ircII in WebAssembly

Introduction

ircII is a free, open-source Unix IRC and ICB client written in C. Initially released in the late 1980s, it is the oldest IRC client still maintained. Wikipedia.

This limited emulation of ircII in WebAssembly demonstrates the use of POSIX standard and similar libraries such as ncurses within the Emscripten environment.

Advantages of this technology can be found if ncurses' output, which is accessible via Emscripten's Standard I/O API, could work inline with Progressive Web Applications (PWAs) and relay screen dimensions dynamically. Further, both ircII and ncurses compile sizes are fairly large meaning optimisations to reduce compile output is needed.

Furthermore, help files and other extended parts of this emulation such as DCC may not work, however, makes the client fun to tinker with as it functions as a working IRC client.

Installation

Important Note: This build of ircII depends on ncurses for Emscripten, see jamesbiv/ncurses-emscripten to compile and build your own copy or you can use what's stored in the build/ directory. Further, be sure to have the absolute path of the build/ directory handy to replace the areas marked PATH_TO_NCURSES throughout the below compilation process.

It's recommended to create a separate directory to build this project in. For example ircii-emscripten/.

Downloading the required files

~$ wget http://ircii.warped.com/ircii-20190117.tar.gz

~$ wget https://raw.githubusercontent.com/jamesbiv/ircii-emscripten/master/ircii-20190117_emscripten.patch

~$ wget https://raw.githubusercontent.com/jamesbiv/ircii-emscripten/master/irc_shell.html

Extracting and patching ircII

~$ tar -zxvf ircii-20190117.tar.gz

Note: Because this is a source tree level patch make sure the patch is in the directory before the installed directory. For example, if the directory for ircii is /home/user/ircii-emscripten/ircii-20190117 then make sure the patch is located at /home/user/ircii-emscripten/ircii-20190117_emscripten.patch.

~$ patch -p0 < ircii-20190117_emscripten.patch

~$ cd ircii-20190117

Change configure

~$ nano -w ./configure

Comment out the following line of code using # to reflect the following:

Line 696
#with_openssl

Save and close nano

Configure and make the Emscripten components

Note: Be sure to replace PATH_TO_NCURSES with the absolute path to the ncurses for emscripten build/ directory.

~$ export CPPFLAGS='-IPATH_TO_NCURSES/include'

~$ export LDFLAGS='-LPATH_TO_NCURSES/lib'

~$ emconfigure ./configure

Change Makefile

~$ nano -w ./Makefile

Line 81
Remove -lssl -lcrypto from LIBS = ... 

Note: Be sure to replace PATH_TO_NCURSES with the absolute path to the ncurses for emscripten build/ directory.

Line 320
Add (append) -IPATH_TO_NCURSES/include to the end of INCLUDES = -I ...

Save and close nano

Change defs.h

~$ nano -w ./defs.h

Change the following segments to reflect the following:

Line 44
/* #undef HAVE_GETNAMEINFO */

To

Line 44
#define HAVE_GETNAMEINFO 1

Change

Line 119
#define HAVE_SYS_FCNTL_H 1

To

Line 119
/* #undef HAVE_SYS_FCNTL_H */

Change

Note: NON_BLOCKING_CONNECTS should be declared but it's best to check it anyway.

Line 180
/* #undef NON_BLOCKING_CONNECTS */

To

Line 180
#define NON_BLOCKING_CONNECTS 1

Change

Line 221
#define USE_OPENSSL 1

To

Line 221
/* #undef USE_OPENSSL */

Save and close nano

Make irc

~$ emmake make irc

~$ cp irc ../irc.bc

~$ cd ..

Final build

Note: Be certain to include the terminfo database files with --preload-file. You can just include the file(s) that you need or include them all but you'll save about 3MB if you strip them down to the ones you just need, in this case we're using xterm-new.

Note: Be sure to replace PATH_TO_NCURSES with the absolute path to the ncurses for emscripten build/ directory.

emcc -o irc.html irc.bc -O3 -g2 --preload-file PATH_TO_NCURSES/share/terminfo@/home/web_user/.terminfo -s WASM=1 -s FORCE_FILESYSTEM=1 --shell-file ./irc_shell.html -s EMTERPRETIFY=1 -s EMTERPRETIFY_ASYNC=1 -s EMTERPRETIFY_WHITELIST='["_main", "_irc_io"]' -s TOTAL_MEMORY=32Mb --no-heap-copy -s ASSERTIONS=1

Installing XTerm.js

Xterm.js is a great library that emulates a terminal very quickly and works well with ncurses.

You'll need to download a copy from xtermjs/xterm.js or you can use the .min versions that I have uploaded on the demo site.

Socket Setup - WebSockets

In order to connect to a working IRC server you’ll need to use something like WebSockify. Ideally WebSocket support for IRCD would be great but for now this does the job fine.

Note: I suggest if you're using WebSockify filter the incoming port from the public as some IRC networks / servers may have proxy protection and will ban you from their server(s) if discovered.

Demo Site

Please see http://68.183.3.42/ircii-emscripten/irc.html for a working demo.

Final Considerations

IrcII for Emscripten was a fun project and opens up many possibilities and areas for improvement. Should a future project arise from this patch level I believe forking and customising the current ircii build would be the best scenario.

Also, since Emscripten relies on WebSockets to handle communications disabling OpenSSL at a C level is required. TLS/SSL communications are evoked using wss:// as the WebSocket connection string.

Further, since Emscripten's WebSockets use binary protocol this also needs to be enabled on the service acting as the server.