diff --git a/dataStore.cpp b/dataStore.cpp
new file mode 100644
index 0000000..a801788
--- /dev/null
+++ b/dataStore.cpp
@@ -0,0 +1,110 @@
+/***************************************************************************
+ * By Théophile Bastian, 2017
+ * M1 Network course project at ENS Cachan, Juliusz Chroboczek.
+ * License: WTFPL v2 <http://www.wtfpl.net/>
+ **************************************************************************/
+
+#include "dataStore.h"
+#include <cstring>
+#include <algorithm>
+using namespace std;
+
+DataStore::DataStore(Protocol* proto) : proto(proto)
+{}
+
+DataStore::~DataStore() {
+}
+
+void DataStore::update() {
+	while(!timeEvents.empty()) {
+		const TimeEvent& evt = timeEvents.top();
+		if(evt.time > time(NULL)) // We're done for now.
+			break;
+
+		timeEvents.pop();
+		switch(evt.type) {
+			case EV_REPUBLISH:
+				handleRepublish(evt.id);
+				break;
+
+			case EV_EXPIRES:
+				handleExpire(evt.id, evt.seqno);
+				break;
+		}
+	}
+}
+
+void DataStore::addData(Bytes pck, u32 seqno, u64 id, bool mine) {
+	if(curSeqno.find(id) != curSeqno.end() && curSeqno[id] >= seqno)
+		return;
+
+	data[id] = Data(pck, mine);
+	curSeqno[id] = seqno;
+
+	if(mine) {
+		timeEvents.push(TimeEvent(
+					time(NULL) + csts::TIME_REPUBLISH_DATA,
+					seqno, id, EV_REPUBLISH));
+
+	}
+	else {
+		timeEvents.push(TimeEvent(
+					time(NULL) + csts::TIMEOUT_DATA,
+					seqno, id, EV_EXPIRES));
+			// If it is not renewed, it will expire.
+	}
+
+	recvTime[id] = time(NULL);
+	fprintf(stderr, "[INFO] Storing data %lX (%u)\n", id, seqno);
+
+	handleFlood(id);
+}
+
+ssize_t DataStore::dataSize(u64 id) {
+	if(data.find(id) == data.end())
+		return -1;
+	return data[id].data.size();
+}
+
+ssize_t DataStore::readData(u64 id, char* buffer, size_t size) {
+	if(data.find(id) == data.end())
+		return -1;
+	ssize_t len = min((ssize_t)size, dataSize(id));
+	data[id].data.writeToBuffer(buffer, size);
+	return len;
+}
+
+void DataStore::ids(std::vector<u64>& out) {
+	for(auto& dat : data)
+		out.push_back(dat.first);
+}
+
+void DataStore::setFlooded(u64 id) {
+	toFlood_.erase(id);
+}
+
+void DataStore::handleExpire(u64 id, u32 seqno) {
+	if(seqno < curSeqno[id])
+		return; // Was updated in time
+
+	cleanData(id);
+}
+
+void DataStore::handleRepublish(u64 id) {
+	if(data.find(id) == data.end() || !data[id].isMine)
+		return;
+
+	curSeqno[id] = time(NULL);
+	handleFlood(id);
+}
+
+void DataStore::handleFlood(u64 id) {
+	toFlood_.insert(id);
+}
+
+void DataStore::cleanData(u64 id) {
+	curSeqno.erase(id);
+	recvTime.erase(id);
+	data.erase(id); // Deletes the Bytes as well
+}
+
diff --git a/dataStore.h b/dataStore.h
new file mode 100644
index 0000000..8c31f4f
--- /dev/null
+++ b/dataStore.h
@@ -0,0 +1,98 @@
+/***************************************************************************
+ * By Théophile Bastian, 2017
+ * M1 Network course project at ENS Cachan, Juliusz Chroboczek.
+ * License: WTFPL v2 <http://www.wtfpl.net/>
+ **************************************************************************/
+
+#pragma once
+#include <queue>
+#include <unordered_map>
+#include <set>
+#include "data.h"
+#include "nw_constants.h"
+#include "protocol.h"
+#include "Bytes.h"
+
+class DataStore {
+	public:
+		DataStore(Protocol* proto);
+		~DataStore();
+
+		void update();
+		/** Performs bookkeeping actions. Sends packets. This function should
+		 * be called often enough.
+		 */
+
+		void addData(Bytes pck, u32 seqno, u64 id, bool mine=false);
+		/** Adds a data in the data storage. If `mine` is `true`, the current
+		 * node considers itself responsible for the data and will republish
+		 * it when needed.
+		 */
+
+		ssize_t dataSize(u64 id);
+		/** Gets the size of the data with id `id`. Returns -1 if there is no
+		 * such data stored.
+		 */
+
+		ssize_t readData(u64 id, char* buffer, size_t size);
+		/** Fills `buffer` with the data of the given `id`.
+		 * If the data does not exist, returs -1; else, returns the length of
+		 * data actually retrieved.
