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Daniel Hilst
50ebc0af43
A chainloaded second stage announces itself in the user class, option 77, and must be handed a script URL rather than the loader it just ran -- otherwise it chainloads itself forever and the machine never finishes booting. RFC 3004 length-prefixes each string in option 77. Plenty of firmware sends the bare string instead, and the same loader sends either depending on how it was built, so both encodings have to be recognised. The Kea policy has always accepted both. The ISC side compared only `option user-class-identifier = "xNBA"`, which is the bare form, so a conforming loader booting against an ISC management node loops -- and does so silently, since from the server's side every exchange looks like a normal first-stage boot. Put the test in one place, isc_xnba_user_class_test, and use it from both the per-network architecture chain and the three per-node statements. The per-node ones reach dhcpd through omshell, so the helper takes the quoting its caller needs. `substring(option user-class-identifier, 1, 4)` skips the length byte; option 77 is declared as a plain string, and the same construct is already used by the onie_vendor branch a few lines below.