Readlogs

Readlogs is an unofficial web app for viewing Signal debug logs without manually downloading or unarchiving them.

To use it, create a debug log via the Signal app on your device as described in this support article, then open readlogs.pages.dev and paste the URL there.

Current functionality

• View information and logs from various sections of debug logs, formatted as tables.
• Search logs by setting a minimum log level (e.g. "Warn" to show warnings, errors, and more important log entries, if any) as well as using a (case-insensitive) search query.
• View and download raw debug log files in plaintext (i.e. unarchived).

Notable behavior

• Log entries that span multiple lines (without introducing a new timestamp and other metadata) are assumed to be one log entry.
• In case of Signal Android, sometimes multiple consecutive log lines repeat the exact same timestamp and metadata. These are collapsed into one entry.
• Some Signal iOS log entries don't seem to have a log level; it's assumed to be LogLevel::Info.

Overview

This repository primarily contains two pieces of software:

• A Rust web app (via WebAssembly) in the readlogs folder (as well as index.html and other files in the root).
  • Utility procedural macros for the Rust web app in in the readlogs-macros folder.
• A small JavaScript Cloudflare Worker in the worker folder.

How it works

1. Parsing the debug log URL

All debug log URLs have one of the below formats. The provided URL is parsed before fetching in order catch any potential copy/paste mistakes earlier, thus minimizing requests to the worker.

https://debuglogs.org/{key}{ext?}
https://debuglogs.org/{platform}/{version}/{key}{ext?}

• platform is ios for Signal iOS, desktop for Signal Desktop, and android for Signal Android.
• version is the Signal app's version.
• key is a 64-character string consisting of a-f and 0-9.
• ext is .zip for Signal iOS, .gz for Signal Desktop, and none for Signal Android.

2. Fetching

In general, the file is fetched using the worker: it's not possible to fetch directly from debuglogs.org due to its Cross-Origin Resource Sharing policy.

There are some differences in the fetching process between Signal Android/Desktop and Signal iOS due to the underlying format that debug logs are uploaded in by the Signal apps:

• Signal Android/Desktop

  The file is gzip-ped plain text. The worker alters the response received from debuglogs.org to indicate this. The web app itself doesn't handle the decompression of the response from the worker (presumably, the browser or its fetch API performs it); the web app receives the debug log in plain text.

• Signal iOS

  The file is a zip archive containing multiple files. The worker delivers it unmodified, and the web app itself handles the decompression.

3. Parsing and displaying

Each file (there is one for Signal Android/Desktop, but multiple in case of Signal iOS) is parsed by the web app immediately after fetching.

Note: Signal Desktop can output each log entry in a structured JSON format (if you start it from a terminal and look at the output), however the file submitted to debuglogs.org has the log in plaintext format, which is what this projects parses.

Privacy considerations

Note that debug logs uploaded by the Signal apps already have sensitive information redacted.

Inferring whether anyone viewed a given debug log

It could be possible to infer that someone has recently viewed a given debug log using this project because of different response times due to potential additional cache (compared to just downloading from debuglogs.org) being hit or missed, etc.

There are multiple caching layers present:

1. debuglogs.org's own cache:

   The behavior of this cache can't be changed by this project. This is also the cache that has an impact in any case, even if you download debug logs from debuglogs.org directly. Though depending on its setup, this cache may be more likely to trigger if the request comes from a certain edge data center of Cloudflare's network (which is the case with this project) because the same data center may be used for multiple users.

2. Cloudflare's caching of the fetch call in the worker (that requests the debug log from debuglogs.org):

   This cache appears to be enabled, based on the cf-cache-status, age, and last-modified headers that were returned with the worker's response (they are now being removed: https://github.com/awaitlink/readlogs/commit/7d0a1e830a65f92a3a4218af6cc84a6d97c65a5f).

   However, the cacheTtl for the fetch call is now set to 0 (https://github.com/awaitlink/readlogs/commit/066dee8148ebd20713dce6756b967f180bd379ff), so this cache immediately expires (see Cloudflare cache responses; if the headers mentioned above aren't removed, the cf-cache-status given to the browser is EXPIRED), meaning the debug log should always be requested from the layer above.

3. Cloudflare's caching of the worker's response:

   It's likely that this cache is not enabled.

   In any case, the worker sets the Cloudflare-CDN-Cache-Control header to no-store as an attempt to disable this cache, but because this header is not removed by Cloudflare, it seems that it is not used by Cloudflare (see CDN-Cache-Control).

4. Caching in the user's browser:

   The response is explicitly cached here (currently, for 7 days) to avoid repeated requests in case the user is viewing the same debug log multiple times.

Building the app

1. Install Yarn.

2. Install CSS dependencies:

   yarn install

3. Install Rust, for example via rustup.

4. Install Trunk, for example via:

   cargo install trunk

5. Build the app:

   trunk build

   Alternatively, serve it locally:

   trunk serve

   Note: Performance of debug builds may be significantly worse than that of release builds. For this reason, when using the app, it's recommended to build/serve in release mode instead:

   trunk build --release

   trunk serve --release

6. The built app is now available in the dist folder.

Deploying the worker

1. Follow steps 1–3 of the Cloudflare Workers Get started guide.
2. Switch to the worker folder.
3. Edit wrangler.toml if necessary (e.g. to change the name of the worker).
4. Run the following command to publish your worker:

   wrangler publish

5. The worker should now be published at <name>.<your-subdomain>.workers.dev.

Disclaimer

This is an unofficial project. It is not affiliated with the Signal Technology Foundation or Signal Messenger, LLC.