超级简单的UDP通信例子，能通信几个UDP包，就接收不到数据了，请帮忙看看？

[fujoey]

做了一个UDP的例子，用来测试PC机和单板通信，UDP的性能。为了对照，也做了PC机的版本。程序分两部分，一个是服务器，收到UDP包，直接发送回去。另外一个是客户端，向服务器发送UDP包，再接收；一直如此循环。
一样的流程，在PC机和单板之间工作正常。但是在PC机上，却工作不正常。客户端发送UDP包后，一直收不到包。想不通原因。
如果是客户端有问题，单板和PC机却能一直通信。如果是服务器段有问题，终止客户端后，再启动客户端，又可以在客户端和服务器短之间发送一些UDP数据。调试客户端，挂在recvfrom上。
下面贴出服务器和客户端的例子，使用visual studio 2010 express版本编译的。
想用wireshark 1.8抓包。UDP通信，只抓到一个方向的包。没有看到另外一个方向的包。很奇怪。应该有两个方向的数据，否则单板通信会停止的。wireshark是不是哪儿有什么显示的过滤设置？


server 代码
============================

// userver.cpp : Defines the entry point for the console application.
//

#include "stdafx.h"

#include <winsock2.h>
#include <ws2tcpip.h>
#include <stdio.h>


//#include <winsock.h>
#include <winsock2.h>

#include <string.h>
#include <stdio.h>
#include <stdlib.h>
#include <time.h>

#include <windows.h>


#pragma comment(lib, "Ws2_32.lib")

#define		UDP_TSET_DATA_BYTES 		20000000
#define		BUFF_MAX_LEN 		8000
#define 		SERV_PORT_NUM 		8888



int udp_echo_server( void )
{
	int iStatus;
	int iLen,iLenSent;
	int sockfd;
	socklen_t i_client_addr_len;
	struct sockaddr_in server_addr, client_addr;
	
	
	char mesg[BUFF_MAX_LEN];

	sockfd = socket(AF_INET, SOCK_DGRAM, 0); /* create a socket */

	/* init server_addr */
	memset(&server_addr, 0, sizeof(server_addr));
	server_addr.sin_family = AF_INET;
	server_addr.sin_addr.s_addr = htonl(INADDR_ANY);
	server_addr.sin_port = htons(SERV_PORT_NUM);

	/* bind address and port to socket */
	iStatus = bind(sockfd, (struct sockaddr *)&server_addr, sizeof(server_addr));
	if(  0 != iStatus )
	{
		printf("bind error:%d", iStatus);
		exit(1);
	}

	i_client_addr_len = sizeof(client_addr);
	for( ; ; )
	{
		//printf("+");
		/* waiting for receive data */
		iLen = recvfrom(sockfd, mesg, BUFF_MAX_LEN, 0, (struct sockaddr *)&client_addr, &i_client_addr_len);
		if(  iLen<0 )
		{
			printf("recvfrom error:%d from:%s", iLen, inet_ntoa(client_addr.sin_addr));
			printf("Winsock error:%d\n", WSAGetLastError());
			exit(1);
		}
		
		/* sent data back to client */
		//printf("-");
		iLenSent=sendto(sockfd, mesg, iLen, 0,  (struct sockaddr *)&client_addr, i_client_addr_len);
		if(  iLenSent!=iLen )
		{
			printf("sendto error:Only sent %d  of %d to %s", iLenSent, iLen, inet_ntoa(client_addr.sin_addr));
			printf("Winsock error:%d\n", WSAGetLastError());
			exit(1);
		}
	}

	return 0;
}


int main( void )
{
	
	WORD wVersionRequested;
	WSADATA wsaData;
	int err;

	/* Use the MAKEWORD(lowbyte, highbyte) macro declared in Windef.h */
	wVersionRequested = MAKEWORD(2, 2);

	err = WSAStartup(wVersionRequested, &wsaData);
	if (err != 0)
	{
		/* Tell the user that we could not find a usable */
		/* Winsock DLL.                                  */
		printf("WSAStartup failed with error: %d\n", err);
		return 1;
	}

	udp_echo_server(  );

	WSACleanup();

	return 0;
}


client 代码
==========================================
// udp_client.cpp : Defines the entry point for the console application.
//

#include "stdafx.h"

