1243 lines
34 KiB
Go
1243 lines
34 KiB
Go
// Copyright (c) 2020 Tailscale Inc & AUTHORS All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package derp
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// TODO(crawshaw): with predefined serverKey in clients and HMAC on packets we could skip TLS
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import (
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"bufio"
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"context"
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crand "crypto/rand"
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"encoding/json"
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"errors"
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"expvar"
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"fmt"
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"io"
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"io/ioutil"
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"math/big"
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"os"
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"runtime"
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"strconv"
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"strings"
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"sync"
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"time"
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"golang.org/x/crypto/nacl/box"
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"golang.org/x/sync/errgroup"
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"tailscale.com/disco"
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"tailscale.com/metrics"
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"tailscale.com/types/key"
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"tailscale.com/types/logger"
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)
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var debug, _ = strconv.ParseBool(os.Getenv("DERP_DEBUG_LOGS"))
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const (
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perClientSendQueueDepth = 32 // packets buffered for sending
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writeTimeout = 2 * time.Second
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)
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const host64bit = (^uint(0) >> 32) & 1 // 1 on 64-bit, 0 on 32-bit
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const pad32bit = 4 - host64bit*4 // 0 on 64-bit, 4 on 32-bit
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// Server is a DERP server.
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type Server struct {
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// WriteTimeout, if non-zero, specifies how long to wait
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// before failing when writing to a client.
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WriteTimeout time.Duration
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// OnlyDisco controls whether, for tests, non-discovery packets
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// are dropped. This is used by magicsock tests to verify that
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// NAT traversal works (using DERP for out-of-band messaging)
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// but the packets themselves aren't going via DERP.
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OnlyDisco bool
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privateKey key.Private
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publicKey key.Public
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logf logger.Logf
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memSys0 uint64 // runtime.MemStats.Sys at start (or early-ish)
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meshKey string
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// Counters:
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_ [pad32bit]byte
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packetsSent, bytesSent expvar.Int
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packetsRecv, bytesRecv expvar.Int
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packetsDropped expvar.Int
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packetsDroppedReason metrics.LabelMap
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packetsDroppedUnknown *expvar.Int // unknown dst pubkey
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packetsDroppedFwdUnknown *expvar.Int // unknown dst pubkey on forward
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packetsDroppedGone *expvar.Int // dst conn shutting down
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packetsDroppedQueueHead *expvar.Int // queue full, drop head packet
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packetsDroppedQueueTail *expvar.Int // queue full, drop tail packet
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packetsDroppedWrite *expvar.Int // error writing to dst conn
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_ [pad32bit]byte
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packetsForwardedOut expvar.Int
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packetsForwardedIn expvar.Int
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peerGoneFrames expvar.Int // number of peer gone frames sent
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accepts expvar.Int
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curClients expvar.Int
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curHomeClients expvar.Int // ones with preferred
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clientsReplaced expvar.Int
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unknownFrames expvar.Int
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homeMovesIn expvar.Int // established clients announce home server moves in
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homeMovesOut expvar.Int // established clients announce home server moves out
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multiForwarderCreated expvar.Int
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multiForwarderDeleted expvar.Int
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removePktForwardOther expvar.Int
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mu sync.Mutex
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closed bool
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netConns map[Conn]chan struct{} // chan is closed when conn closes
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clients map[key.Public]*sclient
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clientsEver map[key.Public]bool // never deleted from, for stats; fine for now
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watchers map[*sclient]bool // mesh peer -> true
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// clientsMesh tracks all clients in the cluster, both locally
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// and to mesh peers. If the value is nil, that means the
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// peer is only local (and thus in the clients Map, but not
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// remote). If the value is non-nil, it's remote (+ maybe also
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// local).
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clientsMesh map[key.Public]PacketForwarder
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// sentTo tracks which peers have sent to which other peers,
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// and at which connection number. This isn't on sclient
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// because it includes intra-region forwarded packets as the
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// src.
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sentTo map[key.Public]map[key.Public]int64 // src => dst => dst's latest sclient.connNum
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}
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// PacketForwarder is something that can forward packets.
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//
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// It's mostly an inteface for circular dependency reasons; the
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// typical implementation is derphttp.Client. The other implementation
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// is a multiForwarder, which this package creates as needed if a
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// public key gets more than one PacketForwarder registered for it.
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type PacketForwarder interface {
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ForwardPacket(src, dst key.Public, payload []byte) error
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}
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// Conn is the subset of the underlying net.Conn the DERP Server needs.
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// It is a defined type so that non-net connections can be used.
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type Conn interface {
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io.Closer
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// The *Deadline methods follow the semantics of net.Conn.
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SetDeadline(time.Time) error
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SetReadDeadline(time.Time) error
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SetWriteDeadline(time.Time) error
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}
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// NewServer returns a new DERP server. It doesn't listen on its own.
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// Connections are given to it via Server.Accept.
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func NewServer(privateKey key.Private, logf logger.Logf) *Server {
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var ms runtime.MemStats
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runtime.ReadMemStats(&ms)
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s := &Server{
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privateKey: privateKey,
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publicKey: privateKey.Public(),
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logf: logf,
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packetsDroppedReason: metrics.LabelMap{Label: "reason"},
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clients: map[key.Public]*sclient{},
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clientsEver: map[key.Public]bool{},
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clientsMesh: map[key.Public]PacketForwarder{},
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netConns: map[Conn]chan struct{}{},
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memSys0: ms.Sys,
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watchers: map[*sclient]bool{},
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sentTo: map[key.Public]map[key.Public]int64{},
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}
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s.packetsDroppedUnknown = s.packetsDroppedReason.Get("unknown_dest")
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s.packetsDroppedFwdUnknown = s.packetsDroppedReason.Get("unknown_dest_on_fwd")
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s.packetsDroppedGone = s.packetsDroppedReason.Get("gone")
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s.packetsDroppedQueueHead = s.packetsDroppedReason.Get("queue_head")
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s.packetsDroppedQueueTail = s.packetsDroppedReason.Get("queue_tail")
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s.packetsDroppedWrite = s.packetsDroppedReason.Get("write_error")
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return s
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}
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// SetMesh sets the pre-shared key that regional DERP servers used to mesh
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// amongst themselves.