+		 */
+
+		const Bytes& operator[](u64 id) {
+			return data[id].data;
+		}
+
+		u32 getSeqno(u64 id) const { return curSeqno.at(id); }
+
+		void ids(std::vector<u64>& out);
+		/** Fills `out` with the IDs of the stored data. */
+
+		const std::set<u64> toFlood() const { return toFlood_; }
+		/** Returns a list of data IDs that should be flooded. */
+
+		void setFlooded(u64 id);
+		/** Marks a data as flooded */
+
+	private: //meth
+		void handleExpire(u64 id, u32 seqno);
+		void handleRepublish(u64 id);
+		void handleFlood(u64 id);
+
+		void cleanData(u64 id);
+
+	private:
+		enum EvType {
+			EV_REPUBLISH, EV_EXPIRES
+		};
+		struct TimeEvent {
+			TimeEvent(time_t time, u32 seqno, u64 id, EvType type) :
+				time(time), seqno(seqno), id(id), type(type) {}
+			time_t time;
+			u32 seqno;
+			u64 id;
+			EvType type;
+
+			bool operator<(const TimeEvent& e) const {
+				return time > e.time; // Max-priority queue
+			}
+		};
+
+		struct Data {
+			Data() : data(), isMine(false) {}
+			Data(Bytes b) : data(b), isMine(false) {}
+			Data(Bytes b, bool mine) : data(b), isMine(mine) {}
+			Bytes data;
+			bool isMine;
+		};
+
+		std::priority_queue<TimeEvent> timeEvents;
+		Protocol* proto;
+		std::unordered_map<u64, Data> data;
+		std::unordered_map<u64, u32> curSeqno;
+		std::unordered_map<u64, time_t> recvTime;
+
+		std::set<u64> toFlood_;
+};
+
diff --git a/flooder.cpp b/flooder.cpp
new file mode 100644
index 0000000..6d54477
--- /dev/null
+++ b/flooder.cpp
@@ -0,0 +1,54 @@
+/***************************************************************************
+ * By Théophile Bastian, 2017
+ * M1 Network course project at ENS Cachan, Juliusz Chroboczek.
+ * License: WTFPL v2 <http://www.wtfpl.net/>
+ **************************************************************************/
+
+#include "flooder.h"
+
+Flooder::Flooder(const Bytes& data, u64 datId, u32 seqno, Protocol* proto,
+		const std::list<Neighbour>& peers) :
+	data(data), datId(datId), seqno(seqno), proto(proto)
+{
+	fprintf(stderr, "[DBG] Created flooder for %lX (%u)\n", datId, seqno);
+	for(auto it=peers.begin(); it != peers.end(); ++it) {
+		triesCount[it->id] = 0;
+		toFlood.push(FloodEvt(time(NULL), it->id));
+	}
+	update();
+}
+
+void Flooder::update() {
+	while(!toFlood.empty()) {
+		const FloodEvt& evt = toFlood.top();
+		if(evt.time > time(NULL))
+			break;
+		toFlood.pop();
+
+		if(triesCount[evt.id] > csts::FLOOD_RETRIES) {
+			fprintf(stderr, "[WARNING] Could not flood to %lX: no IHave.\n",
+					evt.id);
+			continue;
+		}
+		else if(triesCount[evt.id] < 0) {
+			fprintf(stderr, "[DBG] Got your IHave, %lX!\n", evt.id);
+			continue; // IHave received
+		}
+
+		sendTo(evt.id);
+		triesCount[evt.id]++;
+		toFlood.push(FloodEvt(time(NULL) + csts::TIME_RESEND_FLOOD, evt.id));
+	}
+}
+
+void Flooder::gotIHave(u64 id, u32 withSeqno) {
+	if(seqno > withSeqno)
+		return;
+
+	triesCount[id] = -1;
+}
+
+void Flooder::sendTo(u64 id) {
+	proto->sendData(id, data, seqno, datId);
+}
+
diff --git a/flooder.h b/flooder.h
new file mode 100644
index 0000000..ffeca8e
--- /dev/null
+++ b/flooder.h
@@ -0,0 +1,49 @@
+/***************************************************************************
+ * By Théophile Bastian, 2017
+ * M1 Network course project at ENS Cachan, Juliusz Chroboczek.
+ * License: WTFPL v2 <http://www.wtfpl.net/>
+ **************************************************************************/
+
+#pragma once
+
+#include <ctime>
+#include <queue>
+#include <list>
+#include <unordered_map>
+#include "data.h"
+#include "nw_constants.h"
+#include "protocol.h"
+
+class Flooder {
+	public:
+		Flooder(const Bytes& data, u64 datId, u32 seqno, Protocol* proto,
+				const std::list<Neighbour>& peers);
+
+		void update();
+		/** Call often enough (ie ~1s) */
+
+		void gotIHave(u64 id, u32 withSeqno);
+		/** Acknoledges the reception of the resource by peer `id`. */
+
+		bool done() const { return toFlood.empty(); }
+
+	private: //meth
+		void sendTo(u64 id);
+
+	private:
+		struct FloodEvt {
+			FloodEvt(time_t time, u64 id) : time(time), id(id) {}
+			time_t time;
+			u64 id;
+			bool operator<(const FloodEvt& e) const {
+				return time > e.time; // Max priority queue.
+			}
+		};
+		std::unordered_map<u64, int> triesCount;
+		std::priority_queue<FloodEvt> toFlood;
+		Bytes data;
+		u64 datId;
+		u32 seqno;
+		Protocol* proto;
+};
+