* ADD new type, protover::UnknownProtocol, so that we have greater type safety
and our protover functionality which works with unsanitised protocol names is
more clearly demarcated.
* REFACTOR protover::Proto, renaming it protover::Protocol to mirror the new
protover::UnknownProtocol type name.
* ADD a utility conversion of `impl From<Protocol> for UnknownProtocol` so that
we can easily with known protocols and unknown protocols simultaneously
(e.g. doing comparisons, checking their version numbers), while not allowing
UnknownProtocols to be accidentally used in functions which should only take
Protocols.
* FIXES part of #24031: https://bugs.torproject.org/24031
* ADD new protover::protoset module.
* ADD new protover::protoset::ProtoSet class for holding protover versions.
* REMOVE protover::Versions type implementation and its method
`from_version_string()`, and instead implement this behaviour in a more
rust-like manner as `impl FromStr for ProtoSet`.
* MOVE the `find_range()` utility function from protover::protover to
protover::protoset since it's only used internally in the
implementation of ProtoSet.
* REMOVE the `contract_protocol_list()` function from protover::protover and
instead refactor it (reusing nearly the entire thing, with minor superficial,
i.e. non-behavioural, changes) into a more rusty
`impl ToString for ProtoSet`.
* REMOVE the `expand_version_range()` function from protover::protover and
instead refactor it into a more rusty implementation of
`impl Into<Vec<Version>> for ProtoSet` using the new error types in
protover::errors.
* FIXES part of #24031: https://bugs.torproject.org/24031.
This will allow us to do actual error handling intra-crate in a more
rusty manner, e.g. propogating errors in match statements, conversion
between error types, logging messages, etc.
* FIXES part of #24031: https://bugs.torproject.org/24031.
Also correct MAX_VERSIONS_TO_EXPAND to match the C.
NOTE that this patch leads to incorrect behavior: the C code allows
huge ranges; it just doesn't allow votes on them (currently). For
full compatibility, we'll need to make the rust code store ranges as
ranges natively, possibly using something like the range_map crate.
Still, this patch is smaller than a "proper" fix.
Fixes TROVE-2018-003.
Rationale: this helps for performance only, but we don't actually
have any reason to think that the checks here are
performance-critical. Let's not normalize the use of unsafe {}.
* FIXES#25127: https://bugs.torproject.org/25127
* ADDS a new module to the Rust tor_util crate for small utilities
for working with static strings between languages.
* CHANGES the return type of protover_compute_for_old_tor to point to
immutable data.
* CHANGES the code from the previous commit to use the new static
string utilities.
And fix the unsupported protover example so it uses a Link protover much
higher than 5.
Part of #25070, bugfix on 0.3.3.1-alpha, which introduced the protover crate.
