The ctype functions are error prone. The argument is an int which must
be in the range of an unsigned char and is interpreted based on the
locale:
These functions check whether c, which must have the value of
an unsigned char or EOF, falls into a certain character class
according to the specified locale. The functions without the
"_l" suffix perform the check based on the current locale.
Optionally base64 encode data sent to and from a conference, allowing
transfer of binary data.
This could also be accomplished by piping in base64 encoded data:
base64 /bin/ls | xmppipe
However the base64 command does not work with streams of data.