// HttpContextAccessor is initialized through dependency injection
public ClientIdMatchesResourceIdHandler(IHttpContextAccessor httpContextAccessor, IOptions <AzureADConfig> azureAdConfig)
{
_httpContextAccessor = httpContextAccessor ?? throw new ArgumentNullException(nameof(httpContextAccessor));
_azureADConfig = azureAdConfig.Value;
}
public static AuthContext DoTokenValidationsForClientId(AzureADConfig azureAdConfig, HttpContext ctx, string clientId, string requiredRole)
{
// initialize AuthContext
AuthContext authContext = new AuthContext();
authContext.RequiredRole = requiredRole;
authContext.RequestedClientId = clientId;
authContext.Authorized = false; // we default to rejecting
//validate audience
string audience = ctx.User.Claims.FirstOrDefault(c => c.Type == "aud")?.Value;
if (String.IsNullOrEmpty(audience))
{
authContext.ForbidReason = $"Authorization token is invalid";
return(authContext);
}
authContext.Audience = audience;
var expectedAudience = azureAdConfig.AppIdUri;
if (audience != expectedAudience)
{
authContext.ForbidReason = $"Audience was {audience} - expected {expectedAudience}";
return(authContext);
}
// check authorization token has access to this API method
if (!ctx.User.IsInRole(requiredRole))
{
authContext.ForbidReason = $"Authorization token is missing required role {requiredRole}";
return(authContext);
}
//roles are valid but let's get a reference to them anyway
string[] roles = ctx.User.Claims.Where(c => c.Type == "http://schemas.microsoft.com/ws/2008/06/identity/claims/role").Select(c => c.Value).ToArray();
authContext.Roles = roles.ToList();
// get appId from claims
string appId = ctx.User.Claims.FirstOrDefault(c => c.Type == "appid").Value;
authContext.RequesterId = appId;
// set clientId and tenantId from the addConfig
var tenantId = azureAdConfig.TenantId;
var apiClientId = azureAdConfig.ClientId;
authContext.TenantId = tenantId;
authContext.ApiClientId = apiClientId;
// check if it's the brand making the request
if (appId != clientId)
{
// doesn't match - so this is either an invalid call or an aggregator
// check if the additional custom header was supplied
// get request header
StringValues resourceHeaderValue = StringValues.Empty;
var headerExists = ctx.Request.Headers.TryGetValue(CUSTOM_HEADER, out resourceHeaderValue);
if (headerExists)
{
authContext.IsThirdPartyAccessAttempt = true;
// grab secondary token
var handler = new JwtSecurityTokenHandler();
JwtSecurityToken secondaryToken = null;
try
{
secondaryToken = handler.ReadJwtToken(resourceHeaderValue);
}
catch (Exception ex)
{
authContext.ForbidReason = $"Error decoding secondary token - {ex.Message}";
return(authContext);
}
var targetClientId = secondaryToken.Audiences.FirstOrDefault();
if (targetClientId.StartsWith("api://"))
{
targetClientId = targetClientId.Remove(0, 6);
}
// let's validate if this is the right clientId
if (targetClientId != clientId)
{
// the secondary token is for another client
authContext.ForbidReason = $"Secondary Token is for {targetClientId} - expected {clientId}";
return(authContext);
}
// verify brand roles
string[] clientRoles = secondaryToken.Claims.FirstOrDefault(c => c.Type == "roles").Value.Split(",");
authContext.ClientRoles = clientRoles.ToList();
bool hasClientRole = false;
foreach (string role in clientRoles)
{
if (role.EndsWith(requiredRole))
{
hasClientRole = true;
break;
}
}
if (!hasClientRole)
{
// the secondary token is for another client
authContext.ForbidReason = $"{CUSTOM_HEADER} is missing {requiredRole}";
return(authContext);
}
//all required checks passed
authContext.Authorized = true;
}
else //no custom header supplied
{
authContext.ForbidReason = $"Provided Authorization token does not grant access to this resource";
return(authContext);
}
}
else
{
// appId matches clientId
authContext.IsThirdPartyAccessAttempt = false;
authContext.Authorized = true;
}
return(authContext);
}