public async Task <IAuthenticationResult> GetAsync(
AzureSqlConnectionStringBuilder connectionString,
string clientCertificateData,
ILogger logger = null)
{
AccessTokenCacheValue accessToken;
if (TryGetValue(connectionString, out accessToken) && !IsExpired(accessToken))
{
// Refresh access token in background, if near expiry or client certificate has changed.
if (IsNearExpiry(accessToken) || ClientCertificateHasChanged(accessToken, clientCertificateData))
{
TriggerBackgroundRefresh(connectionString, clientCertificateData, logger);
}
// Returned cached access token.
return(accessToken.AuthenticationResult);
}
// Acquire token in foreground, first time or if already expired.
if (await TryRefreshAccessTokenAsync(connectionString, clientCertificateData, logger, ForegroundRefreshTimeoutMilliseconds))
{
if (TryGetValue(connectionString, out accessToken))
{
return(accessToken.AuthenticationResult);
}
}
throw new InvalidOperationException($"Failed to acquire access token for {connectionString.Sql.InitialCatalog}.");
}
/// <summary>
/// Refresh the access token in the token cache.
/// </summary>
private async Task <bool> RefreshAccessTokenAsync(
AzureSqlConnectionStringBuilder connectionString,
string clientCertificateData,
ILogger logger)
{
try
{
var start = DateTimeOffset.Now;
var accessToken = await AcquireAccessTokenAsync(connectionString, clientCertificateData);
Debug.Assert(accessToken != null);
logger?.LogInformation("Refreshed access token {Token} for catalog {Catalog} which expires in {ExpirationMinutes}m (Latency = {ElapsedMilliseconds}ms).",
accessToken.AuthenticationResult.AccessToken.GetHashCode(),
connectionString.Sql.InitialCatalog,
(accessToken.AuthenticationResult.ExpiresOn - DateTimeOffset.Now).TotalMinutes.ToString("F2"),
(DateTimeOffset.Now - start).TotalMilliseconds.ToString("F2"));
_cache.AddOrUpdate(connectionString.ConnectionString, accessToken, (k, v) => accessToken);
return(true);
}
catch (Exception ex)
{
logger?.LogError(0, ex, "Failed to refresh access token for {Catalog}.",
connectionString.Sql.InitialCatalog);
return(false);
}
}
/// <summary>
/// Try to refresh the access token in the token cache.
/// </summary>
private async Task <bool> TryRefreshAccessTokenAsync(
AzureSqlConnectionStringBuilder connectionString,
string clientCertificateData,
ILogger logger,
int refreshTimeoutMilliseconds)
{
if (!await AcquireTokenLock.WaitAsync(refreshTimeoutMilliseconds))
{
return(false);
}
try
{
TryGetValue(connectionString, out var accessToken);
if (accessToken == null || IsNearExpiry(accessToken) ||
ClientCertificateHasChanged(accessToken, clientCertificateData))
{
return(await RefreshAccessTokenAsync(connectionString, clientCertificateData, logger));
}
}
finally
{
AcquireTokenLock.Release();
}
return(true);
}
/// <summary>
/// Refresh the access token in the token cache.
/// </summary>
private async Task <bool> RefreshAccessTokenAsync(
AzureSqlConnectionStringBuilder connectionString,
string clientCertificateData,
ILogger logger)
{
try
{
var start = DateTimeOffset.Now;
var accessToken = await AcquireAccessTokenAsync(connectionString, clientCertificateData);
Debug.Assert(accessToken != null);
logger?.LogInformation("Refreshed access token for {InitialCatalog} in {ElapsedMilliseconds}.",
connectionString.Sql.InitialCatalog,
(DateTimeOffset.Now - start).TotalMilliseconds);
_cache.AddOrUpdate(connectionString.ConnectionString, accessToken, (k, v) => accessToken);
return(true);
}
catch (Exception ex)
{
logger?.LogError(0, ex, "Failed to refresh access token for {InitialCatalog}.",
connectionString.Sql.InitialCatalog);
return(false);
}
}
public AzureSqlConnectionFactory(
AzureSqlConnectionStringBuilder connectionString,
ISecretInjector secretInjector,
ILogger logger = null)
{
ConnectionString = connectionString ?? throw new ArgumentNullException(nameof(connectionString));
SecretInjector = secretInjector ?? throw new ArgumentNullException(nameof(secretInjector));
Logger = logger;
}
public AzureSqlConnectionFactory(string connectionString, ISecretInjector secretInjector, ILogger logger = null)
{
if (string.IsNullOrEmpty(connectionString))
{
throw new ArgumentException("Value cannot be null or empty", nameof(connectionString));
}
ConnectionString = new AzureSqlConnectionStringBuilder(connectionString);
SecretInjector = secretInjector ?? throw new ArgumentNullException(nameof(secretInjector));
Logger = logger;
}
/// <summary>
/// Attempt non-blocking refresh of access token in background with retries.
/// </summary>
private void TriggerBackgroundRefresh(
AzureSqlConnectionStringBuilder connectionString,
string clientCertificateData,
ILogger logger)
{
Task.Run(async() =>
{
await TryRefreshAccessTokenAsync(connectionString, clientCertificateData, logger,
refreshTimeoutMilliseconds: BackgroundRefreshTimeoutMilliseconds);
});
}
/// <summary>
/// Request an access token from the token service.
/// </summary>
protected virtual async Task <AccessTokenCacheValue> AcquireAccessTokenAsync(
AzureSqlConnectionStringBuilder connectionString,
string clientCertificateData)
{
using (var certificate = new X509Certificate2(Convert.FromBase64String(clientCertificateData), string.Empty))
{
var clientAssertion = new ClientAssertionCertificate(connectionString.AadClientId, certificate);
var authContext = new AuthenticationContext(connectionString.AadAuthority, tokenCache: null);
var authResult = await authContext.AcquireTokenAsync(AzureSqlResourceTokenUrl, clientAssertion, connectionString.AadSendX5c);
return(new AccessTokenCacheValue(clientCertificateData, authResult));
}
}
protected virtual bool TryGetValue(
AzureSqlConnectionStringBuilder connectionString,
out AccessTokenCacheValue accessToken)
{
return(_cache.TryGetValue(connectionString.ConnectionString, out accessToken));
}