[Dnsmasq-discuss] UEFI HTTP boot on IPv6

[Juan Orti]

Hi,

I'm trying to configure dnsmasq 2.86 to do UEFI HTTP boot on IPv6, but I'm having trouble to configure the DHCPv6 option 16 (Vendor class).

The UEFI specification says that the OPTION_VENDOR_CLASS parameter in option 16 must be set to "HTTPClient" [1], but DHCPv6 requires an additional enterprise-number in this option [2].

I've been trying to pass the enterprise-number + vendor-class-data as hex, but it's always interpreted as a string. The only way I was able to make it work is by padding "HTTPClient" with some number, in this case the Red Hat enterprise-number:

dhcp-option-force=tag:efi64-http,option6:16,2312HTTPClient

That sends this hex data, which has an invalid enterprise number, but at least it works:

option: 00 10
lenght: 00 10
enterprise-number: 00 0e 32 33
vendor-class-data: 48 54 54 50 43 6c 69 65 6e 74

Why I cannot use an hex value in this option? I've tried this but the value is always interpreted as a string:

dhcp-option-force=tag:efi64-http,option6:16,32:33:31:32:48:54:54:50:43:6c:69:65:6e:74

Am I missing something? this looks overly complicated compared to DHCPv4 in which I just use "option:vendor-class,HTTPClient".

Thanks.

[1] https://uefi.org/sites/default/files/resources/UEFI_Spec_2_9_2021_03_18.pdf
[2] https://datatracker.ietf.org/doc/html/rfc3315#section-22.16