docs: add discovery url docs and sidebar entries

.vitepress/config/cn.ts

@@ -45,6 +45,7 @@ export const cn = defineConfig({
           ] },
           { text: '其他配置', link: '/guide/network/configurations' },
           { text: '配置文件', link: '/guide/network/config-file' },
+          { text: '发现地址', link: '/guide/network/discovery-url' },
         ],
       },
       {

.vitepress/config/en.ts

@@ -44,6 +44,7 @@ export const en = defineConfig({
           ] },
           { text: 'Other Configurations', link: '/en/guide/network/configurations' },
           { text: 'Configuration File', link: '/en/guide/network/config-file' },
+          { text: 'Discovery URL', link: '/en/guide/network/discovery-url' },
         ],
       },
       {

en/guide/network/discovery-url.md

@@ -0,0 +1,91 @@
+# Discovery URL
+
+EasyTier supports using a Discovery URL to automatically resolve the actual connection address of a peer node. When a node's IP changes frequently, or when you want to distribute node addresses dynamically through a domain name, using a discovery URL eliminates the need to manually maintain the address list.
+
+Users only need to provide a discovery URL at startup, and EasyTier will automatically resolve the peer node's **connector URL** (the address actually used to establish a connection, in the format `scheme://host:port`, such as `tcp://1.2.3.4:11010` or `quic://host:port`) and establish a connection accordingly.
+
+```mermaid
+flowchart LR
+
+subgraph Node A
+nodeA[EasyTier]
+end
+
+subgraph Discovery Service
+disc[Discovery URL<br/>http/txt/srv]
+end
+
+subgraph Node B
+nodeB[EasyTier<br/>tcp://1.2.3.4:11010]
+end
+
+nodeA -->|1. Request discovery URL| disc
+disc -->|2. Return candidate address| nodeA
+nodeA -->|3. Establish connection| nodeB
+
+```
+
+## Supported Discovery URL Types
+
+| Prefix | Description | Example |
+| --- | --- | --- |
+| `http://` / `https://` | Sends an HTTP request to the URL and extracts the candidate address from the response | `https://discovery.example.com/peer` |
+| `txt://` | Queries DNS TXT records and extracts the candidate address from them | `txt://my-network.example.com` |
+| `srv://` | Queries DNS SRV records and selects the host and port by priority | `srv://my-network.example.com` |
+
+Simply specify the discovery URL with the `-p` option.
+
+## HTTP / HTTPS
+
+**3xx Redirect**
+
+When the server returns a 302 redirect response, it carries the candidate address information in the `Location` response header. EasyTier first attempts to parse the connector URL from the query parameters of the Location header; if no valid address is found in the query parameters, it then tries to parse the raw value of the `Location` header directly as a connector URL.
+
+```http
+HTTP/1.1 302 Found
+Location: https://example.com/redirect?target=tcp://1.2.3.4:11010
+```
+
+```http
+HTTP/1.1 302 Found
+Location: tcp://1.2.3.4:11010
+```
+
+**2xx Response Body**
+
+The server returns a 200 status code, with each line of the response body providing one candidate address. EasyTier shuffles these addresses randomly and tries to parse them line by line, taking the first valid result.
+
+```http
+HTTP/1.1 200 OK
+Content-Type: text/plain
+
+tcp://1.2.3.4:11010
+quic://5.6.7.8:11010
+ws://9.10.11.12:11011/
+```
+
+::: warning Note
+When multiple candidate addresses exist, EasyTier randomly selects one of them to avoid a single address becoming a hotspot and to distribute load across multiple backends.
+:::
+
+## TXT
+
+EasyTier queries the DNS TXT record for `my-network.example.com`, splits the record content into lines, and tries to parse each line as a connector URL, taking the first valid result. An empty record or unparseable content is treated as a discovery failure.
+
+Example DNS TXT records:
+
+```
+my-network.example.com.  IN  TXT  "tcp://1.2.3.4:11010"
+my-network.example.com.  IN  TXT  "quic://5.6.7.8:11010"
+```
+
+## SRV
+
+After querying the SRV records, EasyTier sorts them by priority and weight and selects an appropriate host and port. It then maps them to a connector URL of the corresponding protocol (such as `quic://host:port`) based on the configured `srv_protocols` (for example, `["tcp","udp","quic"]`), and takes the first valid result.
+
+Example DNS SRV records:
+
+```
+_my-network._tcp.example.com.  IN  SRV  10 60 11010 node1.example.com.
+_my-network._tcp.example.com.  IN  SRV  20 40 11010 node2.example.com.
+```

