Bug: Telnet control character arrays are of the wrong type.
Danger: Low - May or may not be interfering with the use of the telnet IAC command.
Found by: Bobo
Fixed by: David/Samson

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comm.c

Locate:

const char echo_off_str[] = { ( char )IAC, ( char )WILL, TELOPT_ECHO, '\0' };
const char echo_on_str[] = { ( char )IAC, ( char )WONT, TELOPT_ECHO, '\0' };
const char go_ahead_str[] = { ( char )IAC, ( char )GA, '\0' };

Replace with:

const unsigned char echo_off_str[] = { IAC, WILL, TELOPT_ECHO, '\0' };
const unsigned char echo_on_str[] = { IAC, WONT, TELOPT_ECHO, '\0' };
const unsigned char go_ahead_str[] = { IAC, GA, '\0' };

In new_descriptor, locate:

   write_to_buffer( dnew, will_compress2_str, 0 );

Change to:

   write_to_buffer( dnew, (const char *)will_compress2_str, 0 );

In flush_buffer, locate:

         write_to_buffer( d, go_ahead_str, 0 );

Change to:

         write_to_buffer( d, (const char *)go_ahead_str, 0 );

In nanny_get_name, locate:

      write_to_buffer( d, echo_off_str, 0 );

Change to:

      write_to_buffer( d, (const char *)echo_off_str, 0 );

In nanny_get_old_password, locate:

   write_to_buffer( d, echo_on_str, 0 );

Change to:

   write_to_buffer( d, (const char *)echo_on_str, 0 );

In nanny_confirm_new_password, locate:

   write_to_buffer( d, echo_on_str, 0 );

Change to:

   write_to_buffer( d, (const char *)echo_on_str, 0 );

mccp.c

Locate:

char will_compress2_str[] = { ( char )IAC, ( char )WILL, TELOPT_COMPRESS2, '\0' };
char start_compress2_str[] = { ( char )IAC, ( char )SB, TELOPT_COMPRESS2, ( char )IAC, ( char )SE, '\0' };

Change to:

const unsigned char will_compress2_str[] = { IAC, WILL, TELOPT_COMPRESS2, '\0' };
const unsigned char start_compress2_str[] = { IAC, SB, TELOPT_COMPRESS2, IAC, SE, '\0' };

In compressStart, locate:

   write_to_descriptor( d, start_compress2_str, 0 );

Change to:

   write_to_descriptor( d, (const char *)start_compress2_str, 0 );

mccp.h

Locate:

extern char will_compress2_str[];
extern char start_compress2_str[];

Change to:

extern const unsigned char will_compress2_str[];
extern const unsigned char start_compress2_str[];

Telnet opt codes exist in the high range of an unsigned char. The arrays as defined were set up as signed chars, and therefore it was entirely possible the values could be interpreted wrong when assigned.

This was originally reported here: http://www.gammon.com.au/forum/?id=10662