package yggdrasil import ( "errors" "fmt" "sync" "sync/atomic" "time" "github.com/yggdrasil-network/yggdrasil-go/src/crypto" "github.com/yggdrasil-network/yggdrasil-go/src/util" ) // ConnError implements the net.Error interface type ConnError struct { error timeout bool temporary bool maxsize int } // Timeout returns true if the error relates to a timeout condition on the // connection. func (e *ConnError) Timeout() bool { return e.timeout } // Temporary return true if the error is temporary or false if it is a permanent // error condition. func (e *ConnError) Temporary() bool { return e.temporary } // PacketTooBig returns in response to sending a packet that is too large, and // if so, the maximum supported packet size that should be used for the // connection. func (e *ConnError) PacketTooBig() (bool, int) { return e.maxsize > 0, e.maxsize } type Conn struct { core *Core nodeID *crypto.NodeID nodeMask *crypto.NodeID mutex sync.RWMutex closed bool session *sessionInfo readDeadline atomic.Value // time.Time // TODO timer writeDeadline atomic.Value // time.Time // TODO timer searching atomic.Value // bool searchwait chan struct{} // Never reset this, it's only used for the initial search writebuf [][]byte // Packets to be sent if/when the search finishes } // TODO func NewConn() that initializes additional fields as needed func newConn(core *Core, nodeID *crypto.NodeID, nodeMask *crypto.NodeID, session *sessionInfo) *Conn { conn := Conn{ core: core, nodeID: nodeID, nodeMask: nodeMask, session: session, searchwait: make(chan struct{}), } conn.searching.Store(false) return &conn } func (c *Conn) String() string { return fmt.Sprintf("conn=%p", c) } // This method should only be called from the router goroutine func (c *Conn) startSearch() { // The searchCompleted callback is given to the search searchCompleted := func(sinfo *sessionInfo, err error) { defer c.searching.Store(false) // If the search failed for some reason, e.g. it hit a dead end or timed // out, then do nothing if err != nil { c.core.log.Debugln(c.String(), "DHT search failed:", err) return } // Take the connection mutex c.mutex.Lock() defer c.mutex.Unlock() // Were we successfully given a sessionInfo pointer? if sinfo != nil { // Store it, and update the nodeID and nodeMask (which may have been // wildcarded before now) with their complete counterparts c.core.log.Debugln(c.String(), "DHT search completed") c.session = sinfo c.nodeID = crypto.GetNodeID(&sinfo.theirPermPub) for i := range c.nodeMask { c.nodeMask[i] = 0xFF } // Make sure that any blocks on read/write operations are lifted defer func() { recover() }() // So duplicate searches don't panic close(c.searchwait) } else { // No session was returned - this shouldn't really happen because we // should always return an error reason if we don't return a session panic("DHT search didn't return an error or a sessionInfo") } if c.closed { // Things were closed before the search returned // Go ahead and close it again to make sure the session is cleaned up go c.Close() } else { // Send any messages we may have buffered var msgs [][]byte msgs, c.writebuf = c.writebuf, nil go func() { for _, msg := range msgs { c.Write(msg) util.PutBytes(msg) } }() } } // doSearch will be called below in response to one or more conditions doSearch := func() { c.searching.Store(true) // Check to see if there is a search already matching the destination sinfo, isIn := c.core.searches.searches[*c.nodeID] if !isIn { // Nothing was found, so create a new search sinfo = c.core.searches.newIterSearch(c.nodeID, c.nodeMask, searchCompleted) c.core.log.Debugf("%s DHT search started: %p", c.String(), sinfo) } // Continue the search sinfo.continueSearch() } // Take a copy of the session object, in case it changes later c.mutex.RLock() sinfo := c.session c.mutex.RUnlock() if c.session == nil { // No session object is present so previous searches, if we ran any, have // not yielded a useful result (dead end, remote host not found) doSearch() } else { sinfo.worker <- func() { switch { case !sinfo.init: doSearch() case time.Since(sinfo.time) > 6*time.Second: if sinfo.time.Before(sinfo.pingTime) && time.Since(sinfo.pingTime) > 6*time.Second { // TODO double check that the above condition is correct doSearch() } else { c.core.sessions.ping(sinfo) } default: // Don't do anything, to keep traffic throttled } } } } func getDeadlineTimer(value *atomic.Value) *time.Timer { timer := time.NewTimer(24 * 365 * time.Hour) // FIXME for some reason setting this to 0 doesn't always let it stop and drain the channel correctly util.TimerStop(timer) if deadline, ok := value.Load().