structeq looks like a great candidate to have type-aware memmp() of two structures: https://github.com/rustyrussell/ccan/tree/master/ccan/structeq
type-safe callbacks rather than 'void *' pointers: https://github.com/rustyrussell/ccan/blob/master/ccan/typesafe_cb/_info
assert at build time: https://github.com/rustyrussell/ccan/blob/master/ccan/build_assert/_info
fast pseudo-random generator. Too sas that we want real random numbres for authentication challenges in GSUP/OAP? https://github.com/rustyrussell/ccan/blob/master/ccan/isaac/_info