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//
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// It must be called before serving begins.
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func (s *Server) SetMeshKey(v string) {
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s.meshKey = v
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}
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// HasMeshKey reports whether the server is configured with a mesh key.
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func (s *Server) HasMeshKey() bool { return s.meshKey != "" }
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// MeshKey returns the configured mesh key, if any.
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func (s *Server) MeshKey() string { return s.meshKey }
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// PrivateKey returns the server's private key.
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func (s *Server) PrivateKey() key.Private { return s.privateKey }
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// PublicKey returns the server's public key.
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func (s *Server) PublicKey() key.Public { return s.publicKey }
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// Close closes the server and waits for the connections to disconnect.
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func (s *Server) Close() error {
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s.mu.Lock()
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wasClosed := s.closed
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s.closed = true
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s.mu.Unlock()
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if wasClosed {
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return nil
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}
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var closedChs []chan struct{}
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s.mu.Lock()
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for nc, closed := range s.netConns {
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nc.Close()
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closedChs = append(closedChs, closed)
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}
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s.mu.Unlock()
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for _, closed := range closedChs {
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<-closed
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}
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return nil
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}
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func (s *Server) isClosed() bool {
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s.mu.Lock()
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defer s.mu.Unlock()
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return s.closed
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}
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// Accept adds a new connection to the server and serves it.
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//
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// The provided bufio ReadWriter must be already connected to nc.
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// Accept blocks until the Server is closed or the connection closes
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// on its own.
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//
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// Accept closes nc.
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func (s *Server) Accept(nc Conn, brw *bufio.ReadWriter, remoteAddr string) {
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closed := make(chan struct{})
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s.mu.Lock()
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s.accepts.Add(1) // while holding s.mu for connNum read on next line
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connNum := s.accepts.Value() // expvar sadly doesn't return new value on Add(1)
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s.netConns[nc] = closed
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s.mu.Unlock()
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defer func() {
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nc.Close()
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close(closed)
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s.mu.Lock()
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delete(s.netConns, nc)
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s.mu.Unlock()
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}()
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if err := s.accept(nc, brw, remoteAddr, connNum); err != nil && !s.isClosed() {
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s.logf("derp: %s: %v", remoteAddr, err)
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}
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}
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// registerClient notes that client c is now authenticated and ready for packets.
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// If c's public key was already connected with a different connection, the prior one is closed.
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func (s *Server) registerClient(c *sclient) {
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s.mu.Lock()
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defer s.mu.Unlock()
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old := s.clients[c.key]
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if old == nil {
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c.logf("adding connection")
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} else {
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s.clientsReplaced.Add(1)
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c.logf("adding connection, replacing %s", old.remoteAddr)
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go old.nc.Close()
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}
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s.clients[c.key] = c
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s.clientsEver[c.key] = true
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if _, ok := s.clientsMesh[c.key]; !ok {
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s.clientsMesh[c.key] = nil // just for varz of total users in cluster
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}
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s.curClients.Add(1)
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s.broadcastPeerStateChangeLocked(c.key, true)
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}
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// broadcastPeerStateChangeLocked enqueues a message to all watchers
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// (other DERP nodes in the region, or trusted clients) that peer's
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// presence changed.
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//
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// s.mu must be held.
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func (s *Server) broadcastPeerStateChangeLocked(peer key.Public, present bool) {
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for w := range s.watchers {
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w.peerStateChange = append(w.peerStateChange, peerConnState{peer: peer, present: present})
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go w.requestMeshUpdate()
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}
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}
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// unregisterClient removes a client from the server.
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func (s *Server) unregisterClient(c *sclient) {
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s.mu.Lock()
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defer s.mu.Unlock()
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cur := s.clients[c.key]
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if cur == c {
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c.logf("removing connection")
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delete(s.clients, c.key)
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if v, ok := s.clientsMesh[c.key]; ok && v == nil {
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delete(s.clientsMesh, c.key)
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s.notePeerGoneFromRegionLocked(c.key)
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}
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s.broadcastPeerStateChangeLocked(c.key, false)
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}
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if c.canMesh {
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delete(s.watchers, c)
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}
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s.curClients.Add(-1)
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if c.preferred {
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s.curHomeClients.Add(-1)
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}
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}
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// notePeerGoneFromRegionLocked sends peerGone frames to parties that
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// key has sent to previously (whether those sends were from a local
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// client or forwarded). It must only be called after the key has
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// been removed from clientsMesh.
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func (s *Server) notePeerGoneFromRegionLocked(key key.Public) {
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if _, ok := s.clientsMesh[key]; ok {
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panic("usage")
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}
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// Find still-connected peers and either notify that we've gone away
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// so they can drop their route entries to us (issue 150)
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// or move them over to the active client (in case a replaced client
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// connection is being unregistered).
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for pubKey, connNum := range s.sentTo[key] {
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if peer, ok := s.clients[pubKey]; ok && peer.connNum == connNum {
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go peer.requestPeerGoneWrite(key)
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}
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}
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delete(s.sentTo, key)
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}
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func (s *Server) addWatcher(c *sclient) {
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if !c.canMesh {
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panic("invariant: addWatcher called without permissions")
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}
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if c.key == s.publicKey {
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// We're connecting to ourself. Do nothing.
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return
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}
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s.mu.Lock()
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defer s.mu.Unlock()
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// Queue messages for each already-connected client.
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for peer := range s.clients {
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c.peerStateChange = append(c.peerStateChange, peerConnState{peer: peer, present: true})
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}
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// And enroll the watcher in future updates (of both
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// connections & disconnections).
