# Modsurfer

![Modsurfer](.github/img/modsurfer-logo.svg)

> ### Modsurfer provides ops & dev teams with a system of record + diagnostics application to search, browse, and investigate modules.

For developers, SRE, DevOps, and engineering leaders: understand what the
WebAssembly in your system is all about. Modsurfer provides critical information
about WebAssembly code through a handy GUI, or directly at your fingertips via
our CLI.

Use Modsurfer for:

- **at-a-glance insights** into WebAssembly module data (code size & complexity,
  imports/exports & more)
- **search for details** about modules (hash, ID, function names, strings,
  namespaces, errors & more)
- **off-the-shelf** System of Record: easily audit and track all the WebAssembly
  code in your stack
- **debug & triage issues** otherwise difficult to pinpoint in opaque
  WebAssembly format

### Modsurfer Desktop Application

The desktop application is **free** and available to download from
[Dylibso](https://dylibso.com/downloads/modsurfer), and is a useful debugging,
visibility, and diagnostics tool for anyone working with WebAssembly.

![Modsurfer](https://dylibso.com/assets/modsurfer-product-desktop.png)

### Enterprise

If you're running WebAssmebly code in production, you may be interested in using
the Enterprise version of Modsurfer. Please reach out to us at
[support@dylibso.com](mailto:support@dylibso.com) and we'll be happy to get you
more information about licensing and self-managed deployment requirements.

---

## In this repository

This is a collection of Rust crates and other code that is used for a variety of
Modsurfer-related purposes. You can find a list and description of these below.

## `cli`

The Modsurfer CLI provides two primary functions:

1. HTTP Client to interace with Modsurfer (either the desktop app, or your
   Enterprise deployment)
2. Validation to ensure that WebAssembly binaries:

- are compatible with various host ABIs
- have no known security issues / comply with your policy
- meet the runtime requirements in terms of size and code complexity (RAM/CPU
  limits, etc)

### Download the CLI

Modsurfer CLI can be downloaded via:

- the latest
  [GitHub Release](https://github.com/dylibso/modsurfer/releases/latest)
- the GitHub container registry (for Docker environments)
  - `docker pull ghcr.io/dylibso/modsurfer:latest`

### Validate WebAssembly Modules

Modsurfer CLI provides a novel feature to process and validate a WebAssembly
module based on policy/properties of the module that you define. In a
"checkfile" (see the `mod.yaml` below), declare certain properties of a
WebAssembly module and Modsurfer will verify that they are true, or report which
properties of your binary are invalid.

```yaml
validate:
  # simply require that a module can have WASI functionality or not
  allow_wasi: false
  
  # ensure that various imports and exports are included/exlcuded such that a module
  # will run properly in any host environment
  imports:
    include:
      # ensure these named functions are in the imports of this module  
      - log_message
      - proc_exit
      
      # further specify the function beyond its name 
      - namespace: env
        name: http_get
        params: [I32, I32]
        results: [I32]
    exclude: 
      - fd_write
    namespace:
      include:
        - env
      exclude:
        # phasing out old APIs? exclude these from acceptable namespaces/module names
        - some_future_deprecated_module_name
        - wasi_snapshot_preview1

  exports: 
    # only want exactly 2 functions exported: `_start` and `bar` for the host to call:
    max: 2
    # secure your modules by ensuring that there is no superfluous functionality hidden inside a binary
    include:
      - _start
      - name: bar
        params: []
        results: [I32, I32, I32, I32]
    # and/or ensuring no unwanted functions to be exported.
    exclude:
      - name: init
        results: []
      - foo

  # use a human-readable module size to prevent overly large binaries from running in your environment
  size:
    max: 4MB

  # our Cyclomatic Complexity analysis can help prevent risk of CPU exhaustion from deteriorating 
  # your user experience and slowing down your system
  # (override these low, medium, high optional values with environment variables $MODSURFER_RISK_{LOW,MEDIUM,HIGH})
  complexity:
    max_risk: low
```

You can also point to a remote check file to track up-to-date requirements:

```yaml
validate:
  url: https://raw.githubusercontent.com/fermyon/spin/main/tools/modsurfer/http/mod.yaml
```

### Usage

Modsurfer runs validation tests on compiled .wasm binaries. It uses a
"checkfile" to compare with the contents of a .wasm binary. The `modsurfer` CLI
provides
[a number of commands](https://dev.dylib.so/docs/modsurfer/cli#commands) to
create and use a checkfile, as well as to interact as a client to a remote
service that stores and organizes your WebAssembly modules available over HTTP
(via [this `protobuf` API](./proto/v1/api.proto)).

