[Bug Report] Unable to use an IPIP tunnel as a LAN interface

[pcmid]

Checks

• I have searched the existing issues
• I have read the documentation
• Is it your first time sumbitting an issue

Current Behavior

When using an IPIP tunnel as a LAN interface, the LAN network becomes unreachable. After investigation, I discovered that the failure to retrieve the link header length caused the eBPF processing to terminate prematurely without properly redirecting the traffic.

Expected Behavior

No response

Steps to Reproduce

1. Setup IPIP tunnel.
2. Configure the tunnel as a LAN interface.
3. Attempt to request or access a service within the LAN network.
4. Observe that the LAN network is unreachable.

Environment

• Dae version (use dae --version): 0.8.0rc1
• OS (e.g cat /etc/os-release): Archlinux
• Kernel (e.g. uname -a): 6.10.6-arch1-1
• Others:

Anything else?

No response

[dae-prow]

Thanks for opening this issue!

[NNdroid]

There may be an MTU problem. I noticed that the MTU of the dae interface is 1500, and the MTU after using the layer 2 tunnel can never be 1500. After I tried to use the gre tunnel, only some websites could be accessed, and many websites opened slowly, especially Cloudflare, which could not be opened at all.