#include <winsock2.h>
#include <ws2tcpip.h>
#include <stdio.h>


//#include <winsock.h>
#include <winsock2.h>

#include <string.h>
#include <stdio.h>
#include <stdlib.h>
#include <time.h>

#include <windows.h>


#pragma comment(lib, "Ws2_32.lib")

#define		UDP_TSET_DATA_BYTES 		20000000
#define		BUFF_MAX_LEN 				8000
#define 		SERV_PORT_NUM 				8888


int udp_client
(
	int iServAddr, 
	int iPacketSize,
	int iPrePacketNum,
	int iDataNum,
	int iReportDataNum
)
{

	int i;
	int iStatus;
	int iPacketNum;
	int iTransmitLen;
	char sendline[BUFF_MAX_LEN], recvline[BUFF_MAX_LEN + 1];
	
	int iReportPacketNum;

	int 	sockfd;
	int 	begin_second, end_second;
	
	struct sockaddr_in servaddr;
	struct sockaddr_in fromaddr;
	int fromlen;



	/* init server address */
	memset(&servaddr, 0, sizeof(servaddr));
	servaddr.sin_addr.S_un.S_addr=iServAddr;
	servaddr.sin_family = AF_INET;
	servaddr.sin_port = htons(SERV_PORT_NUM);

	/* check args */
	printf("\nServer IP:%s.", inet_ntoa(servaddr.sin_addr));
	printf("\nPacket size:%d bytes.", iPacketSize);
	printf("\nPacket number sent out before loop:%d.", iPrePacketNum);
	printf("\nData :%d bytes.", iDataNum);
	printf("\nReport every data :%d bytes.\n", iReportDataNum);
	iReportPacketNum = iReportDataNum/iPacketSize;

	// Initialize buffer
	for( i=0; i<iPacketSize; i++)
	{
		sendline[i] = 0x30+i;
	}

	sockfd = socket(AF_INET, SOCK_DGRAM, 0);
	if( NULL== sockfd)
	{
		printf("socket error");
		return -1;
	}

#if 1
	/* connect to server */
	iStatus=  connect(sockfd, (struct sockaddr *)&servaddr, sizeof(servaddr));
	if( iStatus < 0 )
	{
		printf("connect error:%d", iStatus);
		return -1;
	}
#endif

	iPacketNum = (iDataNum/iPacketSize);
	begin_second = time((time_t*)NULL);

	// Send out some packets in order to reduce the affect of latency
	for( i=0; i<iPrePacketNum; i++)
	{
		/* send a line to server */
		//write(sockfd, sendline, iPacketSize);
		iTransmitLen = send(sockfd, sendline, iPacketSize, 0);
		//iTransmitLen = sendto(sockfd, sendline, iPacketSize, 0, (LPSOCKADDR)&servaddr, sizeof(servaddr));
		if( iTransmitLen != iPacketSize )
		{
			printf("sendto error:%d for pre-packets\n", iTransmitLen);
			printf("Winsock error:%d\n", WSAGetLastError());
			printf("Server IP:%s.\n", inet_ntoa(servaddr.sin_addr));
			return -1;
		}
	}
	
	for( i=0; i<iPacketNum; i++)
	{
		/* send a line to server */
		//write(sockfd, sendline, iPacketSize);
		iTransmitLen = send(sockfd, sendline, iPacketSize, 0);
		//iTransmitLen = sendto(sockfd, sendline, iPacketSize, 0, (LPSOCKADDR)&servaddr, sizeof(servaddr));
		if( iTransmitLen != iPacketSize )
		{
			printf("sendto error:%d for loop-packets\n", iTransmitLen);
			printf("Winsock error:%d\n", WSAGetLastError());
			printf("Server IP:%s.\n", inet_ntoa(servaddr.sin_addr));
			return -1;
		}

		/* receive data from server */
		fromlen=sizeof(fromaddr);
		//iTransmitLen = read(sockfd, recvline, iPacketSize);
		iTransmitLen = recv(sockfd, recvline, iPacketSize, 0);
		//iTransmitLen=recvfrom(sockfd, recvline, iPacketSize,0,(LPSOCKADDR)&fromaddr,&fromlen);
		if( iTransmitLen < 0 )
		{
			printf("read error:%d for loop-packets\n", iTransmitLen);
			printf("Winsock error:%d\n", WSAGetLastError());
			printf("Server IP:%s.\n", inet_ntoa(servaddr.sin_addr));
			return -1;
		}