##### To create a "checkfile" (passed to `-c`), run the `generate` command:

```
modsurfer generate -p path/to/my.wasm -o mod.yaml
```

> **NOTE:** this checkfile will be very restrictive, and you likely want to edit
> it to fit less (or more) restricted environments.

##### To run validation, you can use our [GitHub Action](https://github.com/dylibso/modsurfer-validate-action), or call the `validate` command directly:

```
modsurfer validate -p path/to/my.wasm -c path/to/mod.yaml
```

If any of the restrictions or expectations declared in your checkfile are not
satisfied, Modsurfer will report them:

```
┌────────┬──────────────────────────────────────────────────┬──────────┬──────────┬───────────────────┬────────────┐
│ Status │ Property                                         │ Expected │ Actual   │ Classification    │ Severity   │
╞════════╪══════════════════════════════════════════════════╪══════════╪══════════╪═══════════════════╪════════════╡
│ FAIL   │ allow_wasi                                       │ false    │ true     │ ABI Compatibility │ |||||||||| │
├────────┼──────────────────────────────────────────────────┼──────────┼──────────┼───────────────────┼────────────┤
│ FAIL   │ complexity.max_risk                              │ <= low   │ medium   │ Resource Limit    │ |          │
├────────┼──────────────────────────────────────────────────┼──────────┼──────────┼───────────────────┼────────────┤
│ FAIL   │ exports.exclude.main                             │ excluded │ included │ Security          │ |||||      │
├────────┼──────────────────────────────────────────────────┼──────────┼──────────┼───────────────────┼────────────┤
│ FAIL   │ exports.include.bar                              │ included │ excluded │ ABI Compatibility │ |||||||||| │
├────────┼──────────────────────────────────────────────────┼──────────┼──────────┼───────────────────┼────────────┤
│ FAIL   │ exports.max                                      │ <= 100   │ 151      │ Security          │ ||||||     │
├────────┼──────────────────────────────────────────────────┼──────────┼──────────┼───────────────────┼────────────┤
│ FAIL   │ imports.include.http_get                         │ included │ excluded │ ABI Compatibility │ ||||||||   │
├────────┼──────────────────────────────────────────────────┼──────────┼──────────┼───────────────────┼────────────┤
│ FAIL   │ imports.include.log_message                      │ included │ excluded │ ABI Compatibility │ ||||||||   │
├────────┼──────────────────────────────────────────────────┼──────────┼──────────┼───────────────────┼────────────┤
│ FAIL   │ imports.namespace.exclude.wasi_snapshot_preview1 │ excluded │ included │ ABI Compatibility │ |||||||||| │
├────────┼──────────────────────────────────────────────────┼──────────┼──────────┼───────────────────┼────────────┤
│ FAIL   │ imports.namespace.include.env                    │ included │ excluded │ ABI Compatibility │ ||||||||   │
├────────┼──────────────────────────────────────────────────┼──────────┼──────────┼───────────────────┼────────────┤
│ FAIL   │ size.max                                         │ <= 4MB   │ 4.4 MiB  │ Resource Limit    │ |          │
└────────┴──────────────────────────────────────────────────┴──────────┴──────────┴───────────────────┴────────────┘
```

> **NOTE**: convert this table into JSON with the `--output-format json` option,
> supported by the `validate` command and many others.

Find more information about the CLI in its dedicated [README](./cli/README.md),
or download the tool and run `modsurfer -h`.

### Validating platform-specific compatibility

Before running or integrating a WebAssembly module on your platform (Emscripten,
Extism, Fastly, Shopify, Spin, Suborbital, wasmCloud, Workers)

#### Contributing

##### Testing the CLI

From the root of the repo, run the following to see a basic validation report:

- `make test-cli`
- `make empty-cli`
- `make unknown-cli`

`test/` contains a `mod.yaml`, which declares expected properties of a
WebAssembly module, as well as a `spidermonkey.wasm` file to use as example
input to use for the validation. `wasm/` contains a set of WebAssembly binaries
downloaded from the [`wapm`](https://wapm.io) package manager used for analysis
and testing.

---

### `proto` Protobuf definitions and libraries

This directory contains the Protobuf definitions for the types used in the API.
Messages have various levels of documentation as well as endpoints if they are
request types. Use the `api.proto` to generate a language client if you'd like
to interact with Modsurfer API programmatically from your application.