C UDP组播接收数据包丢失

Question

I write a C program to receive UDP multicast packets, and it works. However, when the program running few seconds, the packet lost happens frequently. When I press the Ctrl + C to terminate the program and restart it, it will receive most of the packets, but the packet lost will be happened after few seconds. This is very strange, what's the problem? Here is my C code.

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

#include <fcntl.h>
#include <sys/ioctl.h>
#include <android/log.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <sys/time.h>
#include <sys/resource.h>

#define BUF_SIZE 4

int mjpeg_main(){
    int sockfd;
    struct sockaddr_in localSock;
    struct ip_mreq group;
    char buf[BUF_SIZE];
    int len = sizeof(localSock);

/* Create a datagram socket on which to receive. */
if((sockfd = socket(AF_INET, SOCK_DGRAM, 0)) == -1)
{
    perror("Can't create socket!");
    exit(1);
}

/* Enable SO_REUSEADDR to allow multiple instances of this */
/* application to receive copies of the multicast datagrams. */
int reuse = 1;
if(setsockopt(sockfd, SOL_SOCKET, SO_REUSEADDR, (char *)&reuse, sizeof(reuse)) < 0)
{
    perror("Setting SO_REUSEADDR error");
    close(sockfd);
    exit(1);
}

int n = 1024 * 1024;
if (setsockopt(sockfd,SOL_SOCKET,SO_RCVBUFFORCE,(const char*)&n, sizeof(int)) == -1)
{
  // deal with failure, or ignore if you can live with the default size
}



/* Bind to the proper port number with the IP address */
/* specified as INADDR_ANY. */
memset((char *) &localSock, 0, sizeof(localSock));
localSock.sin_family = AF_INET;
localSock.sin_port = htons(2068);
localSock.sin_addr.s_addr = INADDR_ANY;
if(bind(sockfd, (struct sockaddr*)&localSock, sizeof(localSock)))
{
    perror("Binding datagram socket error");
    close(sockfd);
    exit(1);
}

/* Join the multicast group 239.100.15.101 on the local 203.106.93.94 */
/* interface. Note that this IP_ADD_MEMBERSHIP option must be */
/* called for each local interface over which the multicast */
/* datagrams are to be received. */
group.imr_multiaddr.s_addr = inet_addr("239.100.15.101");
group.imr_interface.s_addr = inet_addr("10.100.15.115");
if(setsockopt(sockfd, IPPROTO_IP, IP_ADD_MEMBERSHIP, (char *)&group, sizeof(group)) < 0)
{
    perror("Adding multicast group error");
    close(sockfd);
    exit(1);
}


printf("Start to receive!n");
__android_log_print(ANDROID_LOG_INFO,"mjpeg","mjpeg start !!");

//Wait for connect
while(1)
{
    memset(buf, 0, sizeof(buf));
    int z = recvfrom(sockfd,                      // Socket
                     buf,                         // Receiving buffer
                     sizeof buf,                  // Max recv buf size
                     0,                           // Flags: no options
                     (struct sockaddr *)&localSock,// Addr
                     &len);                       // Addr len, in & out
    if ( z < 0 ) 
    {
        perror("recv");
        exit(1);
    }

    printf("Frame: %02X:%02X, Sequence: %02X:%02X\n", buf[0], buf[1], buf[2], buf[3]);
}

close(sockfd);
return 0;
}

And, this is the result. The sender is a hardware, a frame contains many sequences. The sequence number will sequentially increase.

