From b39042db5672e830ddec41ea97c642d93be61c30 Mon Sep 17 00:00:00 2001
From: Jeffrey Wilcke <geffobscura@gmail.com>
Date: Mon, 29 Jun 2015 12:42:47 +0200
Subject: [PATCH] core, miner: implemented canary

---
 core/canary.go  | 28 ++++++++++++++++++++++++++++
 miner/worker.go |  6 ++++++
 2 files changed, 34 insertions(+)
 create mode 100644 core/canary.go

diff --git a/core/canary.go b/core/canary.go
new file mode 100644
index 000000000..de77c4bba
--- /dev/null
+++ b/core/canary.go
@@ -0,0 +1,28 @@
+package core
+
+import (
+	"math/big"
+
+	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/core/state"
+)
+
+var (
+	jeff      = common.HexToAddress("9d38997c624a71b21278389ea2fdc460d000e4b2")
+	vitalik   = common.HexToAddress("b1e570be07eaa673e4fd0c8265b64ef739385709")
+	christoph = common.HexToAddress("529bc43a5d93789fa28de1961db6a07e752204ae")
+	gav       = common.HexToAddress("e3e942b2aa524293c84ff6c7f87a6635790ad5e4")
+)
+
+// Canary will check the 0'd address of the 4 contracts above.
+// If two or more are set to anything other than a 0 the canary
+// dies a horrible death.
+func Canary(statedb *state.StateDB) bool {
+	r := new(big.Int)
+	r.Add(r, statedb.GetState(jeff, common.Hash{}).Big())
+	r.Add(r, statedb.GetState(vitalik, common.Hash{}).Big())
+	r.Add(r, statedb.GetState(christoph, common.Hash{}).Big())
+	r.Add(r, statedb.GetState(gav, common.Hash{}).Big())
+
+	return r.Cmp(big.NewInt(1)) > 0
+}
diff --git a/miner/worker.go b/miner/worker.go
index ab01ba09e..1e5d47965 100644
--- a/miner/worker.go
+++ b/miner/worker.go
@@ -267,6 +267,12 @@ func (self *worker) wait() {
 
 func (self *worker) push() {
 	if atomic.LoadInt32(&self.mining) == 1 {
+		if core.Canary(self.current.state) {
+			glog.Infoln("Toxicity levels rising to deadly levels. Your canary has died. You can go back or continue down the mineshaft --more--")
+			glog.Infoln("You turn back and abort mining")
+			return
+		}
+
 		self.current.state.Sync()
 		self.current.block.SetRoot(self.current.state.Root())