Gets stuck at gnutls_handshake()

[alex-lt-kong]

I am using Debian 11 (testing) with gnutls installed by apt install gnutls-dev. Note that previously I use Debian 10 (stable), I upgrade to Debian testing only because I would like to try newer version of gnutls.

My Onion instance will get stuck after running for a few days (i.e., it does not respond to any incoming connections). I investigated it for a while and it turns out to be the issue of gnutls_handshake():

https://github.com/davidmoreno/onion/blob/de8ea938342b36c28024fd8393ebc27b8442a161/src/onion/https.c#L222-L225

I revised the above section to:

do{
	ONION_DEBUG("gnutls_handshake()'ing\n");
	ret = gnutls_handshake (session);
	ONION_DEBUG("gnutls_handshake()'ed, ret=%d, strerror=%s\n", ret,gnutls_strerror (ret));
	// https://gnutls.org/reference/gnutls-gnutls.html#gnutls-handshake
}while (ret < 0 && gnutls_error_is_fatal (ret) == 0);
ONION_DEBUG("gnutls_handshake() loop out\n");

and build onion with cmake -DCMAKE_BUILD_TYPE=Debug ../. The below is what I get from log after my instance gets stuck:

[45376E00] [2023-02-04 09:36:56] [DEBUG https.c:228] gnutls_handshake()'ed, ret=-28, strerror=Resource temporarily unavailable, try again.

[45376E00] [2023-02-04 09:36:56] [DEBUG https.c:226] gnutls_handshake()'ing

[45376E00] [2023-02-04 09:42:07] [DEBUG https.c:228] gnutls_handshake()'ed, ret=-28, strerror=Resource temporarily unavailable, try again.

[45376E00] [2023-02-04 09:42:07] [DEBUG https.c:226] gnutls_handshake()'ing

[45376E00] [2023-02-04 09:47:18] [DEBUG https.c:228] gnutls_handshake()'ed, ret=-28, strerror=Resource temporarily unavailable, try again.

[45376E00] [2023-02-04 09:47:18] [DEBUG https.c:226] gnutls_handshake()'ing

[45376E00] [2023-02-04 09:52:30] [DEBUG https.c:228] gnutls_handshake()'ed, ret=-28, strerror=Resource temporarily unavailable, try again.

[45376E00] [2023-02-04 09:52:30] [DEBUG https.c:226] gnutls_handshake()'ing

[45376E00] [2023-02-04 09:57:41] [DEBUG https.c:228] gnutls_handshake()'ed, ret=-28, strerror=Resource temporarily unavailable, try again.

[45376E00] [2023-02-04 09:57:41] [DEBUG https.c:226] gnutls_handshake()'ing

[45376E00] [2023-02-04 10:02:52] [DEBUG https.c:228] gnutls_handshake()'ed, ret=-28, strerror=Resource temporarily unavailable, try again.

[45376E00] [2023-02-04 10:02:52] [DEBUG https.c:226] gnutls_handshake()'ing

[45376E00] [2023-02-04 10:08:04] [DEBUG https.c:228] gnutls_handshake()'ed, ret=-28, strerror=Resource temporarily unavailable, try again.

I am also aware that gnutls's doc on gnutls-handshake() does say that "[o]n these non-fatal errors call this function again, until it returns 0" so I am not sure if this is something Onion can fix.

I am now trying the following, see if it can "solve" the issue (could take weeks to get result):

do{
	ONION_DEBUG("gnutls_handshake()'ing\n");
	ret = gnutls_handshake (session);
	ONION_DEBUG("gnutls_handshake()'ed, ret=%d, strerror=%s\n", ret,gnutls_strerror (ret));
	if (ret == -28) {
		break;
	}
	// https://gnutls.org/reference/gnutls-gnutls.html#gnutls-handshake
}while (ret < 0 && gnutls_error_is_fatal (ret) == 0);

Any idea on this?