Frame: 09:1F, Sequence: 00:00
Frame: 09:1F, Sequence: 00:01
Frame: 09:1F, Sequence: 00:02
Frame: 09:1F, Sequence: 00:03
Frame: 09:1F, Sequence: 00:04
Frame: 09:1F, Sequence: 00:05
Frame: 09:1F, Sequence: 00:06
Frame: 09:1F, Sequence: 00:07
Frame: 09:1F, Sequence: 00:08
Frame: 09:1F, Sequence: 00:09
Frame: 09:1F, Sequence: 00:0A
Frame: 09:1F, Sequence: 00:0B
Frame: 09:1F, Sequence: 00:0C
Frame: 09:1F, Sequence: 00:0D
Frame: 09:1F, Sequence: 00:0E
Frame: 09:1F, Sequence: 00:0F
Frame: 09:1F, Sequence: 00:10
Frame: 09:1F, Sequence: 00:11
Frame: 09:1F, Sequence: 00:12
Frame: 09:1F, Sequence: 00:13
Frame: 09:1F, Sequence: 00:14
Frame: 09:1F, Sequence: 00:15
Frame: 09:1F, Sequence: 00:16
Frame: 09:1F, Sequence: 00:17
Frame: 09:1F, Sequence: 00:18
Frame: 09:1F, Sequence: 00:19
Frame: 09:1F, Sequence: 00:1A
Frame: 09:1F, Sequence: 00:1B
Frame: 09:1F, Sequence: 00:1C
Frame: 09:1F, Sequence: 00:1D
Frame: 09:1F, Sequence: 00:1E
Frame: 09:1F, Sequence: 00:1F
Frame: 09:1F, Sequence: 00:20
Frame: 09:1F, Sequence: 00:21
Frame: 09:1F, Sequence: 00:22
Frame: 09:1F, Sequence: 00:23
Frame: 09:1F, Sequence: 00:24
Frame: 09:1F, Sequence: 00:25
Frame: 09:1F, Sequence: 00:26
Frame: 09:1F, Sequence: 00:27
Frame: 09:1F, Sequence: 00:28
Frame: 09:1F, Sequence: 00:29
Frame: 09:1F, Sequence: 00:2A
Frame: 09:1F, Sequence: 00:2B
Frame: 09:1F, Sequence: 00:2C
Frame: 09:1F, Sequence: 00:2D
Frame: 09:1F, Sequence: 00:2E
Frame: 09:1F, Sequence: 00:2F
Frame: 09:1F, Sequence: 00:30
Frame: 09:1F, Sequence: 00:31
Frame: 09:1F, Sequence: 00:32
Frame: 09:1F, Sequence: 00:33
Frame: 09:1F, Sequence: 00:34
Frame: 09:1F, Sequence: 00:35
Frame: 09:1F, Sequence: 00:36
Frame: 09:1F, Sequence: 00:37
Frame: 09:1F, Sequence: 00:38
Frame: 09:1F, Sequence: 00:39
Frame: 09:1F, Sequence: 00:3A
Frame: 09:1F, Sequence: 00:3B
Frame: 09:1F, Sequence: 00:3C
Frame: 09:1F, Sequence: 00:3D
Frame: 09:1F, Sequence: 00:3E
Frame: 09:1F, Sequence: 00:3F
Frame: 09:1F, Sequence: 00:40
Frame: 09:1F, Sequence: 00:41
Frame: 09:1F, Sequence: 00:42
Frame: 09:1F, Sequence: 00:43
Frame: 09:1F, Sequence: 00:44
Frame: 09:1F, Sequence: 00:45
Frame: 09:1F, Sequence: 00:46
Frame: 09:1F, Sequence: 00:47
Frame: 09:1F, Sequence: 00:48
Frame: 09:1F, Sequence: 00:49
Frame: 09:1F, Sequence: 00:4A
Frame: 09:1F, Sequence: 00:4B
Frame: 09:1F, Sequence: 00:4C
Frame: 09:1F, Sequence: 00:4D
Frame: 09:1F, Sequence: 80:4E
Frame: 09:20, Sequence: 00:00
Frame: 09:20, Sequence: 00:01
Frame: 09:20, Sequence: 00:02
Frame: 09:20, Sequence: 00:03
Frame: 09:20, Sequence: 00:04
Frame: 09:20, Sequence: 00:05
Frame: 09:20, Sequence: 00:06
Frame: 09:20, Sequence: 00:07
Frame: 09:20, Sequence: 00:08
Frame: 09:20, Sequence: 00:09
Frame: 09:20, Sequence: 00:0A
Frame: 09:20, Sequence: 00:0B
Frame: 09:20, Sequence: 00:0C
Frame: 09:20, Sequence: 00:0D
Frame: 09:20, Sequence: 00:0E
Frame: 09:20, Sequence: 00:0F
Frame: 09:20, Sequence: 00:10
Frame: 09:20, Sequence: 00:11
Frame: 09:20, Sequence: 00:12
Frame: 09:20, Sequence: 00:13
Frame: 09:20, Sequence: 00:14
Frame: 09:20, Sequence: 00:15
Frame: 09:20, Sequence: 00:16
Frame: 09:20, Sequence: 00:17
Frame: 09:20, Sequence: 00:18
Frame: 09:20, Sequence: 00:19
Frame: 09:20, Sequence: 00:1A
Frame: 09:20, Sequence: 00:1B
Frame: 09:20, Sequence: 00:1C
Frame: 09:20, Sequence: 00:1D
Frame: 09:20, Sequence: 00:1E
Frame: 09:20, Sequence: 00:1F
Frame: 09:20, Sequence: 00:20
Frame: 09:20, Sequence: 00:21
Frame: 09:20, Sequence: 00:22
Frame: 09:20, Sequence: 00:23
Frame: 09:20, Sequence: 00:24
Frame: 09:20, Sequence: 00:25
Frame: 09:20, Sequence: 00:26
Frame: 09:20, Sequence: 00:27
Frame: 09:20, Sequence: 00:28
Frame: 09:20, Sequence: 00:29
Frame: 09:20, Sequence: 00:2E
Frame: 09:20, Sequence: 00:31
Frame: 09:20, Sequence: 00:37
Frame: 09:20, Sequence: 00:3B
Frame: 09:20, Sequence: 00:3D
Frame: 09:20, Sequence: 00:3F
Frame: 09:20, Sequence: 00:41
Frame: 09:20, Sequence: 00:42
Frame: 09:20, Sequence: 00:44
Frame: 09:20, Sequence: 00:46
Frame: 09:20, Sequence: 00:4B
Frame: 09:20, Sequence: 80:4E
Frame: 09:21, Sequence: 00:00
Frame: 09:21, Sequence: 00:01

