_BITS + 1] = {0x00};
-        int num_bits = binarraytohex(hex, sizeof(hex), (char *)p, len);
+        int num_bits = binarray_2_hex(hex, sizeof(hex), (char *)p, len);
         if (num_bits == 0) {
             p = NULL;
             free(buf);
@@ -3281,6 +3281,7 @@ static int CmdNumCon(const char *Cmd) {
         arg_str0(NULL,  "hex", "<hex>", "hexadecimal value"),
         arg_str0(NULL,  "bin", "<bin>", "binary value"),
         arg_lit0("i",  NULL,  "print inverted value"),
+        arg_lit0("r",  NULL,  "print reversed value"),
         arg_param_end
     };
     CLIExecWithReturn(ctx, Cmd, argtable, false);
@@ -3302,6 +3303,7 @@ static int CmdNumCon(const char *Cmd) {
     res |= CLIParamStrToBuf(arg_get_str(ctx, 3), (uint8_t *)bin, sizeof(bin), &blen);
 
     bool shall_invert = arg_get_lit(ctx, 4);
+    bool shall_reverse = arg_get_lit(ctx, 5);
     CLIParserFree(ctx);
 
     // sanity checks
@@ -3343,11 +3345,6 @@ static int CmdNumCon(const char *Cmd) {
     mbedtls_mpi_init(&base);
     mbedtls_mpi_add_int(&base, &base, 10);
 
-    if (shall_invert) {
-        PrintAndLogEx(INFO, "should invert");
-        MBEDTLS_MPI_CHK(mbedtls_mpi_inv_mod(&N, &N, &base));
-    }
-
     // printing
     typedef struct {
         const char *desc;
@@ -3365,11 +3362,53 @@ static int CmdNumCon(const char *Cmd) {
 
     for (uint8_t i = 0; i < ARRAYLEN(radix); i++) {
         MBEDTLS_MPI_CHK(mbedtls_mpi_write_string(&N, radix[i].radix, s, sizeof(s), &slen));
-        if (slen > 0) {
+        if (slen) {
             PrintAndLogEx(SUCCESS, "%s%s", radix[i].desc, s);
         }
     }
 
+    // reverse
+    if (shall_reverse) {
+        PrintAndLogEx(SUCCESS, _CYAN_("Reversed"));
+        for (uint8_t i = 0; i < ARRAYLEN(radix); i++) {
+            MBEDTLS_MPI_CHK(mbedtls_mpi_write_string(&N, radix[i].radix, s, sizeof(s), &slen));
+
+            str_reverse(s, strlen(s));
+
+            if (slen) {
+                PrintAndLogEx(SUCCESS, "%s%s", radix[i].desc, s);
+            }
+        }
+    }
+
+    // invert
+    if (shall_invert) {
+        PrintAndLogEx(SUCCESS, _CYAN_("Inverted"));
+        for (uint8_t i = 0; i < ARRAYLEN(radix); i++) {
+            MBEDTLS_MPI_CHK(mbedtls_mpi_write_string(&N, radix[i].radix, s, sizeof(s), &slen));
+            if (slen == 0) { 
+                continue;
+            }
+
+            switch(i) {
+                case 0:
+//                    MBEDTLS_MPI_CHK(mbedtls_mpi_inv_mod(&N, &N, &base));
+                    break;
+                case 1:
+                    str_inverse_hex(s, strlen(s));
+                    PrintAndLogEx(SUCCESS, "%s%s", radix[i].desc, s);
+                    break;
+                case 2:
+                    str_inverse_bin(s, strlen(s));
+                    PrintAndLogEx(SUCCESS, "%s%s", radix[i].desc, s);
+                    break;
+                default:
+                    break;
+            }
+        }
+    }
+
+
     // check if number is a prime
     mbedtls_entropy_context entropy;
     mbedtls_ctr_drbg_context ctr_drbg;
diff --git a/client/src/cmdhficlass.c b/client/src/cmdhficlass.c
index 6da027c32..340af551a 100644
--- a/client/src/cmdhficlass.c
+++ b/client/src/cmdhficlass.c
@@ -1349,7 +1349,7 @@ static int iclass_decode_credentials_new_pacs(uint8_t *d) {
     }
 
     uint8_t n = PICOPASS_BLOCK_SIZE - offset - 2;
-    byte_2_binstr(binstr, d + offset + 2, n);
+    bytes_2_binstr(binstr, d + offset + 2, n);
 
