1 files changed, 216 insertions, 0 deletions
diff --git a/src/network/channel.cpp b/src/network/channel.cpp
new file mode 100644
index 0000000..5fff1fa
--- /dev/null
+++ b/src/network/channel.cpp
@@ -0,0 +1,216 @@
+#include "channel.h"
+
+#include <algorithm>
+#include <cstring>
+#include <stdexcept>
+
+#include <endian.h>
+
+using std::remove_const;
+using std::runtime_error;
+
+using namespace erebos;
+
+Ref ChannelRequestData::store(const Storage & st) const
+{
+	vector<Record::Item> items;
+
+	for (const auto & p : peers)
+		items.emplace_back("peer", p);
+	items.emplace_back("key", key);
+
+	return st.storeObject(Record(std::move(items)));
+}
+
+ChannelRequestData ChannelRequestData::load(const Ref & ref)
+{
+	if (auto rec = ref->asRecord()) {
+		if (auto key = rec->item("key").as<PublicKexKey>())
+			return ChannelRequestData {
+				.peers = rec->items("peer").as<Signed<IdentityData>>(),
+				.key = *key,
+			};
+	}
+
+	return ChannelRequestData {
+		.peers = {},
+		.key = Stored<PublicKexKey>::load(ref.storage().zref()),
+	};
+}
+
+Ref ChannelAcceptData::store(const Storage & st) const
+{
+	vector<Record::Item> items;
+
+	items.emplace_back("req", request);
+	items.emplace_back("key", key);
+
+	return st.storeObject(Record(std::move(items)));
+}
+
+ChannelAcceptData ChannelAcceptData::load(const Ref & ref)
+{
+	if (auto rec = ref->asRecord())
+		return ChannelAcceptData {
+			.request = *rec->item("req").as<ChannelRequest>(),
+			.key = *rec->item("key").as<PublicKexKey>(),
+		};
+
+	return ChannelAcceptData {
+		.request = Stored<ChannelRequest>::load(ref.storage().zref()),
+		.key = Stored<PublicKexKey>::load(ref.storage().zref()),
+	};
+}
+
+unique_ptr<Channel> ChannelAcceptData::channel() const
+{
+	if (auto secret = SecretKexKey::load(key))
+		return make_unique<Channel>(
+			request->data->peers,
+			secret->dh(*request->data->key),
+			false
+		);
+
+	if (auto secret = SecretKexKey::load(request->data->key))
+		return make_unique<Channel>(
+			request->data->peers,
+			secret->dh(*key),
+			true
+		);
+
+	throw runtime_error("failed to load secret DH key");
+}
+
+
+Stored<ChannelRequest> Channel::generateRequest(const Storage & st,
+		const Identity & self, const Identity & peer)
+{
+	auto signKey = SecretKey::load(self.keyMessage());
+	if (!signKey)
+		throw runtime_error("failed to load own message key");
+
+	return signKey->sign(st.store(ChannelRequestData {
+		.peers = self.ref()->digest() < peer.ref()->digest() ?
+			vector<Stored<Signed<IdentityData>>> {
+				Stored<Signed<IdentityData>>::load(*self.ref()),
+				Stored<Signed<IdentityData>>::load(*peer.ref()),
+			} :
+			vector<Stored<Signed<IdentityData>>> {
+				Stored<Signed<IdentityData>>::load(*peer.ref()),
+				Stored<Signed<IdentityData>>::load(*self.ref()),
+			},
+		.key = SecretKexKey::generate(st).pub(),
+	}));
+}
+
+optional<Stored<ChannelAccept>> Channel::acceptRequest(const Identity & self,
+		const Identity & peer, const Stored<ChannelRequest> & request)
+{
+	if (!request->isSignedBy(peer.keyMessage()))
+		return nullopt;
+
+	auto & peers = request->data->peers;
+	if (peers.size() != 2 ||
+			std::none_of(peers.begin(), peers.end(), [&self](const auto & x)
+				{ return x.ref().digest() == self.ref()->digest(); }) ||
+			std::none_of(peers.begin(), peers.end(), [&peer](const auto & x)
