UDP broadcast failed

[小川崇]

Greetings,

I made UDP broadcast program as shown below.
I ran the program on i.MX6 board.
but sendto() always reterun -1.

i.MX6 board is setup with IP address 192.168.0.1, subnet 255.255.255.0.

I want to fix this error.
but I don't know how to fix this problem.
I appreciate if someone can help me to solve it

Regards,

takashi

#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <stdio.h>

int
main()
{
int sock;
struct sockaddr_in addr;
int yes = 1;
int ret;
int opt;

sock = socket(AF_INET, SOCK_DGRAM, 0);
if(sock < 0)printf("socket() failed!!\n");

addr.sin_family = AF_INET;
addr.sin_port = htons(8503);
addr.sin_addr.s_addr = inet_addr("255.255.255.255");

opt = setsockopt(sock,SOL_SOCKET, SO_BROADCAST, (char *)&yes, sizeof(yes));
if(opt < 0)printf("setsockopt() failed!!\n");

ret = sendto(sock, "HELLO", 5, 0, (struct sockaddr *)&addr, sizeof(addr));
if(ret!=5)printf("sendto() failed!!\n");

close(sock);

return 0;
}

[BrilliantovKiri]

Hello!

1. check errno variable after sendto

2. your system should have route to destination network

[LeonardoSandova]

In addition, if you can use strace to run your app, you will find more insight. To print the error with useful info, use strerror(errno) and do it just after the call to sendto (this variable is global, so any system call modify it).

Leo

[小川崇]

Hi

I checked errno and error reason by using strerror.

error no. is 101：Network is unreachable.

What does error no. 101 mean?

What is the problem?

takashi

[BrilliantovKiri · Accepted solution]

I think your system havn't routing to destination network.

Because you try send packet on broadcast address I think you solve probleam

after configuration default gateway.

[小川崇]

Hi

after I set default gateway  I ran the program.

sendto returned 5.

The error did not occur.

Thank you for your advice.

takashi