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PSR-15 middleware adapter for [guard-core-php](https://github.com/Guard-Core/guard-core-php): translates any PSR-7 `ServerRequestInterface` to the guard-core engine and translates block verdicts back to PSR-7 responses. Works with Slim 4, Mezzio, Symfony PSR-15 bridges, or any PSR-7/PSR-15 stack.

Website · Docs · Playground · Dashboard · Discord

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Ecosystem

Guard Core is the Python engine. Framework adapters are thin wrappers that translate native request/response types into Guard Core's protocols. The telemetry agents ship security events and metrics to the monitoring backend. Parallel engine implementations exist for Go, PHP, TypeScript (on npm), and Rust (on crates.io) - all ports of the same reference semantics, conformance-tested against the shared adversarial corpus.

Python

Package	Role	PyPI
guard-core	Framework-agnostic security engine
guard-agent	Telemetry agent
fastapi-guard	FastAPI / Starlette adapter
flaskapi-guard	Flask adapter
djapi-guard	Django adapter
tornadoapi-guard	Tornado adapter

Go

Go modules published via GitHub releases. Production-ready.

Package	Role	Release
guard-core-go	Go engine
nethttp-guard	net/http adapter
gin-guard	Gin adapter
echo-guard	Echo (v4) adapter
fiber-guard	Fiber (v3) adapter
guard-agent-go	Telemetry agent

PHP

Published on Packagist under the rennf93 vendor. Production-ready.

Package	Role	Packagist
guard-core-php	PHP engine
laravel-guard	Laravel adapter
symfony-guard	Symfony adapter
psr15-guard	PSR-15 adapter
slim-guard	Slim 4 adapter
guard-agent-php	Telemetry agent

TypeScript / JavaScript

Published under the @guardcore npm scope; source in the guard-core-ts monorepo. Production-ready.

Package	Role	npm
	@guardcore/core	Core engine
@guardcore/express	Express adapter
@guardcore/nestjs	NestJS adapter
@guardcore/fastify	Fastify adapter
@guardcore/hono	Hono (edge) adapter
guardagent	Telemetry agent

Rust

Published on crates.io. Production-ready.

Package	Role	crates.io
guard-core-engine	Core engine crate
guard-core-rs	Facade crate (consumer entry point)
actix-guard-rs	Actix Web adapter
axum-guard-rs	Axum adapter
tower-guard-rs	Tower adapter
rocket-guard-rs	Rocket adapter
guard-agent-rs	Telemetry agent

AI Coding Agents

Package	Role	PyPI
guard-core-mcp	MCP server: config validation, docs search, detection sandbox

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Features

• The full guard-core-php engine pipeline behind any PSR-15 middleware stack: rate limiting, IP lists, payload inspection, security headers
• Framework-agnostic: works anywhere PSR-7/PSR-15 does
• Composable: the Slim adapter composes it

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Documentation

📚 Documentation - full technical documentation for this package.

🛡️ Guard Core - the engine's reference documentation.

🤖 Monitoring Agent Integration - monitor your Guard instance with a monitoring agent.

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Install

composer require rennf93/psr15-guard

Usage

use Nyholm\Psr7\Factory\Psr17Factory;
use RenzoFranceschini\GuardCore\Config\SecurityConfig;
use RenzoFranceschini\GuardCore\Engine\GuardEngine;
use RenzoFranceschini\GuardCorePsr15\GuardMiddleware;

$config = new SecurityConfig(
    enableRedis: false,
    blacklist: ['192.0.2.0/24'],
    rateLimit: 100,
    rateLimitWindow: 60,
    enableRateLimiting: true,
);

$factory = new Psr17Factory();
$engine = new GuardEngine($config);
$guard = new GuardMiddleware($engine, $factory, $factory);

$app->add($guard);

Blocked requests get the engine's BlockResponse translated exactly (status, body, headers), for example 403 Forbidden for a blacklisted IP, 429 Too many requests with Retry-After for a rate limit hit. Passing requests continue down the stack untouched.

Pass-through responses are finished by the middleware too: the engine's security headers and CORS verdict headers are merged on top of the handler's response, and the engine's behavioral return rules observe the response status code plus a body prefix bounded by behaviorMaxResponseBodyInspectBytes (only while behaviorScanResponseBody is on; the PSR-7 stream is rewound after the bounded capture when it is seekable, so emitters still see the full body). Per-route configuration attaches through the middleware's route map or a custom resolver:

use RenzoFranceschini\GuardCore\Routing\RouteConfig;
use RenzoFranceschini\GuardCorePsr15\GuardMiddleware;

$middleware = new GuardMiddleware(
    $engine,
    $responseFactory,
    $streamFactory,
    routes: [
        '/docs/' => new RouteConfig(enableSuspiciousDetection: false),
        '/api/' => new RouteConfig(rateLimit: 5, rateLimitWindow: 10),
    ],
    // optional: country resolver for RouteConfig geoRateLimits tiers
    geoRateLimitResolver: $myResolver,
    // optional: custom resolver receiving the PSR-7 server request
    routeResolver: fn (ServerRequestInterface $r) => str_starts_with($r->getUri()->getPath(), '/admin') ? new RouteConfig(bypassedChecks: ['rate_limit']) : null,
);

routes patterns match a path exactly or as a prefix when they end with /. Geo rate-limit tiers need a country resolver: pass geoRateLimitResolver explicitly, or configure geoIpHandler together with blockedCountries/whitelistCountries (the engine keeps the injected handler only when country lists are set) and the middleware bridges it onto the engine's rate-limit handler automatically.

