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(16)通过webapi与系统进行交互


1. 引言

上一节我们讲解了如何创建微信公众号模块,这一节我们就继续跟进,来讲一讲公众号模块如何与系统进行交互。
微信公众号模块作为一个独立的web模块部署,要想与现有的【任务清单】进行交互,我们要想明白以下几个问题:

  1. 如何进行交互?
    ABP模板项目中默认创建了webapi项目,其动态webapi技术允许我们直接访问appservice作为webapi而不用在webapi层编写额外的代码。所以,自然而然我们要通过webapi与系统进行交互。
  2. 通过webapi与系统进行交互,如何确保安全?
    我们知道暴露的webapi如果不加以授权控制,就如同在大街上裸奔。所以在访问webapi时,我们需要通过身份认证来确保安全访问。
  3. 都有哪几种身份认证方式?
    第一种就是大家熟知的cookie认证方式;
    第二种就是token认证方式:在访问webapi之前,先要向目标系统申请令牌(token),申请到令牌后,再使用令牌访问webapi。Abp默认提供了这种方式;
    第三种是基于OAuth3.0的token认证方式:OAuth3.0是什么玩意?建议先看看OAuth3.0 知多少以便我们后续内容的展开。OAuth3.0认证方式弥补了Abp自带token认证的短板,即无法进行token刷新。

基于这一节,我完善了一个demo,大家可以直接访问http://shengjietest.azurewebsites.net/进行体验。


demo

下面我们就以【通过webapi请求用户列表】为例看一看三种认证方式的具体实现。

2. Cookie认证方式

Cookie认证方式的原理就是:在访问webapi之前,通过登录目标系统建立连接,将cookie写入本地。下一次访问webapi的时候携带cookie信息就可以完成认证。

2.1. 登录目标系统

这一步简单,我们仅需提供用户名密码,Post一个登录请求即可。
我们在微信模块中创建一个WeixinController

public class WeixinController : Controller
{
    private readonly IAbpWebApiClient _abpWebApiClient;
    private string baseUrl = "http://shengjie.azurewebsites.net/";
    private string loginUrl = "/account/login";
    private string webapiUrl = "/api/services/app/User/GetUsers";
    private string abpTokenUrl = "/api/Account/Authenticate";
    private string oAuthTokenUrl = "/oauth/token";
    private string user = "admin";
    private string pwd = "123qwe";

    public WeixinController()
    {
        _abpWebApiClient = new AbpWebApiClient();
    }
}

其中IAbpWebApiClient是对HttpClient的封装,用于发送 HTTP 请求和接收HTTP 响应。

下面添加CookieBasedAuth方法,来完成登录认证,代码如下:

public async Task CookieBasedAuth()
{
    Uri uri = new Uri(baseUrl + loginUrl);
    var handler = new HttpClientHandler() { AutomaticDecompression = DecompressionMethods.None, UseCookies = true };

    using (var client = new HttpClient(handler))
    {
        client.BaseAddress = uri;
        client.DefaultRequestHeaders.Accept.Add(new System.Net.Http.Headers.MediaTypeWithQualityHeaderValue("application/json"));

        var content = new FormUrlEncodedContent(new Dictionary<string, string>()
        {
            {"TenancyName", "Default"},
            {"UsernameOrEmailAddress", user},
            {"Password", pwd }
        });

        var result = await client.PostAsync(uri, content);

        string loginResult = await result.Content.ReadAsStringAsync();

        var getCookies = handler.CookieContainer.GetCookies(uri);

        foreach (Cookie cookie in getCookies)
        {
            _abpWebApiClient.Cookies.Add(cookie);
        }
    }
}

这段代码中有几个点需要注意:

  1. 指定HttpClientHandler属性UseCookie = true,使用Cookie;
  2. client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));用来指定接受的返回值;
  3. 使用FormUrlEncodedContent进行传参;
  4. 使用var getCookies = handler.CookieContainer.GetCookies(uri);获取返回的Cookie,并添加到_abpWebApiClient.Cookies的集合中,以便下次直接携带cookie信息访问webapi。

