Push Relay

This server accepts push requests via HTTP and relays those requests to the appropriate push backends.

Supported backends:

• Google FCM
• Apple APNs
• Huawei HMS

Request Format

• POST request to /push
• Request body must use application/x-www-form-urlencoded encoding

Request keys:

• type: Either fcm, hms or apns
• token: The device push token
• session: SHA256 hash of public permanent key of the initiator
• version: Threema Web protocol version
• affiliation (optional): An identifier for affiliating consecutive pushes
• ttl (optional): The lifespan of a push message, defaults to 90 seconds
• collapse_key: (optional) A parameter identifying a group of push messages that can be collapsed.
• bundleid (APNs only): The bundle id to use
• endpoint (APNs only): Either p (production) or s (sandbox)
• appid (HMS only): Can be used to differentiate between multiple configs

Examples:

curl -X POST -H "Origin: https://localhost" localhost:3000/push \
    -d "type=fcm&token=asdf&session=123deadbeef&version=3"
curl -X POST -H "Origin: https://localhost" localhost:3000/push \
    -d "type=apns&token=asdf&session=123deadbeef&version=3&bundleid=com.example.app&endpoint=s"
curl -X POST -H "Origin: https://localhost" localhost:3000/push \
    -d "type=hms&appid=123456&token=asdf&session=123deadbeef&version=3"

Possible response codes:

• HTTP 204 (No Content): Request was processed successfully
• HTTP 400 (Bad Request): Invalid or missing POST parameters (including expired push tokens)
• HTTP 500 (Internal Server Error): Processing of push request failed on the Push Relay server
• HTTP 502 (Bad Gateway): Processing of push request failed on the FCM, HMS or APNs server

Push Payload

The payload format looks like this:

• wcs: Webclient session (sha256 hash of the public permanent key of the initiator), string
• wca: An optional identifier for affiliating consecutive pushes, string or null
• wct: Unix epoch timestamp of the request in seconds, i64
• wcv: Protocol version, u16

FCM / HMS

The FCM and HMS messages contain the payload data as specified above.

APNs

The APNs message contains a key "3mw" containing the payload data as specified above.

Running

You need the Rust compiler. First, create a config.toml file that looks like this:

[fcm]
api_key = "your-api-key"

[apns]
keyfile = "your-keyfile.p8"
key_id = "AB123456XY"
team_id = "CD987654YZ"

To support HMS as well, you need to add one or more named HMS config sections. The name should correspond to the App ID (and currently matches the Client ID).

[hms.app-id-1]
client_id = "your-client-id"
client_secret = "your-client-secret"

[hms.app-id-2]
client_id = "your-client-id"
client_secret = "your-client-secret"

If you want to log the pushes to InfluxDB, add the following section:

[influxdb]
connection_string = "http://127.0.0.1:8086"
user = "foo"
pass = "bar"
db = "baz"

Then simply run

export RUST_LOG=push_relay=debug,hyper=info,a2=info
cargo run

...to build and start the server in debug mode.

Deployment

• Always create a build in release mode: cargo build --release
• Use a reverse proxy with proper TLS termination (e.g. Nginx)
• Set RUST_LOG=info env variable

Testing

To run tests:

cargo test

Linting

To run lints:

$ rustup component add clippy
$ cargo clean && cargo clippy --all-targets

License

Licensed under either of

• Apache License, Version 2.0, (LICENSE-APACHE or http://www.apache.org/licenses/LICENSE-2.0)
• MIT license (LICENSE-MIT or http://opensource.org/licenses/MIT)

at your option.