SDL2_net emscripten

Question

I try use https://github.com/emscripten-ports/SDL2_net in my crossplatform project wrriten in c++ but when I try open TCP socket by SDLNet_TCP_Open() then function return error "Couldn't connect to remote host" but server is okey, desktop and mobile clients works fine.

Firstly I test generated .js and .html by emscripten as local in browser with url C:/[PATH TO generated.html]/, but I thought that locally I don't have Permission ((as it is in the android, I have same error, then I wrote in manifest request for permission after...working )) but when I upload my client to http-server, error still exists.

Someone have any idea ?

EDIT. I try with -s USE_SDL_NET=2

Note

SDL_net has also been added to ports, use it with -s USE_SDL_NET=2. To see a list of all available ports, run emcc --show-ports.

from https://kripken.github.io/emscripten-site/docs/compiling/Building-Projects.html

but I got error:

WARNING:root:Assigning a non-existent settings attribute "USE_SDL_NET"
WARNING:root: - did you mean one of USE_SDL_TTF, USE_SDL, USE_SDL_IMAGE?
WARNING:root: - perhaps a typo in emcc's  -s X=Y  notation?
WARNING:root: - (see src/settings.js for valid values)

emcc --show-ports, return:

Available ports:
    zlib (USE_ZLIB=1; zlib license)
    libpng (USE_LIBPNG=1; zlib license)
    SDL2 (USE_SDL=2; zlib license)
    SDL2_image (USE_SDL_IMAGE=2; zlib license)
    ogg (USE_OGG=1; zlib license)
    vorbis (USE_VORBIS=1; zlib license)
    bullet (USE_BULLET=1; zlib license)
    freetype (USE_FREETYPE=1; freetype license)
    SDL2_ttf (USE_SDL_TTF=2; zlib license)

EDIT2.

I download from https://github.com/jbaicoianu/emscripten/tree/c46b429ede3f5e015fe3e460867e225c3e45ae95

embuilder.py, sdl-net.py, __init__py and inject to my emscripten next, build process has successfully without upper mentioned problem. But main problem still exists... I've got "Couldn't connect to remote host" error.

Cheers, Luke

Are you sure that you know what you are doing? How would raw TCP/UDP sockets work in the browser? — mostruash
This is not raw socket as is in desktop, code is interpreted by Emscripten builder and emscripten have ported/mapped Unix socket.h((probably to HTML5 WebSocket)), SDL_net based on winsock for windows and socket.h from unix group to non-wnd system. By the way, UDP sockets are not supported. — Łukasz Mleczko
But your server is a raw TCP server right? Because websockets are totally different from raw TCP sockets. It first makes an HTTP request, than upgrades that HTTP connection to a websocket. So it has its own protocol. Does your server handle websockets? That's all assuming SDL is really ported for browser websockets. — mostruash
No server is not RAW such as socket.h or winsock is created on this library so it is should be compatible. When you enter to kripken.github.io/emscripten-site/docs/compiling/… , lower is writen SDL_net has also been added to ports. It is ported :D — Łukasz Mleczko

jsaak jsaak · Accepted Answer · 2016-07-12T18:16:15

A browser can not initiate plain old TCP. It uses websockets, which is basically just a handshake. When all is well, they upgrade the connection to plain old TCP.

Use a tcp -> websocket gateway such us websockify

Edit: I am wrong about plain old tcp, websocket is a different protocol over TCP, but websockify can translate.

SDL2_net emscripten

1 Answers