Question

我无法使用Chrome应用程序通过TCP连接从服务器接收数据。我没有获得onReceived事件。它只是第二次工作，但不是第一次。我复制了文档中的所有内容，但代码不起作用，我不知道出了什么问题。我可以看到我的'ABCDEFGHI'字符串是由服务器在tcpdump窗口中发送的，但由于某些原因Chrome没有得到它。此示例中的错误完全可重现。以下是文件：

THE APP

[niko@dev1 nettest]$ ls -l
total 16
-rw-rw-r-- 1 niko niko 174 Aug  6 16:10 background.js
-rw-rw-r-- 1 niko niko 208 Aug  6 16:11 main.html
-rw-rw-r-- 1 niko niko 928 Aug  6 16:54 main.js
-rw-rw-r-- 1 niko niko 281 Aug  6 16:10 manifest.json
[niko@dev1 nettest]$

的manifest.json：

[niko@dev1 nettest]$ cat manifest.json 
{
  "name": "Receive Test",
  "description": "Network receive test App.",
  "version": "0.1",
  "manifest_version": 2,
  "app": {
    "background": {
      "scripts": ["background.js"]
    }
  },
  "icons": { 
    },

    "sockets": {
        "tcp" : {
              "connect": ["*"]
        }
    }
}
[niko@dev1 nettest]$

background.js：

[niko@dev1 nettest]$ cat background.js 
chrome.app.runtime.onLaunched.addListener(function() {
  chrome.app.window.create('main.html', {
    'outerBounds': {
      'width': 400,
      'height': 500
    }
  });
});
[niko@dev1 nettest]$

main.html中：

[niko@dev1 nettest]$ cat main.html 
<!DOCTYPE html>
<html>
  <head>
    <script type="text/javascript" src="/main.js"></script>
  </head>
  <body>
    <div>Networking test app</div>
    <a href="" id="connect_btn">conect</a>
  </body>
</html>

[niko@dev1 nettest]$

main.js：

[niko@dev1 nettest]$ cat main.js 
var socket;
window.addEventListener("load",init);
function init() {
    var el;
    el=document.getElementById('connect_btn');
    if (el!=null) el.addEventListener("click",connect_click);
}
function connect_click(event) {

    event.preventDefault();

    chrome.sockets.tcp.create({}, function(createInfo) {
        socket=createInfo.socketId;
        chrome.sockets.tcp.setPaused(socket, false);
        chrome.sockets.tcp.connect(socket,"localhost", 4433, connect_callback);
    });
}
function connect_callback(info) {

    console.log("connection accepted: "+info);
    chrome.sockets.tcp.setPaused(socket, false);
    chrome.sockets.tcp.onReceiveError.addListener(receive_error);
    chrome.sockets.tcp.onReceive.addListener(data_received);

}
function data_received(info) {
    console.log("the data has been received:");
    console.log(info);
}   
function receive_error(info) {
    console.log("receive error");
    console.log(info);
}

[niko@dev1 nettest]$

服务器代码：

[niko@dev1 src]$ cat server.c
#include <sys/socket.h>
#include <netinet/in.h>
#include <netinet/tcp.h>
#include <arpa/inet.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <string.h>
#include <sys/types.h>

int main(int argc, char *argv[])
{
    int flag=1;
    int listenfd = 0, connfd = 0;
    struct sockaddr_in serv_addr; 

    char data[10] = {'A','B','C','D','E','F','G','H','I','\n'};
    int result;

    listenfd = socket(AF_INET, SOCK_STREAM, 0);
    memset(&serv_addr, '0', sizeof(serv_addr));

    result = setsockopt(listenfd,IPPROTO_TCP,TCP_NODELAY,(char *) &flag, sizeof(int)); 
    if (result<0) {
        printf("result=%d\n",result);
        return (1);
    }

    serv_addr.sin_family = AF_INET;
    serv_addr.sin_addr.s_addr = htonl(INADDR_ANY);
    serv_addr.sin_port = htons(4433); 

    bind(listenfd, (struct sockaddr*)&serv_addr, sizeof(serv_addr)); 

    listen(listenfd, 10); 

    while(1)
    {
        connfd = accept(listenfd, (struct sockaddr*)NULL, NULL); 
        result = setsockopt(connfd,IPPROTO_TCP,TCP_NODELAY,(char *) &flag, sizeof(int)); 
        if (result<0) {
            printf("result=%d\n",result);
            return (1);
        }
        printf("connection accepted, sending data\n");
        write(connfd, &data, sizeof(data)); 
        sleep(5);

        close(connfd);
        printf("connection closed\n");
        sleep(1);
     }
}
[niko@dev1 src]$

当我运行代码时，这是输出：

connection accepted: 0
main.js:31 receive error
main.js:32 Object {resultCode: -100, socketId: 18}
main.js:20 connection accepted: 0
main.js:27 the data has been received:
main.js:28 Object {data: ArrayBuffer, socketId: 19}
main.js:27 the data has been received:
main.js:28 Object {data: ArrayBuffer, socketId: 19}
main.js:31 receive error
main.js:32 Object {resultCode: -100, socketId: 19}

关于什么可能出错的任何想法？

Answer 1

我发现了什么问题。必须在创建套接字后立即注册onReceived处理程序。否则，会发生什么：客户端发送SYN，但服务器回复ACK +数据。当Chrome获取此数据包时，它还没有设置onReceived处理程序，因此第一个数据包中的数据将丢失。 connect_click（）函数必须像这样重写：

function connect_click(event) {

    event.preventDefault();

    chrome.sockets.tcp.create({}, function(createInfo) {
        socket=createInfo.socketId;
        chrome.sockets.tcp.setPaused(socket, false );
        chrome.sockets.tcp.connect(socket,"localhost", 4433, connect_callback);
        chrome.sockets.tcp.onReceive.addListener(data_received);
        chrome.sockets.tcp.onReceiveError.addListener(receive_error);
    });
}

来自网络示例的Chrome App接收（TCP）数据失败

1 个答案: