ROS 自动 DNS 切换：优化网络连接

以下是一个基于Python的示例代码，用于在ROS中实现自动 DNS 切换逻辑：

import os

def check_dns(dns_servers):
    for dns in dns_servers:
        response = os.system('ping -c 1 ' + dns)
        if response == 0:
            return True
    return False

def switch_dns(dns_servers):
    dns_str = ','.join(dns_servers)
    os.system('nmcli con mod <connection_name> ipv4.dns ' + dns_str)
    os.system('nmcli con down <connection_name>')
    os.system('nmcli con up <connection_name>')

if __name__ == '__main__':
    primary_dns = '10.0.0.1'
    secondary_dns = ['223.5.5.5', '119.29.29.29', '223.6.6.6']
    
    # 检查8.8.8.8是否可达
    response = os.system('ping -c 1 8.8.8.8')
    if response == 0:
        # 如果当前DNS不是10.0.0.1，则切换为10.0.0.1
        current_dns = os.popen('nmcli dev show <connection_name> | grep 'IP4.DNS' | awk '{print $2}'').read().strip()
        if current_dns != primary_dns:
            switch_dns([primary_dns])
    else:
        # 如果当前DNS不是223.5.5.5, 119.29.29.29, 223.6.6.6，则切换为这些DNS
        current_dns = os.popen('nmcli dev show <connection_name> | grep 'IP4.DNS' | awk '{print $2}'').read().strip()
        if current_dns not in secondary_dns:
            switch_dns(secondary_dns)

请注意，上述代码中的<connection_name>应该替换为你的网络连接名称。另外，代码中使用了nmcli命令行工具来修改DNS设置和重新连接网络，因此需要确保你的ROS系统中已安装并配置了nmcli。