Infinite loop occurs when getting dns address of hive mqtt broker

[djpark97]

It happens sometimes.

Once it happens, it happens infinitely and can't get the dns address.

mgr->dnstimeout = 3000; -> changed 5000 but same result.

board : nucleo-h723zg
mongoose version : 7.17

0 2 mongoose.c:21257:mg_phy_init PHY ID: 0x07 0xc131 (LAN87x)
0 1 mongoose.c:19202:mg_random Weak RNG: using rand()
1 2 mongoose.c:4077:mg_mgr_init Driver: stm32h, MAC: 02:3e:c0:06:14:32
Firmware Start...
1f6 3 mongoose.c:3979:mg_connect 1 -1 mqtt://broker.hivemq.com:1883
1f6 2 ap.c:36:mqtt_fn 1 CREATED
1f6 3 mongoose.c:3979:mg_connect 2 -1 udp://8.8.8.8:53
1f6 3 mongoose.c:5189:mg_connect_res 2 192.168.0.77:53037 -> 8.8.8.8:53
1f7 1 mongoose.c:429:mg_error 2 -1 net down
1f7 1 mongoose.c:429:mg_error 2 -1 DNS send
1f7 1 mongoose.c:19202:mg_random Weak RNG: using rand()
1f7 1 mongoose.c:429:mg_error 1 -1 net down
1f7 1 ap.c:46:mqtt_fn 1 ERROR net down
1f8 1 mongoose.c:429:mg_error 1 -1 net down
1f8 1 ap.c:46:mqtt_fn 1 ERROR net down
1f8 1 mongoose.c:429:mg_error 1 -1 net down
1f8 1 ap.c:46:mqtt_fn 1 ERROR net down
1f8 1 mongoose.c:429:mg_error 1 -1 net down
1f9 1 ap.c:46:mqtt_fn 1 ERROR net down
1f9 1 mongoose.c:429:mg_error 1 -1 net down
1f9 1 ap.c:46:mqtt_fn 1 ERROR net down
1f9 1 mongoose.c:429:mg_error 1 -1 net down
1f9 1 ap.c:46:mqtt_fn 1 ERROR net down
1fa 1 mongoose.c:429:mg_error 1 -1 net down
1fa 1 ap.c:46:mqtt_fn 1 ERROR net down
1fa 1 mongoose.c:429:mg_error 1 -1 net down
1fa 1 ap.c:46:mqtt_fn 1 ERROR net down
1fa 1 mongoose.c:429:mg_error 1 -1 net down
1fb 1 ap.c:46:mqtt_fn 1 ERROR net down
1fb 1 mongoose.c:429:mg_error 1 -1 DNS error
1fb 1 ap.c:46:mqtt_fn 1 ERROR DNS error
1fb 3 mongoose.c:3953:mg_close_conn 2 -1 closed
1fb 2 ap.c:85:mqtt_fn 1 CLOSED
1fb 3 mongoose.c:3953:mg_close_conn 1 -1 closed
5de 3 mongoose.c:22919:mg_tcpip_driv Link is 100M full-duplex
5de 1 mongoose.c:4299:onstatechange Got IP
9c6 2 mongoose.c:4295:onstatechange READY, IP: 192.168.0.77
9c6 2 mongoose.c:4296:onstatechange GW: 192.168.0.1
9c6 2 mongoose.c:4297:onstatechange MAC: 02:3e:c0:06:14:32
2906 3 mongoose.c:3979:mg_connect 3 -1 mqtt://broker.hivemq.com:1883
2906 2 ap.c:36:mqtt_fn 3 CREATED
2906 3 mongoose.c:3979:mg_connect 4 -1 udp://8.8.8.8:53
2906 3 mongoose.c:5189:mg_connect_res 4 192.168.0.77:53038 -> 8.8.8.8:53
2907 1 mongoose.c:19202:mg_random Weak RNG: using rand()
34c0 1 mongoose.c:429:mg_error 3 -1 DNS timeout
34c0 1 ap.c:46:mqtt_fn 3 ERROR DNS timeout
34c0 2 ap.c:85:mqtt_fn 3 CLOSED
34c0 3 mongoose.c:3953:mg_close_conn 3 -1 closed
5016 3 mongoose.c:3979:mg_connect 5 -1 mqtt://broker.hivemq.com:1883
5016 2 ap.c:36:mqtt_fn 5 CREATED
5016 1 mongoose.c:19202:mg_random Weak RNG: using rand()
5bcf 1 mongoose.c:429:mg_error 5 -1 DNS timeout
5bcf 1 ap.c:46:mqtt_fn 5 ERROR DNS timeout
5bcf 2 ap.c:85:mqtt_fn 5 CLOSED
5bcf 3 mongoose.c:3953:mg_close_conn 5 -1 closed
7726 3 mongoose.c:3979:mg_connect 6 -1 mqtt://broker.hivemq.com:1883
7726 2 ap.c:36:mqtt_fn 6 CREATED
7726 1 mongoose.c:19202:mg_random Weak RNG: using rand()
82df 1 mongoose.c:429:mg_error 6 -1 DNS timeout
82df 1 ap.c:46:mqtt_fn 6 ERROR DNS timeout
82df 2 ap.c:85:mqtt_fn 6 CLOSED
82df 3 mongoose.c:3953:mg_close_conn 6 -1 closed
9e36 3 mongoose.c:3979:mg_connect 7 -1 mqtt://broker.hivemq.com:1883
9e36 2 ap.c:36:mqtt_fn 7 CREATED
9e36 1 mongoose.c:19202:mg_random Weak RNG: using rand()
a9ef 1 mongoose.c:429:mg_error 7 -1 DNS timeout
a9ef 1 ap.c:46:mqtt_fn 7 ERROR DNS timeout
a9ef 2 ap.c:85:mqtt_fn 7 CLOSED
a9ef 3 mongoose.c:3953:mg_close_conn 7 -1 closed
c546 3 mongoose.c:3979:mg_connect 8 -1 mqtt://broker.hivemq.com:1883
c546 2 ap.c:36:mqtt_fn 8 CREATED
c546 1 mongoose.c:19202:mg_random Weak RNG: using rand()
d0ff 1 mongoose.c:429:mg_error 8 -1 DNS timeout
d0ff 1 ap.c:46:mqtt_fn 8 ERROR DNS timeout
d0ff 2 ap.c:85:mqtt_fn 8 CLOSED
d0ff 3 mongoose.c:3953:mg_close_conn 8 -1 closed
ec56 3 mongoose.c:3979:mg_connect 9 -1 mqtt://broker.hivemq.com:1883
ec56 2 ap.c:36:mqtt_fn 9 CREATED
ec56 1 mongoose.c:19202:mg_random Weak RNG: using rand()
f80f 1 mongoose.c:429:mg_error 9 -1 DNS timeout
f80f 1 ap.c:46:mqtt_fn 9 ERROR DNS timeout
f80f 2 ap.c:85:mqtt_fn 9 CLOSED
f80f 3 mongoose.c:3953:mg_close_conn 9 -1 closed
11366 3 mongoose.c:3979:mg_connect 10 -1 mqtt://broker.hivemq.com:1883
11366 2 ap.c:36:mqtt_fn 10 CREATED
11366 1 mongoose.c:19202:mg_random Weak RNG: using rand()
11f1f 1 mongoose.c:429:mg_error 10 -1 DNS timeout
11f1f 1 ap.c:46:mqtt_fn 10 ERROR DNS timeout
11f1f 2 ap.c:85:mqtt_fn 10 CLOSED
11f1f 3 mongoose.c:3953:mg_close_conn 10 -1 closed
13a76 3 mongoose.c:3979:mg_connect 11 -1 mqtt://broker.hivemq.com:1883
13a76 2 ap.c:36:mqtt_fn 11 CREATED
13a76 1 mongoose.c:19202:mg_random Weak RNG: using rand()
1462f 1 mongoose.c:429:mg_error 11 -1 DNS timeout
1462f 1 ap.c:46:mqtt_fn 11 ERROR DNS timeout
1462f 2 ap.c:85:mqtt_fn 11 CLOSED
1462f 3 mongoose.c:3953:mg_close_conn 11 -1 closed
16186 3 mongoose.c:3979:mg_connect 12 -1 mqtt://broker.hivemq.com:1883
16186 2 ap.c:36:mqtt_fn 12 CREATED
16186 1 mongoose.c:19202:mg_random Weak RNG: using rand()
16d3f 1 mongoose.c:429:mg_error 12 -1 DNS timeout
16d3f 1 ap.c:46:mqtt_fn 12 ERROR DNS timeout
16d3f 2 ap.c:85:mqtt_fn 12 CLOSED
16d3f 3 mongoose.c:3953:mg_close_conn 12 -1 closed
18896 3 mongoose.c:3979:mg_connect 13 -1 mqtt://broker.hivemq.com:1883
18896 2 ap.c:36:mqtt_fn 13 CREATED
18896 1 mongoose.c:19202:mg_random Weak RNG: using rand()
1944f 1 mongoose.c:429:mg_error 13 -1 DNS timeout
1944f 1 ap.c:46:mqtt_fn 13 ERROR DNS timeout
1944f 2 ap.c:85:mqtt_fn 13 CLOSED
1944f 3 mongoose.c:3953:mg_close_conn 13 -1 closed

