+static int hex2num(char c)
+{
+ if (c >= '0' && c <= '9')
+ return c - '0';
+
+ c = toupper(c);
+ if (c >= 'A' && c <= 'F')
+ return c - 'A' + 10;
+
+ return -1;
+}
+
+static int hex2byte(const char *hex)
+{
+ int a, b;
+
+ a = hex2num(*hex++);
+ if (a < 0)
+ return -1;
+
+ b = hex2num(*hex++);
+ if (b < 0)
+ return -1;
+
+ return (a << 4) | b;
+}
+
+static int hexstr2bin(const char *hex, char *buffer, int len)
+{
+ const char *ipos = hex;
+ char *opos = buffer;
+ int i, a;
+
+ for (i = 0; i < len; i++) {
+ a = hex2byte(ipos);
+ if (a < 0)
+ return -1;
+
+ *opos++ = a;
+ ipos += 2;
+ }
+
+ return 0;
+}
+
+static bool convert_message(struct blob_attr *attr)
+{
+ char *data;
+ int len;
+
+ if (!attr)
+ return true;
+
+ data = blobmsg_data(attr);
+ len = strlen(data);
+ if (len % 2)
+ return false;
+
+ return !hexstr2bin(data, data, len / 2);
+}
+