tests/net/nanocoap_cli: allow specifying the token

This adds the client_token shell command that allows to specify the
CoAP Token. This is particularly useful to test extended length Tokens,
as enabled with module `nanocoap_token_ext`.

tests/net/nanocoap_cli/nanocli_client.c

@@ -80,6 +80,14 @@ static ssize_t _send(coap_pkt_t *pkt, size_t len,
     return nanocoap_request(pkt, NULL, &remote, len);
 }
 
+#if MODULE_NANOCOAP_TOKEN_EXT
+#  define CLIENT_TOKEN_LENGTH_MAX   16
+#else
+#  define CLIENT_TOKEN_LENGTH_MAX   COAP_TOKEN_LENGTH_MAX
+#endif
+static uint8_t _client_token[CLIENT_TOKEN_LENGTH_MAX] = {0xDA, 0xEC};
+static uint8_t _client_token_len = 2;
+
 static int _cmd_client(int argc, char **argv)
 {
     /* Ordered like the RFC method code numbers, but off by 1. GET is code 0. */
@@ -88,7 +96,6 @@ static int _cmd_client(int argc, char **argv)
     uint8_t buf[buflen];
     coap_pkt_t pkt;
     size_t len;
-    uint8_t token[2] = {0xDA, 0xEC};
 
     if (argc == 1) {
         /* show help for commands */
@@ -109,7 +116,8 @@ static int _cmd_client(int argc, char **argv)
 
     /* parse options */
     if (argc == 5 || argc == 6) {
-        ssize_t hdrlen = coap_build_hdr(pkt.hdr, COAP_TYPE_CON, &token[0], 2,
+        ssize_t hdrlen = coap_build_hdr(pkt.hdr, COAP_TYPE_CON,
+                                        _client_token, _client_token_len,
                                         code_pos+1, 1);
         coap_pkt_init(&pkt, &buf[0], buflen, hdrlen);
         coap_opt_add_string(&pkt, COAP_OPT_URI_PATH, argv[4], '/');
@@ -164,9 +172,69 @@ static int _cmd_client(int argc, char **argv)
            argv[0]);
     return 1;
 }
-
 SHELL_COMMAND(client, "CoAP client", _cmd_client);
 
+static bool _get_nibble(uint8_t *dest, char _c)
+{
+    uint8_t c = _c;
+    if (((uint8_t)'0' <= c) && (c <= (uint8_t)'9')) {
+        *dest = c - (uint8_t)'0';
+        return true;
+    }
+
+    if (((uint8_t)'a' <= c) && (c <= (uint8_t)'f')) {
+        *dest = c - (uint8_t)'a' + 10;
+        return true;
+    }
+
+    if (((uint8_t)'A' <= c) && (c <= (uint8_t)'F')) {
+        *dest = c - (uint8_t)'A' + 10;
+        return true;
+    }
+
+    return false;
+}
+
+static int _cmd_client_token(int argc, char **argv){
+    if (argc != 2) {
+        printf("Usage: %s <TOKEN_HEX>\n", argv[0]);
+        return 1;
+    }
+
+    size_t len = strlen(argv[1]);
+    if (len & 1) {
+        puts("Token invalid: Must be an even number of hex chars");
+        return 1;
+    }
+
+    if (len > 2 * sizeof(_client_token)) {
+        printf("Token too long (%u B, but max is %u B)\n",
+               (unsigned)(len / 2), (unsigned)sizeof(_client_token));
+        return 1;
+    }
+
+    _client_token_len = len / 2;
+
+    for (size_t pos = 0; pos < _client_token_len; pos++) {
+        uint8_t high, low;
+        if (!_get_nibble(&high, argv[1][pos << 1])) {
+            puts("Token invalid: Must be given in hex");
+            return 1;
+        }
+
+        if (!_get_nibble(&low, argv[1][(pos << 1) + 1])) {
+            puts("Token invalid: Must be given in hex");
+            return 1;
+        }
+
+        _client_token[pos] = (high << 4) | low;
+    }
+
+    return 0;
+}
+SHELL_COMMAND(client_token, "Set Token for CoAP client", _cmd_client_token);
+
+
 static int _blockwise_cb(void *arg, size_t offset, uint8_t *buf,
                          size_t len, int more)
 {