cmd/tailscale: add 'debug ts2021' Noise connectivity subcommand

Updates #3488

Change-Id: I9272e68f66c4cf36fb98dd1248a74d3817447690
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
(cherry picked from commit d3643fa151a4fd011243e786547706b38c579894)

cmd/tailscale/cli/debug.go

@@ -15,6 +15,8 @@ import (
 	"fmt"
 	"io"
 	"log"
+	"net"
+	"net/http"
 	"os"
 	"runtime"
 	"strconv"
@@ -23,11 +25,14 @@ import (
 
 	"github.com/peterbourgon/ff/v3/ffcli"
 	"inet.af/netaddr"
+	"tailscale.com/control/controlhttp"
 	"tailscale.com/hostinfo"
 	"tailscale.com/ipn"
 	"tailscale.com/net/tsaddr"
 	"tailscale.com/paths"
 	"tailscale.com/safesocket"
+	"tailscale.com/tailcfg"
+	"tailscale.com/types/key"
 )
 
 var debugCmd = &ffcli.Command{
@@ -118,6 +123,17 @@ var debugCmd = &ffcli.Command{
 			Exec:      runVia,
 			ShortHelp: "convert between site-specific IPv4 CIDRs and IPv6 'via' routes",
 		},
+		{
+			Name:      "ts2021",
+			Exec:      runTS2021,
+			ShortHelp: "debug ts2021 protocol connectivity",
+			FlagSet: (func() *flag.FlagSet {
+				fs := newFlagSet("ts2021")
+				fs.StringVar(&ts2021Args.host, "host", "controlplane.tailscale.com", "hostname of control plane")
+				fs.IntVar(&ts2021Args.version, "version", int(tailcfg.CurrentCapabilityVersion), "protocol version")
+				return fs
+			})(),
+		},
 	},
 }
 
@@ -425,3 +441,67 @@ func runVia(ctx context.Context, args []string) error {
 	}
 	return nil
 }
+
+var ts2021Args struct {
+	host    string // "controlplane.tailscale.com"
+	version int    // 27 or whatever
+}
+
+func runTS2021(ctx context.Context, args []string) error {
+	log.SetOutput(os.Stdout)
+	log.SetFlags(log.Ltime | log.Lmicroseconds)
+
+	machinePrivate := key.NewMachine()
+	var dialer net.Dialer
+
+	var keys struct {
+		PublicKey key.MachinePublic
+	}
+	keysURL := "https://" + ts2021Args.host + "/key?v=" + strconv.Itoa(ts2021Args.version)
+	log.Printf("Fetching keys from %s ...", keysURL)
+	req, err := http.NewRequestWithContext(ctx, "GET", keysURL, nil)
+	if err != nil {
+		return err
+	}
+	res, err := http.DefaultClient.Do(req)
+	if err != nil {
+		log.Printf("Do: %v", err)
+		return err
+	}
+	if res.StatusCode != 200 {
+		log.Printf("Status: %v", res.Status)
+		return errors.New(res.Status)
+	}
+	if err := json.NewDecoder(res.Body).Decode(&keys); err != nil {
+		log.Printf("JSON: %v", err)
+		return fmt.Errorf("decoding /keys JSON: %w", err)
+	}
+	res.Body.Close()
+
+	dialFunc := func(ctx context.Context, network, address string) (net.Conn, error) {
+		log.Printf("Dial(%q, %q) ...", network, address)
+		c, err := dialer.DialContext(ctx, network, address)
+		if err != nil {
+			log.Printf("Dial(%q, %q) = %v", network, address, err)
+		} else {
+			log.Printf("Dial(%q, %q) = %v / %v", network, address, c.LocalAddr(), c.RemoteAddr())
+		}
+		return c, err
+	}
+
+	conn, err := controlhttp.Dial(ctx, net.JoinHostPort(ts2021Args.host, "80"), machinePrivate, keys.PublicKey, uint16(ts2021Args.version), dialFunc)
+	log.Printf("controlhttp.Dial = %p, %v", conn, err)
+	if err != nil {
+		return err
+	}
+	log.Printf("did noise handshake")
+
+	gotPeer := conn.Peer()
+	if gotPeer != keys.PublicKey {
+		log.Printf("peer = %v, want %v", gotPeer, keys.PublicKey)
+		return errors.New("key mismatch")
+	}
+
+	log.Printf("final underlying conn: %v / %v", conn.LocalAddr(), conn.RemoteAddr())
+	return nil
+}