Telemetry agent and dynamic rules

The adapter forwards an optional agentHandler to the engine (GuardEngine::setAgentHandler()), so security events, metrics and dashboard dynamic rules flow through guard-agent-php. Install it with composer require rennf93/guard-agent-php, create and start the agent where the middleware is built, pass it as the agentHandler argument, and declare it in the config with enableAgent: true:

use RenzoFranceschini\GuardAgent\GuardAgent;
use RenzoFranceschini\GuardCore\Config\SecurityConfig;
use RenzoFranceschini\GuardCore\Engine\GuardEngine;

$agent = new GuardAgent([
    'apiKey' => $_ENV['GUARD_API_KEY'],
    'endpoint' => 'https://api.guard-core.com',
    'projectId' => 'my-project',
]);
$agent->start();

$config = new SecurityConfig(
    enableRedis: true,
    enableAgent: true,
    enableDynamicRules: true,
    dynamicRuleInterval: 300,
    enableEnrichment: true,
    agentProjectId: 'my-project',
);

$guard = new GuardMiddleware(new GuardEngine($config), $responseFactory, $streamFactory, agentHandler: $agent);

register_shutdown_function(static function () use ($agent): void {
    $agent->flushBuffer();
    $agent->stop();
});

enableDynamicRules and enableEnrichment require enableAgent, and dynamic rules need an agent handler that exposes getDynamicRules() (GuardAgent does). The engine builds the dynamic rule manager itself and checks for new rules on the first request and then every dynamicRuleInterval seconds (default 300, minimum 60), because a PHP request process has no background loop. Without an agent handler the engine warns and stays on the static config. agentStats() on the adapter reports {enabled: false, degraded: false} without a handler and merges the handler's getStats() map with one.

Response modifier

SecurityConfig::customResponseModifier is a Closure(GuardResponse): GuardResponse that the engine applies once to every response it returns itself (blocks, redirects and the fail-closed response), after the security headers and before the CORS verdict headers. This adapter applies the same modifier to the pass-through responses it sends, through GuardEngine::applyResponseModifier(), including excluded-path responses and responses of requests that bypass all checks, and it never applies it twice to a response the engine already modified. The order on a pass-through response is security headers, modifier, then CORS verdict headers, so the CORS policy has the last word on its own headers.

use RenzoFranceschini\GuardCore\Request\GuardResponse;

$config = new SecurityConfig(
    customResponseModifier: static function (GuardResponse $response): GuardResponse {
        $response->headers()->set('X-Served-By', 'edge-1');

        return $response;
    },
);

The modifier sees the status, the headers (Set-Cookie is not exposed) and the body, and the changes are merged back onto the PSR-7 response; a response whose body stream is not seekable keeps its body (only its status and headers can change). A modifier that throws leaves the response unmodified. Nothing is read from the response while no modifier is configured. The modifier seam needs guard-core-php 4.4.0 or later.

Lifecycle

PHP shared-nothing applies: construct GuardEngine (and therefore GuardMiddleware) per request in classic FPM, or per worker under Swoole/Octane/RoadRunner. The middleware holds no mutable state of its own. In-memory fallbacks are per-request safety nets; distributed rate limits, IP bans, and cloud-range caches require Redis (set enableRedis: true and point REDIS_HOST/REDIS_PORT at your instance).

Behavior notes

• Fail-closed: if the engine throws, the middleware returns the engine's fail-closed response (500 Security check failed, honorably overridden by customErrorResponses) instead of letting the request through.
• Bounded body read: the request body is scanned as a prefix of at most 256 KiB (PsrGuardRequest::MAX_BODY_BYTES, matching the engine's full-scan window). Payloads beyond the prefix, or signatures split across its boundary, are not detected. The scan does not consume the body for the handler: a seekable stream is rewound to the position it had before the scan, and a non-seekable stream the engine read is replayed to the handler as a php://temp copy of the full body (the only case where the handler receives a request other than the original instance).
• With redisFailOpen: true the middleware constructs and serves requests even when Redis is unreachable; with redisFailOpen: false construction fails closed.
• Security headers and CORS: the adapter computes none of them. On a pass-through response it merges the engine's security header set, then the engine's customResponseModifier output, then the engine's CORS verdict headers (CORS last, so the CORS policy wins on a shared header name). Blocked responses are exact translations of the engine's verdict.

Testing

composer lint
composer test

composer test runs the plain-PHP suite in bin/test_psr15.php (unit coverage always; set REDIS_HOST to a reachable Redis to include the shared-state integration cases).

License

MIT