利用不定长的结构体发送socket数据

//Server端代码

#include<stdio.h>
#include<stdlib.h>
#include<string.h>
#include<sys/types.h>
#include<netinet/in.h>
#include<sys/socket.h>

#include<unistd.h>
//使用不定长的结构体发送数据的关键在于：结构体变量必须分配到堆中，而不是栈中
//即只能用malloc或者new来给结构体分配空间
typedef struct Node
{
int nodeSize;
int bufSize;
char buf[0]; //用0字节表示该结构体不定长
} Node;

int main()
{
int sockfd,new_fd;
struct sockaddr_in server_addr;
struct sockaddr_in client_addr;

if((sockfd = socket(AF_INET,SOCK_STREAM,0)) == -1)
{
printf("socket error!\n");
exit(1);
}
server_addr.sin_family = AF_INET;
server_addr.sin_port = htons(5050);
server_addr.sin_addr.s_addr = INADDR_ANY;
bzero(&(server_addr.sin_zero),8);

if(bind(sockfd,(struct sockaddr *)&server_addr,sizeof(server_addr)) == -1)
{
printf("bind error!\n");
exit(1);
}
if(listen(sockfd,100) == -1)
{
printf("listen error!\n");
exit(1);
}
printf("Server is listening:\n");
while(1)
{
int sin_size = sizeof(struct sockaddr_in);
if((new_fd = accept(sockfd,(struct sockaddr *)&client_addr,(socklen_t *)&sin_size)) == -1)
{
printf("accept error!\n");
exit(1);
}
int recvSize = 0;//data total length
if(recv(new_fd,(char *)&recvSize,sizeof(recvSize),0) == -1)
{
printf("recv error!\n");
exit(1);
}
int leftSize = sizeof(char) * (recvSize - sizeof(int));
char *dataBuf = (char *)malloc(leftSize);
memset(dataBuf,0,leftSize);
if(recv(new_fd,dataBuf,leftSize,0) == -1)
{
printf("recv error!\n");
exit(1);
}
close(new_fd);
Node *p = (Node *)malloc(sizeof(char) * recvSize);
p->nodeSize = recvSize;
memcpy((char *)(&p->bufSize),dataBuf,leftSize);
printf("nodeSize = %d\n",p->nodeSize);
printf("bufSize = %d\n",p->bufSize);
printf("buf = %s\n",p->buf);
}

return 0;
}


//Client端代码

#include<stdio.h>
#include<stdlib.h>
#include<string.h>
#include<sys/types.h>
#include<arpa/inet.h>
#include<netinet/in.h>
#include<sys/socket.h>

#include<unistd.h>

typedef struct Node
{
int nodeSize;
int bufSize;
char buf[0];
} Node;

int main()
{
int sockfd,new_fd;
struct sockaddr_in server_addr;

if((sockfd = socket(AF_INET,SOCK_STREAM,0)) == -1)
{
printf("socket error!\n");
exit(1);
}
server_addr.sin_family = AF_INET;
server_addr.sin_port = htons(5050);
server_addr.sin_addr.s_addr = inet_addr("127.0.0.1");
bzero(&(server_addr.sin_zero),8);

if(connect(sockfd,(struct sockaddr *)&server_addr,sizeof(server_addr)) == -1)
{
printf("connect error!\n");
exit(1);
}
printf("Client is connecting\n");
const char *tmp = "this is a test!";
int tmpLen = strlen(tmp);
Node *dataBuf = (Node *)malloc(sizeof(Node) + tmpLen + 1);
dataBuf->nodeSize = sizeof(Node) + tmpLen + 1;
dataBuf->bufSize = tmpLen;
memset(dataBuf->buf,0,tmpLen + 1);
memcpy(dataBuf->buf,tmp,tmpLen + 1);
printf("nodeSize = %d\n",dataBuf->nodeSize);
printf("bufSize = %d\n",dataBuf->bufSize);
printf("buf = %s\n",dataBuf->buf);
if(send(sockfd,(char *)dataBuf,dataBuf->nodeSize,0) == -1)
{
printf("send error!\n");
exit(1);
}
close(sockfd);
return 0;
}