fix: no chain_root in 1st block of the mmr activated epoch

src/protocols/light_client/components/send_last_state_proof.rs

@@ -1077,7 +1077,7 @@ pub(crate) fn verify_mmr_proof<'a, T: Iterator<Item = &'a HeaderView>>(
     raw_proof: packed::HeaderDigestVecReader,
     headers: T,
 ) -> Result<(), Status> {
-    if last_header.is_valid(mmr_activated_epoch) {
+    if last_header.patched_is_valid(mmr_activated_epoch) {
         trace!(
             "passed: verify extra hash for block-{} ({:#x})",
             last_header.header().number(),

src/protocols/light_client/mod.rs

@@ -260,7 +260,7 @@ impl LightClientProtocol {
     ) -> Result<(), Status> {
         let mmr_activated_epoch = self.mmr_activated_epoch();
         for header in headers {
-            if !header.is_valid(mmr_activated_epoch) {
+            if !header.patched_is_valid(mmr_activated_epoch) {
                 let header = header.header();
                 let errmsg = format!(
                     "failed to verify chain root for block#{}, hash: {:#x}",
@@ -285,7 +285,7 @@ impl LightClientProtocol {
             return Err(StatusCode::InvalidNonce.with_context(errmsg));
         }
         // Check Chain Root
-        if !verifiable_header.is_valid(self.mmr_activated_epoch()) {
+        if !verifiable_header.patched_is_valid(self.mmr_activated_epoch()) {
             let errmsg = format!(
                 "failed to verify chain root for block#{}, hash: {:#x}",
                 header.number(),
@@ -414,8 +414,8 @@ impl LightClientProtocol {
     pub(crate) fn new(storage: Storage, peers: Arc<Peers>, consensus: Consensus) -> Self {
         // Ref: https://github.com/nervosnetwork/rfcs/blob/01f3bc64ef8f54c94c7b0dcf9d30c84b6c8418b0/rfcs/0044-ckb-light-client/0044-ckb-light-client.md#deployment
         let mmr_activated_epoch = match consensus.id.as_str() {
-            mainnet::CHAIN_SPEC_NAME => 8648,
-            testnet::CHAIN_SPEC_NAME => 5676,
+            mainnet::CHAIN_SPEC_NAME => 8651,
+            testnet::CHAIN_SPEC_NAME => 5711,
             _ => 0,
         };
         Self {

src/protocols/light_client/prelude.rs

@@ -1,5 +1,10 @@
 use ckb_network::{CKBProtocolContext, PeerIndex};
-use ckb_types::{core::HeaderView, packed::LightClientMessage, prelude::*};
+use ckb_types::{
+    core::{EpochNumber, EpochNumberWithFraction, ExtraHashView, HeaderView},
+    packed::LightClientMessage,
+    prelude::*,
+    utilities::merkle_mountain_range::VerifiableHeader,
+};
 
 use super::{Status, StatusCode};
 
@@ -38,3 +43,44 @@ impl HeaderUtils for HeaderView {
             && self.hash() == child.parent_hash()
     }
 }
+
+// TODO Remove patch after the upstream fixed.
+//
+// Ref: https://github.com/nervosnetwork/ckb/blob/v0.112.1/util/types/src/utilities/merkle_mountain_range.rs#L212-L241
+pub(crate) trait VerifiableHeaderPatch {
+    fn patched_is_valid(&self, mmr_activated_epoch_number: EpochNumber) -> bool;
+}
+
+impl VerifiableHeaderPatch for VerifiableHeader {
+    fn patched_is_valid(&self, mmr_activated_epoch_number: EpochNumber) -> bool {
+        let mmr_activated_epoch = EpochNumberWithFraction::new(mmr_activated_epoch_number, 0, 1);
+        let has_chain_root = self.header().epoch() > mmr_activated_epoch;
+        if has_chain_root {
+            if self.header().is_genesis() {
+                if !self.parent_chain_root().is_default() {
+                    return false;
+                }
+            } else {
+                let is_extension_beginning_with_chain_root_hash = self
+                    .extension()
+                    .map(|extension| {
+                        let actual_extension_data = extension.raw_data();
+                        let parent_chain_root_hash = self.parent_chain_root().calc_mmr_hash();
+                        actual_extension_data.starts_with(parent_chain_root_hash.as_slice())
+                    })
+                    .unwrap_or(false);
+                if !is_extension_beginning_with_chain_root_hash {
+                    return false;
+                }
+            }
+        }
+
+        let expected_extension_hash = self
+            .extension()
+            .map(|extension| extension.calc_raw_data_hash());
+        let extra_hash_view = ExtraHashView::new(self.uncles_hash(), expected_extension_hash);
+        let expected_extra_hash = extra_hash_view.extra_hash();
+        let actual_extra_hash = self.header().extra_hash();
+        expected_extra_hash == actual_extra_hash
+    }
+}

src/tests/protocols/light_client/send_last_state.rs

@@ -79,7 +79,7 @@ async fn invalid_chain_root() {
 
     let data = {
         let header = HeaderBuilder::default()
-            .epoch(EpochNumberWithFraction::new(1, 0, 10).pack())
+            .epoch(EpochNumberWithFraction::new(1, 1, 10).pack())
             .number(11u64.pack())
             .build();
         let last_header = packed::VerifiableHeader::new_builder()

src/tests/protocols/light_client/send_last_state_proof.rs

@@ -920,6 +920,7 @@ async fn invalid_parent_chain_root_for_the_genesis_block() {
 }
 
 async fn test_parent_chain_root_for_the_genesis_block(should_passed: bool) {
+    setup();
     let chain = MockChain::new_with_dummy_pow("test-light-client").start();
     let nc = MockNetworkContext::new(SupportProtocols::LightClient);
 
@@ -934,8 +935,8 @@ async fn test_parent_chain_root_for_the_genesis_block(should_passed: bool) {
     protocol.set_mmr_activated_epoch(0);
     protocol.set_last_n_blocks(3);
 
-    let num = 1;
-    chain.mine_to(1);
+    let num = 10;
+    chain.mine_to(num + 1);
 
     let snapshot = chain.shared().snapshot();
 
@@ -971,9 +972,11 @@ async fn test_parent_chain_root_for_the_genesis_block(should_passed: bool) {
             let headers = (0..num)
                 .into_iter()
                 .map(|n| {
-                    if !should_passed && n == 0 {
+                    if !should_passed && n == num / 2 {
+                        // Set a wrong parent chain root:
+                        // - Use n's chain root as n's parent chain root
                         let parent_chain_root = snapshot
-                            .chain_root_mmr(1)
+                            .chain_root_mmr(n)
                             .get_root()
                             .expect("has chain root");
                         snapshot