Socket编程 ——UDP 实验报告

一 客户端数据反射交互

（1）实验内容

要求：利用数据报套接字实现数据传输

• 客户端创建UDP套接字，向指定的服务端发送数据；
• 服务端接收到新数据，显示是谁发送过来的，并把该数据回传给发送方；
• 服务端使用多线程来实现并发

（2）实现方法

Client

unsigned int port;
    char recvData[255]; 
    cin >> sendData;
    sendto(sclient,sendData, 255, 0, (sockaddr *)&sin, len);  
    // 向服务器端发送数据

int ret = recvfrom(sclient, (char *)&port, 4, 0, (sockaddr *)&sin, &len);  
    sin.sin_port=htons(port);
     ret = recvfrom(sclient, recvData,255, 0, (sockaddr *)&sin, &len);  
    if(ret > 0)     cout<//接受改变的端口值 并接受反回的信息

while(1)
    {
cout<<"Input your message:";
cin >> sendData;    
sendto(sclient,sendData, sizeof(sendData), 0, (sockaddr *)&sin, len);
int ret = recvfrom(sclient, recvData,255, 0, (sockaddr *)&sin, &len);  
if(ret > 0)             cout<<"From server:"<cin>>s;
        if (s!=s1)//是否关闭套接字
            break;
    }
    //做到与服务器交互

---

server

  while (true) 
    {
     char recvData[255]; 
char sendData[255];
     int ret = recvfrom(serSocket, recvData, 255, 0, (sockaddr *)&remoteAddr, &nAddrLen); 
NUM++;
if (ret > 0)        cout<<"Connect a new user ,total Nummber is "<//如果有新的用户加入8080端口则用户数量加一 

mystruct.client = remoteAddr;
mystruct.userid = NUM;
memcpy(mystruct.recvData,recvData,255);
hThread = CreateThread(NULL, 0, ClientThread, (LPVOID)&mystruct, 0, NULL);
//创建新的线程 在线程里生成新的临时端口与用户进行交互
 }

子线程代码

DWORD WINAPI ClientThread(LPVOID lpParameter)
{
    SOCKET ChildSocket = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP);   //建立新线程

······
}

int PORT=1024;
while ( PORT <= 65535){
        serAddr.sin_family = AF_INET;
        serAddr.sin_port = htons( PORT);
        serAddr.sin_addr.S_un.S_addr = INADDR_ANY;
        if (bind(ChildSocket, (sockaddr *)&serAddr, sizeof(serAddr)) == SOCKET_ERROR)
            PORT++;
        else
            break;
    }
    //寻找并绑定可用的端口

my_struct  mystruct = (my_struct) lpParameter;//接收主进程的客户端参数
client = mystruct ->client;
userid = mystruct->userid;//用户识别号 
nAddrLen = mystruct->nAddrLen;
sendto(ChildSocket,(const char *)&PORT,4, 0, (sockaddr *)&client, nAddrLen);     
    //将端口号发至客户端进行更改

sendto(ChildSocket, mystruct->recvData, 255, 0, (sockaddr *)&client, nAddrLen);
    //第一次信息反弹至客户端

while(1)
{
     int ret = recvfrom(ChildSocket,mystruct-> recvData, 255, 0, (sockaddr *)& client,& nAddrLen);  
     if (ret > 0)        cout<<"FROM user"<":"<recvData<//ntohs(serAddr.sin_port)
     sendto(ChildSocket, mystruct->recvData, 255, 0, (sockaddr *)& client, nAddrLen);
}
//后续的信息反弹

（3）实验实现

服务器端
多个客户端同时连接 ，实现用户识别及交叉发送数据

用户1

用户2

二 使用UDP套接字实现文件传输

（1）实验内容

• 客户端向服务端发送文件名
• 客户端向服务端传输文件内容
• 双方关闭套接字

（2）实验方法

Client

    unsigned int port=0;
    char recvData[255]; 
    cout<<"Input your filename:";
    cin >> name;
    sendto(sclient,name, 20, 0, (sockaddr *)&sin, len);  
    // 向服务器端发送文件名

int ret = recvfrom(sclient, (char *)&port, 4, 0, (sockaddr *)&sin, &len);  
    sin.sin_port=htons(port);
    //接受改变的端口值 并接受反回的信息

fp = fopen(name,"rb");
        if(fp==NULL) {
    cout<<"no suchfile again input:"; }
        fseek(fp,0L,SEEK_END);
        file_size = ftell( fp );
        fseek(fp,0L,SEEK_SET);
        sendto(sclient,(const char *)&file_size, 4, 0, (sockaddr *)&sin, len);
        //文件的建立 长度并发送

while(file_size)
{
if(file_size>=1024){
fread(data,1,1024,fp);
sendto(sclient, data, 1024, 0, (sockaddr *)&sin, len);
file_size -= 1024;
}
else {
fread(data,1,file_size,fp); 
sendto(sclient, data, file_size, 0, (sockaddr *)&sin, len);
file_size = 0;
}
}
    // 读取文件并传送

---

Server

int NUM=0; //计算当前用户的数量

typedef struct MyStruct
{
      sockaddr_in client;
      int nAddrLen;
      char recvData[255];
      int userid;       
      char name[20];
}MyStruct, *my_struct ;
//定义结构体 在创线程的时候使用

 while (true) 
    {
        char recvData[255]; 
        char sendData[255];
        memset(recvData,0,255);
        recvfrom(serSocket,recvData, 20, 0, (sockaddr *)& remoteAddr,& nAddrLen);  
        NUM++;
        cout<<"Connect a new user ,total Nummber is "<//如果有新的用户加入8080端口则用户数量加一 
        mystruct.userid = NUM;
        mystruct.client = remoteAddr;
        memcpy(mystruct.name,recvData,20);
        hThread = CreateThread(NULL, 0, ClientThread, (LPVOID)&mystruct, 0, NULL);

        //创建新的线程 在线程里生成新的临时端口与用户进行交互
    }

创建新线程

SOCKET ChildSocket = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP);   //新的套接字

while ( PORT <= 65535){
    serAddr.sin_family = AF_INET;
    serAddr.sin_port = htons( PORT);
    serAddr.sin_addr.S_un.S_addr = INADDR_ANY;
    if (bind(ChildSocket, (sockaddr *)&serAddr, sizeof(serAddr)) == SOCKET_ERROR)
        PORT++;
    else
        break;
        }
    //寻找可用的端口

    my_struct  mystruct = (my_struct) lpParameter;
    client = mystruct ->client;
    userid = mystruct->userid;
    nAddrLen = mystruct->nAddrLen;
    sendto(ChildSocket,(const char *)&PORT,4, 0, (sockaddr *)&client, nAddrLen);     
    //将端口号发至客户端进行更改

//新建文件
char a[4];
unsigned int len=0;
recvfrom(ChildSocket,(char *)&len, 4, 0, (sockaddr *)& client,& nAddrLen);  

FILE *dest_fp; 
dest_fp = fopen(mystruct->name, "ab");
while(1)
{
while(len)
{
    if(len>=1024) {recvfrom(ChildSocket,data, 1024, 0, (sockaddr *)& client,& nAddrLen) ;fwrite(data,1, 1024, dest_fp);fflush(dest_fp);len = len - 1024;}
    else {recvfrom(ChildSocket,data, len, 0, (sockaddr *)& client,& nAddrLen) ;fwrite(data,1,len,dest_fp);fflush(dest_fp);len  = 0;}
} 
    fclose(dest_fp);
}//文件建立与写入

（3）实验实现

服务器每次用户连接创建新的线程

用户一

用户二

文件夹