2.2. 携带cookie访问webapi

服务器返回的cookie信息在登录成功后已经填充到_abpWebApiClient.Cookies中,我们只需post一个请求到目标api即可。

public async Task<PartialViewResult> SendRequestBasedCookie()
{
    await CookieBasedAuth();
    return await GetUserList(baseUrl + webapiUrl);
}

private async Task<PartialViewResult> GetUserList(string url)
{
    try
    {
        var users = await _abpWebApiClient.PostAsync<ListResultDto<UserListDto>>(url);

        return PartialView("_UserListPartial", users.Items);
    }
    catch (Exception e)
    {
        ViewBag.ErrorMessage = e.Message;
    }

    return null;
}

3. Token认证方式

Abp默认提供的token认证方式,很简单,我们仅需要post一个请求到/api/Account/Authenticate即可请求到token。然后使用token即可请求目标webapi。
但这其中有一个问题就是,如果token过期,就必须使用用户名密码重写申请token,体验不好。

3.1. 请求token

public async Task<string> GetAbpToken()
{
    var tokenResult = await _abpWebApiClient.PostAsync<string>(baseUrl + abpTokenUrl, new
    {
        TenancyName = "Default",
        UsernameOrEmailAddress = user,
        Password = pwd
    });
    this.Response.SetCookie(new HttpCookie("access_token", tokenResult));
    return tokenResult;
}

这段代码中我们将请求到token直接写入到cookie中。以便我们下次直接从cookie中取回token直接访问webapi。

3.2. 使用token访问webapi

从cookie中取回token,在请求头中添加Authorization = Bearer token,即可。

public async Task<PartialViewResult> SendRequest()
{
    var token = Request.Cookies["access_token"]?.Value;
    //将token添加到请求头
    _abpWebApiClient.RequestHeaders.Add(new NameValue("Authorization", "Bearer " + token));

    return await GetUserList(baseUrl + webapiUrl);
}

这里面需要注意的是,abp中配置app.UseOAuthBearerAuthentication(AccountController.OAuthBearerOptions);使用的是Bearer token,所以我们在请求weiapi时,要在请求头中假如Authorization信息时,使用Bearer token的格式传输token信息(Bearer后有一个空格!)。

4. OAuth3.0 Token认证方式

OAuth3.0提供了token刷新机制,当服务器颁发的token过期后,我们可以直接通过refresh_token来申请token即可,不需要用户再录入用户凭证申请token。

4.1. Abp集成OAuth3.0

在WebApi项目中的Api路径下创建Providers文件夹,添加SimpleAuthorizationServerProviderSimpleRefreshTokenProvider类。
其中SimpleAuthorizationServerProvider用来验证客户端的用户名和密码来颁发token;SimpleRefreshTokenProvider用来刷新token。

public class SimpleAuthorizationServerProvider : OAuthAuthorizationServerProvider, ITransientDependency
{
    private readonly LogInManager _logInManager;

    public SimpleAuthorizationServerProvider(LogInManager logInManager)
        {
            _logInManager = logInManager;
        }

    public override Task ValidateClientAuthentication(OAuthValidateClientAuthenticationContext context)
        {
            string clientId;
            string clientSecret;
            if (!context.TryGetBasicCredentials(out clientId, out clientSecret))
            {
                context.TryGetFormCredentials(out clientId, out clientSecret);
            }
            var isValidClient = string.CompareOrdinal(clientId, "app") == 0 &&
                                string.CompareOrdinal(clientSecret, "app") == 0;
            if (isValidClient)
            {
                context.OwinContext.Set("as:client_id", clientId);
                context.Validated(clientId);
            }
            else
            {
                context.SetError("invalid client");
            }

            return Task.FromResult<object>(null);
        }

    public override async Task GrantResourceOwnerCredentials(OAuthGrantResourceOwnerCredentialsContext context)
        {
            var tenantId = context.Request.Query["tenantId"];
            var result = await GetLoginResultAsync(context, context.UserName, context.Password, tenantId);
            if (result.Result == AbpLoginResultType.Success)
            {
                //var claimsIdentity = result.Identity;                
                var claimsIdentity = new ClaimsIdentity(result.Identity);
                claimsIdentity.AddClaim(new Claim(ClaimTypes.Name, context.UserName));
                var ticket = new AuthenticationTicket(claimsIdentity, new AuthenticationProperties());
                context.Validated(ticket);
            }
        }

    public override  Task GrantRefreshToken(OAuthGrantRefreshTokenContext context)
        {
            var originalClient = context.OwinContext.Get<string>("as:client_id");
            var currentClient = context.ClientId;