		if( (iReportPacketNum-1) == (i%iReportPacketNum) )
		{
			printf("+");
		}
		
		// verify if necessary
	}

#if 0	
	printf("\n::...\n");
	for( i=0; i<iPrePacketNum; i++)
	{
		
		/* receive data from server */
		iTransmitLen = recv(sockfd, recvline, iPacketSize, 0);
		fromlen=sizeof(fromaddr);
		//iTransmitLen=recvfrom(sockfd, recvline, iPacketSize,0,(LPSOCKADDR)&fromaddr,&fromlen);
		if( iTransmitLen < 0 )
		{
			printf("read error:%d for post-packets at %d(%d) post-packets", iTransmitLen, i, iPrePacketNum);
			return -1;
		}
	}
#endif

	end_second = time((time_t*)NULL);
	printf("UDP sent %d bytes in %d seconds\n", iDataNum, end_second-begin_second);
	printf("UDP speed:%d KBps for %d bytes packet\n", (iPacketNum*iPacketSize/1000)/(end_second-begin_second), iPacketSize);
	printf("UDP speed:%d Kpps for %d bytes packet\n", (iPacketNum/1000)/(end_second-begin_second), iPacketSize);

	return 0;
}


int main(int argc, char **argv)
{

	int i;
	int iPacketSize;
	int iPrePacketNum;
	int iDataNum;
	int iReportDataNum;
	int iAutoLoop;
	
	int iServAddr;
	int iServerAddrStatus;

	char *endptr;
	
	WORD wVersionRequested;
	WSADATA wsaData;
	int err;

	/* check args */
	if( argc <6 )
	{
		printf("\nUsage:");
		printf("\n%s   server_IP_address   packet_size	packet_num_before  data_size  data_num_report  auto_loop\n", argv[0]);
	}
	

	printf("\n%s    ", argv[0]);
	if( argc > 1 )
	{
		printf("%s    ", argv[1]);
		//iServAddr=inet_addr(argv[1]);
		iServerAddrStatus=inet_pton(AF_INET, argv[1], &iServAddr);
		if( iServerAddrStatus <= 0 )
		{
			printf("[%s] is not a valid IPaddress\n", argv[1]);
			return -1;
		}
	}
	else
	{
		//inet_pton(AF_INET, "127.0.0.1", &servaddr.sin_addr);
		iServAddr=inet_addr("127.0.0.1");
		//iServAddr=inet_addr("192.168.1.10");
	}

	if( argc > 2 )
	{
		printf("%s    ", argv[2]);
		iPacketSize = strtol(argv[2], &endptr, 10);
	}
	else
	{
		iPacketSize = 38;
	}

	if( argc > 3 )
	{
		printf("%s    ", argv[3]);
		iPrePacketNum = strtol(argv[3], &endptr, 10);
	}
	else
	{
		iPrePacketNum = 2000/iPacketSize;
	}

	if( argc > 4 )
	{
		printf("%s    ", argv[4]);
		iDataNum = strtol(argv[4], &endptr, 10);
	}
	else
	{
		iDataNum = UDP_TSET_DATA_BYTES;
	}

	if( argc > 5 )
	{
		printf("%s    ", argv[5]);
		iReportDataNum = strtol(argv[5], &endptr, 10);
	}
	else
	{
		iReportDataNum = UDP_TSET_DATA_BYTES/50;
	}

	if( argc > 6 )
	{
		printf("%s    ", argv[6]);
		if( 0 == strcmp(argv[6], "auto_loop") )
		{
			iAutoLoop = 1;
			printf("\nGo through packet size automatically.\n");
		}
	}
	else
	{
		iAutoLoop = 0;
	}

	/* Use the MAKEWORD(lowbyte, highbyte) macro declared in Windef.h */
	wVersionRequested = MAKEWORD(2, 2);

	err = WSAStartup(wVersionRequested, &wsaData);
	if (err != 0)
	{
		/* Tell the user that we could not find a usable */
		/* Winsock DLL.                                  */
		printf("WSAStartup failed with error: %d\n", err);
		return 1;
	}

	for( i=iPacketSize; i<2000; i+=100 )
	{
		udp_client( iServAddr,	i, iPrePacketNum, iDataNum, iReportDataNum	);
		if ( 1!= iAutoLoop )
		{
			break;
		}
	}

	WSACleanup();

	return 0;
}