HTTP 425 Reserved for WebDAV

Overview

The HTTP 425 Too Early status code indicates that the server is unwilling to risk processing a request that might be replayed, providing a way for the client to wait for a suitable amount of time before retrying the request.

Purpose

The HTTP 425 response is used to inform the client that the server is unwilling to process the request immediately, and the client should wait before retrying.

Usage

Client Behavior:

1. Send Request: The client sends an HTTP request to the server.
2. Receive Response: The client receives the HTTP 425 status code, indicating that the request is too early.
3. Wait and Retry: The client may wait for a suitable amount of time before retrying the request.

Server Behavior:

1. Evaluate Request Timing: The server determines that processing the request immediately poses a risk (e.g., potential replay attack).
2. Send Response: The server responds with a 425 Too Early status, providing information on when it might be safe to retry.

Scenarios

• Replay Attack Prevention: Used to prevent replay attacks by requiring clients to wait before retrying requests.

Sequence Diagram

Illustrating the process for an HTTP 425 response:

sequenceDiagram
    participant Client
    participant Server as Web Server

    Note over Client: Step 1: Client sends a request
    Client->>Server: HTTP Request (Step 1)

    Note over Server: Step 2: Server evaluates request timing
    Server->>Client: HTTP/1.1 425 Too Early (Step 2)
    Server->>Client: Retry-After: Fri, 31 Dec 2022 23:59:59 GMT (Step 3)

Curl Request and Response Example

Sending a request that is too early using Curl:

curl -i http://example.com/resource
# Expected response: HTTP/1.1 425 Too Early
# Retry-After: Fri, 31 Dec 2022 23:59:59 GMT

PHP cURL Request and Response Example

PHP script using cURL to handle a 425 Too Early response:

<?php
$ch = curl_init('http://example.com/resource');
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
$response = curl_exec($ch);
if (curl_getinfo($ch, CURLINFO_HTTP_CODE) == 425) {
    $retryAfter = curl_getinfo($ch, CURLINFO_RETRY_AFTER);
    echo "Too Early. Retry after: $retryAfter";
}
curl_close($ch);
?>

Python Request and Response Example

Python script to handle a 425 Too Early response:

import requests
response = requests.get('http://example.com/resource')
if response.status_code == 425:
    retry_after = response.headers['Retry-After']
    print(f"Too Early. Retry after: {retry_after}")

Apache Configuration for HTTP 425 Too Early

Configuring Apache to handle scenarios where the server is unwilling to process a request immediately:

<VirtualHost *:80>
    ServerName example.com
    <Location "/resource">
        # Additional configuration to evaluate request timing
        # ...
        # Return 425 Too Early with Retry-After header
        Header always set Retry-After "Fri, 31 Dec 2022 23:59:59 GMT"
        ErrorDocument 425 "HTTP/1.1 425 Too Early"
    </Location>
</VirtualHost>

NGINX Configuration for HTTP 425 Too Early

Setting up NGINX to handle scenarios where the server is unwilling to process a request immediately:

server {
    listen 80;
    server_name example.com;
    location /resource {
        # Additional configuration to evaluate request timing
        # ...
        # Return 425 Too Early with Retry-After header
        add_header Retry-After "Fri, 31 Dec 2022 23:59:59 GMT";
        return 425 "HTTP/1.1 425 Too Early";
    }
}

HTTP 424 Failed Dependency (WebDAV) HTTP 426 Upgrade Required