Sending UDP packet to 2 clients and only one receive - c

Question

(sorry by advance for my English...)
I am working on a network between a PC and a set of Zedboards connected by Ethernet. I use the UDP protocol, and here's my problem:
- All my cards and my PC are correctly connected to a switch and have their own IPs (192.168.1.15 for PC , and 11/12 for cards).
- When I try to send a simple packet with unix sockets with the code below, only the last message is received (but both seem to be send) (plus, no error or warning on compilation)
- If I switch the two sending, it is always the last which arrive at destination so it is not a card problem...
main.c
#include "send_tool.h"
static int PORT;
static char LOCAL_ADDRESS[50];
static SOCKADDR_IN client_list[NB_CLIENTS];
static int uc_sock;
int main(int argc, char **argv)
{
char buffer[BUF_SIZE];
int actual;int i;
memset(buffer,0, sizeof(buffer));
SOCKADDR_IN csin = { 0 };
if(argc < 3)
{
PORT = 2005;
sprintf(LOCAL_ADDRESS, "192.168.1.15");
printf("Valeurs de parametre forcees: %d\t%s\n", PORT, LOCAL_ADDRESS);
}
else
{
PORT = atoi(argv[1]);
sprintf(LOCAL_ADDRESS, argv[2]);
}
uc_sock = init_UC_connection(LOCAL_ADDRESS, PORT);
while(actual < NB_CLIENTS)
{
read_UDP(uc_sock, &csin, buffer);
if(!strncmp(buffer, "free:",5))
{
//add_client(client_list, csin);
client_list[actual].sin_addr.s_addr = csin.sin_addr.s_addr;
client_list[actual].sin_port = csin.sin_port;
client_list[actual].sin_family = csin.sin_family;
memcpy(client_list[actual].sin_zero, csin.sin_zero, 8);
//sprintf(buffer, "salut");
//write_UDP(uc_sock, &client_list[actual], buffer, strlen(buffer));
actual++;
}
}
printf("************************************\n");
printf("0: %s:%d/%d\n", inet_ntoa(client_list[0].sin_addr), ntohs(client_list[0].sin_port), client_list[0].sin_family);
printf("1: %s:%d/%d\n", inet_ntoa(client_list[1].sin_addr), ntohs(client_list[1].sin_port), client_list[1].sin_family);
printf("************************************\n");
sprintf(buffer, "au revoir");
write_UDP(uc_sock, &client_list[0], buffer, strlen(buffer));
write_UDP(uc_sock, &client_list[1], buffer, strlen(buffer));
memset(buffer, 0, sizeof(buffer));
while(read_UDP(uc_sock, &csin, buffer) > 0){}
close(uc_sock);
return 0;
}
send_tool.h
/* STD LIBS */
#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <string.h>
#include <fcntl.h>
//#include <sys/types.h>
//#include <sys/stat.h>
/* SOCKETS */
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <unistd.h>
#include <netdb.h>
/* TIME */
#include <sys/timerfd.h>
#include <sys/time.h>
#include <pthread.h>
#include <semaphore.h>
#include <signal.h>
#define BUF_SIZE 60000
#define MULTICAST_ADDRESS "224.0.0.1"
#define NB_CLIENTS 2
typedef struct sockaddr_in SOCKADDR_IN;
typedef struct sockaddr SOCKADDR;
typedef struct in_addr IN_ADDR;
int init_UC_connection(char LOCAL_ADDRESS[], int port);
void write_UDP(int sock, SOCKADDR_IN *sin, const char *buffer, size_t buff_len);
int read_UDP(int sock, SOCKADDR_IN *sin, char *buffer);
send_tool.c
#include "send_tool.h"
int init_UC_connection(char LOCAL_ADDRESS[], int port)
{
/* UDP so SOCK_DGRAM */
int sock = socket(AF_INET, SOCK_DGRAM, 0);
SOCKADDR_IN sin = { 0 };
struct timeval tv;
tv.tv_sec = 3;
tv.tv_usec = 0;
if(sock == -1)
{
perror("socket()");
exit(errno);
}
sin.sin_addr.s_addr = inet_addr(LOCAL_ADDRESS);
sin.sin_port = htons(port);
sin.sin_family = AF_INET;
if(bind(sock,(SOCKADDR *)&sin, sizeof sin) == -1)
{
perror("bind()");
exit(errno);
}
if (setsockopt(sock, SOL_SOCKET, SO_RCVTIMEO,&tv,sizeof(tv)) < 0) {
perror("Error");
}
return sock;
}
void write_UDP(int sock, SOCKADDR_IN *sin, const char *buffer, size_t buff_len)
{
socklen_t sinsize = 16;//sizeof *sin;
printf("sinsize : %d\n", sinsize);
int n;
size_t i;
if((n=sendto(sock, buffer, buff_len, 0, (SOCKADDR *) sin, sinsize)) < 0)
{
perror("send()");
exit(errno);
}
printf("envoi (sinsize = %d; n = %d)|%s| a %s:%d/%d termine \n", sinsize, n, buffer, inet_ntoa(sin->sin_addr), ntohs(sin->sin_port), sin->sin_family);
}
int read_UDP(int sock, SOCKADDR_IN *sin, char *buffer)
{
int n = 0;
socklen_t sinsize = sizeof *sin;
if((n = recvfrom(sock, buffer, BUF_SIZE - 1, 0, (SOCKADDR *) sin, &sinsize)) < 0)
{
perror("recvfrom()");
exit(errno);
}
printf("recu (sinsize = %d; n = %d)|%s| depuis %s:%d/%d termine \n", sinsize, n, buffer, inet_ntoa(sin->sin_addr), ntohs(sin->sin_port), sin->sin_family);
return n;
}
client.c
#include "receive_tool.h"
static int PORT;
static char LOCAL_ADDRESS[50];
/* main function, launching the Server application*/
int main(int argc, char **argv)
{
int uc_sock;
char free_msg[30];
memset(free_msg, 0, sizeof(free_msg));
char buffer[60000];
memset(buffer, 0, sizeof(buffer));
if(argc < 3)
{
PORT = 2005;
sprintf(LOCAL_ADDRESS, "192.168.1.12");
//printf("Valeurs de parametre forcees: %d\t%s\n", PORT, LOCAL_ADDRESS);
}
else
{
PORT = atoi(argv[1]);
sprintf(LOCAL_ADDRESS, argv[2]);
}
sprintf(free_msg, "free:%s", LOCAL_ADDRESS);
SOCKADDR_IN server_sin = { 0 }, receive_sin = { 0 };
server_sin.sin_addr.s_addr = inet_addr(SERVER_ADDRESS); // addresse multicast vers les serveurs
server_sin.sin_family = AF_INET;
server_sin.sin_port = htons(PORT);
memset(&server_sin.sin_zero, 0, sizeof(server_sin.sin_zero));
uc_sock = init_UC_connection(LOCAL_ADDRESS, PORT);
write_UDP(uc_sock, &server_sin, free_msg);
time_t chrono_begin;
chrono_begin = time(NULL);
chrono_begin+= 5;
while(time(NULL) <= chrono_begin)
{
if(read_UDP(uc_sock, &receive_sin, buffer)<0) continue;
write_UDP(uc_sock, &server_sin, buffer);
}
close(uc_sock);
return 0;
}
Do you have any idea why this happen?
Thank you for your help.

Answer 1

The problem was caused by the Zedboards which used the same MAC address. Then, the switch sent only to the last IP address connected to the MAC address.
Bye