tor-bytes: Use InternalError.

This crate's Error type is too low-level to have an ErrorKind, but
it does make sense to use InternalError for the internal errors
here.

Cargo.lock

@@ -2885,6 +2885,7 @@ dependencies = [
  "hex-literal",
  "signature",
  "thiserror",
+ "tor-error",
  "tor-llcrypto",
 ]
 

crates/tor-bytes/Cargo.toml

@@ -12,6 +12,7 @@ repository = "https://gitlab.torproject.org/tpo/core/arti.git/"
 
 [dependencies]
 tor-llcrypto = { path = "../tor-llcrypto", version = "0.0.3"}
+tor-error = { path="../tor-error", version = "0.0.1" }
 
 arrayref = "0.3"
 bytes = "1"

crates/tor-bytes/src/err.rs

@@ -3,7 +3,7 @@
 use thiserror::Error;
 
 /// Error type for decoding Tor objects from bytes.
-#[derive(Error, Debug, PartialEq, Eq, Clone)]
+#[derive(Error, Debug, Clone)]
 #[non_exhaustive]
 pub enum Error {
     /// Tried to read something, but we didn't find enough bytes.
@@ -25,5 +25,18 @@ pub enum Error {
     /// We use this one in lieu of calling assert() and expect() and
     /// unwrap() from within parsing code.
     #[error("internal programming error")]
-    Internal,
+    Internal(#[from] tor_error::InternalError),
+}
+
+impl PartialEq for Error {
+    fn eq(&self, other: &Self) -> bool {
+        use Error::*;
+        match (self, other) {
+            (Truncated, Truncated) => true,
+            (ExtraneousBytes, ExtraneousBytes) => true,
+            (BadMessage(a), BadMessage(b)) => a == b,
+            // notably, this means that an internal error is equal to nothing, not even itself.
+            (_, _) => false,
+        }
+    }
 }

crates/tor-bytes/src/impls.rs

@@ -240,7 +240,8 @@ mod rsa_impls {
     impl Readable for RsaIdentity {
         fn take_from(b: &mut Reader<'_>) -> Result<Self> {
             let m = b.take(RSA_ID_LEN)?;
-            Ok(RsaIdentity::from_bytes(m).expect("take gave wrong length"))
+            RsaIdentity::from_bytes(m)
+                .ok_or_else(|| tor_error::internal!("wrong number of bytes from take").into())
         }
     }
 }