OAuth 2.0简单实战（以新浪开发平台为例）

背景

本人去年在UCLA打酱油的时候曾经要求抓过新浪微博的有关数据。然而要读写这些微博信息和朋友关系，必须要在新浪围脖平台上注册应用。也就是要接触 OAuth 2.0 这个东西。当时基本不懂，今天看到了阮一峰博客上的这篇文章,决定自己动手一试。

准备

首先，你要把阮一峰博客上的这篇文章 粗略的读一遍。

然后你要上 新浪开发平台 注册一个应用，我注册的是微连接 - 网页应用

打开界面你可以看到App Key和App Secret，这是要用的东西

好，接下来下载新浪微博python SDK，我们用Python进行分析

分析

首先，我们先根据微博API上面的HOW-TO 文档上来做

from weibo import APIClient

APP_KEY = '1234567' # app key
APP_SECRET = 'abcdefghijklmn' # app secret
CALLBACK_URL = 'http://www.example.com/callback' 
client = APIClient(app_key=APP_KEY, app_secret=APP_SECRET, redirect_uri=CALLBACK_URL)
url = client.get_authorize_url()

这样就拿到了URL了，你打开这个URL一看，正是提示你要授权应用（出现error:redirect_uri_mismatch 同学请到新浪微博开发界面填好redirect_uri)

好，我们看看源码

class APIClient(object):
    '''
    API client using synchronized invocation.
    '''
    def __init__(self, app_key, app_secret, redirect_uri=None, response_type='code', domain='api.weibo.com', version='2'):
        self.client_id = str(app_key)
        self.client_secret = str(app_secret)
        self.redirect_uri = redirect_uri
        self.response_type = response_type
        self.auth_url = 'https://%s/oauth2/' % domain
        self.api_url = 'https://%s/%s/' % (domain, version)
        self.access_token = None
        self.expires = 0.0
        self.get = HttpObject(self, _HTTP_GET)
        self.post = HttpObject(self, _HTTP_POST)
        self.upload = HttpObject(self, _HTTP_UPLOAD)

    def get_authorize_url(self, redirect_uri=None, **kw):
        '''
        return the authorization url that the user should be redirected to.
        '''
        redirect = redirect_uri if redirect_uri else self.redirect_uri
        if not redirect:
            raise APIError('21305', 'Parameter absent: redirect_uri', 'OAuth2 request')
        response_type = kw.pop('response_type', 'code')
        return '%s%s?%s' % (self.auth_url, 'authorize', \
                _encode_params(client_id = self.client_id, \
                        response_type = response_type, \
                        redirect_uri = redirect, **kw))

client_id,redirect_url,app_key，好熟悉啊，仔细一看，原来是授权码模式的第一步

The client constructs the request URI by adding the following
parameters to the query component of the authorization endpoint URI
using the "application/x-www-form-urlencoded" format, per Appendix B:

response_type
REQUIRED. Value MUST be set to "code".

client_id
REQUIRED. The client identifier as described in Section 2.2.

redirect_uri
OPTIONAL. As described in Section 3.1.2.

scope
OPTIONAL. The scope of the access request as described by
Section 3.3.

state
RECOMMENDED. An opaque value used by the client to maintain
state between the request and callback. The authorization
server includes this value when redirecting the user-agent back
to the client. The parameter SHOULD be used for preventing
cross-site request forgery as described in Section 10.12.

好了，当我们把账号密码填写好了之后验证成功后，你发现你的浏览器上面的URL发生了变化，到底是这么回事呢，请看第二步Authorization Response

If the resource owner grants the access request, the authorization
server issues an authorization code and delivers it to the client by
adding the following parameters to the query component of the
redirection URI using the "application/x-www-form-urlencoded" format,
per Appendix B:

code
REQUIRED. The authorization code generated by the
authorization server. The authorization code MUST expire
shortly after it is issued to mitigate the risk of leaks. A
maximum authorization code lifetime of 10 minutes is
RECOMMENDED. The client MUST NOT use the authorization code more than once. If an authorization code is used more than
once, the authorization server MUST deny the request and SHOULD
revoke (when possible) all tokens previously issued based on
that authorization code. The authorization code is bound to
the client identifier and redirection URI.

state
REQUIRED if the "state" parameter was present in the client
authorization request. The exact value received from the
client.

