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using System.Net.Http.Headers;
using System.Text;
using System.Text.Encodings.Web;
using Microsoft.Extensions.Options;
namespace IOL.GreatOffice.Api.Utilities;
public class BasicAuthenticationHandler : AuthenticationHandler<AuthenticationSchemeOptions>
{
private readonly AppDbContext _context;
private readonly IConfiguration _configuration;
private readonly ILogger<BasicAuthenticationHandler> _logger;
public BasicAuthenticationHandler(
IOptionsMonitor<AuthenticationSchemeOptions> options,
ILoggerFactory logger,
UrlEncoder encoder,
ISystemClock clock,
AppDbContext context,
IConfiguration configuration
) :
base(options, logger, encoder, clock) {
_context = context;
_configuration = configuration;
_logger = logger.CreateLogger<BasicAuthenticationHandler>();
}
protected override Task<AuthenticateResult> HandleAuthenticateAsync() {
var endpoint = Context.GetEndpoint();
if (endpoint?.Metadata.GetMetadata<IAllowAnonymous>() != null)
return Task.FromResult(AuthenticateResult.NoResult());
if (!Request.Headers.ContainsKey("Authorization"))
return Task.FromResult(AuthenticateResult.Fail("Missing Authorization Header"));
try {
var token_entropy = _configuration.GetValue<string>("TOKEN_ENTROPY");
if (token_entropy.IsNullOrWhiteSpace()) {
_logger.LogWarning("No token entropy is available in env:TOKEN_ENTROPY, Basic auth is disabled");
return Task.FromResult(AuthenticateResult.Fail("Invalid Authorization Header"));
}
var authHeader = AuthenticationHeaderValue.Parse(Request.Headers["Authorization"]);
if (authHeader.Parameter == null) return Task.FromResult(AuthenticateResult.Fail("Invalid Authorization Header"));
var credentialBytes = Convert.FromBase64String(authHeader.Parameter);
var decrypted_string = Encoding.UTF8.GetString(credentialBytes).DecryptWithAes(token_entropy);
var token_is_guid = Guid.TryParse(decrypted_string, out var token_id);
if (!token_is_guid) {
return Task.FromResult(AuthenticateResult.Fail("Invalid Authorization Header"));
}
var token = _context.AccessTokens.Include(c => c.User).SingleOrDefault(c => c.Id == token_id);
if (token == default) {
return Task.FromResult(AuthenticateResult.Fail("Invalid Authorization Header: Not Found"));
}
if (token.HasExpired) {
return Task.FromResult(AuthenticateResult.Fail("Invalid Authorization Header: Expired"));
}
var permissions = new List<Claim>() {
new(AppConstants.TOKEN_ALLOW_READ, token.AllowRead.ToString()),
new(AppConstants.TOKEN_ALLOW_UPDATE, token.AllowUpdate.ToString()),
new(AppConstants.TOKEN_ALLOW_CREATE, token.AllowCreate.ToString()),
new(AppConstants.TOKEN_ALLOW_DELETE, token.AllowDelete.ToString()),
};
var claims = token.User.DefaultClaims().Concat(permissions);
var identity = new ClaimsIdentity(claims, AppConstants.BASIC_AUTH_SCHEME);
var principal = new ClaimsPrincipal(identity);
var ticket = new AuthenticationTicket(principal, AppConstants.BASIC_AUTH_SCHEME);
return Task.FromResult(AuthenticateResult.Success(ticket));
} catch (Exception e) {
_logger.LogError(e, $"An exception occured when challenging {AppConstants.BASIC_AUTH_SCHEME}");
return Task.FromResult(AuthenticateResult.Fail("Invalid Authorization Header"));
}
}
}
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