guide/network/discovery-url.md

@@ -0,0 +1,91 @@
+# 发现地址
+
+EasyTier 支持通过发现地址（Discovery URL）来自动解析对端节点的真实连接地址。当节点 IP 经常变动、或希望通过域名动态下发节点地址时，使用发现地址可以免去手动维护地址列表的麻烦。
+
+用户只需在启动时提供一个发现地址，EasyTier 会自动解析出对端节点的**连接地址**（connector URL，即真正用于建立连接的地址，格式为 `协议://主机:端口`，如 `tcp://1.2.3.4:11010`、`quic://host:port`）并据此建立连接。
+
+```mermaid
+flowchart LR
+
+subgraph 节点 A
+nodeA[EasyTier]
+end
+
+subgraph 发现服务
+disc[Discovery URL<br/>http/txt/srv]
+end
+
+subgraph 节点 B
+nodeB[EasyTier<br/>tcp://1.2.3.4:11010]
+end
+
+nodeA -->|1. 请求发现地址| disc
+disc -->|2. 返回候选地址| nodeA
+nodeA -->|3. 建立连接| nodeB
+
+```
+
+## 支持的发现地址类型
+
+| 前缀 | 说明 | 示例 |
+| --- | --- | --- |
+| `http://` / `https://` | 向该 URL 发起 HTTP 请求，从响应中提取候选地址 | `https://discovery.example.com/peer` |
+| `txt://` | 查询 DNS TXT 记录，从中提取候选地址 | `txt://my-network.example.com` |
+| `srv://` | 查询 DNS SRV 记录，按优先级选择主机与端口 | `srv://my-network.example.com` |
+
+使用 `-p` 参数指定发现地址即可
+
+## HTTP / HTTPS
+
+**3xx 重定向**
+
+当服务端返回 302 重定向响应时，会在 `Location` 响应头中携带候选地址信息。EasyTier 会优先尝试从 Location 头的查询参数中解析连接地址；若未在查询参数中找到有效地址，则会尝试将 `Location` 头的原始值直接解析为连接地址。
+
+```http
+HTTP/1.1 302 Found
+Location: https://example.com/redirect?target=tcp://1.2.3.4:11010
+```
+
+```http
+HTTP/1.1 302 Found
+Location: tcp://1.2.3.4:11010
+```
+
+**2xx 响应体**
+
+服务端返回 200 状态码，响应体每行提供一个候选地址。EasyTier 会将这些地址随机打乱后逐行尝试解析，取第一个成功解析的有效结果。
+
+```http
+HTTP/1.1 200 OK
+Content-Type: text/plain
+
+tcp://1.2.3.4:11010
+quic://5.6.7.8:11010
+ws://9.10.11.12:11011/
+```
+
+::: warning 提示
+当存在多个候选地址时，EasyTier 会随机选取其中一个，避免单一地址成为热点，同时在多个后端之间分散负载。
+:::
+
+## TXT
+
+EasyTier 会查询 `my-network.example.com` 的 DNS TXT 记录，将记录内容按行拆分，逐行尝试解析为连接地址，取第一个有效结果。空记录或无可解析内容时视为发现失败。
+
+DNS TXT 记录示例：
+
+```
+my-network.example.com.  IN  TXT  "tcp://1.2.3.4:11010"
+my-network.example.com.  IN  TXT  "quic://5.6.7.8:11010"
+```
+
+## SRV
+
+EasyTier 查询 SRV 记录后，会按照优先级和权重排序，从中选取合适的主机与端口；随后结合配置的 `srv_protocols`（例如 `["tcp","udp","quic"]`），将其映射为对应协议的连接地址（如 `quic://host:port`），最终取第一个有效的结果。
+
+DNS SRV 记录示例：
+
+```
+_my-network._tcp.example.com.  IN  SRV  10 60 11010 node1.example.com.
+_my-network._tcp.example.com.  IN  SRV  20 40 11010 node2.example.com.
+```