#!/bin/bash
# 只读调研：找出还剩下哪些能优化的地方。
# 不动任何配置（基线测量正在跑）。
set -u

echo "════════ 1. 内核和拥塞控制 ════════"
echo "  内核: $(uname -r)"
echo "  可用拥塞控制算法: $(sysctl -n net.ipv4.tcp_available_congestion_control 2>/dev/null)"
echo "  当前算法:         $(sysctl -n net.ipv4.tcp_congestion_control 2>/dev/null)"
echo "  可用排队规则:     $(sysctl -n net.core.default_qdisc 2>/dev/null)"
echo "  ---"
echo "  BBR 模块在不在:"
ls /lib/modules/$(uname -r)/kernel/net/ipv4/ 2>/dev/null | grep -iE 'bbr|tcp_' | head -8 | sed 's/^/    /'
echo "  modprobe 试试（只查不加载）:"
modprobe -n tcp_bbr 2>&1 | head -2 | sed 's/^/    /' || echo "    不能加载"
echo "  内核有没有编进 BBR:"
grep -c 'CONFIG_TCP_CONG_BBR' /boot/config-$(uname -r) 2>/dev/null | sed 's/^/    config 文件: /' || echo "    没有 config 文件"

echo
echo "════════ 2. 当前 TCP 调优项 ════════"
for k in \
    net.ipv4.tcp_keepalive_time net.ipv4.tcp_keepalive_intvl net.ipv4.tcp_keepalive_probes \
    net.ipv4.tcp_mtu_probing net.ipv4.tcp_slow_start_after_idle net.ipv4.tcp_fastopen \
    net.ipv4.tcp_rmem net.ipv4.tcp_wmem net.core.rmem_max net.core.wmem_max \
    net.ipv4.tcp_retries2 net.ipv4.tcp_syn_retries net.ipv4.tcp_synack_retries \
    net.ipv4.tcp_window_scaling net.ipv4.tcp_timestamps net.ipv4.tcp_sack \
    net.ipv4.tcp_fack net.ipv4.tcp_recovery net.ipv4.tcp_notsent_lowat \
    net.core.netdev_max_backlog net.ipv4.tcp_max_syn_backlog net.ipv4.ip_local_port_range; do
    v=$(sysctl -n "$k" 2>/dev/null)
    [ -n "$v" ] && printf "  %-42s = %s\n" "$k" "$v"
done

echo
echo "════════ 3. 网络接口和 MTU ════════"
ip -br addr 2>/dev/null | sed 's/^/  /'
echo "  ---"
for i in $(ls /sys/class/net/ 2>/dev/null | grep -v lo); do
    mtu=$(cat /sys/class/net/$i/mtu 2>/dev/null)
    speed=$(cat /sys/class/net/$i/speed 2>/dev/null || echo '?')
    echo "  $i: MTU=$mtu speed=${speed}Mb"
done
echo "  ---"
echo "  MSS 钳制规则:"
iptables -t mangle -S 2>/dev/null | grep TCPMSS | sed 's/^/    /' || echo "    没有"

echo
echo "════════ 4. 实际路径 MTU 探测 ════════"
for target in 1.1.1.1 198.41.192.227; do
    echo "  到 $target 的最大不分片包:"
    for sz in 1500 1472 1450 1420 1400 1380 1300; do
        if ping -c 1 -W 3 -M do -s $((sz-28)) "$target" > /dev/null 2>&1; then
            echo "    $sz 字节: 通"
            break
        else
            echo "    $sz 字节: 不通"
        fi
    done
done

echo
echo "════════ 5. cloudflared 可选参数（和重连/传输有关的）════════"
cloudflared tunnel run --help 2>&1 | grep -E '^\s+--(retries|protocol|edge|ha-connections|region|grace|compression|tcp)' | sed 's/^/  /'

echo
echo "════════ 6. 隧道当前完整配置 ════════"
systemctl cat lanremote-tunnel 2>/dev/null | grep -vE '^\s*#' | grep -v '^$' | sed 's/^/  /'

echo
echo "════════ 7. cloudflared 的 originRequest 配置 ════════"
cat /root/.cloudflared/config.yml 2>/dev/null | sed 's/^/  /'

echo
echo "════════ 8. 4G 网卡的重传统计（看链路质量）════════"
ip -s link show 2>/dev/null | head -20 | sed 's/^/  /'
echo "  ---"
netstat -s 2>/dev/null | grep -iE 'retrans|timeout|reset|error|失败' | head -10 | sed 's/^/  /'