Fix: don't use outdated merge mining data

And warn the user in the log

src/merge_mining_client.h

@@ -28,10 +28,17 @@ class IMergeMiningClient
 public:
 	struct ChainParameters
 	{
+		ChainParameters() : last_updated(0) {}
+
+		enum {
+			EXPIRE_TIME = 1800,
+		};
+
 		hash aux_id;
 		hash aux_hash;
 		std::vector<uint8_t> aux_blob;
 		difficulty_type aux_diff;
+		uint64_t last_updated;
 	};
 
 public:

src/merge_mining_client_json_rpc.cpp

@@ -281,6 +281,7 @@ bool MergeMiningClientJSON_RPC::parse_merge_mining_get_aux_block(const char* dat
 	m_chainParams.aux_hash = h;
 	m_chainParams.aux_diff.lo = result["aux_diff"].GetUint64();
 	m_chainParams.aux_diff.hi = 0;
+	m_chainParams.last_updated = seconds_since_epoch();
 
 	changed = true;
 
@@ -334,12 +335,19 @@ void MergeMiningClientJSON_RPC::print_status() const
 
 bool MergeMiningClientJSON_RPC::get_params(ChainParameters& out_params) const
 {
+	const uint64_t t = seconds_since_epoch();
+
 	ReadLock lock(m_lock);
 
 	if (m_chainParams.aux_id.empty() || m_chainParams.aux_diff.empty()) {
 		return false;
 	}
 
+	if (t >= m_chainParams.last_updated + ChainParameters::EXPIRE_TIME) {
+		LOGWARN(4, m_host << ':' << m_port << " merge mining data is outdated (" << (t - m_chainParams.last_updated) << " seconds old)");
+		return false;
+	}
+
 	out_params = m_chainParams;
 	return true;
 }

src/merge_mining_client_tari.cpp

@@ -132,12 +132,19 @@ MergeMiningClientTari::~MergeMiningClientTari()
 
 bool MergeMiningClientTari::get_params(ChainParameters& out_params) const
 {
+	const uint64_t t = seconds_since_epoch();
+
 	ReadLock lock(m_chainParamsLock);
 
 	if (m_chainParams.aux_id.empty() || m_chainParams.aux_diff.empty()) {
 		return false;
 	}
 
+	if (t >= m_chainParams.last_updated + ChainParameters::EXPIRE_TIME) {
+		LOGWARN(4, m_hostStr << " merge mining data is outdated (" << (t - m_chainParams.last_updated) << " seconds old)");
+		return false;
+	}
+
 	out_params = m_chainParams;
 	return true;
 }
@@ -659,6 +666,7 @@ void MergeMiningClientTari::run()
 							std::copy(mm_hash.begin(), mm_hash.end(), m_chainParams.aux_hash.h);
 
 							m_chainParams.aux_diff = static_cast<difficulty_type>(response.miner_data().target_difficulty());
+							m_chainParams.last_updated = seconds_since_epoch();
 
 							m_tariBlock = response.block();