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s.watchers[c] = true
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go c.requestMeshUpdate()
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}
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func (s *Server) accept(nc Conn, brw *bufio.ReadWriter, remoteAddr string, connNum int64) error {
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br, bw := brw.Reader, brw.Writer
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nc.SetDeadline(time.Now().Add(10 * time.Second))
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if err := s.sendServerKey(bw); err != nil {
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return fmt.Errorf("send server key: %v", err)
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}
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nc.SetDeadline(time.Now().Add(10 * time.Second))
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clientKey, clientInfo, err := s.recvClientKey(br)
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if err != nil {
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return fmt.Errorf("receive client key: %v", err)
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}
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if err := s.verifyClient(clientKey, clientInfo); err != nil {
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return fmt.Errorf("client %x rejected: %v", clientKey, err)
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}
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// At this point we trust the client so we don't time out.
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nc.SetDeadline(time.Time{})
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ctx, cancel := context.WithCancel(context.Background())
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defer cancel()
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c := &sclient{
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connNum: connNum,
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s: s,
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key: clientKey,
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nc: nc,
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br: br,
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bw: bw,
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logf: logger.WithPrefix(s.logf, fmt.Sprintf("derp client %v/%x: ", remoteAddr, clientKey)),
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done: ctx.Done(),
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remoteAddr: remoteAddr,
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connectedAt: time.Now(),
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sendQueue: make(chan pkt, perClientSendQueueDepth),
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peerGone: make(chan key.Public),
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canMesh: clientInfo.MeshKey != "" && clientInfo.MeshKey == s.meshKey,
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}
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if c.canMesh {
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c.meshUpdate = make(chan struct{})
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}
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if clientInfo != nil {
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c.info = *clientInfo
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}
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s.registerClient(c)
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defer s.unregisterClient(c)
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err = s.sendServerInfo(bw, clientKey)
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if err != nil {
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return fmt.Errorf("send server info: %v", err)
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}
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return c.run(ctx)
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}
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// run serves the client until there's an error.
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// If the client hangs up or the server is closed, run returns nil, otherwise run returns an error.
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func (c *sclient) run(ctx context.Context) error {
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// Launch sender, but don't return from run until sender goroutine is done.
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var grp errgroup.Group
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sendCtx, cancelSender := context.WithCancel(ctx)
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grp.Go(func() error { return c.sendLoop(sendCtx) })
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defer func() {
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cancelSender()
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if err := grp.Wait(); err != nil && !c.s.isClosed() {
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c.logf("sender failed: %v", err)
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}
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}()
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for {
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ft, fl, err := readFrameHeader(c.br)
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if err != nil {
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if errors.Is(err, io.EOF) {
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c.logf("read EOF")
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return nil
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}
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if c.s.isClosed() {
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c.logf("closing; server closed")
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return nil
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}
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return fmt.Errorf("client %x: readFrameHeader: %w", c.key, err)
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}
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switch ft {
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case frameNotePreferred:
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err = c.handleFrameNotePreferred(ft, fl)
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case frameSendPacket:
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err = c.handleFrameSendPacket(ft, fl)
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case frameForwardPacket:
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err = c.handleFrameForwardPacket(ft, fl)
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case frameWatchConns:
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err = c.handleFrameWatchConns(ft, fl)
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case frameClosePeer:
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err = c.handleFrameClosePeer(ft, fl)
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default:
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err = c.handleUnknownFrame(ft, fl)
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}
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if err != nil {
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return err
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}
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}
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}
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func (c *sclient) handleUnknownFrame(ft frameType, fl uint32) error {
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_, err := io.CopyN(ioutil.Discard, c.br, int64(fl))
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return err
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}
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func (c *sclient) handleFrameNotePreferred(ft frameType, fl uint32) error {
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if fl != 1 {
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return fmt.Errorf("frameNotePreferred wrong size")
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}
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v, err := c.br.ReadByte()
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if err != nil {
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return fmt.Errorf("frameNotePreferred ReadByte: %v", err)
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}
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c.setPreferred(v != 0)
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return nil
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}
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func (c *sclient) handleFrameWatchConns(ft frameType, fl uint32) error {
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if fl != 0 {
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return fmt.Errorf("handleFrameWatchConns wrong size")
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}
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if !c.canMesh {
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return fmt.Errorf("insufficient permissions")
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}
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c.s.addWatcher(c)
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return nil
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}
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func (c *sclient) handleFrameClosePeer(ft frameType, fl uint32) error {
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if fl != keyLen {
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return fmt.Errorf("handleFrameClosePeer wrong size")
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}
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if !c.canMesh {
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return fmt.Errorf("insufficient permissions")
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}
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var targetKey key.Public
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if _, err := io.ReadFull(c.br, targetKey[:]); err != nil {
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return err
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}
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s := c.s
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s.mu.Lock()
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defer s.mu.Unlock()
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if target, ok := s.clients[targetKey]; ok {
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c.logf("frameClosePeer closing peer %x", targetKey)
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go target.nc.Close()
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} else {
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c.logf("frameClosePeer failed to find peer %x", targetKey)
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}
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return nil
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}
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// handleFrameForwardPacket reads a "forward packet" frame from the client
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// (which must be a trusted client, a peer in our mesh).
