#!/bin/bash
#by spiritlhl
#from https://github.com/spiritLHLS/one-click-installation-script
#version: 2022.12.18

red(){ echo -e "\033[31m\033[01m$1$2\033[0m"; }
green(){ echo -e "\033[32m\033[01m$1$2\033[0m"; }
yellow(){ echo -e "\033[33m\033[01m$1$2\033[0m"; }
reading(){ read -rp "$(green "$1")" "$2"; }

head() {
  # 支持系统：Ubuntu 18+，Debian 8+，centos 7+，Fedora，Almalinux 8.5+
  ver="2022.12.18"
  changeLog="一键修复linux网络脚本"
  clear
  echo "#######################################################################"
  echo "#                     ${YELLOW}一键修复linux网络脚本${PLAIN}                           #"
  echo "# 版本：$ver                                                    #"
  echo "# 更新日志：$changeLog                                     #"
  echo "# ${GREEN}作者${PLAIN}: spiritlhl                                                     #"
  echo "# ${GREEN}作仓库${PLAIN}: https://github.com/spiritLHLS/one-click-installation-script #"
  echo "#######################################################################"
  echo "支持系统：Ubuntu 18+，Debian 8+，centos 7+，Fedora，Almalinux 8.5+"
  echo "1.检测ping谷歌如果有问题修改nameserver为google源或cloudflare源"
  echo "2.检测ping谷歌还有问题尝试修复为IP类型对应的网络优先级(默认IPV4类型，纯V6类型再替换为IPV6类型)"
  # Display prompt asking whether to proceed with checking and changing
  reading "Do you want to proceed with checking and changing nameserver? [y/n] " confirm
  echo ""

  # Check user's input and exit if they do not want to proceed
  if [ "$confirm" != "y" ]; then
    exit 0
  fi
}

main() {
  external_ip=$(host myip.opendns.com resolver1.opendns.com | grep "myip.opendns.com has" | awk '{print $4}')
  # 判断 IP 类型并执行对应的函数
  if [[ $external_ip =~ ^[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}$ ]]; then
      main_v4
  elif [[ $external_ip =~ ^[0-9a-fA-F]{1,4}:[0-9a-fA-F]{1,4}:[0-9a-fA-F]{1,4}:[0-9a-fA-F]{1,4}:[0-9a-fA-F]{1,4}:[0-9a-fA-F]{1,4}:[0-9a-fA-F]{1,4}:[0-9a-fA-F]{1,4}$ ]]; then
      main_v6
  else
      echo "无法识别外网 IP 地址类型"
  fi
}

main_v4() {
  # Check if /etc/resolv.conf and /etc/gai.conf exist before backing them up
  if [ -f /etc/resolv.conf ]; then
    cp /etc/resolv.conf /etc/resolv.conf.bak
  fi
  if [ -f /etc/gai.conf ]; then
    cp /etc/gai.conf /etc/gai.conf.bak
  fi

  # Check if ping to google.com is successful
  if ping -c 1 google.com; then
    return
  fi

  # Try using Google's nameserver
  echo "nameserver 8.8.8.8" > /etc/resolv.conf
  if ping -c 1 google.com; then
    return
  fi

  # Try using Cloudflare's nameserver
  echo "nameserver 1.1.1.1" > /etc/resolv.conf
  if ping -c 1 google.com; then
    return
  fi
  
  # Display prompt asking whether to proceed with checking and changing priority
  reading "Do you want to proceed with checking and changing network priority? [y/n] " priority
  echo ""

  # Check user's input and exit if they do not want to proceed
  if [ "$priority" != "y" ]; then
    exit 0
  fi

  # Check IP type and network priority
  ip_type=$(curl -s ip.sb | grep -oP '(?<=is )(.+)(?=\.)')
  if [ -z "$ip_type" ]; then
    echo "Error: curl request failed"
    exit 1
  fi

  if [ "$ip_type" = "IPv4" ]; then
    priority=$(grep precedence /etc/gai.conf | grep -oP '(?<=precedence ::ffff:0:0\/96 )\d+')
  else
    priority=$(grep precedence /etc/gai.conf | grep -oP '(?<=precedence ::/0 )\d+')
  fi

  # Modify network priority if necessary
  if [ "$ip_type" = "IPv4" ] && [ "$priority" -gt "100" ]; then
    echo "precedence ::ffff:0:0/96 50" > /etc/gai.conf
  elif [ "$ip_type" = "IPv6" ] && [ "$priority" -lt "100" ]; then
    echo "precedence ::/0 100" > /etc/gai.conf
  fi

  # Check if ping to google.com is successful after modifying network priority
  if ping -c 1 google.com; then
    green "Ping successful after modifying network priority"
    return
  else
    # Restore original configuration if ping fails after modifying network priority
    mv /etc/resolv.conf.bak /etc/resolv.conf
    mv /etc/gai.conf.bak /etc/gai.conf
    echo "Error: Network problem is not related to nameserver or network priority. Original configuration restored."
    exit 1
  fi
}

main_v6() {
    # 定义 nameserver 列表
    nameservers=(
        "2001:67c:2960:5353:5353:5353:5353:5353"
        "2001:67c:2960:6464:6464:6464:6464:6464"
        "2602:fc23:18::7"
        "2001:67c:27e4::60"
        "2001:67c:27e4:15::64"
        "2001:67c:27e4::64"
        "2001:67c:27e4:15::6411"
        "2a01:4f9:c010:3f02::1"
        "2a00:1098:2c::1"
        "2a00:1098:2b::1"
        "2a01:4f8:c2c:123f::1"
        "2001:67c:2960::64"
        "2001:67c:2960::6464"
        "2001:67c:2960::64"
        "2001:67c:2960::6464"
        "2001:67c:2b0::6"
        "2001:67c:2b0::4"
        "2a03:7900:2:0:31:3:104:161"
    )

    # 保存当前 nameserver 的值，以便之后恢复
    current_nameserver=$(cat /etc/resolv.conf | grep "nameserver" | awk '{print $2}')

    # 循环尝试替换 nameserver 并测试网络
    for nameserver in "${nameservers[@]}"; do
        # 替换 nameserver
        echo "nameserver $nameserver" > /etc/resolv.conf

        # 让修改生效
        resolvconf -u

        # ping 测试
        if ping -c 3 google.com &> /dev/null || ping -c 3 github.com &> /dev/null; then
            green "网络恢复成功"
            return
        fi
    done

    # 如果所有 nameserver 都尝试过了仍然无法修复，则恢复为原来的 nameserver
    echo "nameserver $current_nameserver" > /etc/resolv.conf
    resolvconf -u
}



head
main
# ping 测试
if ping -c 3 google.com &> /dev/null || ping -c 3 github.com &> /dev/null; then
    green "V4网络恢复成功"
fi