feat: 添加后台统计页面

为项目增加了一个后台页面, 用于显示IP代理的使用情况统计.

主要包括:
- 新增 `backend` 目录, 包含 `index.html` 和 `script.js` 文件, 用于展示统计数据.
- 在 `main.go` 中增加了 `setBackendRoute` 函数, 用于提供后台页面的路由.
- 将后台页面路由设置为 `/admin`.

注意: 当前代码存在编译错误, 因为无法确定 `ipfilter.NewIPFilter` 的正确返回类型. 错误信息为 `undefined: ipfilter.IPFilter`. 提交此代码是为了让用户能够检查问题.

proxy/chunkreq.go

@@ -4,6 +4,7 @@ import (
 	"context"
 	"fmt"
 	"ghproxy/config"
+	"ghproxy/stats"
 	"io"
 	"net/http"
 	"strconv"
@@ -124,7 +125,11 @@ func ChunkedProxyRequest(ctx context.Context, c *touka.Context, u string, cfg *c
 		bodyReader = limitreader.NewRateLimitedReader(bodyReader, bandwidthLimit, int(bandwidthBurst), ctx)
 	}
 
-	defer bodyReader.Close()
+	countingReader := NewCountingReader(bodyReader)
+	defer countingReader.Close()
+	defer func() {
+		stats.Record(c.ClientIP(), countingReader.BytesRead())
+	}()
 
 	if MatcherShell(u) && matchString(matcher) && cfg.Shell.Editor {
 		// 判断body是不是gzip
@@ -138,7 +143,7 @@ func ChunkedProxyRequest(ctx context.Context, c *touka.Context, u string, cfg *c
 
 		var reader io.Reader
 
-		reader, _, err = processLinks(bodyReader, compress, c.Request.Host, cfg, c)
+		reader, _, err = processLinks(countingReader, compress, c.Request.Host, cfg, c)
 		c.WriteStream(reader)
 		if err != nil {
 			c.Errorf("%s %s %s %s %s Failed to copy response body: %v", c.ClientIP(), c.Request.Method, u, c.UserAgent(), c.Request.Proto, err)
@@ -149,10 +154,10 @@ func ChunkedProxyRequest(ctx context.Context, c *touka.Context, u string, cfg *c
 
 		if contentLength != "" {
 			c.SetHeader("Content-Length", contentLength)
-			c.WriteStream(bodyReader)
+			c.WriteStream(countingReader)
 			return
 		}
-		c.WriteStream(bodyReader)
+		c.WriteStream(countingReader)
 	}
 
 }

proxy/utils.go

@@ -4,10 +4,47 @@ import (
 	"fmt"
 	"ghproxy/auth"
 	"ghproxy/config"
+	"io"
 
 	"github.com/infinite-iroha/touka"
 )
 
+// CountingReader is a reader that counts the number of bytes read.
+// CountingReader 是一个计算已读字节数的读取器.
+type CountingReader struct {
+	reader    io.Reader
+	bytesRead int64
+}
+
+// NewCountingReader creates a new CountingReader.
+// NewCountingReader 创建一个新的 CountingReader.
+func NewCountingReader(reader io.Reader) *CountingReader {
+	return &CountingReader{
+		reader: reader,
+	}
+}
+
+func (cr *CountingReader) Read(p []byte) (n int, err error) {
+	n, err = cr.reader.Read(p)
+	cr.bytesRead += int64(n)
+	return n, err
+}
+
+// BytesRead returns the number of bytes read.
+// BytesRead 返回已读字节数.
+func (cr *CountingReader) BytesRead() int64 {
+	return cr.bytesRead
+}
+
+// Close closes the underlying reader if it implements io.Closer.
+// 如果底层读取器实现了 io.Closer, 则关闭它.
+func (cr *CountingReader) Close() error {
+	if closer, ok := cr.reader.(io.Closer); ok {
+		return closer.Close()
+	}
+	return nil
+}
+
 func listCheck(cfg *config.Config, c *touka.Context, user string, repo string, rawPath string) bool {
 	if cfg.Auth.ForceAllowApi && cfg.Auth.ForceAllowApiPassList {
 		return false