Contributions to this page are welcome!
Plain BSD sockets work, and they are the right place to start. The TV also ships libcurl, OpenSSL and SDL2_net. Check Can I Use for the version on your target.
Warning
Do not link the system OpenSSL. It crosses four SONAMEs between webOS 1 and webOS 11, so a binary linked against one will not start on a TV carrying another. Cryptography covers the spread and the ways out.
Choose a Library
Sockets
The TV runs Linux, so the usual BSD socket calls are there and behave normally. For a protocol you are implementing yourself, this is the answer. Reach for a library when it buys you something, not by default.
libcurl
Present since webOS 1, and the version moves without breaking the ABI. One wrinkle:
before webOS 5, webOS
shipped libcurl as libcurl.so.5
instead of libcurl.so.4.
A shim carries you across that boundary. moonlight-tv ships one at
third_party/commons/platform/webos/curl-abi-fix. It holds no code, only a DT_NEEDED
entry:
- Build an empty library named for the SONAME the TV has, and link it against the real libcurl.
- Build a second empty library named for the SONAME your app links, and link that against the first.
- Ship the second library with your app.
Your app asks for libcurl.so.4, finds the shim you shipped, and the shim pulls in the
system libcurl.so.5. Link curl the normal way and forget the boundary is there. The same
shape of trick works for any library that only changed its SONAME.
OpenSSL
See Cryptography.
SDL2_net
libSDL2_net-2.0.so.0 is on every release, but it is a thin wrapper over the same sockets.
Its selling point is portability, which buys you nothing on a target that is only ever a
TV. Use it if your code already leans on SDL elsewhere. Otherwise skip it.
Discover Devices on the Network
mDNS is the usual answer, and the TV's own client is not it.
libavahi-client shows up from webOS 4 on, and is missing from every release before that.
Where it is present it does not work well enough to build on, so treat the TV as having no
mDNS client and link your own into the app.
moonlight-tv takes that route. It carries
libmicrodns in third_party/, with a
libdns_sd path beside it as a second option.