SmbSharp 1.0.16

SmbSharp

A cross-platform .NET library for SMB/CIFS file operations. Works seamlessly on Windows using native UNC paths and on Linux using smbclient.

Features

• ✅ Cross-Platform: Windows (native UNC) and Linux (smbclient)
• ✅ Dual Authentication: Kerberos and username/password authentication
• ✅ Stream-Based API: Efficient, memory-friendly file operations
• ✅ Async/Await: Full async support with cancellation tokens
• ✅ Dependency Injection: Built-in ASP.NET Core DI integration
• ✅ Health Checks: Monitor SMB share connectivity with ASP.NET Core health checks
• ✅ Multiple .NET Versions: Supports .NET Core 3.1, .NET 6, .NET 8, and .NET 10
• ✅ Secure: Passwords passed via environment variables, not command-line arguments
• ✅ Well-Documented: Comprehensive XML documentation with IntelliSense support

Installation

NuGet Package Manager

Install-Package SmbSharp

.NET CLI

dotnet add package SmbSharp

Package Reference

<PackageReference Include="SmbSharp" Version="1.0.0" />

Platform Requirements

Windows

• No additional requirements - uses native UNC path support

Linux

• Requires smbclient to be installed:

  # Debian/Ubuntu
  sudo apt-get install smbclient
  
  # RHEL/CentOS
  sudo yum install samba-client
  
  # Alpine Linux
  apk add samba-client
  

Docker

Add smbclient to your Dockerfile:

Debian/Ubuntu-based images:

FROM mcr.microsoft.com/dotnet/aspnet:8.0
RUN apt-get update && apt-get install -y smbclient && rm -rf /var/lib/apt/lists/*

Alpine-based images:

FROM mcr.microsoft.com/dotnet/aspnet:8.0-alpine
RUN apk add --no-cache samba-client

RHEL/CentOS-based images:

FROM mcr.microsoft.com/dotnet/aspnet:8.0-rhel
RUN yum install -y samba-client && yum clean all

Quick Start

Using Dependency Injection (Recommended)

Kerberos Authentication (Default)

// Program.cs
builder.Services.AddSmbSharp();

// Usage in a controller/service
public class MyService
{
    private readonly IFileHandler _fileHandler;

    public MyService(IFileHandler fileHandler)
    {
        _fileHandler = fileHandler;
    }

    public async Task<IEnumerable<string>> GetFiles()
    {
        return await _fileHandler.EnumerateFilesAsync("//server/share/folder");
    }
}

Username/Password Authentication

// Program.cs - Direct credentials
builder.Services.AddSmbSharp("username", "password", "DOMAIN");

// Or using configuration
builder.Services.AddSmbSharp(options =>
{
    options.UseKerberos = false;
    options.Username = "username";
    options.Password = "password";
    options.Domain = "DOMAIN";
});

// Or from appsettings.json
builder.Services.AddSmbSharp(options =>
{
    builder.Configuration.GetSection("SmbSharp").Bind(options);
});

Direct Instantiation (Without Dependency Injection)

using Microsoft.Extensions.Logging;
using SmbSharp.Business;

// Without logging
var handler = FileHandler.CreateWithKerberos();
var handler = FileHandler.CreateWithCredentials("username", "password", "DOMAIN");

// With console logging (for debugging)
using var loggerFactory = LoggerFactory.Create(builder =>
{
    builder
        .SetMinimumLevel(LogLevel.Debug)
        .AddConsole();
});

var handler = FileHandler.CreateWithKerberos(loggerFactory);
var handler = FileHandler.CreateWithCredentials("username", "password", "DOMAIN", loggerFactory);

// Usage
var files = await handler.EnumerateFilesAsync("//server/share/folder");

Note: To use console logging, you need to add the Microsoft.Extensions.Logging.Console package:

dotnet add package Microsoft.Extensions.Logging.Console

Path Format

SmbSharp accepts SMB paths in multiple formats for flexibility:

// Forward slashes (recommended for cross-platform code)
await fileHandler.EnumerateFilesAsync("//server/share/folder");

// Backslashes (Windows UNC format)
await fileHandler.EnumerateFilesAsync("\\\\server\\share\\folder");

// Mixed (automatically normalized)
await fileHandler.EnumerateFilesAsync("//server/share\\folder");

Note: All path formats are automatically normalized internally. Forward slashes (/) are recommended for cross-platform compatibility, but backslashes (\) are fully supported for Windows-style UNC paths.

Usage Examples

List Files in a Directory

var files = await fileHandler.EnumerateFilesAsync("//server/share/folder");
foreach (var file in files)
{
    Console.WriteLine(file);
}

Read a File

await using var stream = await fileHandler.ReadFileAsync("//server/share/folder", "file.txt");
using var reader = new StreamReader(stream);
var content = await reader.ReadToEndAsync();

Write a File (String Content)

await fileHandler.WriteFileAsync("//server/share/folder/file.txt", "Hello, World!");

Write a File (Stream)

await using var fileStream = File.OpenRead("local-file.txt");
await fileHandler.WriteFileAsync("//server/share/folder/file.txt", fileStream);

Write with Different Modes

// Overwrite existing file (default)
await fileHandler.WriteFileAsync("//server/share/file.txt", stream, FileWriteMode.Overwrite);

// Create only if doesn't exist (fails if exists)
await fileHandler.WriteFileAsync("//server/share/file.txt", stream, FileWriteMode.CreateNew);

// Append to existing file
await fileHandler.WriteFileAsync("//server/share/file.txt", stream, FileWriteMode.Append);

Delete a File

await fileHandler.DeleteFileAsync("//server/share/folder/file.txt");

Move a File

await fileHandler.MoveFileAsync(
    "//server/share/folder/old.txt",
    "//server/share/folder/new.txt"
);

Note: On Linux, move operations download and re-upload the file, which can be slow for large files. The operation is atomic with automatic retry logic - if the source deletion fails after copying, it retries once before rolling back the destination to maintain consistency.

