IdentityServer Token验证

查看源码：https://github.com/IdentityServer/IdentityServer4/tree/release

API使用Client Credentials的token验证是使用jwt验证的

找到JwtBearerClientAssertionSecretParser 类

public async Task<ParsedSecret> ParseAsync(HttpContext context)
        {
            _logger.LogDebug("Start parsing for JWT client assertion in post body");

            if (!context.Request.HasFormContentType)
            {
                _logger.LogDebug("Content type is not a form");
                return null;
            }

            var body = await context.Request.ReadFormAsync();

            if (body != null)
            {
                var clientAssertionType = body[OidcConstants.TokenRequest.ClientAssertionType].FirstOrDefault();
                var clientAssertion = body[OidcConstants.TokenRequest.ClientAssertion].FirstOrDefault();

                if (clientAssertion.IsPresent()
                    && clientAssertionType == OidcConstants.ClientAssertionTypes.JwtBearer)
                {
                    if (clientAssertion.Length > _options.InputLengthRestrictions.Jwt)
                    {
                        _logger.LogError("Client assertion token exceeds maximum lenght.");
                        return null;
                    }

                    var clientId = GetClientIdFromToken(clientAssertion);
                    if (!clientId.IsPresent())
                    {
                        return null;
                    }

                    if (clientId.Length > _options.InputLengthRestrictions.ClientId)
                    {
                        _logger.LogError("Client ID exceeds maximum lenght.");
                        return null;
                    }

                    var parsedSecret = new ParsedSecret
                    {
                        Id = clientId,
                        Credential = clientAssertion,
                        Type = IdentityServerConstants.ParsedSecretTypes.JwtBearer
                    };

                    return parsedSecret;
                }
            }

            _logger.LogDebug("No JWT client assertion found in post body");
            return null;
        }

首先从Context中拿到token信息

然后从中解析出ClientId

private string GetClientIdFromToken(string token)
        {
            try
            {
                var jwt = new JwtSecurityToken(token);
                return jwt.Subject;
            }
            catch (Exception e)
            {
                _logger.LogWarning("Could not parse client assertion", e);
                return null;
            }
        }

获取到ClientId后进行判断

public async Task<ClientSecretValidationResult> ValidateAsync(HttpContext context)
        {
            _logger.LogDebug("Start client validation");

            var fail = new ClientSecretValidationResult
            {
                IsError = true
            };

            var parsedSecret = await _parser.ParseAsync(context);
            if (parsedSecret == null)
            {
                await RaiseFailureEventAsync("unknown", "No client id found");

                _logger.LogError("No client identifier found");
                return fail;
            }

            // load client
            var client = await _clients.FindEnabledClientByIdAsync(parsedSecret.Id);
            if (client == null)
            {
                await RaiseFailureEventAsync(parsedSecret.Id, "Unknown client");

                _logger.LogError("No client with id '{clientId}' found. aborting", parsedSecret.Id);
                return fail;
            }

            if (!client.RequireClientSecret || client.IsImplicitOnly())
            {
                _logger.LogDebug("Public Client - skipping secret validation success");
            }
            else
            {
                var result = await _validator.ValidateAsync(parsedSecret, client.ClientSecrets);
                if (result.Success == false)
                {
                    await RaiseFailureEventAsync(client.ClientId, "Invalid client secret");
                    _logger.LogError("Client secret validation failed for client: {clientId}.", client.ClientId);

                    return fail;
                }
            }

            _logger.LogDebug("Client validation success");

            var success = new ClientSecretValidationResult
            {
                IsError = false,
                Client = client,
                Secret = parsedSecret
            };

            await RaiseSuccessEventAsync(client.ClientId, parsedSecret.Type);
            return success;
        }

验证

public async Task<SecretValidationResult> ValidateAsync(ParsedSecret parsedSecret, IEnumerable<Secret> secrets)
        {
            var secretsArray = secrets as Secret[] ?? secrets.ToArray();

            var expiredSecrets = secretsArray.Where(s => s.Expiration.HasExpired(_clock.UtcNow.UtcDateTime)).ToList();
            if (expiredSecrets.Any())
            {
                expiredSecrets.ForEach(
                    ex => _logger.LogWarning("Secret [{description}] is expired", ex.Description ?? "no description"));
            }

            var currentSecrets = secretsArray.Where(s => !s.Expiration.HasExpired(_clock.UtcNow.UtcDateTime)).ToArray();

            // see if a registered validator can validate the secret
            foreach (var validator in _validators)
            {
                var secretValidationResult = await validator.ValidateAsync(currentSecrets, parsedSecret);

                if (secretValidationResult.Success)
                {
                    _logger.LogDebug("Secret validator success: {0}", validator.GetType().Name);
                    return secretValidationResult;
                }
            }

            _logger.LogDebug("Secret validators could not validate secret");
            return new SecretValidationResult { Success = false };
        }

在Web API项目中可以直接从Request中拿到token

var bearer = (((Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http.FrameRequestHeaders)Request.Headers).HeaderAuthorization);
            var token = bearer.ToString().Replace("Bearer ", "");
            JwtSecurityToken jwt = new JwtSecurityToken(token);
            var clientId = jwt.Claims.FirstOrDefault(x => x.Type == "client_id").Value;