Move fallback.rs into guardmgr.

This is the logical place for it, I think: the GuardMgr's job is to
pick the first hop for a circuit depending on remembered status for
possible first hops.  Making this change will let us streamline the
code that interacts with these objects.

Cargo.lock

@@ -3361,6 +3361,7 @@ dependencies = [
  "tor-consdiff",
  "tor-dirclient",
  "tor-error",
+ "tor-guardmgr",
  "tor-llcrypto",
  "tor-netdir",
  "tor-netdoc",

crates/tor-circmgr/src/lib.rs

@@ -51,7 +51,8 @@
 #![deny(clippy::unwrap_used)]
 
 use tor_chanmgr::ChanMgr;
-use tor_netdir::{fallback::FallbackDir, DirEvent, NetDir, NetDirProvider};
+use tor_guardmgr::fallback::FallbackDir;
+use tor_netdir::{DirEvent, NetDir, NetDirProvider};
 use tor_proto::circuit::{CircParameters, ClientCirc, UniqId};
 use tor_rtcompat::Runtime;
 

crates/tor-circmgr/src/mgr.rs

@@ -1463,7 +1463,7 @@ mod test {
 
     const FAKE_CIRC_DELAY: Duration = Duration::from_millis(30);
 
-    static DI_EMPTY: [&tor_netdir::fallback::FallbackDir; 0] = [];
+    static DI_EMPTY: [&tor_guardmgr::fallback::FallbackDir; 0] = [];
 
     fn di() -> DirInfo<'static> {
         DI_EMPTY[..].into()

crates/tor-circmgr/src/path.rs

@@ -7,8 +7,9 @@ pub mod dirpath;
 pub mod exitpath;
 
 use tor_error::bad_api_usage;
+use tor_guardmgr::fallback::FallbackDir;
 use tor_linkspec::{OwnedChanTarget, OwnedCircTarget};
-use tor_netdir::{fallback::FallbackDir, Relay};
+use tor_netdir::Relay;
 
 use std::convert::TryFrom;
 

crates/tor-circmgr/src/path/dirpath.rs

@@ -72,8 +72,8 @@ mod test {
     use crate::path::assert_same_path_when_owned;
     use crate::test::OptDummyGuardMgr;
     use std::collections::HashSet;
+    use tor_guardmgr::fallback::FallbackDir;
     use tor_linkspec::ChanTarget;
-    use tor_netdir::fallback::FallbackDir;
     use tor_netdir::testnet;
 
     #[test]

crates/tor-dirmgr/Cargo.toml

@@ -33,6 +33,7 @@ tor-config = { path = "../tor-config", version = "0.1.0" }
 tor-consdiff = { path = "../tor-consdiff", version = "0.1.0" }
 tor-dirclient = { path = "../tor-dirclient", version = "0.1.0" }
 tor-error = { path = "../tor-error", version = "0.1.0" }
+tor-guardmgr = { path = "../tor-guardmgr", version = "0.1.0" }
 tor-netdir = { path = "../tor-netdir", version = "0.1.0" }
 tor-netdoc = { path = "../tor-netdoc", version = "0.1.0" }
 tor-llcrypto = { path = "../tor-llcrypto", version = "0.1.0" }

crates/tor-dirmgr/src/config.rs

@@ -12,7 +12,7 @@ use crate::retry::DownloadSchedule;
 use crate::storage::DynStore;
 use crate::{Authority, Result};
 use tor_config::ConfigBuildError;
-use tor_netdir::fallback::FallbackDir;
+use tor_guardmgr::fallback::FallbackDir;
 use tor_netdoc::doc::netstatus;
 
 use derive_builder::Builder;
@@ -306,8 +306,8 @@ impl DownloadScheduleConfig {
 
 /// Helpers for initializing the fallback list.
 mod fallbacks {
+    use tor_guardmgr::fallback::FallbackDir;
     use tor_llcrypto::pk::{ed25519::Ed25519Identity, rsa::RsaIdentity};
-    use tor_netdir::fallback::FallbackDir;
     /// Return a list of the default fallback directories shipped with
     /// arti.
     pub(crate) fn default_fallbacks() -> Vec<super::FallbackDir> {

crates/tor-dirmgr/src/lib.rs

@@ -101,7 +101,7 @@ pub use docid::DocId;
 pub use err::Error;
 pub use event::{DirBootstrapEvents, DirBootstrapStatus, DirStatus};
 pub use storage::DocumentText;
-pub use tor_netdir::fallback::{FallbackDir, FallbackDirBuilder};
+pub use tor_guardmgr::fallback::{FallbackDir, FallbackDirBuilder};
 
 /// A Result as returned by this crate.
 pub type Result<T> = std::result::Result<T, Error>;

crates/tor-guardmgr/src/lib.rs

@@ -148,6 +148,7 @@ use tor_persist::{DynStorageHandle, StateMgr};
 use tor_rtcompat::Runtime;
 
 mod daemon;
+pub mod fallback;
 mod filter;
 mod guard;
 mod pending;

crates/tor-netdir/src/lib.rs

@@ -56,7 +56,6 @@
 #![deny(clippy::unwrap_used)]
 
 mod err;
-pub mod fallback;
 pub mod params;
 #[cfg(test)]
 mod testing;

doc/semver_status.md

@@ -77,6 +77,14 @@ tor-netdoc:
 
   api-break: changed the return type of GenericRouterStatus::version()
 
+tor-netdir:
+
+   api-break: moved FallbackDir to guardmgr.
+
+tor-guardmgr:
+
+   new-api: moved FallbackDir from netdir.
+
 tor-proto:
   new-api: ClientCirc path accessors.