C语言爬虫

C语言爬虫

http://bbs.bccn.net/thread-504909-1-1.html

https://cloud.tencent.com/developer/information/c%E8%AF%AD%E8%A8%80%E7%BC%96%E5%86%99%E7%88%AC%E8%99%AB
参考爬http的爬虫代码，只要GET + source + HTTP/1.1 +host ，然后接受返回的消息就是网页内容。
现在很多网站都相机改成https的了，我试了还是用爬http的代码爬了一下https的网站，但是得到的是  Your request has bad syntax or is inherently impossible to satisfy.
抓包看了一下，
1、www.zhihu.com
三次握手后(应该是connect之后自带的三次握手之后吧？)，作为访问端发送的还是第一个包还是 GET / HTTP /1.1 和其他的一些内容。但是这里其他的内容有：Host,Connection,Accept,Upgrade-Insecure-Requests,User-Agent,Referer,Accept-Encoding,Accept-Language,Cookie,udid,_zap,d_c0,l_cap_id(抓的是访问知乎首页的包)，服务器返回的是 HTTP/1.1 302 Found 和一些参数包括cookie之类的东西.
然后客户端和服务器互相发了两次TCP包（是不是也是tcp/ip帮我们已经实现的保持通联的或者确认的包？），之后就是client hello 、server hello

2、www.taobao.com
三次握手之后，直接就是 client hello和server hello

问题：
1、访问https网站到底需不需要先GET。如果需要的话，像访问知乎中Cookie,udid,_zap,d_c0,l_cap_id等参数是怎么确定的？（因为我直接用GET + source + HTTP/1.1 +host，返回的是 Your request has bad syntax or is inherently impossible to satisfy）


下面是参考的爬虫代码

程序代码：

//#include <Windows.h>#include <string>
#include <iostream>
#include <fstream>
#include <vector>
#include "winsock2.h"
#include <time.h>
#include <queue>
#include <hash_set>

#pragma comment(lib, "ws2_32.lib") 
using namespace std;

#define DEFAULT_PAGE_BUF_SIZE 1048576

queue<string> hrefUrl;
hash_set<string> visitedUrl;
hash_set<string> visitedImg;
int depth=0;
int g_ImgCnt=1;

//解析URL，解析出主机名，资源名bool ParseURL( const string & url, string & host, string & resource){
    if ( strlen(url.c_str()) > 2000 ) {
        return false;
    }

    const char * pos = strstr( url.c_str(), "http://" );
    if( pos==NULL ) pos = url.c_str();
    else pos += strlen("http://");
    char pHost[100];
    char pResource[2000];
    if( strstr( pos, "/")==0 )
    {
        pResource[0]='/';pResource[1]=0;
        strcpy(pHost,pos);
    }
    else        
        sscanf( pos, "%[^/]%s", pHost, pResource );//以%s的形式读取,  %[^a]表示匹配非a的任意字符，直到遇到a停止读入
            //这里pHost取“http://”后面到第一个‘/’之间的字符串，从第一个‘/’到结束都传给pResource    host = pHost;
    resource = pResource;
    return true;
}

//使用Get请求，得到响应bool GetHttpResponse( const string & url, char * &response, int &bytesRead ){
    string host, resource;
    if(!ParseURL( url, host, resource )){
        cout << "Can not parse the url"<<endl;
        return false;
    }
    
    //建立socket    struct hostent * hp= gethostbyname( host.c_str() );
    if( hp==NULL ){
        cout<< "Can not find host address"<<endl;
        return false;
    }

    SOCKET sock = socket( AF_INET, SOCK_STREAM, IPPROTO_TCP);
    if( sock == -1 || sock == -2 ){
        cout << "Can not create sock."<<endl;
        return false;
    }

    //建立服务器地址    SOCKADDR_IN sa;
    sa.sin_family = AF_INET;
    sa.sin_port = htons( 80 );
    //char addr[5];
    //memcpy( addr, hp->h_addr, 4 );
    //sa.sin_addr.s_addr = inet_addr(hp->h_addr);    memcpy( &sa.sin_addr, hp->h_addr, 4 );