cmd/tailscale/depaware.txt

@@ -8,7 +8,7 @@ tailscale.com/cmd/tailscale dependencies: (generated by github.com/tailscale/dep
    L 💣 github.com/jsimonetti/rtnetlink                              from tailscale.com/net/interfaces
    L    github.com/jsimonetti/rtnetlink/internal/unix                from github.com/jsimonetti/rtnetlink
         github.com/kballard/go-shellquote                            from tailscale.com/cmd/tailscale/cli
-   L    github.com/klauspost/compress/flate                          from nhooyr.io/websocket
+        github.com/klauspost/compress/flate                          from nhooyr.io/websocket
    L 💣 github.com/mdlayher/netlink                                  from github.com/jsimonetti/rtnetlink+
    L 💣 github.com/mdlayher/netlink/nlenc                            from github.com/jsimonetti/rtnetlink+
    L 💣 github.com/mdlayher/socket                                   from github.com/mdlayher/netlink
@@ -31,14 +31,16 @@ tailscale.com/cmd/tailscale dependencies: (generated by github.com/tailscale/dep
         go4.org/unsafe/assume-no-moving-gc                           from go4.org/intern
    W 💣 golang.zx2c4.com/wireguard/windows/tunnel/winipcfg           from tailscale.com/net/interfaces+
         inet.af/netaddr                                              from tailscale.com/cmd/tailscale/cli+
-   L    nhooyr.io/websocket                                          from tailscale.com/derp/derphttp+
+        nhooyr.io/websocket                                          from tailscale.com/derp/derphttp+
-   L    nhooyr.io/websocket/internal/errd                            from nhooyr.io/websocket
+        nhooyr.io/websocket/internal/errd                            from nhooyr.io/websocket
-   L    nhooyr.io/websocket/internal/xsync                           from nhooyr.io/websocket
+        nhooyr.io/websocket/internal/xsync                           from nhooyr.io/websocket
         tailscale.com                                                from tailscale.com/version
         tailscale.com/atomicfile                                     from tailscale.com/ipn+
         tailscale.com/client/tailscale                               from tailscale.com/cmd/tailscale/cli+
         tailscale.com/client/tailscale/apitype                       from tailscale.com/cmd/tailscale/cli+
         tailscale.com/cmd/tailscale/cli                              from tailscale.com/cmd/tailscale
+        tailscale.com/control/controlbase                            from tailscale.com/control/controlhttp
+        tailscale.com/control/controlhttp                            from tailscale.com/cmd/tailscale/cli
         tailscale.com/control/controlknobs                           from tailscale.com/net/portmapper
         tailscale.com/derp                                           from tailscale.com/derp/derphttp
         tailscale.com/derp/derphttp                                  from tailscale.com/net/netcheck
@@ -48,21 +50,22 @@ tailscale.com/cmd/tailscale dependencies: (generated by github.com/tailscale/dep
         tailscale.com/ipn                                            from tailscale.com/cmd/tailscale/cli+
         tailscale.com/ipn/ipnstate                                   from tailscale.com/cmd/tailscale/cli+
      💣 tailscale.com/metrics                                        from tailscale.com/derp
-        tailscale.com/net/dnscache                                   from tailscale.com/derp/derphttp
+        tailscale.com/net/dnscache                                   from tailscale.com/derp/derphttp+
+        tailscale.com/net/dnsfallback                                from tailscale.com/control/controlhttp
         tailscale.com/net/flowtrack                                  from tailscale.com/wgengine/filter+
      💣 tailscale.com/net/interfaces                                 from tailscale.com/cmd/tailscale/cli+
         tailscale.com/net/netcheck                                   from tailscale.com/cmd/tailscale/cli
         tailscale.com/net/neterror                                   from tailscale.com/net/netcheck+
         tailscale.com/net/netknob                                    from tailscale.com/net/netns
         tailscale.com/net/netns                                      from tailscale.com/derp/derphttp+
-        tailscale.com/net/netutil                                    from tailscale.com/client/tailscale
+        tailscale.com/net/netutil                                    from tailscale.com/client/tailscale+
         tailscale.com/net/packet                                     from tailscale.com/wgengine/filter
         tailscale.com/net/portmapper                                 from tailscale.com/net/netcheck+
         tailscale.com/net/stun                                       from tailscale.com/net/netcheck
-        tailscale.com/net/tlsdial                                    from tailscale.com/derp/derphttp
+        tailscale.com/net/tlsdial                                    from tailscale.com/derp/derphttp+
         tailscale.com/net/tsaddr                                     from tailscale.com/net/interfaces+
      💣 tailscale.com/net/tshttpproxy                                from tailscale.com/derp/derphttp+
-   L    tailscale.com/net/wsconn                                     from tailscale.com/derp/derphttp
+        tailscale.com/net/wsconn                                     from tailscale.com/derp/derphttp+
         tailscale.com/paths                                          from tailscale.com/cmd/tailscale/cli+
         tailscale.com/safesocket                                     from tailscale.com/cmd/tailscale/cli+
         tailscale.com/syncs                                          from tailscale.com/net/interfaces+
@@ -93,12 +96,13 @@ tailscale.com/cmd/tailscale dependencies: (generated by github.com/tailscale/dep
         tailscale.com/version/distro                                 from tailscale.com/cmd/tailscale/cli+
         tailscale.com/wgengine/filter                                from tailscale.com/types/netmap
         golang.org/x/crypto/blake2b                                  from golang.org/x/crypto/nacl/box
+        golang.org/x/crypto/blake2s                                  from tailscale.com/control/controlbase
         golang.org/x/crypto/chacha20                                 from golang.org/x/crypto/chacha20poly1305
-        golang.org/x/crypto/chacha20poly1305                         from crypto/tls
+        golang.org/x/crypto/chacha20poly1305                         from crypto/tls+
         golang.org/x/crypto/cryptobyte                               from crypto/ecdsa+
         golang.org/x/crypto/cryptobyte/asn1                          from crypto/ecdsa+
         golang.org/x/crypto/curve25519                               from crypto/tls+
-        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/salsa20/salsa                            from golang.org/x/crypto/nacl/box+