Winsock recv给出乱码和有用的html
[英]Winsock recv giving gibberish mixed with useful html
问题描述
I'm trying to get the html source of a webpage www.chemguide.co.uk (it has pages that aren't miles long) using winsock implemented in c++. 
我正在尝试使用c ++中实现的winsock获取网页www.chemguide.co.uk的html源（它的页面长度不长）。 Most of the data that comes through is good, but at certain points in the output there is a certain character (it looks like |¦ on the console and some sort of I on here) being repeated, I think in groups of 8, and there are some other strange characters as well. 传递的大多数数据都是好的，但是在输出的某些点上有一个重复的字符（在控制台上看起来像| ¦，这里有某种I），我认为每8个一组，还有其他一些奇怪的角色。
Also, some of the document seems to be printed after the end of the page (the tag. Here's the code: 另外，某些文档似乎在页面结尾之后打印（标签。这是代码：
// 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/1.1\r\n";
srequest += "Host: chemguide.co.uk\r\n";
srequest += "Connection: close\r\n";
srequest += "Accept: text/xml,application/xml,application/xhtml+xml,text/html;q=0.9,text/plain;q=0.8,image/png,*/*;q=0.5\r\n";
srequest += "\r\n";
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;
}
And here's the output: 这是输出：
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>
<table align="center" cellpadding="10" border="1">
<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" />
<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">
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I'm using Visual Studio 2013. Here's my stdafx.h file: 我正在使用Visual Studio2013。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
1 个解决方案
解决方案1
1 已采纳 2015-08-03 00:33:46
The problem is that you treat the data you read as strings, but you seem to forget that C-style strings in C++ are terminated by the special character '\\0' . 问题是您将读取的数据视为字符串，但是您似乎忘记了C ++中的C样式字符串以特殊字符'\\0'终止。
So you need to read one character less than the buffer size, and terminate the buffer you read as a string by adding the terminator character at the end: 因此，您需要读取小于缓冲区大小的一个字符，并通过在末尾添加终止符来终止作为字符串读取的缓冲区：
if (i >= 0)
buffer[i] = '\0';
The reason you're getting gibberish is because when you append the buffer to the string server_reply , the += operator function looks for this terminator to find the end of the string to append, if the terminator the += operator function will just continue until it finds a byte corresponding to the terminator character, which might even be beyond the limits of buffer . 之所以变得乱码是因为，当您将缓冲区追加到字符串server_reply ， +=运算符函数将查找此终止符以查找要追加的字符串的结尾，如果终止符，则+=运算符函数将继续执行直到它找到一个与终止符相对应的字节，该字节甚至可能超出buffer的限制。 Not terminating a string leads to undefined behavior . 不终止字符串会导致不确定的行为 。
Also, you don't check for errors when receiving, what do you think will happen if recv returns SOCKET_ERROR (which is not equal to zero)? 另外，您不检查接收时是否有错误，如果recv返回SOCKET_ERROR （不等于零），您会怎么办？ You will end up with an infinite loop. 您将最终陷入无限循环。
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