File Server System

A comprehensive client-server file system implementation in C using socket programming, designed for Linux platforms. The system provides distributed file access capabilities with automatic load balancing between a main server and mirror server.

Features

Core Functionality

• Multi-client Support: Handles multiple concurrent client connections using fork-based process management
• File Search: Find files by name across the user's home directory
• Size-based Retrieval: Get files within specified size ranges
• Date-based Retrieval: Retrieve files modified within date ranges
• Extension-based Retrieval: Fetch files by specific extensions (up to 6 extensions)
• Tar Archive Delivery: All file collections are compressed and delivered as tar.gz archives
• Load Balancing: Automatic distribution of client connections between main and mirror servers

Advanced Features

• Connection Routing: First 4 connections → main server, next 4 → mirror server, then alternating
• Transparent Redirection: Clients are seamlessly redirected to mirror server when needed
• Input Validation: Comprehensive client-side command validation before server communication
• Error Handling: Robust error checking and informative error messages
• Progress Indicators: Visual feedback during file downloads

Architecture

┌─────────────┐    ┌─────────────┐    ┌─────────────┐
│   Client    │◄──►│Main Server  │◄──►│Mirror Server│
│   (8080)    │    │   (8080)    │    │   (8081)    │
└─────────────┘    └─────────────┘    └─────────────┘

Installation

Prerequisites

• Linux operating system
• GCC compiler
• Standard C libraries

Build Instructions

1. Clone the repository:

   git clone https://github.com/heiparth07/Client-Server.git
   cd Client-Server

2. Compile the project:

   # Compile the main server
   gcc -o server src/server.c
   
   # Compile the mirror server
   gcc -o mirror src/mirror.c
   
   # Compile the client
   gcc -o client src/client.c

3. Or compile all at once:

   gcc -o server src/server.c && gcc -o mirror src/mirror.c && gcc -o client src/client.c

Usage

Starting the Servers

1. Start the main server:

   ./server

2. Start the mirror server (in another terminal):

   ./mirror

3. Start the client:

   ./client

Available Commands

Command	Syntax	Description	Example
findfile	findfile <filename>	Find a file by name	findfile document.txt
sgetfiles	sgetfiles <size1> <size2>	Get files within size range (bytes)	sgetfiles 1024 10485760
dgetfiles	dgetfiles <date1> <date2>	Get files within date range	dgetfiles 2023-01-01 2023-12-31
getfiles	getfiles <ext1> [ext2] ... [ext6]	Get files by extensions	getfiles txt pdf jpg
getftar	getftar <filename>	Get specific file as tar	getftar config.conf
quit	quit	Exit client	quit
help	help	Show help message	help

Command Details

File Search (findfile)

• Searches recursively through the user's home directory
• Returns the full path of the first matching file
• Case-sensitive filename matching

Size-based Retrieval (sgetfiles)

• Specify size range in bytes
• size1 must be ≤ size2
• Both sizes must be non-negative integers
• Returns all files within the specified size range as a tar.gz archive

Date-based Retrieval (dgetfiles)

• Date format: YYYY-MM-DD
• Retrieves files modified between the specified dates (inclusive)
• Returns matching files as a tar.gz archive

Extension-based Retrieval (getfiles)

• Accepts 1-6 file extensions
• Extensions should be alphanumeric only
• Returns all matching files as a tar.gz archive

Tar Retrieval (getftar)

• Retrieves a specific file and packages it as a tar.gz archive
• Useful for maintaining file permissions and metadata

Technical Implementation

Server Architecture

• Multi-process: Each client connection is handled by a separate forked process
• Connection Management: Global connection counter tracks client distribution
• Load Balancing Algorithm:
  • Connections 1-4: Main server
  • Connections 5-8: Mirror server
  • Connections 9+: Alternating (odd→main, even→mirror)

Client Features

• Command Validation: Syntax checking before server communication
• Automatic Redirection: Transparent handling of server redirection
• Progress Tracking: Visual feedback during file transfers
• Error Recovery: Graceful handling of connection failures

File Operations

• Recursive Search: Deep directory traversal for comprehensive file discovery
• Efficient Packaging: Dynamic tar.gz creation for file collections
• Memory Management: Bounded file collection (MAX_FILES = 1000)
• Temporary File Cleanup: Automatic cleanup of temporary tar archives

Configuration

Default Ports

• Main Server: 8080
• Mirror Server: 8081

Modifiable Constants

#define PORT 8080           // Main server port
#define MIRROR_PORT 8081    // Mirror server port
#define MAX_BUFFER 4096     // Buffer size for data transfer
#define MAX_FILES 1000      // Maximum files per operation
#define MAX_PATH 1024       // Maximum path length

File Structure

Client-Server/
├── src/
│   ├── server.c          # Main server implementation
│   ├── mirror.c          # Mirror server implementation
│   └── client.c          # Client implementation
├── README.md             # This file
└── .gitignore            # Git ignore file

Testing

Since this is a basic implementation, testing should be done manually:

1. Start the servers in separate terminals:

   # Terminal 1
   ./server
   
   # Terminal 2  
   ./mirror

2. Test with multiple clients:

   # Terminal 3, 4, 5, etc.
   ./client

3. Test each command:

   • Try findfile with existing files
   • Test sgetfiles with different size ranges
   • Test dgetfiles with date ranges
   • Test getfiles with various extensions
   • Test getftar with specific files

Performance Considerations

• Concurrent Connections: Supports multiple simultaneous clients
• Memory Usage: Bounded by MAX_FILES constant
• File Size Limits: Limited by available disk space for temporary files
• Network Efficiency: Binary file transfer with progress tracking

Error Handling

Client-side Validation

• Command syntax verification
• Parameter range checking
• Extension format validation
• Date format validation

Server-side Error Handling

• Invalid command responses
• File system access errors
• Tar creation failures
• Network communication errors

Security Considerations

• Scope Limitation: Searches restricted to user's home directory
• Path Traversal Protection: No absolute path access
• Input Sanitization: Command parameter validation
• Resource Limits: Bounded file collection and buffer sizes

Contributing

1. Fork the repository
2. Create a feature branch (git checkout -b feature/new-feature)
3. Commit your changes (git commit -am 'Add new feature')
4. Push to the branch (git push origin feature/new-feature)
5. Create a Pull Request

Troubleshooting

Common Issues

1. Connection Refused

   • Ensure servers are running before starting client
   • Check if ports 8080 and 8081 are available

2. Permission Denied

   • Verify executable permissions: chmod +x server mirror client
   • Check home directory access permissions

3. File Not Found

   • Ensure search is within user's home directory
   • Verify file names are case-sensitive

4. Mirror Server Connection

   • Confirm mirror server is running on port 8081
   • Check network connectivity between servers

Debug Mode

# Compile with debug symbols
gcc -g -o server src/server.c
gcc -g -o mirror src/mirror.c  
gcc -g -o client src/client.c

# Debug with GDB
gdb ./server

Future Enhancements

• SSL/TLS encryption for secure communication
• Configuration file support
• Logging system implementation
• Web-based client interface
• Database integration for file indexing
• Compression algorithm options
• User authentication system

Authors

• Parth Dangaria
• Riddhi Jobanputra

Acknowledgments

• Socket programming concepts from Stevens' "Unix Network Programming"
• File system operations based on POSIX standards
• Inspired by traditional FTP and file server architectures