bool
    silc_channel_name_check(const unsigned char *identifier,
                            SilcUInt32 identifier_len,
                            SilcStringEncoding identifier_encoding,
                            SilcUInt32 max_allowed_length);

    Checks that the 'identifier' string is valid channel name string
    and does not contain any unassigned or prohibited character.

    If the 'max_allowed_length' is non-zero the identifier cannot be
    longer than that, and NULL is returned if it is.  If zero (0), no
    length limit exist.  For channel names the max length must be 256
    bytes.

    Returns TRUE if the string is valid and FALSE if it is prohibited.