     PrintAndLogEx(NORMAL, "");
     PrintAndLogEx(SUCCESS, "PACS......... " _GREEN_("%s"), sprint_hex_inrow(d + offset + 2, n));
@@ -4562,7 +4562,7 @@ static int CmdHFiClassSAM(const char *Cmd) {
         return PM3_EMALLOC;
     }
 
-    byte_2_binstr(binstr, d + 3, n);
+    bytes_2_binstr(binstr, d + 3, n);
 
     PrintAndLogEx(NORMAL, "");
     PrintAndLogEx(SUCCESS, "PACS......... " _GREEN_("%s"), sprint_hex_inrow(d + 2, resp.length - 2));
diff --git a/client/src/cmdlft55xx.c b/client/src/cmdlft55xx.c
index e181f8667..894ad3b5d 100644
--- a/client/src/cmdlft55xx.c
+++ b/client/src/cmdlft55xx.c
@@ -1677,7 +1677,7 @@ static int CmdT55xxDangerousRaw(const char *Cmd) {
         return PM3_EINVARG;
     }
 
-    int bs_len = binstring2binarray(ng.data, (char *)bin, bin_len);
+    int bs_len = binstr_2_binarray(ng.data, (char *)bin, bin_len);
     if (bs_len == 0) {
         return PM3_EINVARG;
     }
diff --git a/client/src/fileutils.c b/client/src/fileutils.c
index d8c4afe90..a17ca625b 100644
--- a/client/src/fileutils.c
+++ b/client/src/fileutils.c
@@ -986,7 +986,7 @@ int loadFileEML_safe(const char *preferredName, void **pdata, size_t *datalen) {
         if (line[0] == '#')
             continue;
 
-        strcleanrn(line, sizeof(line));
+        str_cleanrn(line, sizeof(line));
 
         res = param_gethex_to_eol(line, 0, buf, sizeof(buf), &hexlen);
         if (res == 0) {
@@ -1059,7 +1059,7 @@ int loadFileNFC_safe(const char *preferredName, void *data, size_t maxdatalen, s
         if (line[0] == '#')
             continue;
 
-        strcleanrn(line, sizeof(line));
+        str_cleanrn(line, sizeof(line));
         str_lower(line);
 
         if (str_startswith(line, "uid:")) {
@@ -1306,7 +1306,7 @@ int loadFileMCT_safe(const char *preferredName, void **pdata, size_t *datalen) {
         if (line[0] == '+')
             continue;
 
-        strcleanrn(line, sizeof(line));
+        str_cleanrn(line, sizeof(line));
 
         res = param_gethex_to_eol(line, 0, buf, sizeof(buf), &hexlen);
         if (res == 0) {
@@ -2261,7 +2261,7 @@ nfc_df_e detect_nfc_dump_format(const char *preferredName, bool verbose) {
             return PM3_EFILE;
         }
 
-        strcleanrn(line, sizeof(line));
+        str_cleanrn(line, sizeof(line));
         str_lower(line);
 
         if (str_startswith(line, "device type: ntag")) {
diff --git a/client/src/loclass/cipherutils.h b/client/src/loclass/cipherutils.h
index 160945f0d..f3dc9d5f3 100644
--- a/client/src/loclass/cipherutils.h
+++ b/client/src/loclass/cipherutils.h
@@ -63,7 +63,7 @@ void push6bits(BitstreamOut_t *stream, uint8_t bits);
 void EncryptDES(bool key[56], bool outBlk[64], bool inBlk[64], int verbose) ;
 void x_num_to_bytes(uint64_t n, size_t len, uint8_t *dest);
 uint64_t x_bytes_to_num(uint8_t *src, size_t len);
-uint8_t reversebytes(uint8_t b);
+uint8_t reversebyte(uint8_t b);
 void reverse_arraybytes(uint8_t *arr, size_t len);
 void reverse_arraycopy(uint8_t *arr, uint8_t *dest, size_t len);
 void printarr(const char *name, uint8_t *arr, int len);
diff --git a/client/src/proxmark3.c b/client/src/proxmark3.c
index 85b85f762..00e93c6d1 100644
--- a/client/src/proxmark3.c
+++ b/client/src/proxmark3.c
@@ -223,7 +223,7 @@ main_loop(char *script_cmds_file, char *script_cmd, bool stayInCommandLoop) {
     uint16_t script_cmd_len = 0;
     if (execCommand) {
         script_cmd_len = strlen(script_cmd);
-        strcreplace(script_cmd, script_cmd_len, ';', '\0');
+        str_creplace(script_cmd, script_cmd_len, ';', '\0');
     }
     bool stdinOnPipe = !isatty(STDIN_FILENO);
     char script_cmd_buf[256] = {0x00};  // iceman, needs lua script the same file_path_buffer as the rest
@@ -312,7 +312,7 @@ check_script:
             prompt_ctx = PROXPROMPT_CTX_SCRIPTFILE;
 
