Networking

Network Module

Overview

The Network module handles all network communication for the browser. It manages HTTP requests, responses, resource fetching, and provides caching mechanisms for efficient resource loading.

Purpose

• Handle HTTP requests and responses
• Fetch web resources (HTML, CSS, images, fonts)
• Manage network timeouts and retries
• Implement resource caching
• Handle redirects and authentication
• Support various content types

Key Concepts

Network Manager

Central component coordinating network operations:

• Manages active connections
• Implements request queuing
• Handles resource caching
• Manages connection pooling
• Tracks download progress

Resource Types

Different types of resources that can be fetched:

Type	Purpose	Example
HTML	Document content	index.html
CSS	Stylesheets	style.css
Image	Visual content	image.png
Font	Typography	roboto.ttf
Script	Executable code	script.js

HTTP Protocol

The module implements HTTP/1.1 protocol:

• Request: Method (GET, POST), URL, headers
• Response: Status code, headers, body
• Methods: GET for fetching, POST for forms
• Status Codes: Success (2xx), Redirect (3xx), Error (4xx, 5xx)

Request Types

GET Requests

Primary method for fetching resources:

• Retrieves resource content
• No request body
• Used for HTML, CSS, images, fonts
• Can be cached

POST Requests (Planned)

For form submissions and data:

• Includes request body
• Used for form data submission
• Generally not cached
• Requires more bandwidth

Response Handling

Status Codes

• 200 OK: Successful request
• 301/302 Redirect: Resource moved
• 304 Not Modified: Cached content valid
• 404 Not Found: Resource doesn't exist
• 500 Error: Server error

Content Types

Handled content MIME types:

• text/html: HTML documents
• text/css: CSS stylesheets
• image/*: Various image formats
• font/*: Font files
• text/javascript: JavaScript code

Caching Strategy

Resources are cached to improve performance:

Cache Types

• Memory Cache: Fast in-memory storage
• Disk Cache: Persistent storage (planned)
• Browser Cache: Managed by HTTP cache headers

Cache Control

Determined by HTTP headers:

• Cache-Control: Caching directives
• Expires: Expiration date
• ETag: Entity tag for validation
• Last-Modified: Last modification time

Cache Validation

Checking if cached content is still valid:

• If-Modified-Since: Conditional request
• ETag: Strong validation
• Expires: Time-based validation

Request Pipeline

URL Input
    ↓
Check Cache
    ↓
If cached and valid → Return cached
If not valid → Send request
    ↓
HTTP Request
    ↓
Response Received
    ↓
Parse Response Headers
    ↓
Cache if applicable
    ↓
Return Content

Timeouts and Retries

Network resilience features:

• Connection Timeout: Maximum time to connect
• Read Timeout: Maximum time to receive data
• Retries: Automatic retry on failure
• Backoff: Exponential backoff for retries

Redirect Handling

Automatic redirect support:

• 3xx Status Codes: Indicate redirect
• Location Header: New URL destination
• Chain Following: Up to limit (default 5)
• Infinite Loop Detection: Prevent redirect loops

Headers Management

HTTP header handling:

Request Headers

• User-Agent: Browser identification
• Accept: Accepted content types
• Accept-Encoding: Compression support
• Referer: Referring page
• Cookie: Session and tracking data

Response Headers

• Content-Type: MIME type of response
• Content-Length: Size of response body
• Content-Encoding: Compression method
• Set-Cookie: Session cookies

Integration with Other Modules

Parser Module

Provides HTML and CSS content for parsing

Font Module

Fetches font files from URLs

Browser Component

Initiates resource requests for page loading

JavaScript Module

Handles XMLHttpRequest and fetch API

Performance Features

• Connection Pooling: Reuse connections
• Pipelining: Multiple requests per connection
• Compression: GZIP/DEFLATE support
• Parallel Downloads: Multiple simultaneous requests
• Priority Queuing: Prioritize critical resources

Standards Compliance

• HTTP/1.1 specification (RFC 7230-7235)
• URL specification
• MIME types standard
• Cache control specifications
• Cookie specifications (RFC 6265)

Supported Features

• HTTP GET requests
• HTTP response parsing
• Status code handling
• Basic header support
• Memory caching
• Simple redirect handling
• Timeout support

Limitations and Planned Features

Current Limitations:

• HTTP/1.1 only (no HTTP/2)
• No disk cache persistence
• Limited POST support
• No authentication
• No compression (GZIP/DEFLATE)
• No proxy support
• No SSL/TLS (HTTP only)

Planned Features:

• HTTP/2 support
• Persistent disk cache
• Full POST support
• Basic authentication
• Compression support
• HTTPS/SSL support
• Proxy support
• Cookie management
• Form data handling

Security Considerations

Current Status:

• No HTTPS support yet
• Limited header validation
• No CSRF protection

Future Plans:

• HTTPS/TLS support
• Security header validation
• CORS support
• CSRF token handling
• Content Security Policy

Error Handling

Network errors are handled gracefully:

• Connection Errors: Network unreachable
• Timeout Errors: Request took too long
• Protocol Errors: Invalid response format
• HTTP Errors: 4xx and 5xx status codes
• DNS Errors: Domain name resolution failure

Resource Types Configuration

Different resources may have different settings:

// HTML document - higher priority
request.priority = RequestPriority::High;
request.timeout = Duration::from_secs(30);

// Image - can be lower priority
request.priority = RequestPriority::Low;
request.timeout = Duration::from_secs(15);

// Font - medium priority
request.priority = RequestPriority::Medium;
request.timeout = Duration::from_secs(20);

Bandwidth Optimization

Techniques to reduce bandwidth usage:

• Caching: Avoid redundant downloads
• Compression: GZIP to reduce size
• Image Optimization: Scaled images
• Lazy Loading: Load resources on demand
• Resource Prioritization: Load critical first