Multipath udp connections - c++

Question

I programmed client and server codes. Both client and server have two interfaces and two separate IP addresses. To check the result, i made two tap loopbacks.
And then, i check the server and client. It seems that client is sending packets over both sockets but server only receives packets from one socket.
Could you please guide me what is the problem with my code or maybe the loopbaks?
client
#include <unistd.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netdb.h>
#include <string.h>
#include <iostream>
#include <arpa/inet.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <netinet/in.h>
#include <netdb.h>
#include <sys/socket.h>
#define BUFLEN 2048
#define MSGS 5 /* number of messages to send */
int main(void)
{
struct sockaddr_in myaddr, remaddr;
int fd, i, slen=sizeof(remaddr);
char buf[BUFLEN]; /* message buffer */
int recvlen; /* # bytes in acknowledgement message */
char *server = "192.168.10.10"; /* change this to use a different server */
//////////////////////////////////
struct sockaddr_in myaddr2, remaddr2;
int fd2, slen2=sizeof(remaddr2);
char buf2[BUFLEN]; /* message buffer */
int recvlen2; /* # bytes in acknowledgement message */
char *server2 = "192.168.11.11"; /* change this to use a different server */
//////////////////////////////
/* create a socket */
if ((fd=socket(AF_INET, SOCK_DGRAM, 0))==-1)
printf("socket created\n");
/////////////////////////////
if ((fd2=socket(AF_INET, SOCK_DGRAM, 0))==-1)
printf("socket2 created\n");
/////////////////////////////
/* bind fd and fd2 */
memset((char *)&myaddr, 0, sizeof(myaddr));
myaddr.sin_family = AF_INET;
//myaddr.sin_addr.s_addr = htonl(INADDR_ANY);
inet_pton(AF_INET, "192.168.10.10", &myaddr.sin_addr.s_addr);
myaddr.sin_port = htons(2000);
/////////////////////////////
memset((char *)&myaddr2, 0, sizeof(myaddr2));
myaddr2.sin_family = AF_INET;
//myaddr.sin_addr.s_addr = htonl(INADDR_ANY);
inet_pton(AF_INET, "192.168.11.11", &myaddr2.sin_addr.s_addr);
myaddr2.sin_port = htons(2001);
/////////////////////////////
if (bind(fd, (struct sockaddr *)&myaddr, sizeof(myaddr)) < 0) {
perror("bind failed");
return 0;
}
/////////////////////////////
if (bind(fd2, (struct sockaddr *)&myaddr2, sizeof(myaddr2)) < 0) {
perror("bind2 failed");
return 0;
}
/////////////////////////////
// printf("binding ip %s to port %d\n", myaddr.sin_addr.s_addr, myaddr.sin_port);
/* now define remaddr, the address to whom we want to send messages */
/* For convenience, the host address is expressed as a numeric IP address */
/* that we will convert to a binary format via inet_aton */
memset((char *) &remaddr, 0, sizeof(remaddr));
remaddr.sin_family = AF_INET;
remaddr.sin_port = htons(3000);
if (inet_aton(server, &remaddr.sin_addr)==0) {
fprintf(stderr, "inet_aton() failed\n");
exit(1);
}
/////////////////////////////
memset((char *) &remaddr2, 0, sizeof(remaddr2));
remaddr2.sin_family = AF_INET;
remaddr2.sin_port = htons(4000);
if (inet_aton(server2, &remaddr2.sin_addr)==0) {
fprintf(stderr, "inet_aton2() failed\n");
exit(1);
}
/////////////////////////////
/* now let's send the messages */
for (i=0; i < MSGS; i++) {
printf("Sending packet %d to %s port %d\n", i, server, remaddr.sin_port);
sprintf(buf, "This is packet %d", i);
if (sendto(fd, buf, strlen(buf), 0, (struct sockaddr *)&remaddr, slen)==-1) {
perror("sendto");
exit(1);
}
printf("socket %i SENT A PACKET \n", fd);
printf("Sending packet %d to %s port %d\n", i, server2, remaddr2.sin_port);
sprintf(buf2, "This is packet %d", i);
if (sendto(fd2, buf2, strlen(buf2), 0, (struct sockaddr *)&remaddr2, slen2)==-1) {
perror("sendto2");
exit(1);
}
printf("socket %i SENT A PACKET \n", fd2);
}
close(fd);
close(fd2);
return 0;
}
