HTTP Proxy Server with LRU Caching

A multi-threaded HTTP proxy server in C with LRU cache for improved performance.

Project Files

• proxy_server_with_cache.c - Main implementation (authored)
• proxy_parse.c, proxy_parse.h - HTTP parsing utilities (from GitHub)

Features

• Multi-threaded (up to 400 concurrent clients)
• LRU caching (200 MB cache, 10 MB max per element)
• HTTP/1.0 and HTTP/1.1 support
• Thread-safe cache operations

Compilation

gcc -o proxy_server proxy_server_with_cache.c proxy_parse.c -lpthread

Usage

./proxy_server <port_number>

Example:

./proxy_server 8080

How It Works

1. Client connects to proxy
2. Proxy checks cache (hit = instant return)
3. On miss: fetches from remote server, sends to client, caches response
4. LRU eviction when cache is full

Configuration

Edit these constants in source code:

#define MAX_BYTES 4096              // Max request/response size
#define MAX_CLIENTS 400             // Max concurrent clients
#define MAX_SIZE 200*(1<<20)        // Cache size (200 MB)
#define MAX_ELEMENT_SIZE 10*(1<<20) // Max element size (10 MB)

Browser Setup

Firefox: Settings → Network Settings → Manual proxy configuration

• HTTP Proxy: localhost, Port: 8080

Testing

curl -x http://localhost:8080 http://example.com

Supported

• HTTP GET requests only
• Error codes: 400, 403, 404, 500, 501, 505

Limitations

• No HTTPS support
• GET requests only
• No persistent cache (resets on restart)

Author

MOHD AFFAN