specs/forgecheck/README.md

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# Webhook endpoints

This repository contains documentation and tests about running webhook endpoints as part of a [forge suite](https://thunix.net/~southerntofu/forge) setup. There are tests for CLI webhook validation programs (such as [whck](https://tildegit.org/forge/whck)), as well as for web validation programs (HTTP endpoints such as [endpoints.php](https://tildegit.org/forge/endpoints.php)). A certain number of conventions (environment variables and folder structure) should make it "just work" for different kinds of setups including shared hosts with unprivileged accounts. **For setup information, please head over to the [Setup section](#setup).**

Below, you will find specifications for the [CLI](#cli) and [Web](#web) programs. For the reference of supported webhook sources and their respective property, please read the [Sources section](#sources)

# Command-line interface {#cli}

A CLI validator is a program that parses an identifier, a webhook body as well as a claimed secret provided by the caller, and attempts to validate the claim against the actual secret matching the provided identifier (if it was found). The following verification mechanisms are supported so far:

- `hmac-sha256`: used by Github and Gitea to sign the JSON payload
- `token`: used by Gitlab without signatures, so the body (payload) is ignored

The secrets are usually stored in your personal folder, but CLI validators support storing the actual secrets on a separate user account. This allows other users (such as `www-data`) to validate data against your secret without enabling them to read them in plaintext (zero-knowledge validation), as explained in the setup section.

The webhook validator uses the following syntax:

- `whck KIND IDENTIFIER CLAIM (+ BODY as STDIN)`, where:
- `KIND` is a supported verification mechanism (`hmac-sha256` or `token`)
- `IDENTIFIER` is the repository unique ID, usually a base16 or base64 encoding of the repo URL
- `CLAIM` is the claimed signature or secret token
- `BODY` is the actual HTTP body (usually a JSON payload), passed via STDIN

## Conventions

In order to facilitate deployment in varied setups, each command-line validator respects the following conventions:

- returns 0 when validation succeeded, or any other exit code if it fails. In the future, error codes could be standardized
- the secrets directory is generated from the following possibilities, in order of precedence:
  - from the `WHCK_DIR` environment variable (automated tests)
  - from the `XDG_CONFIG_HOME` environment variable, with "whck" appended (user operating CLI, or WWW running as user)
  - from the `HOME` environment variable, with ".config/whck" appended (user operating CLI, or WWW running as user)
  - from the current path to the executable, checking if it's inside a /home/ folder, and if so appending ".config/whck" (WWW running as system account, calling a symlink to a user-provided executable)
  -- **TODO:** maybe try ./secrets folder too from pwd?
  - **if all those discovery methods failed, the validator program fails to start and returns an error code**
- a `bin/cli` script builds the command-line validator, returning 0 upon success (or if the code doesn't require building) and outputting a complete path to the executable starting the program ; any other exit code indicates failure
- a `spec` submodule contains this very repository ([forge/endpoints](https://tildegit.org/forge/endpoints))
- a `bin/test.sh` script starts the tests: ensures the spec submodule is cloned, and starts the `spec/test_cli.sh` script, passing the full path to the executable (generated by `bin/cli`) as first argument

## Testing

**If you want to run tests for an existing implementation, please run the bin/test.sh script from the implementation's repository.**

**NOTE:** Running tests requires the bats testing framework. You can usually find it in your distro repositories. If not, head over to the [bats repository](https://github.com/bats-core/bats-core/).

The `test_cli.sh` script is used for testing CLI webhook validators (such as [whck](https://tildegit.org/forge/whck)). It takes as first positional argument a path to the (compiled) program to check. If no program is provided as argument, the implementation's `bin/cli` script will be executed to find a path to a (freshly-compiled) executable. The following paths will be attempted, in order of precedence:

- `bin/cli`, relative to the directory from which you called the tests (eg. if you're running `specs/test_cli.sh` from whck repository)
- `../bin/cli`, relative to the directory containing test_cli.sh (eg. if you're running `./test_web.sh` from specs submodule in whck repository)
- if no path was matched, the test suite fails to start

**To run tests, simply call bin/test.sh from your implementation repository**. If you call tests using `specs/test_cli.sh` directly, it will assume you either want to test a specific implementation (passed by argument), or that you want to test the implementation in the parent repository.

If you're making an implementation from scratch, you need to write your custom `bin/cli` script. Then, you can copy the `test.sh` script from [whck](https://tildegit.org/forge/whck) and it should work.

**Note: to test that the test suites can be called from several folders using different kind of relative/absolute paths, use the `test_tests_cli.sh` script.:**

# Sources

|    Name   |   Payload   |   Secret type   |   Secret location         |   Repo location       |
|:---------:|:-----------:|:---------------:|:-------------------------:|:---------------------:|
| Gitea     | JSON body   | hmac-sha256 sig | header:X_GITEA_SIGNATURE  | repository>html_url   |
| Github    | JSON body   | hmac-sha256 sig | header:X_HUB_SIGNATURE    | repository>html_url   |
| Gitlab    | JSON body   | token           | header:X_GITLAB_TOKEN     | project->git_http_url |

# Setup {#setup}

Now it gets tricky... In all cases you need some kind of shell account!
Talk about sudo, suid, please etc.

## Unprivileged user, web server running as user

## Unprivileged user, web server running as system account

## Privileged user (requires root)


# TODO

- reimplement calling forgehook-notify from endpoints.php
- add test to check it's actually called
- split READMEs separately for CLI and HTTP endpoint
- maybe have all specs/tests/READMEs (with forgebuild) in a single repo?
- make higher-level helper functions that can be shared across test files and implementation, for better consistency