disallow reorg if more than one block has already been signed

Author: rdeioris

stacks-signer/src/chainstate.rs

@@ -439,8 +439,24 @@ impl SortitionsView {
                 continue;
             }
 
+            // disallow reorg if more than one block has already been signed
+            let signed_blocks =
+                signer_db.get_signed_block_count_in_tenure(&tenure.consensus_hash)?;
+            if signed_blocks > 1 {
+                warn!(
+                    "Miner is not building off of most recent tenure, but a tenure they attempted to reorg has already more than one signed block.";
+                    "proposed_block_consensus_hash" => %block.header.consensus_hash,
+                    "proposed_block_signer_sighash" => %block.header.signer_signature_hash(),
+                    "parent_tenure" => %sortition_state.parent_tenure_id,
+                    "last_sortition" => %sortition_state.prior_sortition,
+                    "violating_tenure_id" => %tenure.consensus_hash,
+                    "violating_tenure_first_block_id" => ?tenure.first_block_mined,
+                    "signed_blocks" => signed_blocks,
+                );
+                return Ok(false);
+            }
+
             if tenure.first_block_mined.is_some() {
-                // TODO: roberto -> get the amount of signed blocks
                 let Some(local_block_info) =
                     signer_db.get_first_signed_block_in_tenure(&tenure.consensus_hash)?
                 else {