Create a Directory

await fileHandler.CreateDirectoryAsync("//server/share/newfolder");

Test Connectivity

bool canConnect = await fileHandler.CanConnectAsync("//server/share");
if (canConnect)
{
    Console.WriteLine("Successfully connected!");
}

Using Cancellation Tokens

using var cts = new CancellationTokenSource(TimeSpan.FromSeconds(30));

try
{
    var files = await fileHandler.EnumerateFilesAsync(
        "//server/share/folder",
        cts.Token
    );
}
catch (OperationCanceledException)
{
    Console.WriteLine("Operation timed out!");
}

Authentication

Kerberos Authentication

On Linux, ensure you have a valid Kerberos ticket before using the library:

kinit username@DOMAIN.COM

Verify your ticket:

klist

Username/Password Authentication

Credentials are securely passed to smbclient via environment variables, not command-line arguments, preventing exposure in process listings.

Health Checks

SmbSharp includes built-in health check support for ASP.NET Core applications to monitor SMB share connectivity.

Single Share Health Check

// Program.cs
builder.Services.AddSmbSharp();
builder.Services.AddHealthChecks()
    .AddSmbShareCheck("//server/share/folder");

Named Health Check with Options

builder.Services.AddHealthChecks()
    .AddSmbShareCheck(
        directoryPath: "//server/share/folder",
        name: "primary_smb_share",
        failureStatus: HealthStatus.Degraded,
        tags: new[] { "smb", "storage" },
        timeout: TimeSpan.FromSeconds(10)
    );

Multiple Share Health Checks

var shares = new Dictionary<string, string>
{
    { "primary", "//server1/share1" },
    { "backup", "//server2/share2" },
    { "archive", "//server3/share3" }
};

builder.Services.AddHealthChecks()
    .AddSmbShareChecks(shares, tags: new[] { "smb" });

Health Check Endpoint

// Program.cs
var app = builder.Build();

app.MapHealthChecks("/health");
// Or with detailed response
app.MapHealthChecks("/health", new HealthCheckOptions
{
    ResponseWriter = UIResponseWriter.WriteHealthCheckUIResponse
});

Example Response

Healthy:

{
  "status": "Healthy",
  "results": {
    "smb_share": {
      "status": "Healthy",
      "description": "Successfully connected to SMB share: //server/share/folder"
    }
  }
}

Unhealthy:

{
  "status": "Unhealthy",
  "results": {
    "smb_share": {
      "status": "Unhealthy",
      "description": "Unable to connect to SMB share: //server/share/folder"
    }
  }
}

Health Check Logging

When health checks fail, error logs are automatically generated to help troubleshoot connectivity issues:

// Enable logging in your appsettings.json
{
  "Logging": {
    "LogLevel": {
      "SmbSharp.HealthChecks.SmbShareHealthCheck": "Error"
    }
  }
}

Example error log:

[Error] Health check failed: Unable to connect to SMB share: //server/share/folder
[Error] Health check failed for SMB share //server/share/folder: Access denied

API Reference

IFileHandler Interface

FileWriteMode Enum

Error Handling

The library throws specific exceptions for different error scenarios:

try
{
    await fileHandler.ReadFileAsync("//server/share", "file.txt");
}
catch (FileNotFoundException ex)
{
    // File or path doesn't exist
}
catch (UnauthorizedAccessException ex)
{
    // Access denied or authentication failed
}
catch (DirectoryNotFoundException ex)
{
    // Network path not found
}
catch (IOException ex)
{
    // Other SMB/network errors
}
catch (PlatformNotSupportedException ex)
{
    // Running on unsupported platform (not Windows/Linux)
}

Debugging

To troubleshoot authentication issues or see exactly what commands are being sent to smbclient, enable debug logging:

// In Program.cs or appsettings.json
builder.Logging.SetMinimumLevel(LogLevel.Debug);

// Or configure specific loggers
builder.Logging.AddFilter("SmbSharp.Infrastructure.ProcessWrapper", LogLevel.Debug);

Example debug output:

Executing process: smbclient //server/share -U "username" -c "ls folder/*"
Environment variables set: PASSWD
Process exited with code: 0

Note: Passwords are never logged. Only environment variable names (like PASSWD) are shown, not their values.

Performance Considerations

Windows

• Uses native UNC paths - very efficient
• All operations are direct file system calls
• Move operations are atomic and instant (metadata-only)

Linux

• Uses smbclient subprocess - some overhead
• Read operations download to temp file (auto-cleaned)
• Write operations upload from temp file
• Move operations = download + upload + delete (can be slow for large files)
• For large files, consider alternative approaches or be aware of 2x disk space + network transfer

Security Features

• ✅ Passwords passed via environment variables (not visible in process listings)
• ✅ Command injection protection (input escaping)
• ✅ Comprehensive input validation
• ✅ Path traversal protection

Contributing

Contributions are welcome! Please feel free to submit a Pull Request.

License

This project is licensed under the MIT License - see the LICENSE file for details.

Support

• Issues: GitHub Issues
• Discussions: GitHub Discussions
• Email: diego@dancourt.org

Acknowledgments

Built with ❤️ for the .NET community.