+				{ return x.ref().digest() == peer.ref()->digest(); }))
+		return nullopt;
+
+	auto & st = request.ref().storage();
+
+	auto signKey = SecretKey::load(self.keyMessage());
+	if (!signKey)
+		throw runtime_error("failed to load own message key");
+
+	return signKey->sign(st.store(ChannelAcceptData {
+		.request = request,
+		.key = SecretKexKey::generate(st).pub(),
+	}));
+}
+
+uint64_t Channel::encrypt(BufferCIt plainBegin, BufferCIt plainEnd,
+		Buffer & encBuffer, size_t encOffset)
+{
+	auto plainSize = plainEnd - plainBegin;
+	encBuffer.resize(encOffset + plainSize + 1 /* counter */ + 16 /* tag */);
+	array<uint8_t, 12> iv;
+
+	uint64_t count = counterNextOut.fetch_add(1);
+	uint64_t beCount = htobe64(count);
+	encBuffer[encOffset] = count % 0x100;
+
+	constexpr size_t nonceFixedSize = std::tuple_size_v<decltype(nonceFixedOur)>;
+	static_assert(nonceFixedSize + sizeof beCount == iv.size());
+
+	std::copy_n(nonceFixedOur.begin(), nonceFixedSize, iv.begin());
+	std::memcpy(iv.data() + nonceFixedSize, &beCount, sizeof beCount);
+
+	const unique_ptr<EVP_CIPHER_CTX, void(*)(EVP_CIPHER_CTX*)>
+		ctx(EVP_CIPHER_CTX_new(), EVP_CIPHER_CTX_free);
+	EVP_EncryptInit_ex(ctx.get(), EVP_chacha20_poly1305(),
+			nullptr, key.data(), iv.data());
+
+	int outl = 0;
+	uint8_t * cur = encBuffer.data() + encOffset + 1;
+
+	if (EVP_EncryptUpdate(ctx.get(), cur, &outl, &*plainBegin, plainSize) != 1)
+		throw runtime_error("failed to encrypt data");
+	cur += outl;
+
+	if (EVP_EncryptFinal(ctx.get(), cur, &outl) != 1)
+		throw runtime_error("failed to encrypt data");
+	cur += outl;
+
+	EVP_CIPHER_CTX_ctrl(ctx.get(), EVP_CTRL_AEAD_GET_TAG, 16, cur);
+	return count;
+}
+
+optional<uint64_t> Channel::decrypt(BufferCIt encBegin, BufferCIt encEnd,
+			Buffer & decBuffer, const size_t decOffset)
+{
+	auto encSize = encEnd - encBegin;
+	decBuffer.resize(decOffset + encSize);
+	array<uint8_t, 12> iv;
+
+	if (encBegin + 1 /* counter */ + 16 /* tag */ > encEnd)
+		return nullopt;
+
+	uint64_t expectedCount = counterNextIn.load();
+	uint64_t guessedCount = expectedCount - 0x80u + ((0x80u + encBegin[0] - expectedCount) % 0x100u);
+	uint64_t beCount = htobe64(guessedCount);
+
+	constexpr size_t nonceFixedSize = std::tuple_size_v<decltype(nonceFixedPeer)>;
+	static_assert(nonceFixedSize + sizeof beCount == iv.size());
+
+	std::copy_n(nonceFixedPeer.begin(), nonceFixedSize, iv.begin());
+	std::memcpy(iv.data() + nonceFixedSize, &beCount, sizeof beCount);
+
+	const unique_ptr<EVP_CIPHER_CTX, void(*)(EVP_CIPHER_CTX*)>
+		ctx(EVP_CIPHER_CTX_new(), EVP_CIPHER_CTX_free);
+	EVP_DecryptInit_ex(ctx.get(), EVP_chacha20_poly1305(),
+			nullptr, key.data(), iv.data());
+
+	int outl = 0;
+	uint8_t * cur = decBuffer.data() + decOffset;
+
+	if (EVP_DecryptUpdate(ctx.get(), cur, &outl,
+				&*encBegin + 1, encSize - 1 - 16) != 1)
+		return nullopt;
+	cur += outl;
+
+	if (!EVP_CIPHER_CTX_ctrl(ctx.get(), EVP_CTRL_AEAD_SET_TAG, 16,
+				(void *) (&*encEnd - 16)))
+		return nullopt;
+
+	if (EVP_DecryptFinal_ex(ctx.get(), cur, &outl) != 1)
+		return nullopt;
+	cur += outl;
+
+	while (expectedCount < guessedCount + 1 &&
+			not counterNextIn.compare_exchange_weak(expectedCount, guessedCount + 1))
+		; // empty loop body
+
+	decBuffer.resize(cur - decBuffer.data());
+	return guessedCount;
+}