             // remove linebreaks
-            strcleanrn(script_cmd_buf, sizeof(script_cmd_buf));
+            str_cleanrn(script_cmd_buf, sizeof(script_cmd_buf));
 
             cmd = str_dup(script_cmd_buf);
             if (cmd != NULL) {
@@ -354,9 +354,9 @@ check_script:
                     fromInteractive = false;
                     script_cmd = script_cmd_buf;
                     script_cmd_len = strlen(script_cmd);
-                    strcreplace(script_cmd, script_cmd_len, ';', '\0');
+                    str_creplace(script_cmd, script_cmd_len, ';', '\0');
                     // remove linebreaks
-                    strcleanrn(script_cmd, script_cmd_len);
+                    str_cleanrn(script_cmd, script_cmd_len);
                     goto check_script;
                 } else {
                     pm3line_check(check_comm);
@@ -376,9 +376,9 @@ check_script:
                         stayInCommandLoop = true;
                         fromInteractive = true;
                         script_cmd_len = strlen(script_cmd);
-                        strcreplace(script_cmd, script_cmd_len, ';', '\0');
+                        str_creplace(script_cmd, script_cmd_len, ';', '\0');
                         // remove linebreaks
-                        strcleanrn(script_cmd, script_cmd_len);
+                        str_cleanrn(script_cmd, script_cmd_len);
                         goto check_script;
                     }
                     fflush(NULL);
diff --git a/client/src/util.c b/client/src/util.c
index 205c2d32f..76a7b24ea 100644
--- a/client/src/util.c
+++ b/client/src/util.c
@@ -92,6 +92,30 @@ int kbd_enter_pressed(void) {
 }
 #endif
 
+static char inv_b2s(char v, bool uppercase) {
+
+    if (isxdigit(v) == 0) {
+        return '.';
+    }
+
+    uint8_t lut[] = {
+        'f', 'e', 'd', 'c',
+        'b', 'a', '9', '8',
+        '7', '6', '5', '4',
+        '3', '2', '1', '0'
+    };
+    
+    uint8_t tmp = (tolower(v) - 'a' + 10);
+    if (isdigit(v)) {
+        tmp = (v - 0x30);
+    }
+
+    if (uppercase)
+        return toupper(lut[tmp]);
+    else 
+        return lut[tmp];
+}
+
 static char b2s(uint8_t v, bool uppercase) {
     // clear higher bits
     v &= 0xF;
@@ -938,12 +962,12 @@ int hextobinstring_n(char *target, char *source, int sourcelen) {
     if (length == 0) {
         return 0;
     }
-    binarraytobinstring(target, target, length);
+    binarray_2_binstr(target, target, length);
     return length;
 }
 
 // convert bytes to binary string
-void byte_2_binstr(char *target,  const uint8_t *source, size_t sourcelen) {
+void bytes_2_binstr(char *target,  const uint8_t *source, size_t sourcelen) {
     //uint8_t *p = *source;
     for (int i = 0 ; i < sourcelen; ++i) {
         uint8_t b = *(source++);
@@ -961,7 +985,7 @@ void byte_2_binstr(char *target,  const uint8_t *source, size_t sourcelen) {
 
 // convert binary array of 0x00/0x01 values to hex
 // return number of bits converted
-int binarraytohex(char *target, const size_t targetlen, const char *source, size_t srclen) {
+int binarray_2_hex(char *target, const size_t targetlen, const char *source, size_t srclen) {
     uint8_t i = 0, x = 0;
     uint32_t t = 0; // written target chars
     uint32_t r = 0; // consumed bits
@@ -1007,14 +1031,14 @@ int binarraytohex(char *target, const size_t targetlen, const char *source, size
 }
 
