LicenseServer.Client 1.1.7

LicenseServer.Client

Full .NET license client SDK for integrating with LicenseServer. Provides license activation, background sync, ASP.NET Core middleware, hardware fingerprinting, and lifecycle events.

Installation

dotnet add package LicenseServer.Client

This transitively brings in LicenseServer.Client.Abstractions and LicenseServer.Abstractions.

Quick Start

1. Basic Setup (Console App)

var builder = Host.CreateApplicationBuilder(args);

builder.Services.AddLicenseClient(opts =>
{
    opts.BaseUrl = "https://license.example.com";
    opts.ApiKey = builder.Configuration["LicenseServer:ApiKey"]!;
});

var host = builder.Build();
var client = host.Services.GetRequiredService<ILicenseClient>();

2. Activate a License

var fingerprint = await host.Services
    .GetRequiredService<IFingerprintCollector>()
    .CollectAsync();
var hash = await host.Services
    .GetRequiredService<IFingerprintCollector>()
    .HashAsync(fingerprint);

var result = await client.ActivateAsync(new ActivateRequest(
    Serial: "XXXX-XXXX-XXXX-XXXX",
    ActivationCode: "123456",
    Fingerprint: fingerprint.ToDictionary(k => k.Key, v => v.Value),
    Hash: hash,
    InstanceKey: Environment.MachineName,
    Label: null));

var license = client.ParseLicense(result.License);
Console.WriteLine($"Licensed to: {license!.Customer.Name}");
Console.WriteLine($"Expires: {license.ExpiresAt}");

3. Background Sync

builder.Services.AddFileLicenseStore("license.dat", encrypt: true);
builder.Services.AddLicenseSyncManager(opts =>
{
    opts.Serial = "XXXX-XXXX-XXXX-XXXX";
    opts.Hash = hash;
    opts.Interval = TimeSpan.FromHours(24);
});

4. ASP.NET Core Integration

var builder = WebApplication.CreateBuilder(args);

builder.Services.AddLicenseClient(opts =>
{
    opts.BaseUrl = builder.Configuration["LicenseServer:BaseUrl"]!;
    opts.ApiKey = builder.Configuration["LicenseServer:ApiKey"]!;
});
builder.Services.AddFileLicenseStore("license.dat", encrypt: true);
builder.Services.AddLicenseMiddleware();

var app = builder.Build();
app.UseLicenseValidation();

// Public endpoint
app.MapGet("/health", () => Results.Ok("healthy"));

// Feature-gated endpoint
app.MapGet("/analytics", () => Results.Ok("premium data"))
    .RequireLicenseFeature("advanced_analytics");

app.Run();

5. Lifecycle Events

builder.Services.AddLicenseEventHandler<MyHandler>();

public class MyHandler(ILogger<MyHandler> logger) : LicenseEventHandlerBase
{
    public override Task OnExpiredAsync(ParsedLicense license, CancellationToken ct)
    {
        logger.LogWarning("License expired at {ExpiresAt}", license.ExpiresAt);
        return Task.CompletedTask;
    }
}

6. Error Handling

All API errors are mapped to typed exceptions for ergonomic try/catch:

try
{
    await client.ActivateAsync(request);
}
catch (InvalidActivationCodeException)
{
    Console.WriteLine("Wrong activation code");
}
catch (DeviceLimitException)
{
    Console.WriteLine("Too many devices");
}
catch (LicenseClientException ex)
{
    Console.WriteLine($"License error: {ex.Message} ({ex.ResponseCode})");
}

Features

Storage Options

Middleware Pipeline

Authorization Policies

Use LicenseFeatureRequirement with ASP.NET Core authorization for attribute-based gating:

builder.Services.AddAuthorization(opts =>
{
    opts.AddPolicy("PremiumFeature", policy =>
        policy.AddRequirements(new LicenseFeatureRequirement("premium")));
});

Hardware Fingerprint

The SDK automatically detects the platform and collects hardware identifiers:

• Windows: CPU ProcessorId, BaseBoard Serial, Machine GUID, MAC address (via WMI)
• Linux: /proc/cpuinfo, /sys/class/dmi/id/board_serial, /etc/machine-id, MAC address
• Other: Hostname + MAC address (fallback)

Fingerprint matching uses weighted scoring (CPU 30%, Board 30%, GUID 25%, MAC 15%) with a configurable threshold (default 70%) to tolerate minor hardware changes.

Security

• ECDSA response verification (opt-in): Verifies server response signatures to prevent tampering
• Clock guard: Detects system clock manipulation by comparing local time with server time
• Anti-rollback: Prevents clock rollback attacks by tracking monotonic server timestamps
• Configurable retry: Linear or exponential backoff for transient failures

Observability

• Structured logging via ILogger for all operations
• ActivitySource tracing (LicenseServer.Client) for OpenTelemetry integration
• Health check (license-server) for monitoring server connectivity

Configuration Validation

Missing or invalid configuration fails fast at startup with descriptive error messages:

LicenseClient: BaseUrl is required. Set the license server URL (e.g., "https://license.example.com").
LicenseClient: ApiKey is required. Set your license server API key.
LicenseClient: VerifyResponseSignatures is enabled but TrustedResponseKey is not set.
SyncManager: Interval must be at least 30 seconds to avoid rate limiting.

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