From f5423f846353f20cf6438e46a9eac7000af812a3 Mon Sep 17 00:00:00 2001
From: Revertron <r@revertron.com>
Date: Fri, 30 Apr 2021 12:27:24 +0200
Subject: [PATCH] Added Limited Confidence to work with forks.

---
 src/blockchain/chain.rs  | 16 +++++++++++-----
 src/commons/constants.rs |  8 ++++++--
 2 files changed, 17 insertions(+), 7 deletions(-)

diff --git a/src/blockchain/chain.rs b/src/blockchain/chain.rs
index 6a915b6..fd0cef0 100644
--- a/src/blockchain/chain.rs
+++ b/src/blockchain/chain.rs
@@ -748,21 +748,27 @@ impl Chain {
             return Bad;
         }
         if !check_block_hash(block) {
-            warn!("Block {:?} has wrong hash! Ignoring!", &block);
+            warn!("Ignoring block with wrong hash:\n{:?}", &block);
             return Bad;
         }
         if !check_block_signature(&block) {
-            warn!("Block {:?} has wrong signature! Ignoring!", &block);
+            warn!("Ignoring block with wrong signature:\n{:?}", &block);
             return Bad;
         }
         if let Some(prev_block) = self.get_block(block.index - 1) {
+            // https://en.bitcoinwiki.org/wiki/Limited_Confidence_Proof-of-Activity
             if block.prev_block_hash.ne(&prev_block.hash) {
-                warn!("Ignoring block with wrong previous hash:\n{:?}", &block);
-                return Rewind;
+                if block.index < self.get_height() - LIMITED_CONFIDENCE_DEPTH {
+                    warn!("Ignoring block from shorter chain:\n{:?}", &block);
+                    return Bad;
+                } else {
+                    warn!("Rewinding chain of block with wrong previous hash:\n{:?}", &block);
+                    return Rewind;
+                }
             }
         }
         if matches!(Transaction::get_type(&block.transaction), TransactionType::Zone) {
-            if self.get_zones().len() >= 10 {
+            if self.get_zones().len() >= MAXIMUM_ZONES {
                 warn!("Ignoring excess zone block");
                 return Bad;
             }
diff --git a/src/commons/constants.rs b/src/commons/constants.rs
index 02234bc..86aca44 100644
--- a/src/commons/constants.rs
+++ b/src/commons/constants.rs
@@ -20,12 +20,16 @@ pub const BLOCK_SIGNERS_MIN: u64 = 4;
 /// Signers have 30 minutes to sign, after that time any owner of first 1000 block can add needed signature
 pub const BLOCK_SIGNERS_TIME: i64 = 1800;
 
-/// PoS signers, that sign blocks when chosen signers didn't sign
-pub const BLOCK_POS_SIGNERS: u64 = 1000;
+/// Limited Confidence depth
+/// https://en.bitcoinwiki.org/wiki/Limited_Confidence_Proof-of-Activity
+pub const LIMITED_CONFIDENCE_DEPTH: u64 = 4;
 
 /// We start mining signing blocks after random delay, this is the max delay
 pub const BLOCK_SIGNERS_START_RANDOM: i64 = 180;
 
+/// Maximum zones in blockchain
+pub const MAXIMUM_ZONES: usize = 10;
+
 pub const NEW_DOMAINS_INTERVAL: i64 = 86400; // One day in seconds
 pub const DOMAIN_LIFETIME: i64 = 86400 * 365; // One year