用的是公开的协议
如有侵权，联系删除。
进入到某个用户的私信页面，发送私信。

可以发现，是个post请求
主要关注data里面的数据
text ：要发送的内容
uid:要发送私信的用户id
clientid:一个加密的参数，服务端返回，或js生成
source:本人的id,但和用户主页的id不同，还不知道从哪里来。

刷新一下页面，重新捕获一下链接，看是否能找到clientid
在某个链接里面发现了他

这条链接是post请求

https://web.im.weibo.com/im/handshake
data:[{"id":"1","version":"1.0","minimumVersion":"1.0","channel":"/meta/handshake","supportedConnectionTypes":["long-polling","callback-polling"],"advice":{"timeout":60000,"interval":0}}]

data没有特殊的值，固定就好。

clientid的话，也可以在某个js文件中找到

https://conchfairy.sinajs.cn/chat/js/app.000f4c48.js
这样的话，参数就找齐了。
需要注意一点的是各个链接content-type的类型。

import requests
from urllib.parse import quote
import json
import re
import time

class wp():
    def __init__(self):
        self.cookie = '你的cookie'
        self.get_clientid()
        self.getsoureid()

    # 得到sourceid
    def getsoureid(self):
        url = 'https://conchfairy.sinajs.cn/chat/js/app.000f4c48.js'
        headers = {
            'Cookie':self.cookie,

        }
        rg = requests.get(url,headers = headers)
        rt = rg.text
        sourceid = re.findall(r'source=(\d+)"',rt)[-1]
        self.sourceid = sourceid

    # 得到clientid
    def get_clientid(self):
        url = 'https://web.im.weibo.com/im/handshake'
        headers = {
            'Content-Type': 'application/json;charset=UTF-8',
            'Cookie': self.cookie,
            'Referer': 'https://api.weibo.com/'
        }
        data = [{"id":"1","version":"1.0","minimumVersion":"1.0","channel":"/meta/handshake","supportedConnectionTypes":["long-polling","callback-polling"],"advice":{"timeout":60000,"interval":0}}]
        r = requests.post(url,headers = headers,data = json.dumps(data),verify = False)
        if r.status_code == 200:
            rj = r.json()
            print(rj)
            self.clientid = rj[0]['clientId']

    # 私信
    def sixin(self,uid,content):
        source = self.sourceid
        content = quote(content)
        url = 'https://api.weibo.com/webim/2/direct_messages/new.json'
        data = f'text={content}&uid={uid}&extensions=%7B%22clientid%22%3A%22{self.clientid}%22%7D&is_encoded=0&decodetime=1&source={source}'
        print(data)
        headers = {
            'Content-Type': 'application/x-www-form-urlencoded',
            'Cookie': self.cookie,
            'Referer': 'https://api.weibo.com/chat/'

        }
        rp = requests.post(url,headers = headers,data = data)
        print(rp.status_code)
        if rp.status_code == 200:
            print(rp.text)

仅用于自己的账号，请不要批量操作，非法操作。