[GUACAMOLE-278] Add support for xterm's 256-color control codes

• Type: Improvement
• Status: Resolved
• Priority: Major
• Resolution: Done
• Fix Version/s: 0.9.13-incubating
• Component/s: SSH, Telnet, Terminal
• Assignee: Mike Jumper
• Reporter: Mike Jumper
• Created: 23/Apr/17 20:22
• Updated: 08/May/17 05:30
• Resolved: 08/May/17 05:30

Description

Guacamole currently only supports 16 colors in its terminal, whereas xterm and its various other modern derivatives all support 256+ colors, as well as arbitrary RGB colors. This support should be added to the Guacamole terminal, such that applications needing 256 colors have console codes to work with.

xterm's 256-color codes are defined at http://invisible-island.net/xterm/ctlseqs/ctlseqs.html. There are code sequences which apply:

• Set foreground to RGB color: CSI 38 ; 2 ; R ; G ; B
• Set foreground to 256-color palette index N: CSI 38 ; 5 ; N
• Set background to RGB color: CSI 48 ; 2 ; R ; G ; B
• Set background to 256-color palette index N: CSI 48 ; 5 ; N

There is an additional OSC sequence for redefining the 256-color palette, but that can probably be omitted for now. We have similarly omitted the Linux-specific console code for redefining the 16-color palette, even though we otherwise aim to support the same control sequences as the Linux console.

Issue Links

• is part of: GUACAMOLE-277 Achieve compatibility with xterm