(time.Time); ok { timer.Reset(time.Until(deadline)) } return timer } func (c *Conn) Read(b []byte) (int, error) { // Take a copy of the session object c.mutex.RLock() sinfo := c.session c.mutex.RUnlock() timer := getDeadlineTimer(&c.readDeadline) defer util.TimerStop(timer) // If there is a search in progress then wait for the result if sinfo == nil { // Wait for the search to complete select { case <-c.searchwait: case <-timer.C: return 0, ConnError{errors.New("timeout"), true, false, 0} } // Retrieve our session info again c.mutex.RLock() sinfo = c.session c.mutex.RUnlock() // If sinfo is still nil at this point then the search failed and the // searchwait channel has been recreated, so might as well give up and // return an error code if sinfo == nil { return 0, errors.New("search failed") } } for { // Wait for some traffic to come through from the session select { case <-timer.C: return 0, ConnError{errors.New("timeout"), true, false, 0} case p, ok := <-sinfo.recv: // If the session is closed then do nothing if !ok { return 0, errors.New("session is closed") } defer util.PutBytes(p.Payload) var err error done := make(chan struct{}) workerFunc := func() { defer close(done) // If the nonce is bad then drop the packet and return an error if !sinfo.nonceIsOK(&p.Nonce) { err = ConnError{errors.New("packet dropped due to invalid nonce"), false, true, 0} return } // Decrypt the packet bs, isOK := crypto.BoxOpen(&sinfo.sharedSesKey, p.Payload, &p.Nonce) defer util.PutBytes(bs) // FIXME commenting this out leads to illegal buffer reuse, this implies there's a memory error somewhere and that this is just flooding things out of the finite pool of old slices that get reused // Check if we were unable to decrypt the packet for some reason and // return an error if we couldn't if !isOK { err = ConnError{errors.New("packet dropped due to decryption failure"), false, true, 0} return } // Return the newly decrypted buffer back to the slice we were given copy(b, bs) // Trim the slice down to size based on the data we received if len(bs) < len(b) { b = b[:len(bs)] } // Update the session sinfo.updateNonce(&p.Nonce) sinfo.time = time.Now() sinfo.bytesRecvd += uint64(len(b)) } // Hand over to the session worker select { // Send to worker case sinfo.worker <- workerFunc: case <-timer.C: return 0, ConnError{errors.New("timeout"), true, false, 0} } <-done // Wait for the worker to finish, failing this can cause memory errors (util.[Get||Put]Bytes stuff) // Something went wrong in the session worker so abort if err != nil { if ce, ok := err.(*ConnError); ok && ce.Temporary() { continue } return 0, err } // If we've reached this point then everything went to plan, return the // number of bytes we populated back into the given slice return len(b), nil } } } func (c *Conn) Write(b []byte) (bytesWritten int, err error) { c.mutex.RLock() sinfo := c.session c.mutex.RUnlock() // If the session doesn't exist, or isn't initialised (which probably means // that the search didn't complete successfully) then we may need to wait for // the search to complete or start the search again if sinfo == nil || !sinfo.init { // Is a search already taking place? if searching, sok := c.searching.Load().(bool); !sok || (sok && !searching) { // No search was already taking place so start a new one c.core.router.doAdmin(c.startSearch) } // Buffer the packet to be sent if/when the search is finished c.mutex.Lock() defer c.mutex.Unlock() c.writebuf = append(c.writebuf, append(util.GetBytes(), b...)) for len(c.writebuf) > 32 { util.PutBytes(c.writebuf[0]) c.writebuf = c.writebuf[1:] } return len(b), nil } else { // This triggers some session keepalive traffic // FIXME this desparately needs to be refactored, since the ping case needlessly goes through the router goroutine just to have it pass a function to the session worker when it determines that a session already exists. c.core.router.doAdmin(c.startSearch) } var packet []byte done := make(chan struct{}) written := len(b) workerFunc := func() { defer close(done) // Does the packet exceed the permitted size for the session? if uint16(len(b)) > sinfo.getMTU() { written, err = 0, ConnError{errors.New("packet too big"), true, false, int(sinfo.getMTU())} return } // Encrypt the packet payload, nonce := crypto.BoxSeal(&sinfo.sharedSesKey, b, &sinfo.myNonce) defer util.PutBytes(payload) // Construct the wire packet to send to the router p := wire_trafficPacket{ Coords: sinfo.coords, Handle: sinfo.theirHandle, Nonce: *nonce, Payload: payload, } packet = p.encode() sinfo.bytesSent += uint64(len(b)) } // Set up a timer so this doesn't block forever timer := getDeadlineTimer(&c.writeDeadline) defer util.TimerStop(timer) // Hand over to the session worker select { // Send to worker case sinfo.worker <- workerFunc: case <-timer.C: return 0, ConnError{errors.New("timeout"), true, false, 0} } // Wait for the worker to finish, otherwise there are memory errors ([Get||Put]Bytes stuff) <-done // Give the packet to the router if written > 0 { sinfo.core.router.out(packet) } // Finally return the number of bytes we wrote return written, err } func (c *Conn) Close() error { c.mutex.Lock() defer c.mutex.Unlock() if c.session != nil { // Close the session, if it hasn't been closed already c.session.close() c.session = nil } // This can't fail yet - TODO? c.closed = true return nil } func (c *Conn) LocalAddr() crypto.NodeID { return *crypto.GetNodeID(&c.session.core.boxPub) } func (c *Conn) RemoteAddr() crypto.NodeID { c.mutex.RLock() defer c.mutex.RUnlock() return *c.nodeID } func (c *Conn) SetDeadline(t time.Time) error { c.SetReadDeadline(t) c.SetWriteDeadline(t) return nil } func (c *Conn) SetReadDeadline(t time.Time) error { c.readDeadline.Store(t) return nil } func (c *Conn) SetWriteDeadline(t time.Time) error { c.writeDeadline.Store(t) return nil }