 // convert binary array to human readable binary
-void binarraytobinstring(char *target, char *source,  int length) {
+void binarray_2_binstr(char *target, char *source,  int length) {
     for (int i = 0 ; i < length; ++i) {
         *(target++) = *(source++) + '0';
     }
     *target = '\0';
 }
 
-int binstring2binarray(uint8_t *target, char *source, int length) {
+int binstr_2_binarray(uint8_t *target, char *source, int length) {
     int count = 0;
     char *start = source;
     while (length--) {
@@ -1171,13 +1195,13 @@ void clean_ascii(unsigned char *buf, size_t len) {
 }
 
 // replace \r \n to \0
-void strcleanrn(char *buf, size_t len) {
-    strcreplace(buf, len, '\n', '\0');
-    strcreplace(buf, len, '\r', '\0');
+void str_cleanrn(char *buf, size_t len) {
+    str_creplace(buf, len, '\n', '\0');
+    str_creplace(buf, len, '\r', '\0');
 }
 
 // replace char in buffer
-void strcreplace(char *buf, size_t len, char from, char to) {
+void str_creplace(char *buf, size_t len, char from, char to) {
     for (size_t i = 0; i < len; i++) {
         if (buf[i] == from)
             buf[i] = to;
@@ -1208,6 +1232,34 @@ size_t str_nlen(const char *src, size_t maxlen) {
     return len;
 }
 
+void str_reverse(char *buf,  size_t len) {
+    for (size_t i = 0; i < (len>>1); i++) {
+        char tmp = buf[i];
+        buf[i] = buf[len - i - 1];
+        buf[len - i - 1] = tmp;
+    }
+}
+
+void str_inverse_hex(char *buf, size_t len) {
+   for (size_t i = 0; i < len; i++) {
+        buf[i] = inv_b2s(buf[i], true);
+    }
+}
+
+void str_inverse_bin(char *buf, size_t len) {
+    for (size_t i = 0; i < len; i++) {
+
+        char c = buf[i];
+        if (c == '1')
+            buf[i] = '0';
+        else if ( c == '0')
+            buf[i] = '1';
+        else 
+            buf[i] = '.';
+    }
+}
+
+
 /**
  * Converts a hex string to component "hi2", "hi" and "lo" 32-bit integers
  * one nibble at a time.
diff --git a/client/src/util.h b/client/src/util.h
index 1d6df987d..1949c1d53 100644
--- a/client/src/util.h
+++ b/client/src/util.h
@@ -117,11 +117,11 @@ int hextobinarray_n(char *target, char *source, int sourcelen);
 int hextobinstring(char *target, char *source);
 int hextobinstring_n(char *target, char *source, int sourcelen);
 
-int binarraytohex(char *target, const size_t targetlen, const char *source, size_t srclen);
-void binarraytobinstring(char *target,  char *source, int length);
-int binstring2binarray(uint8_t *target, char *source, int length);
+int binarray_2_hex(char *target, const size_t targetlen, const char *source, size_t srclen);
+void binarray_2_binstr(char *target,  char *source, int length);
+int binstr_2_binarray(uint8_t *target, char *source, int length);
 
-void byte_2_binstr(char *target,  const uint8_t *source, size_t sourcelen);
+void bytes_2_binstr(char *target,  const uint8_t *source, size_t sourcelen);
 void binstr_2_bytes(uint8_t *target, size_t *targetlen, const char *src);
 
 uint8_t GetParity(const uint8_t *bits, uint8_t type, int length);
@@ -143,8 +143,12 @@ void strn_upper(char *s, size_t n);
 bool str_startswith(const char *s,  const char *pre);  // check for prefix in string
 bool str_endswith(const char *s,  const char *suffix);    // check for suffix in string
 void clean_ascii(unsigned char *buf, size_t len);
-void strcleanrn(char *buf, size_t len);
-void strcreplace(char *buf, size_t len, char from, char to);
+void str_cleanrn(char *buf, size_t len);
+void str_creplace(char *buf, size_t len, char from, char to);
+void str_reverse(char *buf,  size_t len);
+void str_inverse_hex(char *buf, size_t len);
+void str_inverse_bin(char *buf, size_t len);
+
 char *str_dup(const char *src);
 char *str_ndup(const char *src, size_t len);
 size_t str_nlen(const char *src, size_t maxlen);