{"id":4171,"date":"2018-11-17T09:23:28","date_gmt":"2018-11-17T01:23:28","guid":{"rendered":"https:\/\/ixyzero.com\/blog\/?p=4171"},"modified":"2018-11-17T09:23:28","modified_gmt":"2018-11-17T01:23:28","slug":"go%e8%af%ad%e8%a8%80%e5%ad%a6%e4%b9%a018-%e5%ae%9e%e7%8e%b0%e4%b8%80%e4%b8%aa%e7%ab%af%e5%8f%a3%e6%89%ab%e6%8f%8f%e5%99%a8","status":"publish","type":"post","link":"https:\/\/ixyzero.com\/blog\/archives\/4171.html","title":{"rendered":"Go\u8bed\u8a00\u5b66\u4e60#18-\u5b9e\u73b0\u4e00\u4e2a\u7aef\u53e3\u626b\u63cf\u5668"},"content":{"rendered":"

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package main\r\n\r\nimport (\r\n    \"context\"\r\n    \"fmt\"\r\n    \"net\"\r\n    \"os\/exec\"\r\n    \"strconv\"\r\n    \"strings\"\r\n    \"sync\"\r\n    \"time\"\r\n\r\n    \"golang.org\/x\/sync\/semaphore\"\r\n)\r\n\r\n\/*\r\n    https:\/\/medium.com\/@KentGruber\/building-a-high-performance-port-scanner-with-golang-9976181ec39d\r\n*\/\r\n\r\n\/\/ \u5c06\u5bf9IP\u7684\u7aef\u53e3\u626b\u63cf\u62bd\u8c61\u6210 PortScanner \u7ed3\u6784\u4f53\r\ntype PortScanner struct {\r\n    ip   string\r\n    lock *semaphore.Weighted \/\/ \u52a0\u6743\u4fe1\u53f7\u91cf\r\n}\r\n\r\n\/\/ \u901a\u8fc7 os\/exec \u6a21\u5757\u8c03\u7528\u547d\u4ee4 `ulimit -n` \u5e76\u5c06\u5b83\u8f93\u51fa\u4f5c\u4e3a\u8fd4\u56de\r\nfunc Ulimit() int64 {\r\n    out, err := exec.Command(\"ulimit\", \"-n\").Output()\r\n    if err != nil {\r\n        panic(err)\r\n    }\r\n\r\n    s := strings.TrimSpace(string(out))\r\n\r\n    i, err := strconv.ParseInt(s, 10, 64)\r\n    if err != nil {\r\n        panic(err)\r\n    }\r\n\r\n    return i\r\n}\r\n\r\n\/\/ \u626b\u63cf\u539f\u7406\u7684\u6838\u5fc3\u903b\u8f91\u2014\u2014\u4f7f\u7528 net.DialTimeout \u8fdb\u884c\u8fde\u63a5\u5c1d\u8bd5\r\nfunc ScanPort(ip string, port int, timeout time.Duration) {\r\n    target := fmt.Sprintf(\"%s:%d\", ip, port)\r\n    conn, err := net.DialTimeout(\"tcp\", target, timeout)\r\n\r\n    if err != nil {\r\n        if strings.Contains(err.Error(), \"too many open files\") {\r\n            time.Sleep(timeout)\r\n            ScanPort(ip, port, timeout)\r\n        } else {\r\n            fmt.Println(port, \"closed\")\r\n        }\r\n        return\r\n    }\r\n\r\n    conn.Close()\r\n    fmt.Println(port, \"open\")\r\n}\r\n\r\nfunc (ps *PortScanner) Start(f, l int, timeout time.Duration) {\r\n    wg := sync.WaitGroup{}\r\n    defer wg.Wait()\r\n\r\n    for port := f; port <= l; port++ {\r\n        ps.lock.Acquire(context.TODO(), 1) \/\/ \u5bf9\u6bcf\u4e00\u4e2a ScanPort \u8c03\u7528\u90fd\u52a0\u9501\u5904\u7406\r\n        wg.Add(1)\r\n        go func(port int) {\r\n            defer ps.lock.Release(1)\r\n            defer wg.Done()\r\n            ScanPort(ps.ip, port, timeout)\r\n        }(port)\r\n    }\r\n}\r\n\r\nfunc main() {\r\n    start_time := time.Now()\r\n\r\n    ps := &PortScanner{\r\n        ip:   \"127.0.0.1\",\r\n        lock: semaphore.NewWeighted(Ulimit()),\r\n    }\r\n    ps.Start(1, 65535, 500*time.Millisecond)\r\n\r\n    fmt.Printf(\"Spend %v seconds.\\n\", time.Since(start_time).Seconds())\r\n}<\/pre>\n
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