start packet lost...

Frame: 09:21, Sequence: 00:06
Frame: 09:21, Sequence: 00:10
Frame: 09:21, Sequence: 00:1C
Frame: 09:21, Sequence: 00:25
Frame: 09:21, Sequence: 00:2F
Frame: 09:21, Sequence: 00:35
Frame: 09:21, Sequence: 00:3B
Frame: 09:21, Sequence: 00:3C
Frame: 09:21, Sequence: 00:3E
Frame: 09:21, Sequence: 00:40
Frame: 09:21, Sequence: 00:42
Frame: 09:21, Sequence: 00:43
Frame: 09:21, Sequence: 00:45
Frame: 09:21, Sequence: 00:47
Frame: 09:21, Sequence: 00:4D
Frame: 09:22, Sequence: 00:01
Frame: 09:22, Sequence: 00:05
Frame: 09:22, Sequence: 00:0D
Frame: 09:22, Sequence: 00:1B
Frame: 09:22, Sequence: 00:23
Frame: 09:22, Sequence: 00:2F
Frame: 09:22, Sequence: 00:34
Frame: 09:22, Sequence: 00:3A
Frame: 09:22, Sequence: 00:3C
Frame: 09:22, Sequence: 00:3E
Frame: 09:22, Sequence: 00:40
Frame: 09:22, Sequence: 00:41
Frame: 09:22, Sequence: 00:43
Frame: 09:22, Sequence: 00:45
Frame: 09:22, Sequence: 00:47
Frame: 09:22, Sequence: 00:4D
Frame: 09:23, Sequence: 00:01
Frame: 09:23, Sequence: 00:04
Frame: 09:23, Sequence: 00:0A
Frame: 09:23, Sequence: 00:19
Frame: 09:23, Sequence: 00:20
Frame: 09:23, Sequence: 00:2E
Frame: 09:23, Sequence: 00:32
Frame: 09:23, Sequence: 00:39
Frame: 09:23, Sequence: 00:3C
Frame: 09:23, Sequence: 00:3E
Frame: 09:23, Sequence: 00:3F
Frame: 09:23, Sequence: 00:41
Frame: 09:23, Sequence: 00:43
Frame: 09:23, Sequence: 00:45
Frame: 09:23, Sequence: 00:46
Frame: 09:23, Sequence: 00:4D

Answer 1

The problem was solved. The reason is that our PHY is using external crystal, and the configuration of clock of the kernel is incorrect.