    //建立连接    if( 0!= connect( sock, (SOCKADDR*)&sa, sizeof(sa) ) ){
        cout << "Can not connect: "<< url <<endl;
        closesocket(sock);
        return false;
    };

    //准备发送数据    string request = "GET " + resource + " HTTP/1.1
Host:" + host + "
Connection:Close

";//字符串拼接

    //发送数据    if( SOCKET_ERROR ==send( sock, request.c_str(), request.size(), 0 ) ){//request.size()=strlen(request.c_str)        cout << "send error" <<endl;
        closesocket( sock );
        return false;
    }

    //接收数据    int m_nContentLength = DEFAULT_PAGE_BUF_SIZE;
    char *pageBuf = (char *)malloc(m_nContentLength);
    memset(pageBuf, 0, m_nContentLength);

    bytesRead = 0;
    int ret = 1;
    cout <<"Read: ";
    while(ret > 0)
    {
        ret = recv(sock, pageBuf + bytesRead, m_nContentLength - bytesRead, 0);        
        if(ret > 0)
        {
            bytesRead += ret;
        }

        if( m_nContentLength - bytesRead<100)
        {
            cout << "
Realloc memorry"<<endl;
            m_nContentLength *=2;
            pageBuf = (char*)realloc( pageBuf, m_nContentLength);       //重新分配内存        }
        cout << ret <<"";
    }
    cout <<endl;

    pageBuf[bytesRead] = '';
    response = pageBuf;
    closesocket( sock );
    return true;
    //cout<< response <<endl;}

//提取所有的URL以及图片URLvoid HTMLParse ( string & htmlResponse, vector<string> & imgurls, const string & host ){
    //Sleep(10000);
    //找所有连接，加入queue中    const char *p= htmlResponse.c_str();
    char *tag="href="";//href的内容 就是指要跳转的路由 或 方法     const char *pos = strstr( p, tag );
    ofstream ofile("url.txt", ios::app);//以追加的方式打开文件    while( pos )
    {
        pos +=strlen(tag);
        const char * nextQ = strstr( pos, """ );
        if( nextQ )
        {
            char * url = new char[ nextQ-pos+1 ];
            //char url[100]; //固定大小的会发生缓冲区溢出的危险            sscanf( pos, "%[^"]", url);
            string surl = url;  // 转换成string类型，可以自动释放内存            if( visitedUrl.find( surl ) == visitedUrl.end() ){//   visitedUrl.find( surl )=visitedUrl.end() 表示visitedUrl中没有sur1                visitedUrl.insert( surl );
                ofile << surl<<endl;
                hrefUrl.push( surl );//将sur1插到队列末            }
            pos = strstr(pos, tag );
            delete [] url;  // 释放掉申请的内存        }
    }
    ofile << endl << endl;
    ofile.close();

    tag ="<img ";
    const char* att1= "src="";//规定图像|音视频等的 URL。    const char* att2="lazy-src="";//lazy_src=还是lazy-src=    const char *pos0 = strstr( p, tag );
    while( pos0 )
    {
        pos0 += strlen( tag );
        const char* pos2 = strstr( pos0, att2 );
        if( !pos2 || pos2 > strstr( pos0, ">") ) 
        {
            pos = strstr( pos0, att1);//非延迟加载项            if(!pos) 
            {
                pos0 = strstr(att1, tag );
                continue;
            } 
            else 
            {
                pos = pos + strlen(att1);
            }
        }
        else //如果是延迟加载项        {
            pos = pos2 + strlen(att2);
        }

        const char * nextQ = strstr( pos, """);
        if( nextQ )
        {
            char * url = new char[nextQ-pos+1];
            sscanf( pos, "%[^"]", url);
            cout << url<<endl;
            string imgUrl = url;
            if( visitedImg.find( imgUrl ) == visitedImg.end() )
            {
                visitedImg.insert( imgUrl );
                imgurls.push_back( imgUrl );//imgurls作为模板队列，push_back的参数由单个字符变成string类型            }
            pos0 = strstr(pos0, tag );
            delete [] url;
        }
    }
    cout << "end of Parse this html"<<endl;
}

