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// This file is part of gnunet-go, a GNUnet-implementation in Golang.
// Copyright (C) 2019-2022 Bernd Fix >Y<
//
// gnunet-go is free software: you can redistribute it and/or modify it
// under the terms of the GNU Affero General Public License as published
// by the Free Software Foundation, either version 3 of the License,
// or (at your option) any later version.
//
// gnunet-go is distributed in the hope that it will be useful, but
// WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
// Affero General Public License for more details.
//
// You should have received a copy of the GNU Affero General Public License
// along with this program. If not, see <http://www.gnu.org/licenses/>.
//
// SPDX-License-Identifier: AGPL3.0-or-later
package dht
import (
"context"
"gnunet/config"
"gnunet/core"
"gnunet/message"
"gnunet/service"
"gnunet/service/dht/blocks"
"time"
"github.com/bfix/gospel/logger"
)
//======================================================================
// "DHT" implementation
//======================================================================
//----------------------------------------------------------------------
// Put and get blocks into/from a DHT.
//----------------------------------------------------------------------
// Module handles the permanent storage of blocks under a query key.
type Module struct {
service.ModuleImpl
store service.DHTStore // reference to the block storage mechanism
cache service.DHTStore // transient block cache
core *core.Core // reference to core services
rtable *RoutingTable // routing table
}
// NewModule returns a new module instance. It initializes the storage
// mechanism for persistence.
func NewModule(ctx context.Context, c *core.Core) (m *Module, err error) {
// create permanent storage handler
var store, cache service.DHTStore
if store, err = service.NewDHTStore(config.Cfg.DHT.Storage); err != nil {
return
}
// create cache handler
if cache, err = service.NewDHTStore(config.Cfg.DHT.Cache); err != nil {
return
}
// create routing table
rt := NewRoutingTable(NewPeerAddress(c.PeerID()))
// return module instance
m = &Module{
ModuleImpl: *service.NewModuleImpl(),
store: store,
cache: cache,
core: c,
rtable: rt,
}
// register as listener for core events
listener := m.Run(ctx, m.event, m.Filter(), 15*time.Minute, m.heartbeat)
c.Register("dht", listener)
return
}
//----------------------------------------------------------------------
// Get a block from the DHT ["dht:get"]
func (m *Module) Get(ctx context.Context, query blocks.Query) (block blocks.Block, err error) {
// check if we have the requested block in cache or permanent storage.
block, err = m.cache.Get(query)
if err == nil {
// yes: we are done
return
}
block, err = m.store.Get(query)
if err == nil {
// yes: we are done
return
}
// retrieve the block from the DHT
return nil, nil
}
// Put a block into the DHT ["dht:put"]
func (m *Module) Put(ctx context.Context, key blocks.Query, block blocks.Block) error {
return nil
}
//----------------------------------------------------------------------
// Filter returns the event filter for the module
func (m *Module) Filter() *core.EventFilter {
f := core.NewEventFilter()
// events we are interested in
f.AddEvent(core.EV_CONNECT)
f.AddEvent(core.EV_DISCONNECT)
// messages we are interested in:
// (1) DHT messages
f.AddMsgType(message.DHT_CLIENT_GET)
f.AddMsgType(message.DHT_CLIENT_GET_RESULTS_KNOWN)
f.AddMsgType(message.DHT_CLIENT_GET_STOP)
f.AddMsgType(message.DHT_CLIENT_PUT)
f.AddMsgType(message.DHT_CLIENT_RESULT)
// (2) DHT_P2P messages
f.AddMsgType(message.DHT_P2P_PUT)
f.AddMsgType(message.DHT_P2P_GET)
f.AddMsgType(message.DHT_P2P_RESULT)
f.AddMsgType(message.DHT_P2P_HELLO)
return f
}
// Event handler for infrastructure signals
func (m *Module) event(ctx context.Context, ev *core.Event) {
switch ev.ID {
// New peer connected:
case core.EV_CONNECT:
// Add peer to routing table
logger.Printf(logger.INFO, "[dht] Peer %s connected", ev.Peer)
m.rtable.Add(NewPeerAddress(ev.Peer))
// Peer disconnected:
case core.EV_DISCONNECT:
// Remove peer from routing table
logger.Printf(logger.INFO, "[dht] Peer %s disconnected", ev.Peer)
m.rtable.Remove(NewPeerAddress(ev.Peer))
// Message received.
case core.EV_MESSAGE:
logger.Printf(logger.INFO, "[dht] Message received: %s", ev.Msg.String())
// process message (if applicable)
if m.ProcessFcn != nil {
m.ProcessFcn(ctx, ev.Msg, ev.Resp)
}
}
}
// Heartbeat handler for periodic tasks
func (m *Module) heartbeat(ctx context.Context) {
// update the estimated network size
m.rtable.l2nse = m.core.L2NSE()
// run heartbeat for routing table
m.rtable.heartbeat(ctx)
}
//----------------------------------------------------------------------
// Export functions
func (m *Module) Export(fcn map[string]any) {
// add exported functions from module
fcn["dht:get"] = m.Get
fcn["dht:put"] = m.Put
}
// Import functions
func (m *Module) Import(fcm map[string]any) {
// nothing to import now.
}
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