1 files changed, 133 insertions, 0 deletions
diff --git a/include/erebos/pairing.h b/include/erebos/pairing.h
new file mode 100644
index 0000000..71c9288
--- /dev/null
+++ b/include/erebos/pairing.h
@@ -0,0 +1,133 @@
+#pragma once
+
+#include <erebos/identity.h>
+#include <erebos/network.h>
+#include <erebos/service.h>
+
+#include <future>
+#include <map>
+#include <mutex>
+#include <string>
+#include <variant>
+#include <vector>
+
+namespace erebos {
+
+using std::function;
+using std::future;
+using std::map;
+using std::mutex;
+using std::promise;
+using std::string;
+using std::variant;
+using std::vector;
+
+/**
+ * Template-less base class for the paring functionality that does not depend
+ * on the result parameter.
+ */
+class PairingServiceBase : public Service
+{
+public:
+	enum class Outcome
+	{
+		Success,
+		PeerRejected,
+		UserRejected,
+		UnexpectedMessage,
+		NonceMismatch,
+		Stale,
+	};
+
+	using RequestInitHook = function<void(const Peer &)>;
+	using ConfirmHook = function<future<bool>(const Peer &, string, future<Outcome> &&)>;
+	using RequestNonceFailedHook = function<void(const Peer &)>;
+
+	class Config
+	{
+	public:
+		Config & onRequestInit(RequestInitHook);
+		Config & onResponse(PairingServiceBase::ConfirmHook);
+		Config & onRequest(PairingServiceBase::ConfirmHook);
+		Config & onRequestNonceFailed(RequestNonceFailedHook);
+
+	private:
+		friend class PairingServiceBase;
+		RequestInitHook requestInitHook;
+		ConfirmHook responseHook;
+		ConfirmHook requestHook;
+		RequestNonceFailedHook requestNonceFailedHook;
+	};
+
+	PairingServiceBase(Config &&);
+	virtual ~PairingServiceBase();
+
+protected:
+	void requestPairing(UUID serviceId, const Peer & peer);
+	virtual void handle(Context &) override;
+	virtual Ref handlePairingCompleteRef(const Peer &) = 0;
+	virtual void handlePairingResult(Context &) = 0;
+
+private:
+	static vector<uint8_t> nonceDigest(const Identity & id1, const Identity & id2,
+			const vector<uint8_t> & nonce1, const vector<uint8_t> & nonce2);
+	static string confirmationNumber(const vector<uint8_t> &);
+
+	const Config config;
+	optional<Ref> result;
+
+	enum class StatePhase {
+		NoPairing,
+		OurRequest,
+		OurRequestConfirm,
+		OurRequestReady,
+		PeerRequest,
+		PeerRequestConfirm,
+		PairingDone,
+		PairingFailed
+	};
+
+	struct State {
+		mutex lock;
+		StatePhase phase;
+		optional<Identity> idReq;
+		optional<Identity> idRsp;
+		vector<uint8_t> nonce;
+		vector<uint8_t> peerCheck;
+		promise<Outcome> outcome;
+	};
+
+	map<Peer, shared_ptr<State>> peerStates;
+	mutex stateLock;
+
+	void waitForConfirmation(Peer peer, weak_ptr<State> state, string confirm, ConfirmHook hook);
+};
+
+template<class Result>
+class PairingService : public PairingServiceBase
+{
+public:
+	PairingService(Config && config):
+		PairingServiceBase(move(config)) {}
+
+protected:
+	virtual Stored<Result> handlePairingComplete(const Peer &) = 0;
+	virtual void handlePairingResult(Context &, Stored<Result>) = 0;
+
+	virtual Ref handlePairingCompleteRef(const Peer &) override final;
+	virtual void handlePairingResult(Context &) override final;
+};
+
+template<class Result>
+Ref PairingService<Result>::handlePairingCompleteRef(const Peer & peer)
+{
+	return handlePairingComplete(peer).ref();
+}
+
+template<class Result>
+void PairingService<Result>::handlePairingResult(Context & ctx)
+{
+	handlePairingResult(ctx, Stored<Result>::load(ctx.ref()));
+}
+
+}