From fa6c9c8f575a617f6603935b5a77c9624dd5b9fb Mon Sep 17 00:00:00 2001
From: SessionHu <102411014+SessionHu@users.noreply.github.com>
Date: Fri, 26 Jul 2024 15:22:32 +0800
Subject: [PATCH] feat: get buvid3 b_nut from response header

---
 README.md             |  2 +-
 docs/misc/buvid3_4.md | 39 ++++++++++++++++++++++++++++++++++++++-
 2 files changed, 39 insertions(+), 2 deletions(-)

diff --git a/README.md b/README.md
index 3ffdecf..2364b21 100644
--- a/README.md
+++ b/README.md
@@ -73,7 +73,7 @@ B站 API 采用 C/S 结构，大多数接口为 REST API 和 gRPC，少部分接
 - [x] [图片格式化](docs/misc/picture.md)
 - [x] [bvid 说明](docs/misc/bvid_desc.md)
 - [ ] [设备唯一标识BUVID](docs/misc/device_identity.md)
-- [ ] [获取 buvid3 / buvid4](docs/misc/buvid3_4.md)
+- [ ] [获取 buvid3 / buvid4 / b_nut](docs/misc/buvid3_4.md)
 - [ ] [gRPC API 接口定义](grpc_api)
 - [ ] [登录](docs/login)
     - [x] [登录操作 (人机认证)](docs/login/login_action)
diff --git a/docs/misc/buvid3_4.md b/docs/misc/buvid3_4.md
index 13d386e..91441d0 100644
--- a/docs/misc/buvid3_4.md
+++ b/docs/misc/buvid3_4.md
@@ -1,4 +1,4 @@
-# 获取 buvid3 / buvid4
+# 获取 buvid3 / buvid4 / b_nut
 
 ## 游客获取 buvid3 / buvid4
 
@@ -46,3 +46,40 @@ curl -G 'https://api.bilibili.com/x/frontend/finger/spi'
 ```
 
 </details>
+
+## 从响应头获取 buvid3 / b_nut
+
+使用 `GET` 或 `HEAD` 方法请求 `https://www.bilibili.com/`, 且请求头中 `User-Agent` 字段不包含 `curl` `python` `awa` 等敏感子字符串, 且相同 `User-Agent` 字段不得短时多次请求. 在响应头中的 `Set-Cookie` 字段中, 即可找到 `buvid3` 和 `b_nut`.
+
+若不带任何 Cookie 请求, 则 `b_nut` 为响应生成时刻的 UNIX 秒级时间戳.
+若请求 Cookie 仅带有 `buvid3`, 则 `b_nut` 为 `100`.
+若请求 Cookie 仅带有 `b_nut`, 则与不带任何 Cookie 的响应相同.
+若请求 Cookie 仅带有 `buvid3` 和 `b_nut`, 则响应无 `Set-Cookie` 字段.
+若请求 Cookie 带有其他字段, 无影响.
+
+**示例:**
+
+```shell
+curl -I "https://www.bilibili.com/" -A "awa"
+```
+
+<details>
+<summary>查看响应示例:</summary>
+
+```http
+HTTP/2 200 
+date: Fri, 26 Jul 2024 06:38:43 GMT
+content-type: text/html; charset=utf-8
+support: nantianmen
+set-cookie: buvid3=805E4894-96A2-0684-6F00-C6EA1FFB911023315infoc; path=/; expires=Sat, 26 Jul 2025 06:38:43 GMT; domain=.bilibili.com
+set-cookie: b_nut=1721975923; path=/; expires=Sat, 26 Jul 2025 06:38:43 GMT; domain=.bilibili.com
+vary: Origin,Accept-Encoding
+idc: shjd
+expires: Fri, 26 Jul 2024 06:38:42 GMT
+cache-control: no-cache
+x-cache-webcdn: MISS from blzone01
+x-cache-time: 0
+x-save-date: Fri, 26 Jul 2024 06:38:43 GMT
+```
+
+</details>