These tests handle incoming and outgoing cells on a three-hop
circuit, and make sure that the crypto works end-to-end.  They don't
yet test spec conformance, leaky-pipe, or various error cases.

Additionally, this change extracts the functions that created and
freed these elements.

These structures had common "forward&reverse stream&digest"
elements, but they were initialized and freed through cpath objects,
and different parts of the code depended on them.  Now all that code
is extacted, and kept in relay_crypto.c

This should help us improve modularity, and should also make it
easier for people to experiment with other relay crypto strategies
down the road.

This commit is pure function movement.

This function is used upon receiving a cell, and only handles the
decrypting part.  The encryption part is currently handled inside
circuit_package_relay_cell.

Fixes bug 25474; bugfix on 0.3.2.5-alpha.

Signed-off-by: Fernando Fernandez Mancera <ffmancera@riseup.net>

Fixes bug 25415; bugfix on 0.3.3.2-alpha.

Alexander Hansen Færøy authored 7 years ago and Nick Mathewson committed 7 years ago

See: https://bugs.torproject.org/25378

"ours" merge to avoid version bump.

"ours" merge to avoid version bump.

"ours" merge to avoid version bump