[scaprile]

No, it does not. We have a CI/CD pipeline in place and test our code
No, that is not an infinite loop, that is you or HiveMQ having networking issues, or you running faulty code.
Please see our documentation, and follow the guidelines in our tutorials.

• Please sniff your network (using Wireshark, for example) and observe the traffic.
• If, after your network inspection, you find an actual issue, feel free to open an issue, fill the issue template, and provide us with pertinent information (including useful network capture files; no snapshots, please attach capture files) in order to reproduce and fix the issue. We don't inspect your code for errors, please attach the minimum piece of code that can reproduce the issue. If you post code, please correctly format it so Github shows it as code.

[djpark97]

Thank you for your quick reply.
I will look into the documentation and related tutorials in more detail.

Note
The while loop mg_mgr_poll() is not stuck, but it is repeatedly trying to connect to hivemq because it cannot get the dns address.

[djpark97]

wireshark_log.zip

It may be because the school's private network does not use the designated DNS server.
I will try applying the DNS address designated by the school's computer department.
I left the wireshark log file just in case.

[scaprile]

There is no such thing as "designated DNS", there is the DNS you configure Mongoose to use and it defaults to Google's if you don't. I suggest you request help from your network administrators, Mongoose does not care about what your environment does or suggests, it will use DNS as you configure it or not, as described above, so if you have a firewall that is blocking access to Google DNS (thing that becomes evident if you see no response in the network sniff), you need to either remove that block (network admins do that) or configure other DNS, thing you can do by following our docs.