HTTP 状态码详解：1xx ~ 5xx 完整速查手册

# curl 模拟 100-continue
curl -X POST -H "Expect: 100-continue" \
  -H "Content-Type: application/json" \
  -d '{"large":"payload"}' https://api.example.com/upload

# WebSocket 升级请求
curl -i -N -H "Connection: Upgrade" \
  -H "Upgrade: websocket" \
  -H "Sec-WebSocket-Version: 13" \
  -H "Sec-WebSocket-Key: dGhlIHNhbXBsZSBub25jZQ==" \
  http://localhost:8080

# 响应：
# HTTP/1.1 101 Switching Protocols
# Upgrade: websocket
# Connection: Upgrade

curl -i https://api.example.com/users/1
# HTTP/1.1 200 OK

curl -i -X POST \
  -H "Content-Type: application/json" \
  -d '{"name":"张三"}' https://api.example.com/users

# HTTP/1.1 201 Created
# Location: /users/42

app.post('/users', async (req, res) => {
  const user = await User.create(req.body);
  res.status(201)
     .location(`/users/${user.id}`)
     .json(user);
});

curl -i -X DELETE https://api.example.com/users/42
# HTTP/1.1 204 No Content

# 只下载前 1024 字节
curl -i -H "Range: bytes=0-1023" https://example.com/video.mp4
# HTTP/1.1 206 Partial Content
# Content-Range: bytes 0-1023/10485760
# Content-Length: 1024

# Nginx：301 永久重定向到 HTTPS
server {
    listen 80;
    server_name example.com;
    return 301 https://$host$request_uri;
}

# Nginx：302 临时维护页面
location /app {
    return 302 /maintenance.html;
}

# Nginx：308 保持 POST 方法
location /api/v1 {
    return 308 /api/v2$request_uri;
}

curl -i -H "If-None-Match: \"abc123\"" https://example.com/style.css
# HTTP/1.1 304 Not Modified

// Express 默认启用 ETag，也可手动控制
app.set('etag', 'strong');  // 或 'weak'

app.get('/data', (req, res) => {
  const data = { time: Date.now() };
  // Express 自动生成 ETag 并处理 304
  res.json(data);
});

curl -i -X POST \
  -H "Content-Type: application/json" \
  -d "这不是JSON" https://api.example.com/users
# HTTP/1.1 400 Bad Request

curl -i https://api.example.com/admin
# HTTP/1.1 401 Unauthorized
# WWW-Authenticate: Bearer realm="api"

curl -i https://api.example.com/users/99999
# HTTP/1.1 404 Not Found

curl -i -X POST https://api.example.com/health
# HTTP/1.1 405 Method Not Allowed
# Allow: GET, HEAD

# 模拟触发限流
for i in $(seq 1 100); do
  curl -s -o /dev/null -w "%{http_code}\n" https://api.example.com/data &
done

# HTTP/1.1 429 Too Many Requests
# Retry-After: 60
# X-RateLimit-Limit: 100
# X-RateLimit-Remaining: 0
# X-RateLimit-Reset: 1720950000

const rateLimit = require('express-rate-limit');

const limiter = rateLimit({
  windowMs: 15 * 60 * 1000,  // 15 分钟
  max: 100,                   // 最多 100 次
  standardHeaders: true,
  legacyHeaders: false,
  message: { error: '请求过于频繁，请稍后再试' }
});

app.use('/api/', limiter);

# 限流区域：每秒 10 个请求
limit_req_zone $binary_remote_addr zone=mylimit:10m rate=10r/s;

server {
    location /api/ {
        limit_req zone=mylimit burst=20 nodelay;
        proxy_pass http://backend;
    }
}

// ❌ 危险：裸奔的错误处理
app.get('/data', async (req, res) => {
  const result = await riskyOperation(); // 可能抛异常 → 500
  res.json(result);
});

// ✅ 安全：全局错误处理中间件
app.use((err, req, res, next) => {
  console.error('服务器错误:', err.stack);
  res.status(500).json({
    error: '服务器内部错误',
    requestId: req.id  // 方便关联日志排查
  });
});

# 自定义 502 错误页
error_page 502 /502.html;
location = /502.html {
    root /usr/share/nginx/html;
}

curl -i https://example.com
# HTTP/1.1 503 Service Unavailable
# Retry-After: 3600

# 延长上游超时
location /slow-api/ {
    proxy_pass http://backend;
    proxy_read_timeout 120s;
    proxy_connect_timeout 10s;
}

# 1. 只看状态码
curl -o /dev/null -s -w "%{http_code}\n" https://example.com

# 2. 看完整响应头 + 体
curl -i https://example.com

# 3. 看详细过程（含 DNS、TCP、TLS 握手时间）
curl -w "@curl-format.txt" -o /dev/null -s https://example.com

# curl-format.txt 内容：
#   time_namelookup:  %{time_namelookup}\n
#   time_connect:     %{time_connect}\n
#   time_appconnect:  %{time_appconnect}\n
#   time_pretransfer: %{time_pretransfer}\n
#   time_redirect:    %{time_redirect}\n
#   time_starttransfer: %{time_starttransfer}\n
#   time_total:       %{time_total}\n