c 套接字服务器端发送消息,在C中通过套接字发送struct

我正在开发一个客户端/服务器程序,我的客户端必须向服务器发送消息.

示例消息C结构：

struct Registration

{

char multicastGroup[24];

pid_t clientPid;

};

用于序列化struct的客户端代码段

struct Registration regn ;

regn.clientPid = getpid();

strcpy(regn.multicastGroup,"226.1.1.1");

printf("PID:%d\n",regn.clientPid);

printf("MG:%s\n",regn.multicastGroup);

printf("Size:%d\n",sizeof(regn)); //Size is 28

data = (unsigned char*)malloc(sizeof(regn));

memcpy(data,&regn,sizeof(regn));

printf("Size:%d\n",sizeof(data)); //Size is 4.

用于反序列化数据的服务器代码

if(recvfrom(sd,recvBuf,recvBufSize,(struct sockaddr*)&clientAddr,&len) < 0)

{

printf("Error receiving message from client\n");

}

else

{

printf("Message received:%s\n",recvBuf);

printf("Size :%d\n",strlen(recvBuf));

memcpy(&regn,sizeof(regn));

printf("PID:%d\n",regn.clientPid);

printf("MG:%s\n",regn.multicastGroup);

}

将结构复制到unsigned char *后,数组的大小仅为4.

为什么数据没有完全复制到数组？

服务器无法从char数组重构结构.

请让我知道我做错了什么.