Adding support for reading encryption/key password from a file descriptor.

* Added tests to the test suite.
 * Updated the usage message.
 * Fixed the password functions.

reference : mrash/fwknop#74

client/utils.h

@@ -48,6 +48,9 @@
 
 #define PROTOCOL_BUFSIZE    16      /*!< Maximum number of chars for a protocol string (TCP for example) */
 
+#define FD_INVALID          -1
+#define FD_IS_VALID(x)      ((x)>=0)
+
 /* Prototypes
 */
 void    hex_dump(const unsigned char *data, const int size);