Winsock接收给乱码混合有用的html
Winsock recv giving gibberish mixed with useful html
我试图得到一个网页的html源www.chemguide.co.uk(它有页面不长英里)使用winsock实现在c++中。大多数数据都是好的，但是在输出的某些点上有一个特定的字符(在控制台上看起来像_，在这里看起来像I)被重复，我认为是8个一组，还有一些其他奇怪的字符。
而且，文档的某些部分似乎打印在页面末尾(标记)之后。下面是代码:
// Portprog.cpp : Defines the entry point for the console application.
//
#include "stdafx.h"
#include <winsock2.h>
#include <sys/types.h>
#include <stdio.h>
#include <iostream>
#include <string>
#include <fstream>
#pragma comment(lib, "ws2_32.lib") //Winsock library
int getHTML(std::string *result)
{
WSADATA wsa;
SOCKET s;
SOCKADDR_IN server;
using std::string;
using std::cout;
using std::endl;
cout << "Initialising Winsock...";
if (WSAStartup(MAKEWORD(2, 2), &wsa) != 0)
{
cout << "Failed. Error Code: " << WSAGetLastError();
return 1;
}
cout << "Winsock initialised." << endl;
if ((s = socket(AF_INET, SOCK_STREAM, 0)) == INVALID_SOCKET)
{
cout << "Could not create socket: " << WSAGetLastError() << endl;
return 1;
}
cout << "Socket created." << endl;
server.sin_addr.s_addr = inet_addr("217.27.240.124");
server.sin_family = AF_INET;
server.sin_port = htons(80); //host to network endian short
//Connect to remote server
if (connect(s, (SOCKADDR *)&server, sizeof(server)) < 0)
{
cout << "Connection failed." << endl;
return 1;
}
cout << "Connected." << endl;
//Send some data
string srequest = "GET / HTTP/1.1rn";
srequest += "Host: chemguide.co.ukrn";
srequest += "Connection: closern";
srequest += "Accept: text/xml,application/xml,application/xhtml+xml,text/html;q=0.9,text/plain;q=0.8,image/png,*/*;q=0.5rn";
srequest += "rn";
char crequest[10000];
int requestSize = srequest.length() + 1;
strncpy_s(crequest, srequest.c_str(), requestSize);
if (send(s, crequest, requestSize, 0) < 0)
{
cout << "Data could not be sent." << endl;
return 1;
}
cout << "Data sent." << endl;
//Receive a reply from the server
std::string server_reply = "";
int recv_length;
char buffer[1000];
int i = 0;
do
{
i = recv_length = recv(s, buffer, sizeof(buffer), 0);
server_reply += buffer;
} while (i != 0);
cout << "Reply received." << endl;
*result = server_reply;
closesocket(s);
WSACleanup();
return 0;
}
int main(int argc, char *argv[])
{
std::string response = "";
getHTML(&response);
std::cout << response << std::endl;
std::ofstream file("output.txt");
file << response;
file.close();
return 0;
}
输出如下:
HTTP/1.1 200 OK
Date: Mon, 03 Aug 2015 00:22:17 GMT
Server: Apache/2.2.11
Last-Modified: Mon, 13 Apr 2015 11:56:25 GMT
ETag: "99190a-1ec2-51399cdaacc40"
Accept-Ranges: bytes
Content-Length: 7874
Connection: close
Content-Type: text/html
<html>
<head>
<title>chemguide: helping you to understand Chemistry - Main Menu</title>
<meta name="description"
content="Main menu of a site aimed to help advanced level chemistry students to understand chemistry" />
<meta name="keywords"
content="chemistry, A'level, a level, a'level, a-level, advanced level, advanced, help, understand, understanding, guide, guidebook" />
</head>
<body bgcolor="#ffffcc" link="blue" vlink="teal" alink="red">
<a name="top"></a>
<center>
<table align="center" border="0" width="480" cellspacing="10">
<tr>
<td colspan="2" bgcolor="#ccffcc" height="50" align="center" valign="middle">
<font color="#006600" size="7" face="Helvetica, Arial"><b>chemguide</b></font></td>
</tr>
<tr>
<td colspan="2">
<font colorÌÌÌÌÌÌÌÌè="#006600" size="6" face="Helvetica, Arial"><p align="center"><b>Helping you to understand Chemistry</b></p></font>
<font color="#000000" size="5" face="Helvetica, Arial">
<p align="center"><b>MAIN MENU</b></p>
</font>
<pre>
</pre>
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<tr valign="top"><td bgcolor="#cccccc"> <font color="#ff0000" face="Helvetica, Arial" size="2"><b>New! </b></a></font><font color="#000000" face="Helvetica, Arial" size="2">stry" />
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content="chemistry, A'level, a level, a'level, a-level, advanced level, advanced, help, understand, understanding, guide, guidebook" />
</head>
<body bgcolor="#ffffcc" link="blue" vlink="teal" alink="red">
<a name="top"></a>
<center>
<table align="center" border="0" width="480" cellspacing="10">
<tr>
<td colspan="2" bgcolor="#ccffcc" height="50" align="center" valign="middle">
<font color="#006600" size="7" face="Helvetica, Arial"><b>chemguide</b></font></td>
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<tr>
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我使用的是Visual Studio 2013。这是我的stdafx.h文件:
// stdafx.h : include file for standard system include files,
// or project specific include files that are used frequently, but
// are changed infrequently
//
#pragma once
#define _WINSOCK_DEPRECATED_NO_WARNINGS
//#define _CRT_SECURE_NO_WARNINGS
#include "targetver.h"
#include <stdio.h>
#include <tchar.h>
// TODO: reference additional headers your program requires here
问题是您将读取的数据视为字符串，但您似乎忘记了c++中的C风格字符串以特殊字符' '结束。
因此，您需要读取比缓冲区大小少一个字符，并通过在末尾添加结束符来结束您读取的缓冲区:
if (i >= 0)
buffer[i] = ' ';
您得到乱码的原因是因为当您将缓冲区附加到字符串server_reply时，+=操作符函数查找此终止符以找到要附加的字符串的末尾，如果终止符+=操作符函数将继续直到找到与终止符字符对应的字节，这甚至可能超出buffer的限制。不终止字符串会导致未定义行为。
另外，当接收时，您不检查错误，如果recv返回SOCKET_ERROR(不等于零)，您认为会发生什么?你将以一个无限循环结束。
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