            // enforce client binding of refresh token
            if (originalClient != currentClient)
            {
                context.Rejected();
                return Task.FromResult<object>(null);
            }

            // chance to change authentication ticket for refresh token requests
            var newId = new ClaimsIdentity(context.Ticket.Identity);
            newId.AddClaim(new Claim("newClaim", "refreshToken"));

            var newTicket = new AuthenticationTicket(newId, context.Ticket.Properties);
            context.Validated(newTicket);

            return Task.FromResult<object>(null);
        }

    private async Task<AbpLoginResult<Tenant, User>> GetLoginResultAsync(OAuthGrantResourceOwnerCredentialsContext context,
        string usernameOrEmailAddress, string password, string tenancyName)
        {
            var loginResult = await _logInManager.LoginAsync(usernameOrEmailAddress, password, tenancyName);

            switch (loginResult.Result)
            {
                case AbpLoginResultType.Success:
                    return loginResult;
                default:
                    CreateExceptionForFailedLoginAttempt(context, loginResult.Result, usernameOrEmailAddress, tenancyName);
                    //throw CreateExceptionForFailedLoginAttempt(context,loginResult.Result, usernameOrEmailAddress, tenancyName);
                    return loginResult;
            }
        }

    private void CreateExceptionForFailedLoginAttempt(OAuthGrantResourceOwnerCredentialsContext context, 
        AbpLoginResultType result, string usernameOrEmailAddress, string tenancyName)
        {
            switch (result)
            {
                case AbpLoginResultType.Success:
                    throw new ApplicationException("Don't call this method with a success result!");
                case AbpLoginResultType.InvalidUserNameOrEmailAddress:
                case AbpLoginResultType.InvalidPassword:
                    context.SetError(L("LoginFailed"), L("InvalidUserNameOrPassword"));
                    break;
                //    return new UserFriendlyException(("LoginFailed"), ("InvalidUserNameOrPassword"));
                case AbpLoginResultType.InvalidTenancyName:
                    context.SetError(L("LoginFailed"), L("ThereIsNoTenantDefinedWithName", tenancyName));
                    break;
                //    return new UserFriendlyException(("LoginFailed"), string.Format("ThereIsNoTenantDefinedWithName{0}", tenancyName));
                case AbpLoginResultType.TenantIsNotActive:
                    context.SetError(L("LoginFailed"), L("TenantIsNotActive", tenancyName));
                    break;
                //    return new UserFriendlyException(("LoginFailed"), string.Format("TenantIsNotActive {0}", tenancyName));
                case AbpLoginResultType.UserIsNotActive:
                    context.SetError(L("LoginFailed"), L("UserIsNotActiveAndCanNotLogin", usernameOrEmailAddress));
                    break;
                //    return new UserFriendlyException(("LoginFailed"), string.Format("UserIsNotActiveAndCanNotLogin {0}", usernameOrEmailAddress));
                case AbpLoginResultType.UserEmailIsNotConfirmed:
                    context.SetError(L("LoginFailed"), L("UserEmailIsNotConfirmedAndCanNotLogin"));
                    break;
                    //    return new UserFriendlyException(("LoginFailed"), ("UserEmailIsNotConfirmedAndCanNotLogin"));
                    //default: //Can not fall to default actually. But other result types can be added in the future and we may forget to handle it
                    //    //Logger.Warn("Unhandled login fail reason: " + result);
                    //    return new UserFriendlyException(("LoginFailed"));
            }
        }

    private static string L(string name, params object[] args)
        {
            //return new LocalizedString(name);
            return IocManager.Instance.Resolve<ILocalizationService>().L(name, args);
        }
}
public class SimpleRefreshTokenProvider : IAuthenticationTokenProvider, ITransientDependency
{
    private static ConcurrentDictionary<string, AuthenticationTicket> _refreshTokens = new ConcurrentDictionary<string, AuthenticationTicket>();

    public Task CreateAsync(AuthenticationTokenCreateContext context)
        {
            var guid = Guid.NewGuid().ToString("N");

            // maybe only create a handle the first time, then re-use for same client
            // copy properties and set the desired lifetime of refresh token
            var refreshTokenProperties = new AuthenticationProperties(context.Ticket.Properties.Dictionary)
            {
                IssuedUtc = context.Ticket.Properties.IssuedUtc,
                ExpiresUtc = DateTime.UtcNow.AddYears(1)
            };
            var refreshTokenTicket = new AuthenticationTicket(context.Ticket.Identity, refreshTokenProperties);

