Fix UDPv6 checksum

[csujedihy]

Description

UDPv6 requires checksum to be non-zero.

Testing

CI

[nibanks]

Also, UDPv4 can be skipped.

Why?

[csujedihy]

Also, UDPv4 can be skipped.

Why?

UDPv4 checksum is optional. UDP checksum is required only with IPv6.

[nibanks]

Also, UDPv4 can be skipped.

Why?

UDPv4 checksum is optional. UDP checksum is required only with IPv6.

I assume you haven't validated this in a real environment (i.e. Azure VM)? I will sign off, and leave it up to you if you're sure enough to merge without further validation.

[csujedihy]

Also, UDPv4 can be skipped.

Why?

UDPv4 checksum is optional. UDP checksum is required only with IPv6.

I assume you haven't validated this in a real environment (i.e. Azure VM)? I will sign off, and leave it up to you if you're sure enough to merge without further validation.

Some middleboxes might not like zero UDPv4 checksum. Though, I am pretty sure it works fine over azure with linux and windows. I am gonna revert this change to be safe. We could add a knob to disable UDPv4 checksum in the future even for regular QUIC. We have UDP_NOCHECKSUM for windows UDP sockets to disable it, and UDPv4 checksum is default on.

[mtfriesen]

Does this handle the UDPv6 case that we recently fixed in XDP? That is, the UDPv6 checksum must not be zero?

[mtfriesen]

Does this handle the UDPv6 case that we recently fixed in XDP? That is, the UDPv6 checksum must not be zero?

Yes it does. I was looking at the wrong commit diff.