From 20b45006254a33aa809d1dfeee85e80b08791781 Mon Sep 17 00:00:00 2001
From: Antioch Peverell <apeverell@protonmail.com>
Date: Mon, 22 Jun 2020 15:04:09 +0100
Subject: [PATCH] make sure header PMMR is init correctly based on header_head
from db (#3362)
* make sure header PMMR is init correctly based on header_head from db
* fix to ensure header PMMR is consistent with header_head in db on chain init
* change order of operations - validate header earlier
and avoid applying header to header PMMR before validation
as this potentially leaves the PMMR in a tricky state to rewind from
---
chain/src/chain.rs | 12 ++++++++---
chain/src/pipe.rs | 7 ++++++-
chain/src/txhashset/txhashset.rs | 35 ++++++++++++++++++++++++++++++++
3 files changed, 50 insertions(+), 4 deletions(-)
diff --git a/chain/src/chain.rs b/chain/src/chain.rs
index ec94c1bcf..b790e52eb 100644
--- a/chain/src/chain.rs
+++ b/chain/src/chain.rs
@@ -1449,9 +1449,15 @@ fn setup_head(
}
}
- // Setup our header_head if we do not already have one.
- // Migrating back to header_head in db and some nodes may note have one.
- if batch.header_head().is_err() {
+ // Make sure our header PMMR is consistent with header_head from db if it exists.
+ // If header_head is missing in db then use head of header PMMR.
+ if let Ok(head) = batch.header_head() {
+ header_pmmr.init_head(&head)?;
+ txhashset::header_extending(header_pmmr, &mut batch, |ext, batch| {
+ let header = batch.get_block_header(&head.hash())?;
+ ext.rewind(&header)
+ })?;
+ } else {
let hash = header_pmmr.head_hash()?;
let header = batch.get_block_header(&hash)?;
batch.save_header_head(&Tip::from_header(&header))?;
diff --git a/chain/src/pipe.rs b/chain/src/pipe.rs
index 2db6b1bf2..ae1b753f8 100644
--- a/chain/src/pipe.rs
+++ b/chain/src/pipe.rs
@@ -250,6 +250,11 @@ pub fn process_block_header(header: &BlockHeader, ctx: &mut BlockContext<'_>) ->
}
}
+ // We want to validate this individual header before applying it to our header PMMR.
+ validate_header(header, ctx)?;
+
+ // Apply the header to the header PMMR, making sure we put the extension in the correct state
+ // based on previous header first.
txhashset::header_extending(&mut ctx.header_pmmr, &mut ctx.batch, |ext, batch| {
rewind_and_apply_header_fork(&prev_header, ext, batch)?;
ext.validate_root(header)?;
@@ -260,7 +265,7 @@ pub fn process_block_header(header: &BlockHeader, ctx: &mut BlockContext<'_>) ->
Ok(())
})?;
- validate_header(header, ctx)?;
+ // Add this new block header to the db.
add_block_header(header, &ctx.batch)?;
if has_more_work(header, &header_head) {
diff --git a/chain/src/txhashset/txhashset.rs b/chain/src/txhashset/txhashset.rs
index 548562822..f22946ba6 100644
--- a/chain/src/txhashset/txhashset.rs
+++ b/chain/src/txhashset/txhashset.rs
@@ -74,6 +74,41 @@ impl<T: PMMRable> PMMRHandle<T> {
}
impl PMMRHandle<BlockHeader> {
+ /// Used during chain init to ensure the header PMMR is consistent with header_head in the db.
+ pub fn init_head(&mut self, head: &Tip) -> Result<(), Error> {
+ let head_hash = self.head_hash()?;
+ let expected_hash = self.get_header_hash_by_height(head.height)?;
+ if head.hash() != expected_hash {
+ error!(
+ "header PMMR inconsistent: {} vs {} at {}",
+ expected_hash,
+ head.hash(),
+ head.height
+ );
+ return Err(ErrorKind::Other("header PMMR inconsistent".to_string()).into());
+ }
+
+ // 1-indexed pos and we want to account for subsequent parent hash pos.
+ // so use next header pos to find our last_pos.
+ let next_height = head.height + 1;
+ let next_pos = pmmr::insertion_to_pmmr_index(next_height + 1);
+ let pos = next_pos.saturating_sub(1);
+
+ debug!(
+ "init_head: header PMMR: current head {} at pos {}",
+ head_hash, self.last_pos
+ );
+ debug!(
+ "init_head: header PMMR: resetting to {} at pos {} (height {})",
+ head.hash(),
+ pos,
+ head.height
+ );
+
+ self.last_pos = pos;
+ Ok(())
+ }
+
/// Get the header hash at the specified height based on the current header MMR state.
pub fn get_header_hash_by_height(&self, height: u64) -> Result<Hash, Error> {
let pos = pmmr::insertion_to_pmmr_index(height + 1);