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func (c *sclient) handleFrameForwardPacket(ft frameType, fl uint32) error {
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if !c.canMesh {
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return fmt.Errorf("insufficient permissions")
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}
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s := c.s
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srcKey, dstKey, contents, err := s.recvForwardPacket(c.br, fl)
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if err != nil {
|
|
return fmt.Errorf("client %x: recvForwardPacket: %v", c.key, err)
|
|
}
|
|
s.packetsForwardedIn.Add(1)
|
|
|
|
s.mu.Lock()
|
|
dst := s.clients[dstKey]
|
|
if dst != nil {
|
|
s.notePeerSendLocked(srcKey, dst)
|
|
}
|
|
s.mu.Unlock()
|
|
|
|
if dst == nil {
|
|
s.packetsDropped.Add(1)
|
|
s.packetsDroppedFwdUnknown.Add(1)
|
|
if debug {
|
|
c.logf("dropping forwarded packet for unknown %x", dstKey)
|
|
}
|
|
return nil
|
|
}
|
|
|
|
return c.sendPkt(dst, pkt{
|
|
bs: contents,
|
|
src: srcKey,
|
|
})
|
|
}
|
|
|
|
// notePeerSendLocked records that src sent to dst. We keep track of
|
|
// that so when src disconnects, we can tell dst (if it's still
|
|
// around) that src is gone (a peerGone frame).
|
|
func (s *Server) notePeerSendLocked(src key.Public, dst *sclient) {
|
|
m, ok := s.sentTo[src]
|
|
if !ok {
|
|
m = map[key.Public]int64{}
|
|
s.sentTo[src] = m
|
|
}
|
|
m[dst.key] = dst.connNum
|
|
}
|
|
|
|
// handleFrameSendPacket reads a "send packet" frame from the client.
|
|
func (c *sclient) handleFrameSendPacket(ft frameType, fl uint32) error {
|
|
s := c.s
|
|
|
|
dstKey, contents, err := s.recvPacket(c.br, fl)
|
|
if err != nil {
|
|
return fmt.Errorf("client %x: recvPacket: %v", c.key, err)
|
|
}
|
|
|
|
if s.OnlyDisco && !disco.LooksLikeDiscoWrapper(contents) {
|
|
s.packetsDropped.Add(1)
|
|
return nil
|
|
}
|
|
|
|
var fwd PacketForwarder
|
|
s.mu.Lock()
|
|
dst := s.clients[dstKey]
|
|
if dst == nil {
|
|
fwd = s.clientsMesh[dstKey]
|
|
} else {
|
|
s.notePeerSendLocked(c.key, dst)
|
|
}
|
|
s.mu.Unlock()
|
|
|
|
if dst == nil {
|
|
if fwd != nil {
|
|
s.packetsForwardedOut.Add(1)
|
|
if err := fwd.ForwardPacket(c.key, dstKey, contents); err != nil {
|
|
// TODO:
|
|
return nil
|
|
}
|
|
return nil
|
|
}
|
|
s.packetsDropped.Add(1)
|
|
s.packetsDroppedUnknown.Add(1)
|
|
if debug {
|
|
c.logf("dropping packet for unknown %x", dstKey)
|
|
}
|
|
return nil
|
|
}
|
|
|
|
p := pkt{
|
|
bs: contents,
|
|
}
|
|
if dst.info.Version >= protocolSrcAddrs {
|
|
p.src = c.key
|
|
}
|
|
return c.sendPkt(dst, p)
|
|
}
|
|
|
|
func (c *sclient) sendPkt(dst *sclient, p pkt) error {
|
|
s := c.s
|
|
dstKey := dst.key
|
|
|
|
// Attempt to queue for sending up to 3 times. On each attempt, if
|
|
// the queue is full, try to drop from queue head to prioritize
|
|
// fresher packets.
|
|
for attempt := 0; attempt < 3; attempt++ {
|
|
select {
|
|
case <-dst.done:
|
|
s.packetsDropped.Add(1)
|
|
s.packetsDroppedGone.Add(1)
|
|
if debug {
|
|
c.logf("dropping packet for shutdown client %x", dstKey)
|
|
}
|
|
return nil
|
|
default:
|
|
}
|
|
select {
|
|
case dst.sendQueue <- p:
|
|
return nil
|
|
default:
|
|
}
|
|
|
|
select {
|
|
case <-dst.sendQueue:
|
|
s.packetsDropped.Add(1)
|
|
s.packetsDroppedQueueHead.Add(1)
|
|
if debug {
|
|
c.logf("dropping packet from client %x queue head", dstKey)
|
|
}
|
|
default:
|
|
}
|
|
}
|
|
// Failed to make room for packet. This can happen in a heavily
|
|
// contended queue with racing writers. Give up and tail-drop in
|
|
// this case to keep reader unblocked.
|
|
s.packetsDropped.Add(1)
|
|
s.packetsDroppedQueueTail.Add(1)
|
|
if debug {
|
|
c.logf("dropping packet from client %x queue tail", dstKey)
|
|
}
|
|
|
|
return nil
|
|
}
|
|
|
|
// requestPeerGoneWrite sends a request to write a "peer gone" frame
|
|
// that the provided peer has disconnected. It blocks until either the
|
|
// write request is scheduled, or the client has closed.
|
|
func (c *sclient) requestPeerGoneWrite(peer key.Public) {
|
|
select {
|
|
case c.peerGone <- peer:
|
|
case <-c.done:
|
|
}
|
|
}
|
|
|
|
func (c *sclient) requestMeshUpdate() {
|
|
if !c.canMesh {
|
|
panic("unexpected requestMeshUpdate")
|
|
}
|
|
select {
|
|
case c.meshUpdate <- struct{}{}:
|
|
case <-c.done:
|
|
}
|
|
}
|
|
|
|
func (s *Server) verifyClient(clientKey key.Public, info *clientInfo) error {
|
|
// TODO(crawshaw): implement policy constraints on who can use the DERP server
|
|
// TODO(bradfitz): ... and at what rate.
|
|
return nil
|
|
}
|
|
|
|
func (s *Server) sendServerKey(bw *bufio.Writer) error {
|
|
buf := make([]byte, 0, len(magic)+len(s.publicKey))
|
|
buf = append(buf, magic...)
|
|
buf = append(buf, s.publicKey[:]...)
