Files
sync_replay_project/docs/PROTOCOL.md
T
foxyzandClaude Opus 5.5 45f4c1bc84 Jellyfin refs on the wire + guest relay (proto 7)
- Media can be a Jellyfin ref {serverId, itemId, mediaSourceId, title,
  subtitle, runtimeSecs}; the server never stores or broadcasts a URL
  or token for it.
- Optional server-side Jellyfin credential (serve map / --jellyfin
  file) enables GET /j/<sid>/<token>/<itemId>: range-faithful proxy of
  the active item only, exact client header fields, upstream aborted on
  disconnect, bytes counted. welcome.relayUrl / state.relay advertise it.
- Members report jf access (own account vs relay).
- /m now sends the real Content-Type (Relic overrode it).

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
2026-10-07 01:57:04 +03:00

170 lines
8.8 KiB
Markdown

# Protocol (proto = 7)
Wire format only. Behavior (gate, clock, timeouts) is in
[ARCHITECTURE.md](ARCHITECTURE.md). Source of truth:
`packages/core/lib/src/protocol.dart` and `packages/server/lib/src/server_hub.dart`.
Any wire change bumps `RelayConstants.protoVersion` and edits this file in
the same commit. Changes are additive where possible; a client and server
with different `proto` refuse each other at `hello` (`proto mismatch`).
## Transport
- WebSocket at `/sync`, JSON text frames, each an object with a `t` field.
- The first client frame must be `hello` within 10 s. Server pings every 5 s.
- Match incoming frames by `t`, never by order: `welcome` can race `state`.
- Failures: server sends `{"t":"err","message":...}` and closes.
Messages: `bad hello: ...`, `proto mismatch: got X, want Y`, `wrong secret`,
`rejected: <reason>` (e.g. avatar too large), `bad message: ...` (a frame
with a non-finite number, e.g. NaN position), `bad swap media`,
`swap needs a url or the hosted file` (empty swap).
- `GET /health` returns JSON (`ok`, `name`, `proto`, `viewers`, `bytesServed`,
`uptimeSecs`; unauthenticated). `GET /m/<sid>/<token>/<name>`
serves the host's file (Range table in ARCHITECTURE.md).
`GET /j/<sid>/<token>/<itemId>` relays the current Jellyfin media (see
"Jellyfin media" below).
## Client to server
```
{"t":"hello","proto":7,"secret":"","user":{"name":"","avatar":""},
"media":{"name":"","size":0,"duration":0,"url":null},"hostKey":"...",
"resume":"<token>"}
{"t":"ready","ready":true,"source":"manual"} source: manual | auto
{"t":"force","target":"all"|"<memberId>","ready":true}
{"t":"seek","position":123.4,"seq":3}
{"t":"swap","media":{"name":"","size":0,"duration":0,"url":"..."}}
{"t":"swap","media":{"name":"","size":0,"duration":0,"jellyfin":{<ref>}}}
{"t":"report","position":123.1,"buffered":6.2,"eventId":41,
"duration":1440.5,"mediaId":2,"jf":{"<serverId>":true}}
{"t":"ping","c":1767225600000}
{"t":"chat","text":"..."}
{"t":"kick","target":"<memberId>","reason":""}
```
Field notes:
- `hello.secret`: the server password; a server with an empty secret is open.
`hello.media` is carried but not used by the server today.
- `hello.hostKey` (optional, omitted when empty): the hosting app
generates a random key per hosting, gives it to its server and sends it
from its own client. The member whose key equals the server's is the host
and cannot be kicked. A server without a key (the dedicated server) has no
host. Where the connection comes from does not matter.
- `hello.resume` (optional, omitted when empty): the token from this
client's previous `welcome`, sent on reconnect. If the server still has
that member and it is not kicked, the connection takes it over: `welcome`
returns the same `token` and `memberId`, the member keeps its flags, and
there is no `join`/`leave` feed. Otherwise it is ignored and a new member
joins.
- `seek.seq` (optional, default 0): increasing per client; echoed in
`state.seekSeq` so the sender recognises its own seek.
- `report.duration` / `report.mediaId` (optional, omitted when 0): the open
media's length in seconds and the `mediaId` it belongs to. The server takes
the first one whose `mediaId` is current while its media duration is 0.
- `report.jf` (optional): Jellyfin access per `ServerId`, `true` = this
client plays the item with its own account, `false` = through the relay.
Sticky: a report without `jf` keeps the last one. At most 8 entries, keys
up to 64 characters; others are dropped.
- `ping.c`: the client's clock in epoch ms; answered with `pong`.
- `user.avatar`: base64 image, at most 256 KiB of characters. `name` is
trimmed, empty becomes `?`, cut to 32 characters.
- `chat.text` is cut to 500 characters.
- `swap.media.url` is the link; `name`, `size`, `duration` are informational.
`swap.media.jellyfin` makes it Jellyfin media (see below); then `url` is
dropped.
- Frames before `welcome` (other than `hello`) are ignored; unparsable or
unknown frames are ignored silently.
## Server to client
```
