EPERM error on setsockopt() on UDP socket

[krog1]

Hi,, I'm trying to set a recv timeout on a UDP socket (coap) using setsockopt() and getting an EPERM error. I've tried the setsockopt() call both before and after the (successful) connect(), with the same result. Am I doing this right? Or is there a problem with timeout support on UDP sockets? I've looked at this post: https://devzone.nordicsemi.com/f/nordic-q-a/52437/nrf_poll-may-be-consuming-data-when-not-supposed-to-on-nrf9160, and can't see a difference in my usage, other than the different socket type.

Code snippet:

------------------------------

for (addr = result; addr != NULL; addr = addr->ai_next) {

sock = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP);
if (sock < 0) {
err = sock;
continue;
}

err = connect(sock, addr->ai_addr, addr->ai_addrlen);
if (err < 0) {
continue;
}

// Set the timeout here for responses.
struct timeval tv;
// tv.tv_sec = COAP_RESPONSE_TIMEOUT_MS / 1000;
tv.tv_sec = 1;
// tv.tv_usec = (COAP_RESPONSE_TIMEOUT_MS % 1000) * 1000;
tv.tv_usec = 0;
err = setsockopt(sock, SOL_SOCKET, SO_RCVTIMEO, (const char*) &tv, sizeof(tv));
if (err < 0) {
LOG_ERR("setsockopt() failed, err = %d.", err);
} else {
LOG_DBG("setsockopt() succeeded.");
}

// If connect() succeeded, use this address.
break;
}

--------------------

Thanks,

Chris.

[Håkon Alseth]

Hi,

 

It worked when injecting your code into this ntp sample:

https://github.com/Rallare/fw-nrfconnect-nrf/blob/nrf9160_samples/samples/nrf9160/ntp/src/main.c

 

Output:

***** Booting Zephyr OS build v2.0.99-ncs1-rc1-11-g9be97c63368a *****
getaddrinfo err: 0
client_fd: 3
setsockopt() succeeded.bind err: 0
sendto ret: 48
Flags: 36
Stratum: 2
Poll: 3
Precision: 4294967273
Root delay: 788725760
Root dispersion: 721813504
Ref ID: 348928706
Ref timestamp: 3783923305111899737
Orig Timestamp: 00
Receive timestamp: 37839236151286592714
Transmit: 37839236151286882532
Unix time: 1574934815
Time: Thu Nov 28 09:53:35 2019

 

 

for (addr = result; addr != NULL; addr = addr->ai_next) {

sock = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP);
if (sock < 0) {
err = sock;
continue;
}

err = connect(sock, addr->ai_addr, addr->ai_addrlen);
if (err < 0) {
continue;
}

Compared to your solution, I placed the setsockopt call just after creating the socket. I tried your exact order, and it also succeeded at my end.

I had a suspicion on the struct timeval, but tested it with newlib and minimal libc (the default libc in zephyr), and no problems there either.

 

I'm running on "v1.1-branch". Which revision of nrf are you testing on?

 

Kind regards,

Håkon

[krog1]

Hi Håkon,

Thanks for the response. I copied the ntp sample into my tree, and added the setsockopt() code into the blocking_connect() function. I get the same error, although I realized it's actually EINVAL, not EPERM (I was looking at the return code, not errno).

int blocking_connect(int fd, struct sockaddr *local_addr, socklen_t len)
{
	int err;

	do {
		err = connect(fd, local_addr, len);
	} while (err < 0 && errno == EAGAIN);

    // BEGIN CLB INSERT

    // Set the timeout here for responses.
    struct timeval tv;
    tv.tv_sec = 1;
    tv.tv_usec = 0;
    err = setsockopt(fd, SOL_SOCKET, SO_RCVTIMEO, (const char*) &tv, sizeof(tv));
    if (err < 0) {
        printk("setsockopt() failed, err = %d, errno = %d.\n", err, errno);
    } else {
        printk("setsockopt() succeeded.\n");
    }

    // END CLB INSERT

	return err;
}

Output:

***** Booting Zephyr OS v1.14.99-ncs1 *****
getaddrinfo err: 0
client_fd: 2
bind err: 0
setsockopt() failed, err = -1, errno = 22.
connect err: 22
sendto ret: 48
Flags: 36
Stratum: 2
Poll: 3
Precision: 4294967273
Root delay: 788725760
Root dispersion: 2416246784
Ref ID: 2496412354
Ref timestamp: 37841176532514736270
Orig Timestamp: 00
Receive timestamp: 37841180551702783404
Transmit: 37841180551703091902
Unix time: 1575129255
Time: Sat Nov 30 15:54:15 2019

The only difference I can see at this point is the version; I'm still at 1.14.99-ncs1. This might be the issue, but unfortunately, I'm not at a point where I can upgrade to check this. For now, I'll change to NOWAIT polling with sleep for the recv, and revisit the setsockopt() error when I upgrade. I'll post a reply to this when I confirm that the version is the issue.

Thanks,

Chris.