|
|
return writeFrame(bw, frameServerKey, buf)
|
|
}
|
|
|
|
type serverInfo struct {
|
|
Version int // `json:"version,omitempty"`
|
|
}
|
|
|
|
func (s *Server) sendServerInfo(bw *bufio.Writer, clientKey key.Public) error {
|
|
var nonce [24]byte
|
|
if _, err := crand.Read(nonce[:]); err != nil {
|
|
return err
|
|
}
|
|
msg, err := json.Marshal(serverInfo{Version: protocolVersion})
|
|
if err != nil {
|
|
return err
|
|
}
|
|
|
|
msgbox := box.Seal(nil, msg, &nonce, clientKey.B32(), s.privateKey.B32())
|
|
if err := writeFrameHeader(bw, frameServerInfo, nonceLen+uint32(len(msgbox))); err != nil {
|
|
return err
|
|
}
|
|
if _, err := bw.Write(nonce[:]); err != nil {
|
|
return err
|
|
}
|
|
if _, err := bw.Write(msgbox); err != nil {
|
|
return err
|
|
}
|
|
return bw.Flush()
|
|
}
|
|
|
|
// recvClientKey reads the frameClientInfo frame from the client (its
|
|
// proof of identity) upon its initial connection. It should be
|
|
// considered especially untrusted at this point.
|
|
func (s *Server) recvClientKey(br *bufio.Reader) (clientKey key.Public, info *clientInfo, err error) {
|
|
fl, err := readFrameTypeHeader(br, frameClientInfo)
|
|
if err != nil {
|
|
return zpub, nil, err
|
|
}
|
|
const minLen = keyLen + nonceLen
|
|
if fl < minLen {
|
|
return zpub, nil, errors.New("short client info")
|
|
}
|
|
// We don't trust the client at all yet, so limit its input size to limit
|
|
// things like JSON resource exhausting (http://github.com/golang/go/issues/31789).
|
|
if fl > 256<<10 {
|
|
return zpub, nil, errors.New("long client info")
|
|
}
|
|
if _, err := io.ReadFull(br, clientKey[:]); err != nil {
|
|
return zpub, nil, err
|
|
}
|
|
var nonce [24]byte
|
|
if _, err := io.ReadFull(br, nonce[:]); err != nil {
|
|
return zpub, nil, fmt.Errorf("nonce: %v", err)
|
|
}
|
|
msgLen := int(fl - minLen)
|
|
msgbox := make([]byte, msgLen)
|
|
if _, err := io.ReadFull(br, msgbox); err != nil {
|
|
return zpub, nil, fmt.Errorf("msgbox: %v", err)
|
|
}
|
|
msg, ok := box.Open(nil, msgbox, &nonce, (*[32]byte)(&clientKey), s.privateKey.B32())
|
|
if !ok {
|
|
return zpub, nil, fmt.Errorf("msgbox: cannot open len=%d with client key %x", msgLen, clientKey[:])
|
|
}
|
|
info = new(clientInfo)
|
|
if err := json.Unmarshal(msg, info); err != nil {
|
|
return zpub, nil, fmt.Errorf("msg: %v", err)
|
|
}
|
|
return clientKey, info, nil
|
|
}
|
|
|
|
func (s *Server) recvPacket(br *bufio.Reader, frameLen uint32) (dstKey key.Public, contents []byte, err error) {
|
|
if frameLen < keyLen {
|
|
return zpub, nil, errors.New("short send packet frame")
|
|
}
|
|
if _, err := io.ReadFull(br, dstKey[:]); err != nil {
|
|
return zpub, nil, err
|
|
}
|
|
packetLen := frameLen - keyLen
|
|
if packetLen > MaxPacketSize {
|
|
return zpub, nil, fmt.Errorf("data packet longer (%d) than max of %v", packetLen, MaxPacketSize)
|
|
}
|
|
contents = make([]byte, packetLen)
|
|
if _, err := io.ReadFull(br, contents); err != nil {
|
|
return zpub, nil, err
|
|
}
|
|
s.packetsRecv.Add(1)
|
|
s.bytesRecv.Add(int64(len(contents)))
|
|
return dstKey, contents, nil
|
|
}
|
|
|
|
// zpub is the key.Public zero value.
|
|
var zpub key.Public
|
|
|
|
func (s *Server) recvForwardPacket(br *bufio.Reader, frameLen uint32) (srcKey, dstKey key.Public, contents []byte, err error) {
|
|
if frameLen < keyLen*2 {
|
|
return zpub, zpub, nil, errors.New("short send packet frame")
|
|
}
|
|
if _, err := io.ReadFull(br, srcKey[:]); err != nil {
|
|
return zpub, zpub, nil, err
|
|
}
|
|
if _, err := io.ReadFull(br, dstKey[:]); err != nil {
|
|
return zpub, zpub, nil, err
|
|
}
|
|
packetLen := frameLen - keyLen*2
|
|
if packetLen > MaxPacketSize {
|
|
return zpub, zpub, nil, fmt.Errorf("data packet longer (%d) than max of %v", packetLen, MaxPacketSize)
|
|
}
|
|
contents = make([]byte, packetLen)
|
|
if _, err := io.ReadFull(br, contents); err != nil {
|
|
return zpub, zpub, nil, err
|
|
}
|
|
// TODO: was s.packetsRecv.Add(1)
|
|
// TODO: was s.bytesRecv.Add(int64(len(contents)))
|
|
return srcKey, dstKey, contents, nil
|
|
}
|
|
|
|
// sclient is a client connection to the server.
|
|
//
|
|
// (The "s" prefix is to more explicitly distinguish it from Client in derp_client.go)
|
|
type sclient struct {
|
|
// Static after construction.
|
|
connNum int64 // process-wide unique counter, incremented each Accept
|
|
s *Server
|
|
nc Conn
|
|
key key.Public
|
|
info clientInfo
|
|
logf logger.Logf
|
|
done <-chan struct{} // closed when connection closes
|
|
remoteAddr string // usually ip:port from net.Conn.RemoteAddr().String()
|
|
sendQueue chan pkt // packets queued to this client; never closed
|
|
peerGone chan key.Public // write request that a previous sender has disconnected (not used by mesh peers)
|
|
meshUpdate chan struct{} // write request to write peerStateChange
|
|
canMesh bool // clientInfo had correct mesh token for inter-region routing
|
|
|
|
// Owned by run, not thread-safe.
