如何使用Go语言进行代码安全审计

package main

import (
    "fmt"
    "net/http"
    "os"
)

func main() {
    http.HandleFunc("/", handler)
    http.ListenAndServe(":8080", nil)
}

func handler(w http.ResponseWriter, r *http.Request) {
    filePath := r.URL.Path

    if filePath == "" {
        filePath = "index.html"
    }

    // 验证文件路径是否合法
    if !isValidPath(filePath) {
        http.Error(w, "Invalid file path", http.StatusBadRequest)
        return
    }

    // 响应文件内容
    content, err := readFile(filePath)
    if err != nil {
        http.Error(w, "Failed to read file", http.StatusInternalServerError)
        return
    }

    fmt.Fprintf(w, "%s", content)
}

func isValidPath(filePath string) bool {
    // 验证文件路径是否包含非法字符
    invalidChars := []string{"..", "~", "*", "/./", "//"}
    for _, char := range invalidChars {
        if strings.Contains(filePath, char) {
            return false
        }
    }

    // 验证文件路径是否存在
    _, err := os.Stat(filePath)
    if os.IsNotExist(err) {
        return false
    }

    return true
}

func readFile(filePath string) ([]byte, error) {
    file, err := os.Open(filePath)
    if err != nil {
        return nil, err
    }
    defer file.Close()

    stat, err := file.Stat()
    if err != nil {
        return nil, err
    }

    content := make([]byte, stat.Size())
    _, err = file.Read(content)
    if err != nil {
        return nil, err
    }

    return content, nil
}