golang tcp keepalive实践

- 日理万妓 2022-01-27 13:23 260阅读 0赞

[前文][Link 1]中已经介绍了TCP keep alive的做了详尽说明，本文结合golang，介绍如何使用TCP keep alive。

目前golang net包不提供TCP keep alive `空闲多长时间开始探测`、 `探测总次数`直接设置。

可以使用第三方包。

# 1.下载第三方包 #

git clone git@github.com:felixge/tcpkeepalive.git

注意放到`GOPATH`目录下。

# 2.例子 #

## 2.1 server ##

server端，接受client连接请求，建立连接后，设置连接的`空闲多长时间开始探测`、`探测时间间隔`、`探测总次数`。

本例中，我们设置的参数如下：

*  `空闲多长时间开始探测` `keepAliveIdle`: 10s
 *  `探测时间间隔` `keepAliveInterval`: 10s
 *  `探测总次数` `keepAliveCount`:9

server端发送一次数据后，停住。等待10s，开始发送tcp keep alive.

server 代码如下：

package main
    
    import (
            "net"
            "log"
            "time"
    
            "github.com/tcpkeepalive"
    )
    
    func main() { 
    
            addr := "0.0.0.0:8080"
    
            tcpAddr, err := net.ResolveTCPAddr("tcp",addr)
    
            if err != nil { 
                    log.Fatalf("net.ResovleTCPAddr fail:%s", addr)
            }
    
            listener, err := net.ListenTCP("tcp", tcpAddr)
            if err != nil { 
                    log.Fatalf("listen %s fail: %s", addr, err)
            } else { 
    
                    log.Println("rpc listening", addr)
            }
            
            
                    for { 
                    conn, err := listener.Accept()
                    if err != nil { 
                            log.Println("listener.Accept error:", err)
                            continue
                    }
    
                    go handleConnection(conn)
    
            }
    
    }
    
    func setTcpKeepAlive(conn net.Conn) (*tcpkeepalive.Conn, error) { 
    
            newConn, err := tcpkeepalive.EnableKeepAlive(conn)
            if err != nil { 
                    log.Println("EnableKeepAlive failed:", err)
                    return nil, err
            }
    
            err = newConn.SetKeepAliveIdle(10*time.Second)
            if err != nil { 
                    log.Println("SetKeepAliveIdle failed:", err)
                    return nil, err
            }
    
    
            err = newConn.SetKeepAliveCount(9)
            if err != nil { 
                    log.Println("SetKeepAliveCount failed:", err)
                    return nil, err
            }
            
            err = newConn.SetKeepAliveInterval(10*time.Second)
            if err != nil { 
                    log.Println("SetKeepAliveInterval failed:", err)
                    return nil, err
            }
    
            return newConn, nil
    }
    
    
    func handleConnection(conn net.Conn) { 
            defer conn.Close()
    
            newConn, err := setTcpKeepAlive(conn)
            if err != nil { 
                    log.Println("setTcpKeepAlive failed:", err)
                    return
            }
    
            var buffer []byte = []byte("You are welcome. I'm server.")
    
    
            for { 
    
                    time.Sleep(1*time.Second)
                    n, err := newConn.Write(buffer)
                    if err != nil { 
                            log.Println("Write error:", err)
                            break
                    }
                    log.Println("send:", n)
    
                    select{ }
            }
    
            log.Println("connetion end")
    
    }

## 2.2 client ##

client端很简单，负责接收数据。

package main
    
    
    import (
            "fmt"
            "net"
            "os"
    )
    
    func main() { 
    
            conn, err := net.Dial("tcp", "127.0.0.1:8080")
            if err != nil { 
                    fmt.Println("dial failed:", err)
                    os.Exit(1)
            }
            defer conn.Close()
    
    
            buffer := make([]byte, 512)
    
            for { 
    
                    n, err := conn.Read(buffer)
                    if err != nil { 
                            fmt.Println("Read failed:", err)
                            return
                    }
    
                    fmt.Println("count:", n, "msg:", string(buffer))
            }
    
    }

# 3.查看结果 #

server输出

019/05/26 22:22:00 rpc listening 0.0.0.0:8080
    2019/05/26 22:22:15 send: 28

client输出

count: 28 msg: You are welcome. I'm server.

通过tcpdump 或者wireshark抓包，可以看到TCP Keep-Alive的数据包发送情况。  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2xhbnlhbmcxMjM0NTY_size_16_color_FFFFFF_t_70]

# 4.参考 #

[Using TCP keepalive with Go][]

[github tcpkeepalive][]

[Link 1]: https://blog.csdn.net/lanyang123456/article/details/90578453
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2xhbnlhbmcxMjM0NTY_size_16_color_FFFFFF_t_70]: /images/20220127/1caa27c00c3a4649907da84da7f0733f.png
[Using TCP keepalive with Go]: https://felixge.de/2014/08/26/tcp-keepalive-with-golang.html
[github tcpkeepalive]: https://github.com/felixge/tcpkeepalive