|
|
br *bufio.Reader
|
|
connectedAt time.Time
|
|
preferred bool
|
|
|
|
// Owned by sender, not thread-safe.
|
|
bw *bufio.Writer
|
|
|
|
// Guarded by s.mu
|
|
//
|
|
// peerStateChange is used by mesh peers (a set of regional
|
|
// DERP servers) and contains records that need to be sent to
|
|
// the client for them to update their map of who's connected
|
|
// to this node.
|
|
peerStateChange []peerConnState
|
|
}
|
|
|
|
// peerConnState represents whether a peer is connected to the server
|
|
// or not.
|
|
type peerConnState struct {
|
|
peer key.Public
|
|
present bool
|
|
}
|
|
|
|
// pkt is a request to write a data frame to an sclient.
|
|
type pkt struct {
|
|
// src is the who's the sender of the packet.
|
|
src key.Public
|
|
|
|
// bs is the data packet bytes.
|
|
// The memory is owned by pkt.
|
|
bs []byte
|
|
|
|
// TODO(danderson): enqueue time, to measure queue latency?
|
|
}
|
|
|
|
func (c *sclient) setPreferred(v bool) {
|
|
if c.preferred == v {
|
|
return
|
|
}
|
|
c.preferred = v
|
|
var homeMove *expvar.Int
|
|
if v {
|
|
c.s.curHomeClients.Add(1)
|
|
homeMove = &c.s.homeMovesIn
|
|
} else {
|
|
c.s.curHomeClients.Add(-1)
|
|
homeMove = &c.s.homeMovesOut
|
|
}
|
|
|
|
// Keep track of varz for home serve moves in/out. But ignore
|
|
// the initial packet set when a client connects, which we
|
|
// assume happens within 5 seconds. In any case, just for
|
|
// graphs, so not important to miss a move. But it shouldn't:
|
|
// the netcheck/re-STUNs in magicsock only happen about every
|
|
// 30 seconds.
|
|
if time.Since(c.connectedAt) > 5*time.Second {
|
|
homeMove.Add(1)
|
|
}
|
|
}
|
|
|
|
func (c *sclient) sendLoop(ctx context.Context) error {
|
|
defer func() {
|
|
// If the sender shuts down unilaterally due to an error, close so
|
|
// that the receive loop unblocks and cleans up the rest.
|
|
c.nc.Close()
|
|
|
|
// Drain the send queue to count dropped packets
|
|
for {
|
|
select {
|
|
case <-c.sendQueue:
|
|
c.s.packetsDropped.Add(1)
|
|
c.s.packetsDroppedGone.Add(1)
|
|
if debug {
|
|
c.logf("dropping packet for shutdown %x", c.key)
|
|
}
|
|
default:
|
|
return
|
|
}
|
|
}
|
|
}()
|
|
|
|
jitterMs, err := crand.Int(crand.Reader, big.NewInt(5000))
|
|
if err != nil {
|
|
panic(err)
|
|
}
|
|
jitter := time.Duration(jitterMs.Int64()) * time.Millisecond
|
|
keepAliveTick := time.NewTicker(keepAlive + jitter)
|
|
defer keepAliveTick.Stop()
|
|
|
|
var werr error // last write error
|
|
for {
|
|
if werr != nil {
|
|
return werr
|
|
}
|
|
// First, a non-blocking select (with a default) that
|
|
// does as many non-flushing writes as possible.
|
|
select {
|
|
case <-ctx.Done():
|
|
return nil
|
|
case peer := <-c.peerGone:
|
|
werr = c.sendPeerGone(peer)
|
|
continue
|
|
case <-c.meshUpdate:
|
|
werr = c.sendMeshUpdates()
|
|
continue
|
|
case msg := <-c.sendQueue:
|
|
werr = c.sendPacket(msg.src, msg.bs)
|
|
continue
|
|
case <-keepAliveTick.C:
|
|
werr = c.sendKeepAlive()
|
|
continue
|
|
default:
|
|
// Flush any writes from the 3 sends above, or from
|
|
// the blocking loop below.
|
|
if werr = c.bw.Flush(); werr != nil {
|
|
return werr
|
|
}
|
|
}
|
|
|
|
// Then a blocking select with same:
|
|
select {
|
|
case <-ctx.Done():
|
|
return nil
|
|
case peer := <-c.peerGone:
|
|
werr = c.sendPeerGone(peer)
|
|
case <-c.meshUpdate:
|
|
werr = c.sendMeshUpdates()
|
|
continue
|
|
case msg := <-c.sendQueue:
|
|
werr = c.sendPacket(msg.src, msg.bs)
|
|
case <-keepAliveTick.C:
|
|
werr = c.sendKeepAlive()
|
|
}
|
|
}
|
|
}
|
|
|
|
func (c *sclient) setWriteDeadline() {
|
|
c.nc.SetWriteDeadline(time.Now().Add(writeTimeout))
|
|
}
|
|
|
|
// sendKeepAlive sends a keep-alive frame, without flushing.
|
|
func (c *sclient) sendKeepAlive() error {
|
|
c.setWriteDeadline()
|
|
return writeFrameHeader(c.bw, frameKeepAlive, 0)
|
|
}
|
|
|
|
// sendPeerGone sends a peerGone frame, without flushing.
|
|
func (c *sclient) sendPeerGone(peer key.Public) error {
|
|
c.s.peerGoneFrames.Add(1)
|
|
c.setWriteDeadline()
|
|
if err := writeFrameHeader(c.bw, framePeerGone, keyLen); err != nil {
|
|
return err
|
|
}
|
|
_, err := c.bw.Write(peer[:])
|
|
return err
|
|
}
|
|
|
|
// sendPeerPresent sends a peerPresent frame, without flushing.
