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javascript - 如何在nodejs http模块上限制从rest服务器传入的块大小？

问题描述

我正在使用 nodejs 请求模块从 nodejs 请求一个休息服务器。如果传入的数据大小超出允许的限制，我想取消流。这里的目的是确保我的网络没有被锁定。

我的代码示例如下； 

var http = require("http");

async function httpRequest({
  host,
  method,
  port,
  path
} = params, data) {
  if (method.toUpperCase() === "GET") {
    let query = "";
    data = JSON.parse(data);

    for (var key in data) {
      if (data.hasOwnProperty(key)) {
        let value = data[key];
        console.log(key + " -> " + value);
        query = query
          .concat("&")
          .concat(key)
          .concat("=")
          .concat(value);
      }
    }
    if (query) {
      query = "?".concat(query.substring(1));
    }
    path = encodeURI(path.concat(query));
    console.log("path : " + path);
  }
  var opts = {
    hostname: host,
    port: port,
    path: path,
    method: method,
    timeout: 30 * 1000,
    headers: {
      "Content-Type": "application/json"
    }
  };
  return new Promise(function (resolve, reject) {
    const req = http.request(opts, function (response) {
      console.log("Status Code : " + response.statusCode);
      if (response.statusCode < 200 || response.statusCode >= 300) {
        req.end();
        return reject("Fetch data failed  = " + response.statusCode);
      }
      var str = "";
      response.on("data", function (chunk) {
        console.log("chunk : " + chunk);
        str += chunk;
        if (str.length > 256) {
          req.abort();
          reject(
            new Error(
              "The size of the incoming data is larger than the allowable limit."
            )
          );
        }
      });

      response.on("end", function () {
        console.log("\n Result from web service : ", str);
        try {
          let jsonData = JSON.parse(str);
          if (jsonData.status) {
            if (jsonData.status.toLowerCase === "success") {
              if (!("result" in jsonData)) {
                reject("Json Structure Error");
              }
            } else if (jsonData.status.toLowerCase === "error") {
              if (!jsonData.error) {
                reject("Json Structure Error");
              }
            }
            resolve(jsonData);
          } else {
            reject("Json Structure Error");
          }
        } catch (error) {
          reject("Response json error : " + error);
        }
      });
    });

    if (method.toUpperCase() !== "GET" && data) {
      req.write(data);
    }
    //req bitti
    req.on("timeout", function () {
      console.log("timeout! " + opts.timeout / 1000 + " seconds expired");
      req.abort();
    });

    req.on("error", function (err) {
      console.log("Error : " + err);
      if (err.code === "ECONNRESET") {
        req.abort();
        console.log("Timeout occurs : " + err);
        reject(new Error("Timeout occurs : " + err));
      } else if (err.code === "ENOTFOUND") {
        req.abort();
        console.log("Address cannot be reachable : " + err);
        reject(new Error("Address cannot be reachable : " + err));
      } else {
        req.abort();
        reject(new Error(err));
      }
    });
    req.end();
  });
}

let data = JSON.stringify({
  username: "monetrum",
  password: "123456",
  name: "Loremipsumdolorsitamet,consecteturadipiscingelit" +
    ".Aeneaninaliquamodio,egetfac"
});

let params = {
  host: "127.0.0.1",
  method: "GET",
  port: 3010,
  path: "/login"
};

httpRequest(params, data);

到目前为止一切都很好。但是有一个问题。我正在控制传入的数据。我允许的数据大小不得大于 256 字节。但是第一次获取的块大于允许的大小。所以我的大小控制是无稽之谈。有没有处理它的方法。是否可以限制块的大小。提前致谢。

标签： javascriptnode.jsstreamnode-https

解决方案

“可读”事件

您想使用readable事件而不是data事件：

var byteCount = 0;
var chunkSize = 32;
var maxBytes = 256;

req.on('readable', function () {
  var chunks = [];
  var data;

  while(true) {
    data = this.read(chunkSize);
    if (!data) { break; }

    byteCount += data.byteLength;
    if (byteCount > maxBytes) {
      req.abort();
      break;
    }

    chunks.push(data);
  }

  // do something with chunks
});

req.on('abort', function () {
  // do something to handle the error
});

Since your question is very specific I made the example a little more generic so that hopefully others will be able to glean from it as well.

See https://nodejs.org/api/stream.html#stream_event_readable

However...

The Network Does't Care

However, you're going to get more data than that. TCP packet size is 64k. Over non-gigabit ethernet that gets MTU truncated to 1500 bytes (1.5k).

There's nothing that you can do to prevent the network activity from happening other than closing the connection, and you can't get less than 1.5k of data per data event unless there is less than 1.5k of data being sent (or crazy network issues happen, which you have no control over).t

P.S.

I'd recommend that you use a code editor, like VSCode. It's very difficult to read code that has mixes of tabs and spaces and different blocks at different levels. It will suggest plugins that can help you catch mistakes earlier and reformat your code so that it's easier for others (and yourself) to read it.

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