imp: make it easier to use custom verifiers for Tendermint clients

.changelog/unreleased/breaking-changes/1168-discard-TmVerifier.md

@@ -0,0 +1,4 @@
+- [ibc-client-tendermint] Simplify custom verifiers usage for Tendermint
+  clients by directly binding with `tendermint_light_client_verifier::Verifier`
+  and removing the unused `TmVerifier` trait.
+  ([\#1168](https://github.com/cosmos/ibc-rs/pull/1168))

ibc-clients/ics07-tendermint/src/client_state/misbehaviour.rs

@@ -15,7 +15,6 @@ use tendermint_light_client_verifier::options::Options;
 use tendermint_light_client_verifier::Verifier;
 
 use crate::types::Header;
-use crate::verifier::TmVerifier;
 
 /// Determines whether or not two conflicting headers at the same height would
 /// have convinced the light client.
@@ -25,7 +24,7 @@ pub fn verify_misbehaviour<V, H>(
     client_id: &ClientId,
     chain_id: &ChainId,
     options: &Options,
-    verifier: &impl TmVerifier,
+    verifier: &impl Verifier,
 ) -> Result<(), ClientError>
 where
     V: ExtClientValidationContext,
@@ -87,7 +86,7 @@ pub fn verify_misbehaviour_header<H>(
     trusted_timestamp: Time,
     trusted_next_validator_hash: Hash,
     current_timestamp: Timestamp,
-    verifier: &impl TmVerifier,
+    verifier: &impl Verifier,
 ) -> Result<(), ClientError>
 where
     H: MerkleHash + Sha256 + Default,
@@ -134,7 +133,6 @@ where
     })?;
 
     verifier
-        .verifier()
         .verify_misbehaviour_header(untrusted_state, trusted_state, options, current_timestamp)
         .into_result()?;
 

ibc-clients/ics07-tendermint/src/client_state/update_client.rs

@@ -12,15 +12,13 @@ use tendermint_light_client_verifier::options::Options;
 use tendermint_light_client_verifier::types::{TrustedBlockState, UntrustedBlockState};
 use tendermint_light_client_verifier::Verifier;
 
-use crate::verifier::TmVerifier;
-
 pub fn verify_header<V, H>(
     ctx: &V,
     header: &TmHeader,
     client_id: &ClientId,
     chain_id: &ChainId,
     options: &Options,
-    verifier: &impl TmVerifier,
+    verifier: &impl Verifier,
 ) -> Result<(), ClientError>
 where
     V: ExtClientValidationContext,
@@ -92,7 +90,6 @@ where
 
         // main header verification, delegated to the tendermint-light-client crate.
         verifier
-            .verifier()
             .verify_update_header(untrusted_state, trusted_state, options, now)
             .into_result()?;
     }

ibc-clients/ics07-tendermint/src/client_state/validation.rs

@@ -13,20 +13,35 @@ use ibc_primitives::proto::Any;
 use tendermint::crypto::default::Sha256;
 use tendermint::crypto::Sha256 as Sha256Trait;
 use tendermint::merkle::MerkleHash;
+use tendermint_light_client_verifier::{ProdVerifier, Verifier};
 
 use super::{check_for_misbehaviour_on_misbehavior, check_for_misbehaviour_on_update, ClientState};
 use crate::client_state::{verify_header, verify_misbehaviour};
-use crate::verifier::{DefaultVerifier, TmVerifier};
 
 impl<V> ClientStateValidation<V> for ClientState
 where
     V: ExtClientValidationContext,
     V::ConsensusStateRef: Convertible<ConsensusStateType, ClientError>,
 {
     /// The default verification logic exposed by ibc-rs simply delegates to a
-    /// standalone `verify_client_message` function. This is to make it as simple
-    /// as possible for those who merely need the `DefaultVerifier` behaviour, as
-    /// well as those who require custom verification logic.
+    /// standalone `verify_client_message` function. This is to make it as
+    /// simple as possible for those who merely need the default
+    /// [`ProdVerifier`] behaviour, as well as those who require custom
+    /// verification logic.
+    ///
+    /// In a situation where the Tendermint [`ProdVerifier`] doesn't provide the
+    /// desired outcome, users should define a custom verifier struct and then
+    /// implement the [`Verifier`] trait for it.
+    ///
+    /// In order to wire up the custom verifier, create a newtype `ClientState`
+    /// wrapper similar to [`ClientState`] and implement all client state traits
+    /// for it. For method implementation, the simplest way is to import and
+    /// call their analogous standalone versions under the
+    /// [`crate::client_state`] module, unless bespoke logic is desired for any
+    /// of those functions. Then, when it comes to implementing the
+    /// `verify_client_message` method, use the [`verify_client_message`]
+    /// function and pass your custom verifier object as the `verifier`
+    /// parameter.
     fn verify_client_message(
         &self,
         ctx: &V,
@@ -38,7 +53,7 @@ where
             ctx,
             client_id,
             client_message,
-            &DefaultVerifier,
+            &ProdVerifier::default(),
         )
     }
 
@@ -63,9 +78,9 @@ where
 /// Verify the client message as part of the client state validation process.
 ///
 /// Note that this function is typically implemented as part of the
-/// [`ClientStateValidation`] trait, but has been made a standalone function
-/// in order to make the ClientState APIs more flexible. It mostly adheres to
-/// the same signature as the `ClientStateValidation::verify_client_message`
+/// [`ClientStateValidation`] trait, but has been made a standalone function in
+/// order to make the ClientState APIs more flexible. It mostly adheres to the
+/// same signature as the `ClientStateValidation::verify_client_message`
 /// function, except for an additional `verifier` parameter that allows users
 /// who require custom verification logic to easily pass in their own verifier
 /// implementation.
@@ -74,7 +89,7 @@ pub fn verify_client_message<V, H>(
     ctx: &V,
     client_id: &ClientId,
     client_message: Any,
-    verifier: &impl TmVerifier,
+    verifier: &impl Verifier,
 ) -> Result<(), ClientError>
 where
     V: ExtClientValidationContext,

ibc-clients/ics07-tendermint/src/lib.rs

@@ -1,5 +1,5 @@
-//! ICS 07: Tendermint light client implementation along with re-exporting data
-//! structures and implementations of IBC core client module.
+//! ICS 07: Tendermint light client implementation along with re-exporting the
+//! necessary types from `ibc-client-tendermint-types` crate.
 #![no_std]
 #![forbid(unsafe_code)]
 #![cfg_attr(not(test), deny(clippy::unwrap_used))]
@@ -18,11 +18,11 @@ extern crate std;
 
 pub mod client_state;
 pub mod consensus_state;
-pub mod verifier;
 
 pub const TENDERMINT_CLIENT_TYPE: &str = "07-tendermint";
 
-/// Re-export of Tendermint light client data structures from `ibc-client-tendermint` crate.
+/// Re-exports Tendermint light client data structures from the
+/// `ibc-client-tendermint-type` crate.
 pub mod types {
     #[doc(inline)]
     pub use ibc_client_tendermint_types::*;