server
#include <unistd.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netdb.h>
#include <string.h>
#include <errno.h>
#include <iostream>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <sys/select.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <netdb.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#define BUFSIZE 2048
int
main(int argc, char **argv)
{
int n;
fd_set readfds;
struct timeval tv;
struct sockaddr_in myaddr; /* our address */
struct sockaddr_in remaddr; /* remote address */
socklen_t addrlen = sizeof(remaddr); /* length of addresses */
int recvlen; /* # bytes received */
int fd; /* our socket */
unsigned char buf[BUFSIZE]; /* receive buffer */
/////////////////////
struct sockaddr_in myaddr2; /* our address */
struct sockaddr_in remaddr2; /* remote address */
socklen_t addrlen2 = sizeof(remaddr2); /* length of addresses */
int recvlen2; /* # bytes received */
int fd2; /* our socket */
unsigned char buf2[BUFSIZE]; /* receive buffer */
/////////////////////
/* create a UDP socket */
if ((fd = socket(AF_INET, SOCK_DGRAM, 0)) < 0) {
perror("cannot create socket\n");
return 0;
}
printf("socket %i is open \n", fd);
///////////////////////////////
if ((fd2 = socket(AF_INET, SOCK_DGRAM, 0)) < 0) {
perror("cannot create socket2\n");
return 0;
}
printf("socket %i is open \n", fd2);
///////////////////////////////
// clear the set ahead of time
FD_ZERO(&readfds);
// add our descriptors to the set
FD_SET(fd, &readfds);
FD_SET(fd2, &readfds);
// since we got s2 second, it's the "greater", so we use that for
// the n param in select()
n = fd2 + 1;
/* bind the socket to any valid IP address and a specific port */
memset((char *)&myaddr, 0, sizeof(myaddr));
myaddr.sin_family = AF_INET;
//myaddr.sin_addr.s_addr = htonl(INADDR_ANY);
inet_pton(AF_INET, "192.168.10.10", &myaddr.sin_addr.s_addr);
myaddr.sin_port = htons(3000);
if (bind(fd, (struct sockaddr *)&myaddr, sizeof(myaddr)) < 0) {
perror("bind failed");
return 0;
}
///////////////////////////
memset((char *)&myaddr2, 0, sizeof(myaddr2));
myaddr2.sin_family = AF_INET;
//myaddr2.sin_addr.s_addr = htonl(INADDR_ANY);
inet_pton(AF_INET, "192.168.11.11", &myaddr2.sin_addr.s_addr);
myaddr2.sin_port = htons(4000);
if (bind(fd2, (struct sockaddr *)&myaddr2, sizeof(myaddr2)) < 0) {
perror("bind2 failed");
return 0;
}
// wait until either socket has data ready to be recv()d (timeout 10.5 secs)
tv.tv_sec = 50;
tv.tv_usec = 500000;
for (;;) {
int rv = select(n, &readfds, NULL, NULL, &tv);
if (rv == -1) {
perror("select"); // error occurred in select()
} else if (rv == 0) {
printf("Timeout occurred! No data after 10.5 seconds.\n");
} else {
// one or both of the descriptors have data
if (FD_ISSET(fd, &readfds)) {
printf("socket %i RECEIVED A PACKET \n", fd);
printf("waiting on port %d\n", myaddr.sin_port);
recvlen = recvfrom(fd, buf, BUFSIZE, 0, (struct sockaddr *)&remaddr, &addrlen);
if (recvlen > 0) {
buf[recvlen] = 0;
printf("received message: \"%s\" (%d bytes)\n", buf, recvlen);
}
else
printf("uh oh - something went wrong!\n");
//sprintf(buf, "ack %d", msgcnt++);
}
if (FD_ISSET(fd2, &readfds)) {
printf("socket %i RECEIVED A PACKET \n", fd2);
printf("waiting on port %d\n", myaddr2.sin_port);
recvlen2 = recvfrom(fd2, buf2, BUFSIZE, 0, (struct sockaddr *)&remaddr2, &addrlen2);
if (recvlen2 > 0) {
buf[recvlen2] = 0;
printf("received message2: \"%s\" (%d bytes)\n", buf2, recvlen2);
}
else
printf("uh oh - something went wrong2!\n");
//sprintf(buf, "ack %d", msgcnt++);
}
}
}
}
result is shown in the picture:
================
Right now i checked the program in ns3 simulator network. It works correctly. so it seems that problem is with loopback. Please guide me how could i make loopback and test it over localhost.