//把URL转化为文件名string ToFileName( const string &url ){
    string fileName;
    fileName.resize( url.size());
    int k=0;
    for( int i=0; i<(int)url.size(); i++){
        char ch = url[i];
        if( ch!='\'&&ch!='/'&&ch!=':'&&ch!='*'&&ch!='?'&&ch!='"'&&ch!='<'&&ch!='>'&&ch!='|')
            fileName[k++]=ch;
    }
    return fileName.substr(0,k) + ".txt";//从第0位开始，长度为k的字符串 + .txt}

//下载图片到img文件夹void DownLoadImg( vector<string> & imgurls, const string &url ){

    //生成保存该url下图片的文件夹    string foldname = ToFileName( url );
    foldname = "./img/"+foldname;
    if(!CreateDirectory( foldname.c_str(),NULL ))
        cout << "Can not create directory:"<< foldname<<endl;
    char *image;
    int byteRead;
    for( int i=0; i<imgurls.size(); i++)
    {
        //判断是否为图片，bmp，jgp，jpeg，gif         string str = imgurls[i];
        int pos = str.find_last_of(".");//返回值为相对于起点的偏移位        if( pos == string::npos )
            continue;
        else
        {
            string ext = str.substr( pos+1, str.size()-pos-1 );
            if( ext!="bmp"&& ext!="jpg" && ext!="jpeg"&& ext!="gif"&&ext!="png")
                continue;
        }
        //下载其中的内容        if( GetHttpResponse(imgurls[i], image, byteRead))
        {
            if ( strlen(image) ==0 ) 
            {
                continue;
            }
            const char *p=image;
            const char * pos = strstr(p,"

")+strlen("

");
            int index = imgurls[i].find_last_of("/");
            if( index!=string::npos )
            {
                string imgname = imgurls[i].substr( index , imgurls[i].size() );
                ofstream ofile( foldname+imgname, ios::binary );
                if( !ofile.is_open() )
                    continue;
                cout <<g_ImgCnt++<< foldname+imgname<<endl;
                ofile.write( pos, byteRead- (pos-p) );
                ofile.close();
            }
            free(image);
        }
    }
}

//广度遍历void BFS( const string & url ){
    char * response;
    int bytes;
    // 获取网页的相应，放入response中。    if( !GetHttpResponse( url, response, bytes ) ){
        cout << "The url is wrong! ignore." << endl;
        return;
    }
    string httpResponse=response;
    free( response );
    string filename = ToFileName( url );
    ofstream ofile( "./html/"+filename );
    if( ofile.is_open() ){
        // 保存该网页的文本内容        ofile << httpResponse << endl;
        ofile.close();
    }
    vector<string> imgurls;
    //解析该网页的所有图片链接，放入imgurls里面    HTMLParse( httpResponse,  imgurls, url );
    
    //下载所有的图片资源    DownLoadImg( imgurls, url );
}

void main()
{
    //初始化socket，用于tcp网络连接    WSADATA wsaData;
    if( WSAStartup(MAKEWORD(2,2), &wsaData) != 0 ){
        return;
    }

    // 创建文件夹，保存图片和网页文本文件    CreateDirectory( "./img",0);
    CreateDirectory("./html",0);
    //string urlStart = "http://hao.360.cn/meinvdaohang.html";

    // 遍历的起始地址
    // string urlStart = "http://www.wmpic.me/tupian";
    //string urlStart = "http://item.taobao.com/item.htm?spm=a230r.1.14.19.sBBNbz&id=36366887850&ns=1#detail";    string urlStart = "www.ruanyifeng.com/blog/2014/02/ssl_tls.html";
    
    // 使用广度遍历
    // 提取网页中的超链接放入hrefUrl中，提取图片链接，下载图片。    BFS( urlStart );

    // 访问过的网址保存起来    visitedUrl.insert( urlStart );

    while( hrefUrl.size()!=0 ){
        string url = hrefUrl.front();  // 从队列的最开始取出一个网址        cout << url << endl;
        BFS( url );                      // 遍历提取出来的那个网页，找它里面的超链接网页放入hrefUrl，下载它里面的文本，图片        hrefUrl.pop();                 // 遍历完之后，删除这个网址    }
    WSACleanup();
    system("pause");
    return;
}

 

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