|
|
func (c *sclient) sendPeerPresent(peer key.Public) error {
|
|
c.setWriteDeadline()
|
|
if err := writeFrameHeader(c.bw, framePeerPresent, keyLen); err != nil {
|
|
return err
|
|
}
|
|
_, err := c.bw.Write(peer[:])
|
|
return err
|
|
}
|
|
|
|
// sendMeshUpdates drains as many mesh peerStateChange entries as
|
|
// possible into the write buffer WITHOUT flushing or otherwise
|
|
// blocking (as it holds c.s.mu while working). If it can't drain them
|
|
// all, it schedules itself to be called again in the future.
|
|
func (c *sclient) sendMeshUpdates() error {
|
|
c.s.mu.Lock()
|
|
defer c.s.mu.Unlock()
|
|
|
|
writes := 0
|
|
for _, pcs := range c.peerStateChange {
|
|
if c.bw.Available() <= frameHeaderLen+keyLen {
|
|
break
|
|
}
|
|
var err error
|
|
if pcs.present {
|
|
err = c.sendPeerPresent(pcs.peer)
|
|
} else {
|
|
err = c.sendPeerGone(pcs.peer)
|
|
}
|
|
if err != nil {
|
|
// Shouldn't happen, though, as we're writing
|
|
// into available buffer space, not the
|
|
// network.
|
|
return err
|
|
}
|
|
writes++
|
|
}
|
|
|
|
remain := copy(c.peerStateChange, c.peerStateChange[writes:])
|
|
c.peerStateChange = c.peerStateChange[:remain]
|
|
|
|
// Did we manage to write them all into the bufio buffer without flushing?
|
|
if len(c.peerStateChange) == 0 {
|
|
if cap(c.peerStateChange) > 16 {
|
|
c.peerStateChange = nil
|
|
}
|
|
} else {
|
|
// Didn't finish in the buffer space provided; schedule a future run.
|
|
go c.requestMeshUpdate()
|
|
}
|
|
return nil
|
|
}
|
|
|
|
// sendPacket writes contents to the client in a RecvPacket frame. If
|
|
// srcKey.IsZero, uses the old DERPv1 framing format, otherwise uses
|
|
// DERPv2. The bytes of contents are only valid until this function
|
|
// returns, do not retain slices.
|
|
// It does not flush its bufio.Writer.
|
|
func (c *sclient) sendPacket(srcKey key.Public, contents []byte) (err error) {
|
|
defer func() {
|
|
// Stats update.
|
|
if err != nil {
|
|
c.s.packetsDropped.Add(1)
|
|
c.s.packetsDroppedWrite.Add(1)
|
|
if debug {
|
|
c.logf("dropping packet to %x: %v", c.key, err)
|
|
}
|
|
} else {
|
|
c.s.packetsSent.Add(1)
|
|
c.s.bytesSent.Add(int64(len(contents)))
|
|
}
|
|
}()
|
|
|
|
c.setWriteDeadline()
|
|
|
|
withKey := !srcKey.IsZero()
|
|
pktLen := len(contents)
|
|
if withKey {
|
|
pktLen += len(srcKey)
|
|
}
|
|
if err = writeFrameHeader(c.bw, frameRecvPacket, uint32(pktLen)); err != nil {
|
|
return err
|
|
}
|
|
if withKey {
|
|
if _, err = c.bw.Write(srcKey[:]); err != nil {
|
|
return err
|
|
}
|
|
}
|
|
_, err = c.bw.Write(contents)
|
|
return err
|
|
}
|
|
|
|
// AddPacketForwarder registers fwd as a packet forwarder for dst.
|
|
// fwd must be comparable.
|
|
func (s *Server) AddPacketForwarder(dst key.Public, fwd PacketForwarder) {
|
|
s.mu.Lock()
|
|
defer s.mu.Unlock()
|
|
if prev, ok := s.clientsMesh[dst]; ok {
|
|
if prev == fwd {
|
|
// Duplicate registration of same forwarder. Ignore.
|
|
return
|
|
}
|
|
if m, ok := prev.(multiForwarder); ok {
|
|
if _, ok := m[fwd]; !ok {
|
|
// Duplicate registration of same forwarder in set; ignore.
|
|
return
|
|
}
|
|
m[fwd] = m.maxVal() + 1
|
|
return
|
|
}
|
|
if prev != nil {
|
|
// Otherwise, the existing value is not a set,
|
|
// not a dup, and not local-only (nil) so make
|
|
// it a set.
|
|
fwd = multiForwarder{
|
|
prev: 1, // existed 1st, higher priority
|
|
fwd: 2, // the passed in fwd is in 2nd place
|
|
}
|
|
s.multiForwarderCreated.Add(1)
|
|
}
|
|
}
|
|
s.clientsMesh[dst] = fwd
|
|
}
|
|
|
|
// RemovePacketForwarder removes fwd as a packet forwarder for dst.
|
|
// fwd must be comparable.
|
|
func (s *Server) RemovePacketForwarder(dst key.Public, fwd PacketForwarder) {
|
|
s.mu.Lock()
|
|
defer s.mu.Unlock()
|
|
v, ok := s.clientsMesh[dst]
|
|
if !ok {
|
|
return
|
|
}
|
|
if m, ok := v.(multiForwarder); ok {
|
|
if len(m) < 2 {
|
|
panic("unexpected")
|
|
}
|
|
delete(m, fwd)
|
|
// If fwd was in m and we no longer need to be a
|
|
// multiForwarder, replace the entry with the
|
|
// remaining PacketForwarder.
|
|
if len(m) == 1 {
|
|
var remain PacketForwarder
|
|
for k := range m {
|
|
remain = k
|
|
}
|
|
s.clientsMesh[dst] = remain
|
|
s.multiForwarderDeleted.Add(1)
|
|
}
|
|
return
|
|
}
|
|
if v != fwd {
|
|
s.removePktForwardOther.Add(1)
|
|
// Delete of an entry that wasn't in the
|
|
// map. Harmless, so ignore.