For example, the authorization server redirects the user-agent by
sending the following HTTP response:

 HTTP/1.1 302 Found
 Location: https://client.example.com/cb?code=SplxlOBeZQQYbYS6WxSbIA
           &state=xyz

然后我们继续按照API的指示做

# 获取URL参数code:
code = your.web.framework.request.get('code')
r = client.request_access_token(code)

def request_access_token(self, code, redirect_uri=None):
        redirect = redirect_uri if redirect_uri else self.redirect_uri
        if not redirect:
            raise APIError('21305', 'Parameter absent: redirect_uri', 'OAuth2 request')
        r = _http_post('%s%s' % (self.auth_url, 'access_token'), \
                client_id = self.client_id, \
                client_secret = self.client_secret, \
                redirect_uri = redirect, \
                code = code, grant_type = 'authorization_code')
        return self._parse_access_token(r)

这个获得code 方法通常可以有很多，但是我们既然是实验，就手动复制code 吧。

哈哈，很明显request_access_token 这个方法就是发一个HTTP POST 包嘛

第三步Access Token Request

The client makes a request to the token endpoint by sending the
following parameters using the "application/x-www-form-urlencoded"
format per Appendix B with a character encoding of UTF-8 in the HTTP
request entity-body:

grant_type
REQUIRED. Value MUST be set to "authorization_code".

code
REQUIRED. The authorization code received from the
authorization server.

redirect_uri
REQUIRED, if the "redirect_uri" parameter was included in the
authorization request as described in Section 4.1.1, and their
values MUST be identical.

client_id
REQUIRED, if the client is not authenticating with the
authorization server as described in Section 3.2.1.

If the client type is confidential or the client was issued client
credentials (or assigned other authentication requirements), the
client MUST authenticate with the authorization server as described
in Section 3.2.1.

For example, the client makes the following HTTP request using TLS
(with extra line breaks for display purposes only):

 POST /token HTTP/1.1
 Host: server.example.com
 Authorization: Basic czZCaGRSa3F0MzpnWDFmQmF0M2JW
 Content-Type: application/x-www-form-urlencoded

 grant_type=authorization_code&code=SplxlOBeZQQYbYS6WxSbIA
 &redirect_uri=https%3A%2F%2Fclient%2Eexample%2Ecom%2Fcb

最后一步

access_token = r.access_token # 新浪返回的token，类似abc123xyz456
expires_in = r.expires_in # token过期的UNIX时间：http://zh.wikipedia.org/wiki/UNIX%E6%97%B6%E9%97%B4
# TODO: 在此可保存access token
client.set_access_token(access_token, expires_in)

就是从服务器返回的HTTP 包中解析access_token 和 expire_in 数据

同样来看RFC 文档中写的

If the access token request is valid and authorized, the
authorization server issues an access token and optional refresh
token as described in Section 5.1. If the request client
authentication failed or is invalid, the authorization server returns
an error response as described in Section 5.2.

An example successful response:

 HTTP/1.1 200 OK
 Content-Type: application/json;charset=UTF-8
 Cache-Control: no-store
 Pragma: no-cache

 {
   "access_token":"2YotnFZFEjr1zCsicMWpAA",
   "token_type":"example",
   "expires_in":3600,
   "refresh_token":"tGzv3JOkF0XG5Qx2TlKWIA",
   "example_parameter":"example_value"
 }

接下来就可以调用API啦~

对于最后两步看的很累的话，可以自己尝试写一个

import urllib, urllib2

APP_KEY = '2613134348'
APP_SECRET = '5a14f41598a7444c7e0dc0422519b091' # app secret
ACCESS_TOKEN = '9cd1b3869e62491331caf444456953e8'
data = {
        'grant_type' : 'authorization_code', 
        'code' :ACCESS_TOKEN, 
        'redirect_uri':'http://www.ceclinux.org',
        'client_id':APP_KEY,
        'client_secret':APP_SECRET   
        }
headers = {'host':'api.weibo.com','Authorization':'OAuth2 %s' % ACCESS_TOKEN}
data = urllib.urlencode(data)
request = urllib2.Request('https://api.weibo.com/oauth2/access_token', data, headers)
response = urllib2.urlopen(request)
print response.read()

运行这个文件
最后也能得到一个包含access_token和expire_date的JSON文件

没了～

参考

• http://github.liaoxuefeng.com/sinaweibopy/
• https://github.com/michaelliao/sinaweibopy/wiki/OAuth2-HOWTO
• http://www.ruanyifeng.com/blog/2014/05/oauth_2_0.html