Module media_server 

A loopback HTTP server for locally downloaded media.

Tauri’s built-in asset protocol cannot serve a downloaded film to the webview. Its response to a request without a Range header reads the whole file into a Vec<u8>, and it only advertises Accept-Ranges: bytes from inside the range branch — so the first request never learns ranges are available and a multi-gigabyte body is attempted instead. Chromium abandoned it with PIPELINE_ERROR_READ after ~31s, which reached the user as “downloaded video does not play offline”.

Serving over real HTTP on 127.0.0.1 rather than a custom URI scheme is deliberate: it makes range support a property of the transport instead of depending on whether a platform’s webview forwards Range to a custom scheme, which differs between Android and the desktop webviews.

Two things confine it, because loopback is shared between apps on Android — any other installed app can connect to this port:

• it binds 127.0.0.1 only, so nothing off-device can reach it; and
• every URL carries a random per-session token, so another app cannot guess a working URL, and paths are confined to the app data directory even if one did.

Phase 1 serves local files only. The same origin is the intended home for remote passthrough (and download-while-watching) later; see the stage-2 spec.

TRACES: UR-071 | DR-137 | UT-127

Structs

MediaServer

A running server. Dropping this does not stop the thread; the server lives for the life of the process by design, since playback can start at any time.

MediaServerWrapper

Managed state. None when the server could not bind — local playback then fails with a clear error instead of the app refusing to start.

Span

The byte range a response should carry. end is inclusive.

Enums

Resolved

What a request path resolved to, before any file is touched.

Constants

CHUNK_LEN 🔒

Bytes per response. Large enough that a film needs relatively few round trips, small enough that one response is never a memory problem on a phone. Tauri’s asset protocol uses 1 MiB; 4 MiB quarters the request count for the multi-gigabyte files this exists to serve.

Functions

content_type 🔒

Guess a content type.

empty 🔒

handle 🔒

header 🔒

resolve_path

Resolve a percent-encoded request path to a file inside root.

route 🔒

Check the token and resolve the path, or return the status to answer with.

span_for

Decide which span to send for a Range header (or its absence).

start

Bind to an ephemeral loopback port and start serving root in a background thread.