计算机网路课程设计——电子邮件客户端的设计与实现——接收邮件（POP3协议）

上一篇已经写了SMTP发送邮件客户端的代码
https://blog.csdn.net/dayexiaofan/article/details/85257320
这一篇我们来写一下POP3接收方的代码

注意这里的密码也是授权码

看代码
如果你能理解上一篇这一篇自然很好理解了

/**
    Email客户端接收（POP3）的实现
*/
#include<windows.h>
#include<stdio.h>
#include<WinSock.h>
#include<iostream>
using namespace std;
#pragma comment(lib,"ws2_32.lib")
int OpenSocket(struct sockaddr *addr);//打开socket套接字
// 发送邮件
int main()
{
    int sockfd ={0};
    char buf[1500]={0};
    char rbuf[1500]={0};//POP协议传送邮件的应答
    char login[128]={0};
    char pass[128]={0};
    WSADATA WSAData;
    struct sockaddr_in their_addr ={0};
    WSAStartup(MAKEWORD(2,2),&WSAData);
    memset(&their_addr,0,sizeof(their_addr));
    their_addr.sin_family =AF_INET;
    their_addr.sin_port =htons(110);
    hostent*hptr =gethostbyname("pop3.163.com"); // 用的是163服务器
    memcpy(&their_addr.sin_addr.S_un.S_addr,hptr->h_addr_list[0],hptr->h_length);
    printf("IP of pop3.163.com is : %d:%d:%d:%d\n",
    their_addr.sin_addr.S_un.S_un_b.s_b1,
    their_addr.sin_addr.S_un.S_un_b.s_b2,
    their_addr.sin_addr.S_un.S_un_b.s_b3,
    their_addr.sin_addr.S_un.S_un_b.s_b4);
    //OK,163邮箱的IP地址已获取到，下面就要开始进行连接了
    sockfd =OpenSocket((struct sockaddr *)&their_addr);
    cout<<"look:"<<sockfd<<endl;
    memset(rbuf,0,1500);
    while(recv(sockfd,rbuf,1500,0)==0)
    {
        cout<<"重新连接..."<<endl;
        Sleep(5);
        sockfd =OpenSocket((struct sockaddr *)&their_addr);
        memset(rbuf,0,1500);
    }
    cout<<rbuf<<endl;//返回220表示recv成功（访问163邮箱成功）

    // USER
    memset(buf,0,1500);
    sprintf(buf,"%s\r\n","user xxxxxxx");//输入你的邮箱账号
    send(sockfd,buf,strlen(buf),0);
    cout<<buf<<endl;
    memset(rbuf,0,1500);
    recv(sockfd,rbuf,1500,0);
    cout<<rbuf<<endl;

    // PASSWORD
    sprintf(buf,"%s\r\n","pass xxxxxxx");//你的邮箱密码
    send(sockfd,buf,strlen(buf),0);
    cout<<buf<<endl;
    memset(rbuf,0,1500);
    recv(sockfd,rbuf,1500,0);
    cout<<rbuf<<endl;
    //cout<<"通过"<<endl;

    //LIST
    memset(buf,0,1500);
    sprintf(buf,"%s\r\n","list");
    send(sockfd,buf,strlen(buf),0);
    cout<<buf<<endl;
    memset(rbuf,0,1500);
    recv(sockfd,rbuf,1500,0);
    cout<<rbuf<<endl;
    //cout<<"通过List"<<endl;

    //RETR
    string input;
    cout<<"请输入查询命令:"<<endl;
    getline(cin,input);
    sprintf(buf,"%s\r\n",input.c_str());
    send(sockfd,buf,strlen(buf),0);
    memset(rbuf,0,1500);
    recv(sockfd,rbuf,1500,0);
    cout<<rbuf<<endl;
    //cout<<"通过retr"<<endl;

    // QUIT
    sprintf(buf,"QUIT\r\n");
    send(sockfd,buf,strlen(buf),0);
    memset(rbuf,0,1500);
    recv(sockfd,rbuf,1500,0);
    cout<<"Quit Receive: "<<rbuf<<endl;

    //清理工作
    closesocket(sockfd);
    WSACleanup();
    return 0;
}
// 打开TCP Socket连接
int OpenSocket(struct sockaddr *addr)
{
    int sockfd =0;
    sockfd=socket(PF_INET,SOCK_STREAM,0);
    if(sockfd <0)
    {
        cout<<"Open sockfd(TCP) error!"<<endl;
        exit(-1);
    }
    if(connect(sockfd,addr,sizeof(struct sockaddr))<0)
    {
        cout<<"Connect sockfd(TCP) error!"<<endl;
        exit(-1);
    }
    return sockfd;
}

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