Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

FS#4140 - umdns does not respect legacy queries (not from port 5353) #9121

Open
openwrt-bot opened this issue Nov 17, 2021 · 1 comment
Open
Labels
core packages flyspray

Comments

@openwrt-bot
Copy link

openwrt-bot commented Nov 17, 2021

kirelagin:

According to [[https://datatracker.ietf.org/doc/html/rfc6762#section-6.7|Section 6.7 of the RFC]], if the query was sent not from port 5353, the responder MUST respond over unicast and, most importantly, to the same port that the query was sent from.

This is what currently prevents

dig -p 5353 @224.0.0.251

from working, since dig is expecting the response on the random port it sent its query from, but umdns, contrary to the specifiation, always sends to port 5353.

@openwrt-bot
Copy link
Author

openwrt-bot commented Nov 17, 2021

kirelagin:

I made a patch (untested!) that will ensure the response goes to the right address/port.

However, there are additional requirements that, IIUC, are currently not satisfied:

This unicast response MUST be a
conventional unicast response as would be generated by a conventional
Unicast DNS server; for example, it MUST repeat the query ID and the
question given in the query message. In addition, the cache-flush
bit described in Section 10.2, "Announcements to Flush Outdated Cache
Entries", MUST NOT be set in legacy unicast responses.

@aparcar aparcar added the core packages label Feb 22, 2022
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment
Labels
core packages flyspray
Projects
None yet
Development

No branches or pull requests

2 participants