我有UDP客户端和服务器的写代码片段。我使用相同的端口进行发送和接收。我的问题是客户端有很多消息丢失，所以有人可以帮助我优化我的代码，这是我的UDP客户端代码：
#define SERVERIP "192.168.170.155"
#define SERVERPORT 5000
#define DEVICE_SEND_PORT 5000
#define DEVICE_RECEIVE_PORT 5000
#define BUFFERSIZE 2048
/**For socket file descriptor identification*/
#define S1READY 0x01
int m_SendSocketId;
int m_ReceiveSocketId;
int msgcount;
int socketbuffsize = 1*1024*1024;
/**
* FUNCTION NAME : waitToRead
* Implementation of select and non-blocking socket mechanism
* @param socket Socket that needs to be in select and non blocking mode
* @return Returnd the file descriptors which, returned by select function
*/
int waitToRead(int socket)
{
fd_set fds;
struct timeval timeout;
int rc; // number of file descriptor returned
int result; // result
int fd; // file descriptor
fd=fcntl(socket,F_GETFL,0);
fcntl(socket,F_SETFL,fd | O_NONBLOCK);
// Set time limit.
timeout.tv_sec = 1;
timeout.tv_usec = 0;
// Create a descriptor containing our sockets.
FD_ZERO(&fds);
FD_SET(socket, &fds);
rc = select(sizeof(fds)*8, &fds, NULL, NULL, &timeout);
if (rc==-1)
{
printf("[%s:%d#%s] Select Failed\n",__FILE__, __LINE__,__func__);
return -1;
}
result = 0;
if (rc > 0)
{
if (FD_ISSET(socket, &fds))
result |= S1READY;
}
return result;
}
/**
* FUNCTION NAME : receiveMessage
* This function opens particular port that is defined in the
* Configuration file, and listens on that port.
* @return if there'll be any issue in listening, then it will return
* false otherwise it will return true.
*/
bool receiveMessage()
{
struct sockaddr_in serverAddr; //Information about the Device UDP Server
struct sockaddr_in client_addr; // Information about Qgate Server
char buffer[BUFFERSIZE]; // Buffer to store incoming message
int addr_len; // to store client address length
int serverlen; // to store server address length
int sockResult; // to store result given by waitToRead
int optval = 1;
int receivedByte = 0;
//Open a datagram Socket
if((m_ReceiveSocketId = socket(AF_INET, SOCK_DGRAM, 0)) < 0)
{
printf("[%s:%d#%s] UDP Client - socket() error\n",__FILE__, __LINE__,__func__);
return false;
}
//Configure Server Address.
//set family and port
serverAddr.sin_family = AF_INET;
serverAddr.sin_port = htons(DEVICE_RECEIVE_PORT);
setsockopt(m_ReceiveSocketId, SOL_SOCKET,SO_REUSEADDR, &optval, sizeof(optval));
/*if (setsockopt(m_ReceiveSocketId, SOL_SOCKET, SO_RCVBUF, &socketbuffsize, sizeof(socketbuffsize)) == -1)
{
printf("Recieve Socket memory Allocation fail\n");
}*/
if((serverAddr.sin_addr.s_addr = INADDR_ANY) == (unsigned long)INADDR_NONE)
{
printf("[%s:%d#%s] Host Not found(%d)\n",__FILE__, __LINE__,__func__,h_errno);
close(m_ReceiveSocketId); // close the socket
return false;
}
if (bind(m_ReceiveSocketId, (struct sockaddr *) &serverAddr,sizeof(struct sockaddr_in)) < 0 )
{
printf("[%s:%d#%s] UDP Client- Socket Bind error=%s\n",__FILE__, __LINE__,__func__,strerror(errno));
close(m_ReceiveSocketId); // close the socket
return false;
}
serverlen = (int )sizeof(serverAddr);
addr_len = sizeof(struct sockaddr);
// Loop and listen for incoming message
while(1)
{
//wait at select to, read
sockResult = waitToRead(m_ReceiveSocketId);
if(sockResult == S1READY)
{
receivedByte = read(m_ReceiveSocketId,buffer,BUFFERSIZE);
buffer[receivedByte] = '\0';
if(receivedByte == -1)
{
printf("[%s:%d#%s] UDP Client - receive error", __FILE__,__LINE__,__func__);
close(m_ReceiveSocketId);
return false;
}
else if(receivedByte > 0)
{
//printf("[%s:%d#%s] received message = %d bytes\n",__FILE__,__LINE__,__func__,(int)strlen(buffer));
printf("count: %d, buffer %s \n", msgcount++, buffer);
}
}
memset(buffer, 0, BUFFERSIZE);
fflush(stdout);
}
close(m_ReceiveSocketId); // close the socket
printf("[%s:%d#%s] Recieve socket closed:%s\n",
__FILE__, __LINE__,__func__, strerror(errno));
return true;
}
bool sendMessage(char *message)
{
struct sockaddr_in serverAddr; //Information about the server
struct sockaddr_in deviceAddr; //Device UDP Client Address for sending message
int optval = 1;
//Open a datagram Socket
if((m_SendSocketId = socket(AF_INET, SOCK_DGRAM, 0)) < 0)
{
printf("[%s:%d#%s] UDP Client - socket() error\n",__FILE__, __LINE__,__func__);
return false;
}
// Clear out the device struct
memset(&deviceAddr, 0x00, sizeof(struct sockaddr_in));
deviceAddr.sin_family = AF_INET;
deviceAddr.sin_port = htons(DEVICE_SEND_PORT);
setsockopt(m_SendSocketId, SOL_SOCKET, SO_REUSEADDR, &optval, sizeof(optval));
/*if (setsockopt(m_SendSocketId, SOL_SOCKET, SO_SNDBUF, &socketbuffsize, sizeof(socketbuffsize)) == -1)
{
printf("send Socket memory Allocation fail\n");
}*/
if((deviceAddr.sin_addr.s_addr = INADDR_ANY) == (unsigned long)INADDR_NONE)
{
// in netdb.h
printf("[%s:%d#%s] Host Not found(%d)\n",__FILE__, __LINE__,__func__, h_errno);
close(m_SendSocketId); // close the socket
return false;
}
if (bind(m_SendSocketId, (struct sockaddr *) &deviceAddr,sizeof(struct sockaddr_in)) < 0 )
{
printf("[%s:%d#%s] UDP Client- Socket Bind error=%s\n",__FILE__, __LINE__,__func__,strerror(errno));
close(m_SendSocketId); // close the socket
return false;
}
// Clear out the server struct
memset(&serverAddr, 0x00, sizeof(struct sockaddr_in));
//Configure Server Address.
