dns error

[zhen86889]

2024/01/24 03:32:09 [error] 40#0: *412372185 [lua] job.lua:284: execute(): [timer-ng] failed to run timer unix_timestamp=1706067129907.000000;counter=6761692:meta=debug off: /usr/local/openresty/lualib/resty/dns/resolver.lua:384: bad argument #1 to 'lshift' (number expected, got nil), context: ngx.timer

[chronolaw]

@chobits, could you take a look? thanks.

[chronolaw]

Perhaps we should create a fix PR for lua-resty-dns?

[chobits]

hi @zhen86889
Cool!
Could you show your DNS response if there are no sensitive information, like dig @<dns server ip> <domain>

And I found some one has filed an issue to lua-resty-dns official: openresty/lua-resty-dns#70

[zhen86889]

Due to sensitive information, I've masked part of the content. Here's the translation:

nslookup xxxxxxxx-xx-xxxxx.xxx-x-xxxxxx.x.xx.xxxx.xxxxxx.xxxxxx.xxxxx
Server:         xxx.xx.xxx.x
Address:        xxx.xx.xxx.x#53

Name:   xxxxxxxx-xx-xxxxx.xxx-x-xxxxxx.x.xx.xxxx.xxxxxx.xxxxxx.xxxxx
Address: 17.183.214.161
Name:   xxxxxxxx-xx-xxxxx.xxx-x-xxxxxx.x.xx.xxxx.xxxxxx.xxxxxx.xxxxx
Address: 17.183.214.162
Name:   xxxxxxxx-xx-xxxxx.xxx-x-xxxxxx.x.xx.xxxx.xxxxxx.xxxxxx.xxxxx
Address: 17.183.214.163
Name:   xxxxxxxx-xx-xxxxx.xxx-x-xxxxxx.x.xx.xxxx.xxxxxx.xxxxxx.xxxxx
Address: 17.183.214.164
Name:   xxxxxxxx-xx-xxxxx.xxx-x-xxxxxx.x.xx.xxxx.xxxxxx.xxxxxx.xxxxx
Address: 17.183.214.165
Name:   xxxxxxxx-xx-xxxxx.xxx-x-xxxxxx.x.xx.xxxx.xxxxxx.xxxxxx.xxxxx
Address: 17.183.214.166
...
Total of 54 records

[zhen86889]

Hello, Following the testing method outlined in https://github.com/openresty/lua-resty-dns/issues/70 , we set up a simplified DNS server and were unable to reproduce the issue. Therefore, we shifted our troubleshooting focus to our production DNS service. After analysis, we discovered that the issue was caused by our DNS server truncating the response without setting the tc flag when transmitting information that exceeded the UDP packet size limit. Thanks again to the community for your assistance.