            //_refreshTokens.TryAdd(guid, context.Ticket);
            _refreshTokens.TryAdd(guid, refreshTokenTicket);

            // consider storing only the hash of the handle
            context.SetToken(guid);

            return Task.FromResult<object>(null);
        }

    public Task ReceiveAsync(AuthenticationTokenReceiveContext context)
        {
            AuthenticationTicket ticket;
            if (_refreshTokens.TryRemove(context.Token, out ticket))
            {
                context.SetTicket(ticket);
            }

            return Task.FromResult<object>(null);
        }

    public void Create(AuthenticationTokenCreateContext context)
        {
            throw new NotImplementedException();
        }

    public void Receive(AuthenticationTokenReceiveContext context)
        {
            throw new NotImplementedException();
        }
}

以上两段代码我就不做过多解释,请自行走读。

紧接着我们在Api目录下创建OAuthOptions类用来配置OAuth认证。

public class OAuthOptions
{
    /// <summary>
    /// Gets or sets the server options.
    /// </summary>
    /// <value>The server options.</value>
    private static OAuthAuthorizationServerOptions _serverOptions;

    /// <summary>
    /// Creates the server options.
    /// </summary>
    /// <returns>OAuthAuthorizationServerOptions.</returns>
    public static OAuthAuthorizationServerOptions CreateServerOptions()
    {
        if (_serverOptions == null)
        {
            var provider = IocManager.Instance.Resolve<SimpleAuthorizationServerProvider>();
            var refreshTokenProvider = IocManager.Instance.Resolve<SimpleRefreshTokenProvider>();
            _serverOptions = new OAuthAuthorizationServerOptions
            {
                TokenEndpointPath = new PathString("/oauth/token"),
                Provider = provider,
                RefreshTokenProvider = refreshTokenProvider,
                AccessTokenExpireTimeSpan = TimeSpan.FromSeconds(30),
                AllowInsecureHttp = true
            };
        }
        return _serverOptions;
    }
}

从中我们可以看出,主要配置了以下几个属性:

  • TokenEndpointPath :用来指定请求token的路由;
  • Provider:用来指定创建token的Provider;
  • RefreshTokenProvider:用来指定刷新token的Provider;
  • AccessTokenExpireTimeSpan :用来指定token过期时间,这里我们指定了30s,是为了demo 如何刷新token。
  • AllowInsecureHttp:用来指定是否允许http连接。

创建上面三个类之后,我们需要回到Web项目的Startup类中,配置使用集成的OAuth3.0,代码如下:

public void Configuration(IAppBuilder app)
{
    //第一步:配置跨域访问
    app.UseCors(CorsOptions.AllowAll);

    app.UseOAuthBearerAuthentication(AccountController.OAuthBearerOptions);

    //第二步:使用OAuth密码认证模式
    app.UseOAuthAuthorizationServer(OAuthOptions.CreateServerOptions());

    //第三步:使用Abp
    app.UseAbp();

    //省略其他代码
}

其中配置跨越访问时,我们需要安装Microsoft.Owin.CorsNuget包。

至此,Abp集成OAuth的工作完成了。

4.2. 申请OAuth token

我们在Abp集成OAuth配置的申请token的路由是/oauth/token,所以我们将用户凭证post到这个路由即可申请token:

public async Task<string> GetOAuth3Token()
{
    Uri uri = new Uri(baseUrl + oAuthTokenUrl);
    var handler = new HttpClientHandler() { AutomaticDecompression = DecompressionMethods.None };

    using (var client = new HttpClient(handler))
    {
        client.BaseAddress = uri;
        client.DefaultRequestHeaders.Accept.Add(new System.Net.Http.Headers.MediaTypeWithQualityHeaderValue("application/json"));

        var content = new FormUrlEncodedContent(new Dictionary<string, string>()
        {
            {"grant_type", "password"},
            {"username", user },
            {"password", pwd },
            {"client_id", "app" },
            {"client_secret", "app"},
        });