//set family and port
serverAddr.sin_family = AF_INET;
serverAddr.sin_port = htons(SERVERPORT);
//serverAddr.sin_addr.s_addr = htonl(39898);
if((serverAddr.sin_addr.s_addr = inet_addr(SERVERIP)) == (unsigned long)INADDR_NONE)
{
printf("[%s:%d#%s] Host Not found %d\n",__FILE__, __LINE__,__func__,h_errno);
close(m_SendSocketId);
return false;
}
// Send data to the server.
if( sendto(m_SendSocketId, message,strlen(message) ,0, (struct sockaddr *)&serverAddr, sizeof(serverAddr)) < 0 )
{
printf("[%s:%d#%s] UDP Client - sendto() error=%s \n",__FILE__, __LINE__,__func__,strerror(errno));
close(m_SendSocketId);
return false;
}
close(m_SendSocketId);
return true;
}
int main ()
{
int loop;
char str[10];
msgcount = 1;
pthread_t receiveThread;
if(pthread_create(&receiveThread, NULL,(void *)&receiveMessage, NULL) != 0)
{
printf("[%s:%d#%s] thread create Failed(%s)\n",
__FILE__, __LINE__,__func__, strerror(errno));
return false;
}
for(loop =0; loop < 1000; loop++)
{
sprintf(str,"%4d",loop);
sendMessage(str);
}
pthread_join(receiveThread, NULL);
return 0;
}
这是临时UDP服务器代码，它接收的消息几乎超过90％并且也发送相同的消息，但是udpclient无法接收消息。
int main()
{
int sock;
int addr_len, bytes_read, bytes_send;
char recv_data[1024];
int i;
int count=0;
struct sockaddr_in server_addr , client_addr;
if ((sock = socket(AF_INET, SOCK_DGRAM, 0)) == -1) {
perror("Socket");
exit(1);
}
server_addr.sin_family = AF_INET;
server_addr.sin_port = htons(5000);
server_addr.sin_addr.s_addr = INADDR_ANY;
bzero(&(server_addr.sin_zero),8);
//client_addr.sin_family = AF_INET;
setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, &optval, sizeof(optval));
if (bind(sock,(struct sockaddr *)&server_addr,sizeof(struct sockaddr)) == -1)
{
perror("Bind");
exit(1);
}
addr_len = sizeof(struct sockaddr);
printf("\nUDPServer Waiting for client on port 5000");
fflush(stdout);
while (1)
{
bytes_read = recvfrom(sock,recv_data,1024,0,(struct sockaddr *)&client_addr, (socklen_t *)&addr_len);
recv_data[bytes_read] = '\0';
if(recv_data[0]!=0x07)
{
recv_data[0] = 0x09;
//client_addr.sin_port = htons(51254);
bytes_send = sendto(sock, recv_data, bytes_read, 0, (struct sockaddr *)&client_addr, (socklen_t)sizeof(client_addr));
if(bytes_send < 0 )
{
perror("send to ");
}
printf("\nNumber %d", ++count);
memset(&recv_data, 0x00, 1024);
}
else
{
printf("Received Keep ALive\n");
}
memset(&client_addr, 0x00, sizeof(struct sockaddr_in));
fflush(stdout);
}
return 0;
}
任何帮助都将受到高度赞赏。 谢谢Yuvi
答案 0 :(得分：1)
您的代码与UDP丢弃数据包无关，除非您为网络或接收器发送数据包太快。 UDP不可靠。它丢弃数据包。如果您的应用程序协议不需要丢弃数据包，则必须通过基于ACK或基于NACK的协议重新构建该级别的可靠性。
或者在这种情况下像其他人一样使用TCP。
答案 1 :(得分：0)
问题出在sendMessage函数中，每次我需要发送消息时都会重新创建套接字，我认为这需要时间。我还不知道哪个是调用阻塞但是发送套接字解决了我的问题。现在消息的丢失率只有20％到30％。