{"t":"welcome","token":"...","memberId":"m1","mediaUrl":"...","relayUrl":"...",
"state":{<state>}}
{"t":"state","eventId":7,"transport":"playing"|"held"|"finished","position":12.3,
"serverTime":"<ISO-8601 UTC>","mediaId":1,
"media":{name,size,duration,url?,jellyfin?}|absent,
"members":[{"id","name","avatar","ready","inSet","buffered","stale","jf"?}],
"seekBy":"m1","seekSeq":3,"relay":true}
{"t":"pong","c":1767225600000,"s":1767225600012}
{"t":"feed","actor":"","action":"","target":"","reason":"","at":"<ISO-8601>"}
{"t":"chat","text":"...","from":"<name>"}
{"t":"kicked","reason":""}
{"t":"err","message":""}
```
- `welcome.token` is private to its owner and appears only in that member's
media URL. `mediaUrl` is omitted when there is no media; it is a built
`/m/...` URL for a host file (host part = what the client dialled), otherwise
the shared link.
`welcome.state` has the same shape as `state`. `relayUrl` is present only
when `state.relay` is: this member's `/j/...` URL for the current
Jellyfin media (private like `token`).
- `state` is sent every second and on every change. `position` is the value at
`serverTime` (server clock); clients extrapolate while `transport` is
`playing`, on the server's clock (see `pong`). `finished`: the media
reached its end (`position` = duration); it stays until a seek or swap.
`eventId` increases on seek, swap and transport changes.
`mediaId` increases on swap. `media.duration` is 0 until a client reports
it. `seekBy` (member id) and `seekSeq` are present only while the current
`eventId` came from a seek. `relay` (omitted when false): the server can
relay the current Jellyfin media. `members[].jf` is the member's last
`report.jf`, omitted when it never sent one.
- `pong.c` echoes the ping's `c`; `pong.s` is the server's clock in epoch ms
(the clock `serverTime` uses). With `t3` the local receive time, the offset
is `s - (c + t3) / 2`, accurate to half the round trip.
- `feed.action` values: `ready`, `unready`, `force-ready`, `force-unready`,
`force-play`, `force-hold`, `kick`, `join`, `leave`, `stale`, `swap`,
`seek`, `pause`, `resume`, `finished`, `chat`. `target` and `reason` are optional;
`reason` carries `auto`/`manual` for ready and `silent too long` or
`no signal` for leave/stale.
- Chat is delivered twice: a `chat` frame with the text and a textless
`feed` with `action:"chat"`. Render the `chat` frame only; the reference
client drops the textless feed entry.
## Jellyfin media
```
<ref> = {"serverId":"<Jellyfin ServerId>","itemId":"<32 hex>",
"mediaSourceId":"...","title":"Pilot","subtitle":"Show - S01E01",
"runtimeSecs":1440.5}
```
- `serverId`, `itemId` required; `mediaSourceId`, `subtitle`, `runtimeSecs`
optional (omitted when absent); `title` always sent (may be empty).
`runtimeSecs` is informational: the sync clock still uses the duration a
client reports.
- The server keeps only the ref: for Jellyfin media no URL or token is stored
or broadcast (a `url` sent along is dropped). `serverId`, `itemId` and
`mediaSourceId` must match `[A-Za-z0-9-]{1,64}`, otherwise `bad swap media`.
`media.name` is the swap's name, else the ref's `title`; names are
sanitized like link names.
- Each client resolves the ref with its own account on that server. A client
without one plays the relay URL when `state.relay` is true: `welcome.relayUrl`,
or after a swap built like the `/m` one from the host it dialled:
`http://<host>/j/default/<token>/<itemId>`.
- `GET /j/<sid>/<token>/<itemId>`: the server fetches
`/Videos/<itemId>/stream?static=true&mediaSourceId=<id>` (the original
file) with its own credential and streams it through. `Range` is forwarded
as sent; status, `Content-Range`, `Content-Length`, `Content-Type` and
`Accept-Ranges` come back as Jellyfin sent them. Errors: 401 bad token,
403 kicked or not the current item, 404 no relay for the current media,
410 unknown session, 502 Jellyfin unreachable or rejecting the server's
credential. Bytes count toward `bytesServed`.
- Pasted Jellyfin links sent as plain `url` stay plain links.
## Join and reconnect
`hello` then `welcome`, then the app opens `mediaUrl`, seeks to the server
position and buffers. A joining member is `ready=false, inSet=false` until
the first `ready`. A socket the server sees close loses its token; reconnect
is a fresh `hello` (with `resume` = the old token), after which the client
re-sends its prior ready flag. If the old member was still there (unclean
drop), `resume` takes it over and the token and media URL stay the same.
## Reserved, not implemented
Server-held queue (`queue-add`, `queue-skip`) would auto-advance like a swap.
`RelayConstants.chunkBytes`, `creditWindowChunks`, `maxConcurrentOpen` and the
`open`, `ack`, `cancel`, `eof`, `buffered`, `state`, `event` kinds in
`MessageKind` are unused leftovers (the `state` frame does not use the enum).