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package yggdrasil
import (
"errors"
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"fmt"
"sync"
"sync/atomic"
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"time"
"github.com/yggdrasil-network/yggdrasil-go/src/crypto"
"github.com/yggdrasil-network/yggdrasil-go/src/util"
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)
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// ConnError implements the net.Error interface
type ConnError struct {
error
timeout bool
temporary bool
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closed bool
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maxsize int
}
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// Timeout returns true if the error relates to a timeout condition on the
// connection.
func (e *ConnError) Timeout() bool {
return e.timeout
}
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// 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
}
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// 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
}
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// Closed returns if the session is already closed and is now unusable.
func (e *ConnError) Closed() bool {
return e.closed
}
type Conn struct {
core *Core
nodeID *crypto.NodeID
nodeMask *crypto.NodeID
mutex sync.RWMutex
close chan bool
session *sessionInfo
readDeadline atomic.Value // time.Time // TODO timer
writeDeadline atomic.Value // time.Time // TODO timer
}
// 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,
close: make(chan bool),
}
return &conn
}
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func (c *Conn) String() string {
return fmt.Sprintf("conn=%p", c)
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}
// This should never be called from the router goroutine
func (c *Conn) search() error {
var sinfo *searchInfo
var isIn bool
c.core.router.doAdmin(func() { sinfo, isIn = c.core.searches.searches[*c.nodeID] })
if !isIn {
done := make(chan struct{}, 1)
var sess *sessionInfo
var err error
searchCompleted := func(sinfo *sessionInfo, e error) {
sess = sinfo
err = e
// FIXME close can be called multiple times, do a non-blocking send instead
select {
case done <- struct{}{}:
default:
}
}
c.core.router.doAdmin(func() {
sinfo = c.core.searches.newIterSearch(c.nodeID, c.nodeMask, searchCompleted)
sinfo.continueSearch()
})
<-done
c.session = sess
if c.session == nil && err == nil {
panic("search failed but returned no error")
}
if c.session != nil {
c.nodeID = crypto.GetNodeID(&c.session.theirPermPub)
for i := range c.nodeMask {
c.nodeMask[i] = 0xFF
}
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}
return err
} else {
return errors.New("search already exists")
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}
return nil
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}
func getDeadlineTimer(value *atomic.Value) *time.Timer {
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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
}
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func (c *Conn) Read(b []byte) (int, error) {
// Take a copy of the session object
sinfo := c.session
timer := getDeadlineTimer(&c.readDeadline)
defer util.TimerStop(timer)
var bs []byte
for {
// Wait for some traffic to come through from the session
select {
case <-c.close:
return 0, ConnError{errors.New("session closed"), false, false, true, 0}
case <-timer.C:
return 0, ConnError{errors.New("read timeout"), true, false, false, 0}
case p, ok := <-sinfo.recv:
// If the session is closed then do nothing
if !ok {
return 0, ConnError{errors.New("session closed"), false, false, true, 0}
}
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) {
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err = ConnError{errors.New("packet dropped due to invalid nonce"), false, true, false, 0}
return
}
// Decrypt the packet
var isOK bool
bs, isOK = crypto.BoxOpen(&sinfo.sharedSesKey, p.Payload, &p.Nonce)
// Check if we were unable to decrypt the packet for some reason and
// return an error if we couldn't
if !isOK {
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err = ConnError{errors.New("packet dropped due to decryption failure"), false, true, false, 0}
return
}
// Update the session
sinfo.updateNonce(&p.Nonce)
sinfo.time = time.Now()
sinfo.bytesRecvd += uint64(len(bs))
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}
// Hand over to the session worker
defer func() {
if recover() != nil {
err = ConnError{errors.New("read failed, session already closed"), false, false, true, 0}
close(done)
}
}() // In case we're racing with a close
// Send to worker
select {
case sinfo.worker <- workerFunc:
case <-c.close:
return 0, ConnError{errors.New("session closed"), false, false, true, 0}
case <-timer.C:
return 0, ConnError{errors.New("read timeout"), true, false, false, 0}
}
// Wait for the worker to finish
select {
case <-done: // Wait for the worker to finish, failing this can cause memory errors (util.[Get||Put]Bytes stuff)
case <-c.close:
return 0, ConnError{errors.New("session closed"), false, false, true, 0}
case <-timer.C:
return 0, ConnError{errors.New("read timeout"), true, false, false, 0}
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}
// Something went wrong in the session worker so abort
if err != nil {
if ce, ok := err.(*ConnError); ok && ce.Temporary() {
continue
}
return 0, err
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}
// Copy results to the output slice and clean up
copy(b, bs)
util.PutBytes(bs)
// 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(bs), nil
}
}
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}
func (c *Conn) Write(b []byte) (bytesWritten int, err error) {
sinfo := c.session
var packet []byte
done := make(chan struct{})
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written := len(b)
workerFunc := func() {
defer close(done)
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// Does the packet exceed the permitted size for the session?
if uint16(len(b)) > sinfo.getMTU() {
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written, err = 0, ConnError{errors.New("packet too big"), true, false, false, int(sinfo.getMTU())}
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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))
// The rest of this work is session keep-alive traffic
doSearch := func() {
routerWork := func() {
// 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
searchCompleted := func(sinfo *sessionInfo, e error) {}
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()
}
go func() { c.core.router.admin <- routerWork }()
}
switch {
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 {
sinfo.core.sessions.ping(sinfo)
}
case sinfo.reset && sinfo.pingTime.Before(sinfo.time):
sinfo.core.sessions.ping(sinfo)
default: // Don't do anything, to keep traffic throttled
}
}
// Set up a timer so this doesn't block forever
timer := getDeadlineTimer(&c.writeDeadline)
defer util.TimerStop(timer)
// Hand over to the session worker
defer func() {
if recover() != nil {
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err = ConnError{errors.New("write failed, session already closed"), false, false, true, 0}
close(done)
}
}() // In case we're racing with a close
select { // Send to worker
case sinfo.worker <- workerFunc:
case <-timer.C:
return 0, ConnError{errors.New("write timeout"), true, false, false, 0}
}
// Wait for the worker to finish, otherwise there are memory errors ([Get||Put]Bytes stuff)
<-done
// Give the packet to the router
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if written > 0 {
sinfo.core.router.out(packet)
}
// Finally return the number of bytes we wrote
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return written, err
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}
func (c *Conn) Close() (err error) {
c.mutex.Lock()
defer c.mutex.Unlock()
if c.session != nil {
// Close the session, if it hasn't been closed already
c.core.router.doAdmin(c.session.close)
}
func() {
defer func() {
recover()
err = ConnError{errors.New("close failed, session already closed"), false, false, true, 0}
}()
close(c.close) // Closes reader/writer goroutines
}()
return
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}
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
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}
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)
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return nil
}
func (c *Conn) SetWriteDeadline(t time.Time) error {
c.writeDeadline.Store(t)
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return nil
}