Check for space before writing packets to simplex connections.

briar-core/src/net/sf/briar/messaging/simplex/OutgoingSimplexConnection.java

@@ -58,8 +58,6 @@ class OutgoingSimplexConnection {
 		transportId = ctx.getTransportId();
 	}
 
-	// FIXME: Write each packet to a buffer, check for capacity before writing
-	// it to the connection (except raw messages, which are already serialised)
 	void write() {
 		connRegistry.registerConnection(contactId, transportId);
 		try {
@@ -72,26 +70,12 @@ class OutgoingSimplexConnection {
 			PacketWriter writer = protoFactory.createPacketWriter(out,
 					transport.shouldFlush());
 			// Send the initial packets: updates and acks
-			Collection<TransportAck> transportAcks =
-					db.generateTransportAcks(contactId);
-			if(transportAcks != null) {
-				for(TransportAck ta : transportAcks)
-					writer.writeTransportAck(ta);
-			}
-			Collection<TransportUpdate> transportUpdates =
-					db.generateTransportUpdates(contactId);
-			if(transportUpdates != null) {
-				for(TransportUpdate tu : transportUpdates)
-					writer.writeTransportUpdate(tu);
-			}
-			SubscriptionAck sa = db.generateSubscriptionAck(contactId);
-			if(sa != null) writer.writeSubscriptionAck(sa);
-			SubscriptionUpdate su = db.generateSubscriptionUpdate(contactId);
-			if(su != null) writer.writeSubscriptionUpdate(su);
-			RetentionAck ra = db.generateRetentionAck(contactId);
-			if(ra != null) writer.writeRetentionAck(ra);
-			RetentionUpdate ru = db.generateRetentionUpdate(contactId);
-			if(ru != null) writer.writeRetentionUpdate(ru);
+			boolean hasSpace = writeTransportAcks(conn, writer);
+			if(hasSpace) hasSpace = writeTransportUpdates(conn, writer);
+			if(hasSpace) hasSpace = writeSubscriptionAck(conn, writer);
+			if(hasSpace) hasSpace = writeSubscriptionUpdate(conn, writer);
+			if(hasSpace) hasSpace = writeRetentionAck(conn, writer);
+			if(hasSpace) hasSpace = writeRetentionUpdate(conn, writer);
 			// Write acks until you can't write acks no more
 			long capacity = conn.getRemainingCapacity();
 			int maxMessages = writer.getMaxMessagesForAck(capacity);
@@ -126,6 +110,67 @@ class OutgoingSimplexConnection {
 		}
 	}
 
+	private boolean writeTransportAcks(ConnectionWriter conn,
+			PacketWriter writer) throws DbException, IOException {
+		assert conn.getRemainingCapacity() >= MAX_PACKET_LENGTH;
+		Collection<TransportAck> acks = db.generateTransportAcks(contactId);
+		if(acks == null) return true;
+		for(TransportAck a : acks) {
+			writer.writeTransportAck(a);
+			if(conn.getRemainingCapacity() < MAX_PACKET_LENGTH) return false;
+		}
+		return true;
+	}
+
+	private boolean writeTransportUpdates(ConnectionWriter conn,
+			PacketWriter writer) throws DbException, IOException {
+		assert conn.getRemainingCapacity() >= MAX_PACKET_LENGTH;
+		Collection<TransportUpdate> updates =
+				db.generateTransportUpdates(contactId);
+		if(updates == null) return true;
+		for(TransportUpdate u : updates) {
+			writer.writeTransportUpdate(u);
+			if(conn.getRemainingCapacity() < MAX_PACKET_LENGTH) return false;
+		}
+		return true;
+	}
+
+	private boolean writeSubscriptionAck(ConnectionWriter conn,
+			PacketWriter writer) throws DbException, IOException {
+		assert conn.getRemainingCapacity() >= MAX_PACKET_LENGTH;
+		SubscriptionAck a = db.generateSubscriptionAck(contactId);
+		if(a == null) return true;
+		writer.writeSubscriptionAck(a);
+		return conn.getRemainingCapacity() >= MAX_PACKET_LENGTH;
+	}
+
+	private boolean writeSubscriptionUpdate(ConnectionWriter conn,
+			PacketWriter writer) throws DbException, IOException {
+		assert conn.getRemainingCapacity() >= MAX_PACKET_LENGTH;
+		SubscriptionUpdate u = db.generateSubscriptionUpdate(contactId);
+		if(u == null) return true;
+		writer.writeSubscriptionUpdate(u);
+		return conn.getRemainingCapacity() >= MAX_PACKET_LENGTH;
+	}
+
+	private boolean writeRetentionAck(ConnectionWriter conn,
+			PacketWriter writer) throws DbException, IOException {
+		assert conn.getRemainingCapacity() >= MAX_PACKET_LENGTH;
+		RetentionAck a = db.generateRetentionAck(contactId);
+		if(a == null) return true;
+		writer.writeRetentionAck(a);
+		return conn.getRemainingCapacity() >= MAX_PACKET_LENGTH;
+	}
+
+	private boolean writeRetentionUpdate(ConnectionWriter conn,
+			PacketWriter writer) throws DbException, IOException {
+		assert conn.getRemainingCapacity() >= MAX_PACKET_LENGTH;
+		RetentionUpdate u = db.generateRetentionUpdate(contactId);
+		if(u == null) return true;
+		writer.writeRetentionUpdate(u);
+		return conn.getRemainingCapacity() >= MAX_PACKET_LENGTH;
+	}
+
 	private void dispose(boolean exception) {
 		ByteUtils.erase(ctx.getSecret());
 		try {