在GO中获取传入的TTL [英] Getting incoming TTL in GO

问题描述

我正在为一个正在从事的小项目而苦苦挣扎.我想在GO中实现功能，该功能允许我在传出的UDP数据包上设置IP标头TTL，然后再发送该数据包并查看另一端的接收到的TTL.我尝试使用'net'库提供的许​​多连接，但到目前为止没有成功(我可以设置TTL，但无法读取).谁能建议一种发送和接收UDP数据包的方法，该数据包提供对数据包TTL字段的访问?

I'm struggling with a small project I am working on. I want to implement functionality in GO that allows me to set the IP header TTL on an outgoing UDP packet that I then send and view the received TTL on the other end. I have a tried using a number of connections provided by the 'net' library and have so far had no success (I can set the TTL but I can't read it). Can anyone suggest a way of sending and receiving UDP packets that provide access to the packet's TTL field?

推荐答案

设置TTL:

var conn *icmp.PacketConn

// for IPv4
conn.IPv4PacketConn().SetTTL(p.ttl) 
conn.IPv4PacketConn().SetControlMessage(ipv4.FlagTTL, true)

// for IPv6
conn.IPv6PacketConn().SetHopLimit(p.ttl) 
conn.IPv6PacketConn().SetControlMessage(ipv6.FlagHopLimit, true)

接收TTL:

    var ttl, n int
    bytes := make([]byte, 512)
    if IPv4 {
        var cm *ipv4.ControlMessage
        n, cm, _, err = conn.IPv4PacketConn().ReadFrom(bytes)
        if cm != nil {
            ttl = cm.TTL
        }
    } else {
        var cm *ipv6.ControlMessage
        n, cm, _, err = conn.IPv6PacketConn().ReadFrom(bytes)
        if cm != nil {
            ttl = cm.HopLimit
        }
    }

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