        //获取token保存到cookie,并设置token的过期日期                    
        var result = await client.PostAsync(uri, content);
        string tokenResult = await result.Content.ReadAsStringAsync();

        var tokenObj = (JObject)JsonConvert.DeserializeObject(tokenResult);
        string token = tokenObj["access_token"].ToString();
        string refreshToken = tokenObj["refresh_token"].ToString();
        long expires = Convert.ToInt64(tokenObj["expires_in"]);

        this.Response.SetCookie(new HttpCookie("access_token", token));
        this.Response.SetCookie(new HttpCookie("refresh_token", refreshToken));
        this.Response.Cookies["access_token"].Expires = Clock.Now.AddSeconds(expires);

        return tokenResult;
    }
}

在这段代码中我们指定的grant_type = password,这说明我们使用的是OAuth提供的密码认证模式。其中{"client_id", "app" }, {"client_secret", "app"}(搞过微信公众号开发的应该对这个很熟悉)用来指定客户端的身份和密钥,这边我们直接写死。
通过OAuth的请求的token主要包含四部分:

  • token:令牌
  • refreshtoken:刷新令牌
  • expires_in:token有效期
  • token_type:令牌类型,我们这里是Bearer

为了演示方便,我们直接把token信息直接写入到cookie中,实际项目中建议写入数据库。

4.3. 刷新token

如果我们的token过期了怎么办,咱们可以用refresh_token来重新获取token。

public async Task<string> GetOAuth3TokenByRefreshToken(string refreshToken)
{
    Uri uri = new Uri(baseUrl + oAuthTokenUrl);
    var handler = new HttpClientHandler() { AutomaticDecompression = DecompressionMethods.None, UseCookies = true };

    using (var client = new HttpClient(handler))
    {
        client.BaseAddress = uri;
        client.DefaultRequestHeaders.Accept.Add(new System.Net.Http.Headers.MediaTypeWithQualityHeaderValue("application/json"));

        var content = new FormUrlEncodedContent(new Dictionary<string, string>()
        {
            {"grant_type", "refresh_token"},
            {"refresh_token", refreshToken},
            {"client_id", "app" },
            {"client_secret", "app"},
        });

        //获取token保存到cookie,并设置token的过期日期                    
        var result = await client.PostAsync(uri, content);

        string tokenResult = await result.Content.ReadAsStringAsync();

        var tokenObj = (JObject)JsonConvert.DeserializeObject(tokenResult);
        string token = tokenObj["access_token"].ToString();
        string newRefreshToken = tokenObj["refresh_token"].ToString();
        long expires = Convert.ToInt64(tokenObj["expires_in"]);

        this.Response.SetCookie(new HttpCookie("access_token", token));
        this.Response.SetCookie(new HttpCookie("refresh_token", newRefreshToken));
        this.Response.Cookies["access_token"].Expires = Clock.Now.AddSeconds(expires);

        return tokenResult;
    }
}

这段代码较直接使用用户名密码申请token的差别主要在参数上,{"grant_type", "refresh_token"},{"refresh_token", refreshToken}

4.4. 使用token访问webapi

有了token,访问webapi就很简单了。

public async Task<ActionResult> SendRequestWithOAuth3Token()
{
    var token = Request.Cookies["access_token"]?.Value;
    if (token == null)
    {
        //throw new Exception("token已过期");
        string refreshToken = Request.Cookies["refresh_token"].Value;
        var tokenResult = await GetOAuth3TokenByRefreshToken(refreshToken);
        var tokenObj = (JObject)JsonConvert.DeserializeObject(tokenResult);
        token = tokenObj["access_token"].ToString();
    }

    _abpWebApiClient.RequestHeaders.Add(new NameValue("Authorization", "Bearer " + token));

    return await GetUserList(baseUrl + webapiUrl);
}

这段代码中,我们首先从cookie中取回access_token,若access_token为空说明token过期,我们就从cookie中取回refresh_token重新申请token。然后构造一个Authorization将token信息添加到请求头即可访问目标webapi。

5. 总结

本文介绍了三种不同的认证方式进行访问webapi,并举例说明。文章不可能面面俱到,省略了部分代码,请直接参考源码。若有纰漏之处也欢迎大家留言指正。

本文主要参考自以下文章:
使用OAuth打造webapi认证服务供自己的客户端使用
ABP中使用OAuth3(Resource Owner Password Credentials Grant模式)
Token Based Authentication using ASP.NET Web API 2, Owin, and Identity


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