control/controlclient: add Noise client

Updates #3488

Signed-off-by: Maisem Ali <maisem@tailscale.com>

cmd/tailscaled/depaware.txt

@@ -170,7 +170,9 @@ tailscale.com/cmd/tailscaled dependencies: (generated by github.com/tailscale/de
         tailscale.com/client/tailscale                               from tailscale.com/derp
         tailscale.com/client/tailscale/apitype                       from tailscale.com/client/tailscale+
         tailscale.com/cmd/tailscaled/childproc                       from tailscale.com/cmd/tailscaled+
+        tailscale.com/control/controlbase                            from tailscale.com/control/controlclient+
         tailscale.com/control/controlclient                          from tailscale.com/ipn/ipnlocal+
+        tailscale.com/control/controlhttp                            from tailscale.com/control/controlclient
         tailscale.com/control/controlknobs                           from tailscale.com/control/controlclient+
         tailscale.com/derp                                           from tailscale.com/derp/derphttp+
         tailscale.com/derp/derphttp                                  from tailscale.com/cmd/tailscaled+
@@ -276,7 +278,7 @@ tailscale.com/cmd/tailscaled dependencies: (generated by github.com/tailscale/de
    W 💣 tailscale.com/wgengine/winnet                                from tailscale.com/wgengine/router
         golang.org/x/crypto/acme                                     from tailscale.com/ipn/localapi
         golang.org/x/crypto/blake2b                                  from golang.org/x/crypto/nacl/box
-        golang.org/x/crypto/blake2s                                  from golang.zx2c4.com/wireguard/device
+        golang.org/x/crypto/blake2s                                  from golang.zx2c4.com/wireguard/device+
   LD    golang.org/x/crypto/blowfish                                 from golang.org/x/crypto/ssh/internal/bcrypt_pbkdf
         golang.org/x/crypto/chacha20                                 from golang.org/x/crypto/chacha20poly1305+
         golang.org/x/crypto/chacha20poly1305                         from crypto/tls+
@@ -284,7 +286,7 @@ tailscale.com/cmd/tailscaled dependencies: (generated by github.com/tailscale/de
         golang.org/x/crypto/cryptobyte/asn1                          from crypto/ecdsa+
         golang.org/x/crypto/curve25519                               from crypto/tls+
   LD    golang.org/x/crypto/ed25519                                  from golang.org/x/crypto/ssh
-        golang.org/x/crypto/hkdf                                     from crypto/tls
+        golang.org/x/crypto/hkdf                                     from crypto/tls+
         golang.org/x/crypto/nacl/box                                 from tailscale.com/types/key
         golang.org/x/crypto/nacl/secretbox                           from golang.org/x/crypto/nacl/box
         golang.org/x/crypto/poly1305                                 from golang.org/x/crypto/chacha20poly1305+
@@ -303,7 +305,7 @@ tailscale.com/cmd/tailscaled dependencies: (generated by github.com/tailscale/de
         golang.org/x/net/proxy                                       from tailscale.com/net/netns
    D    golang.org/x/net/route                                       from net+
         golang.org/x/sync/errgroup                                   from github.com/tailscale/goupnp/httpu+
-        golang.org/x/sync/singleflight                               from tailscale.com/net/dnscache
+        golang.org/x/sync/singleflight                               from tailscale.com/net/dnscache+
         golang.org/x/sys/cpu                                         from golang.org/x/crypto/blake2b+
   LD    golang.org/x/sys/unix                                        from github.com/insomniacslk/dhcp/interfaces+
    W    golang.org/x/sys/windows                                     from github.com/go-ole/go-ole+

control/controlclient/direct.go

@@ -27,6 +27,7 @@
 	"time"
 
 	"go4.org/mem"
+	"golang.org/x/sync/singleflight"
 	"inet.af/netaddr"
 	"tailscale.com/control/controlknobs"
 	"tailscale.com/envknob"
@@ -73,6 +74,9 @@ type Direct struct {
 	serverKey      key.MachinePublic // original ("legacy") nacl crypto_box-based public key
 	serverNoiseKey key.MachinePublic
 
+	sfGroup     singleflight.Group // protects noiseClient creation.
+	noiseClient *noiseClient
+
 	persist      persist.Persist
 	authKey      string
 	tryingNewKey key.NodePrivate
@@ -203,6 +207,19 @@ func NewDirect(opts Options) (*Direct, error) {
 	return c, nil
 }
 
+// Close closes the underlying Noise connection(s).
+func (c *Direct) Close() error {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+	if c.noiseClient != nil {
+		if err := c.noiseClient.Close(); err != nil {
+			return err
+		}
+	}
+	c.noiseClient = nil
+	return nil
+}
+
 // SetHostinfo clones the provided Hostinfo and remembers it for the
 // next update. It reports whether the Hostinfo has changed.
 func (c *Direct) SetHostinfo(hi *tailcfg.Hostinfo) bool {
@@ -1204,6 +1221,39 @@ func sleepAsRequested(ctx context.Context, logf logger.Logf, timeoutReset chan<-
 	}
 }
 