|
|
// (This might happen if a user is moving around
|
|
// between nodes and/or the server sent duplicate
|
|
// connection change broadcasts.)
|
|
return
|
|
}
|
|
|
|
if _, isLocal := s.clients[dst]; isLocal {
|
|
s.clientsMesh[dst] = nil
|
|
} else {
|
|
delete(s.clientsMesh, dst)
|
|
s.notePeerGoneFromRegionLocked(dst)
|
|
}
|
|
}
|
|
|
|
// multiForwarder is a PacketForwarder that represents a set of
|
|
// forwarding options. It's used in the rare cases that a client is
|
|
// connected to multiple DERP nodes in a region. That shouldn't really
|
|
// happen except for perhaps during brief moments while the client is
|
|
// reconfiguring, in which case we don't want to forget where the
|
|
// client is. The map value is unique connection number; the lowest
|
|
// one has been seen the longest. It's used to make sure we forward
|
|
// packets consistently to the same node and don't pick randomly.
|
|
type multiForwarder map[PacketForwarder]uint8
|
|
|
|
func (m multiForwarder) maxVal() (max uint8) {
|
|
for _, v := range m {
|
|
if v > max {
|
|
max = v
|
|
}
|
|
}
|
|
return
|
|
}
|
|
|
|
func (m multiForwarder) ForwardPacket(src, dst key.Public, payload []byte) error {
|
|
var fwd PacketForwarder
|
|
var lowest uint8
|
|
for k, v := range m {
|
|
if fwd == nil || v < lowest {
|
|
fwd = k
|
|
lowest = v
|
|
}
|
|
}
|
|
return fwd.ForwardPacket(src, dst, payload)
|
|
}
|
|
|
|
func (s *Server) expVarFunc(f func() interface{}) expvar.Func {
|
|
return expvar.Func(func() interface{} {
|
|
s.mu.Lock()
|
|
defer s.mu.Unlock()
|
|
return f()
|
|
})
|
|
}
|
|
|
|
// ExpVar returns an expvar variable suitable for registering with expvar.Publish.
|
|
func (s *Server) ExpVar() expvar.Var {
|
|
m := new(metrics.Set)
|
|
m.Set("counter_unique_clients_ever", s.expVarFunc(func() interface{} { return len(s.clientsEver) }))
|
|
m.Set("gauge_memstats_sys0", expvar.Func(func() interface{} { return int64(s.memSys0) }))
|
|
m.Set("gauge_watchers", s.expVarFunc(func() interface{} { return len(s.watchers) }))
|
|
m.Set("gauge_current_connections", &s.curClients)
|
|
m.Set("gauge_current_home_connections", &s.curHomeClients)
|
|
m.Set("gauge_clients_total", expvar.Func(func() interface{} { return len(s.clientsMesh) }))
|
|
m.Set("gauge_clients_local", expvar.Func(func() interface{} { return len(s.clients) }))
|
|
m.Set("gauge_clients_remote", expvar.Func(func() interface{} { return len(s.clientsMesh) - len(s.clients) }))
|
|
m.Set("accepts", &s.accepts)
|
|
m.Set("clients_replaced", &s.clientsReplaced)
|
|
m.Set("bytes_received", &s.bytesRecv)
|
|
m.Set("bytes_sent", &s.bytesSent)
|
|
m.Set("packets_dropped", &s.packetsDropped)
|
|
m.Set("counter_packets_dropped_reason", &s.packetsDroppedReason)
|
|
m.Set("packets_sent", &s.packetsSent)
|
|
m.Set("packets_received", &s.packetsRecv)
|
|
m.Set("unknown_frames", &s.unknownFrames)
|
|
m.Set("home_moves_in", &s.homeMovesIn)
|
|
m.Set("home_moves_out", &s.homeMovesOut)
|
|
m.Set("peer_gone_frames", &s.peerGoneFrames)
|
|
m.Set("packets_forwarded_out", &s.packetsForwardedOut)
|
|
m.Set("packets_forwarded_in", &s.packetsForwardedIn)
|
|
m.Set("multiforwarder_created", &s.multiForwarderCreated)
|
|
m.Set("multiforwarder_deleted", &s.multiForwarderDeleted)
|
|
m.Set("packet_forwarder_delete_other_value", &s.removePktForwardOther)
|
|
return m
|
|
}
|
|
|
|
func (s *Server) ConsistencyCheck() error {
|
|
s.mu.Lock()
|
|
defer s.mu.Unlock()
|
|
|
|
var errs []string
|
|
|
|
var nilMeshNotInClient int
|
|
for k, f := range s.clientsMesh {
|
|
if f == nil {
|
|
if _, ok := s.clients[k]; !ok {
|
|
nilMeshNotInClient++
|
|
}
|
|
}
|
|
}
|
|
if nilMeshNotInClient != 0 {
|
|
errs = append(errs, fmt.Sprintf("%d s.clientsMesh keys not in s.clients", nilMeshNotInClient))
|
|
}
|
|
|
|
var clientNotInMesh int
|
|
for k := range s.clients {
|
|
if _, ok := s.clientsMesh[k]; !ok {
|
|
clientNotInMesh++
|
|
}
|
|
}
|
|
if clientNotInMesh != 0 {
|
|
errs = append(errs, fmt.Sprintf("%d s.clients keys not in s.clientsMesh", clientNotInMesh))
|
|
}
|
|
|
|
if s.curClients.Value() != int64(len(s.clients)) {
|
|
errs = append(errs, fmt.Sprintf("expvar connections = %d != clients map says of %d",
|
|
s.curClients.Value(),
|
|
len(s.clients)))
|
|
}
|
|
if len(errs) == 0 {
|
|
return nil
|
|
}
|
|
return errors.New(strings.Join(errs, ", "))
|
|
}
|