我在 C 套接字中运行时出现问题。 有一个服务器，有一个客户端。服务器向客户端发送大量数据。当我按CTRL+C终止客户端时，我重新启动服务器(1、关闭套接字fd，2、再次构建套接字fd)。 但是当我再次运行客户端时，它从上次连接中接收到大量数据。我猜数据在服务器发送缓冲区中。当我上次关闭客户端时，那里仍然有数据。 有什么办法可以清除数据吗？ 谢谢
示例代码
void socket_server_init(unsigned short port)
{
struct sockaddr_in serverAddress;
struct sockaddr_in clientAddress;
if((serverSocket=socket(AF_INET,SOCK_STREAM,IPPROTO_TCP))<0){
printf("create socket error??");
exit(-1);
}
memset(&serverAddress,0,sizeof(serverAddress));
serverAddress.sin_family=AF_INET;
serverAddress.sin_addr.s_addr = htonl(INADDR_ANY);
serverAddress.sin_port = htons(port);
int optval = -1;
socklen_t optlen = -1;
optval = 1;
optlen = sizeof(optval);
setsockopt(serverSocket, SOL_SOCKET, SO_REUSEADDR, &optval, optlen);
if(bind(serverSocket,(struct sockaddr*)&serverAddress,sizeof(serverAddress))<0)
{
printf("bind socket to port failed??port: %d\n",port);
exit(-1);
}
if(listen(serverSocket,SOMAXCONN)<0){
printf("listen failed!\n");
exit(-1);
}
printf("Server %d is listening......\n",port);
memset(&clientAddress,0,sizeof(clientAddress));
int addrlen = sizeof(clientAddress);
if((clientSocket=accept(serverSocket,(struct sockaddr*)&clientAddress,&addrlen))<0){
printf("accept client connection failed??\n");
exit(-1);
}
return;
}
void stop_sever(void)
{
server_status = SOCKET_STATUS_INIT;
send_mode = SOCKET_SENDING_MODE_NORMAL;
send_flag = 0;
pc_transfer_mode = 0;//1 normal //2 through
Image_transfer_status = SERVER_STATUS_STOP_IMAGE;
Pre_Image_transfer_status = SERVER_STATUS_STOP_IMAGE;
data_received_once = 0;
}
void reset_server(void)
{
printf("reset servern");
stop_sever();
printf("Close server socket\n");
//close(clientSocket);
//shutdown(clientSocket, SHUT_RDWR);
close(serverSocket);
printf("shutdown server socket\n");
shutdown(serverSocket, SHUT_RDWR);
//shutdown(serverSocket_alert, SHUT_RDWR);
printf("restart server socket\n");
socket_server_init(port);
//socket_server_init_alert(8001);
}
void send_image(unsigned char *virt_addr_to_display, unsigned char cmd, unsigned char res)
{
printf("[display] Entering: %s,,, %p\n", __FUNCTION__, virt_addr_to_display);
int i = 0;
int len = 0;
if(cmd == SERVER_STATUS_TRANSFER_1)
{
if(res == IMAGE_RESOLUTION_1280X720)
{
len = FRAME_SIZE_1;
}
else if(res == IMAGE_RESOLUTION_640X480)
{
len = PHONE_FRAME_SIZE_1;
}
else//error
{
len = FRAME_SIZE_1;
printf("Error\n");
}
}
else if(cmd == SERVER_STATUS_TRANSFER_2)
{
if(res == IMAGE_RESOLUTION_1280X720)
{
len = FRAME_SIZE_2;
}
else if(res == IMAGE_RESOLUTION_640X480)
{
len = PHONE_FRAME_SIZE_2;
}
else//error
{
len = FRAME_SIZE_2;
printf("Error\n");
}
}
else if(cmd == SERVER_STATUS_TRANSFER_3)
{
if(res == IMAGE_RESOLUTION_1280X720)
{
len = FRAME_SIZE_2;
}
else if(res == IMAGE_RESOLUTION_640X480)
{
len = PHONE_FRAME_SIZE_2;
}
else//error
{
len = FRAME_SIZE_2;
printf("Error SERVER_STATUS_TRANSFER_3\n");
}
}
else
{
printf("here error\n");
//return;
}
printf("len %d\n", len);
int cur_len;
while(len > 0)
{
cur_len = (len > DATA_PACKET_SIZE) ? DATA_PACKET_SIZE : len;
if(send(clientSocket, virt_addr_to_display, cur_len,0)<0)
{
printf("send Image Data failed??\n");
reset_server();
break;
}
len -= cur_len;
virt_addr_to_display += cur_len;
}
printf("[display] After send, len = %d\n ",len);
return;
}
int main(int argc, char **argv)
{
status = STATUS_START;
socket_server_init(port);
pthread_t cmd_t;
pthread_create(&cmd_t, NULL, (void*)cmd_process, NULL);
int ret;
ret = signal(SIGPIPE,sig_pipe);
if(SIG_ERR == ret)
{
printf("sig pipe error \n");
return -1;
}
else
{
printf("signal pipe succeed\n") ;
}
char *client_buf;
client_buf = (char*)malloc(sizeof(client_cmd));
while(1)
{
if(status == STATUS_START)
{
if(((get_send_flag() == 1)||(Image_transfer_status != SERVER_STATUS_STOP_IMAGE))||(pc_transfer_mode != 0))
{
set_send_flag(0);
int send_ret;
send_ret = send(clientSocket, (const char*)&server_cmd, sizeof(server_cmd), 0);
if(send_ret< 0) //Server send head packet to client.
{
printf("Server send head packet fail!\n");
reset_server();
break;
}
printf("Image_transfer_status != 0, send finished\n");
//see if send cmd
static unsigned int i = 0;
{
{
static int cnt = 0;
if(pc_transfer_mode == 1)
{
printf("Send 1\n");
send_image(buf_right + (i%30)*FRAME_SIZE_2, SERVER_STATUS_TRANSFER_3, server_cmd.res);
printf("Send 2\n");
send_image(buf_disparity + (i%30)*FRAME_SIZE_1, SERVER_STATUS_TRANSFER_1, server_cmd.res);
i++;
}
else if(pc_transfer_mode == 2)
{
printf("Send 1\n");
send_image(buf_right + (i%30)*FRAME_SIZE_2, SERVER_STATUS_TRANSFER_3, server_cmd.res);
printf("Send 2\n");
send_image(buf_left + (i%30)*FRAME_SIZE_2, SERVER_STATUS_TRANSFER_2, server_cmd.res);
i++;
}
else
{
}
printf("Image %d\n", cnt%30);
cnt++;
}
}
}
usleep(10000);
}
}
return 0;
}
最佳答案
据我了解，您在服务器代码中做了类似的事情:
int srv;
srv = socket(srv,...);
//(...)
bind(srv,...);
//(...)
listen(srv,...);
//(...)
int fd;
char message[BUFSIZE];
//accept any client connection and build a specific socket for it
while(true){
fd = accept(srv,...);
//(...)
int len = read(fd,message,BUFSIZE);
//(...)
//closing the connection to that client once the task is over
close(fd);
}
close(srv);
如果是这种情况，您应该在执行 read() 之前清除缓冲区消息。
一个简单的方法是使用 memset() ，所以这部分代码将如下所示:
//(...)
memset(message,'0',BUFSIZE);
int len = read(fd,message,BUFSIZE);
//(...)
关于C套接字客户端重新连接到服务器时收到大量数据，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/46048586/