+// getNoiseClient returns the noise client, creating one if one doesn't exist.
+func (c *Direct) getNoiseClient() (*noiseClient, error) {
+	c.mu.Lock()
+	serverNoiseKey := c.serverNoiseKey
+	nc := c.noiseClient
+	c.mu.Unlock()
+	if serverNoiseKey.IsZero() {
+		return nil, errors.New("zero serverNoiseKey")
+	}
+	if nc != nil {
+		return nc, nil
+	}
+	np, err, _ := c.sfGroup.Do("noise", func() (interface{}, error) {
+		k, err := c.getMachinePrivKey()
+		if err != nil {
+			return nil, err
+		}
+
+		nc, err = newNoiseClient(k, serverNoiseKey, c.serverURL)
+		if err != nil {
+			return nil, err
+		}
+		c.mu.Lock()
+		defer c.mu.Unlock()
+		c.noiseClient = nc
+		return nc, nil
+	})
+	if err != nil {
+		return nil, err
+	}
+	return np.(*noiseClient), nil
+}
+
 // SetDNS sends the SetDNSRequest request to the control plane server,
 // requesting a DNS record be created or updated.
 func (c *Direct) SetDNS(ctx context.Context, req *tailcfg.SetDNSRequest) (err error) {

control/controlclient/noise.go

@@ -0,0 +1,141 @@
+// Copyright (c) 2022 Tailscale Inc & AUTHORS All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package controlclient
+
+import (
+	"context"
+	"crypto/tls"
+	"fmt"
+	"net"
+	"net/http"
+	"net/url"
+	"sync"
+	"time"
+
+	"golang.org/x/net/http2"
+	"tailscale.com/control/controlbase"
+	"tailscale.com/control/controlhttp"
+	"tailscale.com/types/key"
+	"tailscale.com/util/multierr"
+)
+
+// noiseConn is a wrapper around controlbase.Conn.
+// It allows attaching an ID to a connection to allow
+// cleaning up references in the pool when the connection
+// is closed.
+type noiseConn struct {
+	*controlbase.Conn
+	id   int
+	pool *noiseClient
+}
+
+func (c *noiseConn) Close() error {
+	if err := c.Conn.Close(); err != nil {
+		return err
+	}
+	c.pool.connClosed(c.id)
+	return nil
+}
+
+// noiseClient provides a http.Client to connect to tailcontrol over
+// the ts2021 protocol.
+type noiseClient struct {
+	*http.Client // HTTP client used to talk to tailcontrol
+	privKey      key.MachinePrivate
+	serverPubKey key.MachinePublic
+	serverHost   string // the host:port part of serverURL
+
+	// mu only protects the following variables.
+	mu       sync.Mutex
+	nextID   int
+	connPool map[int]*noiseConn // active connections not yet closed; see noiseConn.Close
+}
+
+// newNoiseClient returns a new noiseClient for the provided server and machine key.
+// serverURL is of the form https://<host>:<port> (no trailing slash).
+func newNoiseClient(priKey key.MachinePrivate, serverPubKey key.MachinePublic, serverURL string) (*noiseClient, error) {
+	u, err := url.Parse(serverURL)
+	if err != nil {
+		return nil, err
+	}
+	var host string
+	if u.Port() != "" {
+		// If there is an explicit port specified use it.
+		host = u.Host
+	} else {
+		// Otherwise, controlhttp.Dial expects an http endpoint.
+		host = fmt.Sprintf("%v:80", u.Hostname())
+	}
+	np := &noiseClient{
+		serverPubKey: serverPubKey,
+		privKey:      priKey,
+		serverHost:   host,
+	}
+
+	// Create a new http.Client which dials out using nc.Dial.
+	np.Client = &http.Client{
+		Transport: &http2.Transport{
+			ReadIdleTimeout: time.Minute,
+			DialTLS:         np.dial,
+		},
+	}
+
+	return np, nil
+}
+
+// connClosed removes the connection with the provided ID from the pool
+// of active connections.
+func (nc *noiseClient) connClosed(id int) {
+	nc.mu.Lock()
+	defer nc.mu.Unlock()
+	delete(nc.connPool, id)
+}
+
+// Close closes all the underlying noise connections.
+// It is a no-op and returns nil if the connection is already closed.
+func (nc *noiseClient) Close() error {
+	nc.mu.Lock()
+	conns := nc.connPool
+	nc.connPool = nil
+	nc.mu.Unlock()
+
+	var errors []error
+	for _, c := range conns {
+		if err := c.Close(); err != nil {
+			errors = append(errors, err)
+		}
+	}
+	return multierr.New(errors...)
+}
+
+// dial opens a new connection to tailcontrol, fetching the server noise key
+// if not cached. It implements the signature needed by http2.Transport.DialTLS
+// but ignores all params as it only dials out to the server the noiseClient was
+// created for.
+func (nc *noiseClient) dial(_, _ string, _ *tls.Config) (net.Conn, error) {
+	nc.mu.Lock()
+	connID := nc.nextID
+	if nc.connPool == nil {
+		nc.connPool = make(map[int]*noiseConn)
+	}
+	nc.nextID++
+	nc.mu.Unlock()
+
+	// Timeout is a little arbitrary, but plenty long enough for even the
+	// highest latency links.
+	ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
+	defer cancel()
+
+	conn, err := controlhttp.Dial(ctx, nc.serverHost, nc.privKey, nc.serverPubKey)
+	if err != nil {
+		return nil, err
+	}
+
+	nc.mu.Lock()
+	defer nc.mu.Unlock()
+	ncc := &noiseConn{Conn: conn, id: connID, pool: nc}
+	nc.connPool[ncc.id] = ncc
+	return ncc, nil
+}