Node.js网络库：从'data'事件中获取完整数据 [英] Node.js net library: getting complete data from 'data' event

问题描述

我已经四处寻找，要么找不到我想要回答的确切问题，要么我需要有人向我解释，就像我5岁。

I've searched around, and either can't find the exact question I'm trying to answer, or I need someone to explain it to me like I'm 5.

基本上，我有一个使用Net库的Node.js脚本。我正在连接多个主机，发送命令和侦听返回数据。

Basically, I have a Node.js script using the Net library. I'm connecting to multiple hosts, and sending commands, and listening for return data.

var net = require('net');

var nodes = [
    'HOST1,192.168.179.8',
    'HOST2,192.168.179.9',
    'HOST3,192.168.179.10',
    'HOST4,192.168.179.11'
];

function connectToServer(tid, ip) {
    var conn = net.createConnection(23, ip);
    conn.on('connect', function() {
        conn.write (login_string);  // login string hidden in pretend variable
    });
    conn.on('data', function(data) {
        var read = data.toString();
        if (read.match(/Login Successful/)) {
            console.log ("Connected to " + ip);
            conn.write(command_string);
        }

        else if (read.match(/Command OK/)) { // command_string returned successful,
                                                    // read until /\r\nEND\r\n/

                    // First part of data comes in here
            console.log("Got a response from  " + ip + ':' + read);
        }
        else {
                 //rest of data comes in here
             console.log("Atonomous message from " + ip + ':' + read);
        }
    });
    conn.on('end', function() {
        console.log("Lost conncection to " + ip + "!!");
    });
    conn.on('error', function(err) {
        console.log("Connection error: " + err + " for ip " + ip);
    });
}

nodes.forEach(function(node) {
    var nodeinfo = node.split(",");
    connectToServer(nodeinfo[0], nodeinfo[1]);
});

数据最终被分成两个块。即使我将数据存储在哈希中，并在读取/ \\\\\\\\ / / /分隔符时将第一部分附加到余数中，但是中间缺少一个块。如何正确缓冲数据以确保从流中获取完整的消息？

The data ends up being split into two chunks. Even if I store the data in a hash and append the first part to the remainder when I read the /\r\nEND\r\n/ delimiter, there's a chunk missing out of the middle. How do I properly buffer the data in order to make sure I get the complete message from the stream?

编辑：好的，这似乎工作得更好：

Ok, this seems to be working better:

function connectToServer(tid, ip) {
        var conn = net.createConnection(23, ip);

        var completeData = '';

        conn.on('connect', function() {
                conn.write (login_string);
        });
        conn.on('data', function(data) {
                var read = data.toString();

                if (read.match(/Login Successful/)) {
                        console.log ("Connected to " + ip);

                        conn.write(command_string);
                }
                else {
                        completeData += read;
                }

                if (completeData.match(/Command OK/)) {
                        if (completeData.match(/\r\nEND\r\n/)) {
                                console.log("Response: " + completeData);
                        }
                }
        });
        conn.on('end', function() {
                console.log("Connection closed to " + ip );
        });
        conn.on('error', function(err) {
                console.log("Connection error: " + err + " for ip " + ip);
        });
}

我最大的问题显然是逻辑错误。我要么等待开始回复的块，要么等待结束它的块。我没有在中间保存所有内容。

My biggest problem was apparently a logic error. I was either waiting for the chunk that began the reply, or the chunk that ended it. I wasn't saving everything in-between.

我想如果我想获得所有Node-ish的话，我应该在发出完整的消息时触发事件（以空白行开头，单独以END结尾），并在那里进行处理。

I guess if I wanted to get all Node-ish about it, I should fire an event whenever a complete message came in (beginning with a blank line, ending with 'END' on a line by itself), and do the processing there.

推荐答案

我的问题是一个逻辑问题。我要么寻找开始消息的块，要么是结束消息的块，而忽略它们之间的所有内容。我猜想整个回复会以一两个块的形式进入。

My problem was a logic problem. I was either looking for the chunk that began the message, or the chunk that ended the message, and ignoring everything in between. I guess expected the entirety of the reply to come in in one or two chunks.

这是从上面粘贴的工作代码。可能有更多的Node-ish方法（我应该为每个信息块发出一个事件），但我会将此标记为答案，除非有人明天这个时候发布更好的版本。

Here's the working code, pasted from above. There's probably a more Node-ish way of doing it (I should really emit an event for each chunk of information), but I'll mark this as the answer unless someone posts a better version by this time tomorrow.

function connectToServer(tid, ip) {
        var conn = net.createConnection(23, ip);

        var completeData = '';

        conn.on('connect', function() {
                conn.write (login_string);
        });
        conn.on('data', function(data) {
                var read = data.toString();

                if (read.match(/Login Successful/)) {
                        console.log ("Connected to " + ip);

                        conn.write(command_string);
                }
                else {
                        completeData += read;
                }

                if (completeData.match(/Command OK/)) {
                        if (completeData.match(/\r\nEND\r\n/)) {
                                console.log("Response: " + completeData);
                        }
                }
        });
        conn.on('end', function() {
                console.log("Connection closed to " + ip );
        });
        conn.on('error', function(err) {
                console.log("Connection error: " + err + " for ip " + ip);
        });
}

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