tsnet,client/tailscale: add APIClient which runs API over Noise.

Updates tailscale/corp#4383

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

client/tailscale/tailscale.go

@@ -18,6 +18,9 @@ import (
 	"fmt"
 	"io"
 	"net/http"
+	"net/url"
+
+	"tailscale.com/types/key"
 )
 
 // I_Acknowledge_This_API_Is_Unstable must be set true to use this package
@@ -90,6 +93,29 @@ func (c *Client) setAuth(r *http.Request) {
 	}
 }
 
+// nodeKeyAuth is an AuthMethod for NewClient that authenticates requests
+// using a node key over the Noise protocol.
+type nodeKeyAuth key.NodePublic
+
+func (k nodeKeyAuth) modifyRequest(req *http.Request) {
+	// QueryEscape the node key since it has a colon in it.
+	nk := url.QueryEscape(key.NodePublic(k).String())
+	req.SetBasicAuth(nk, "")
+}
+
+// NewNoiseClient is a convenience method for instantiating a new Client
+// that uses the Noise protocol for authentication.
+//
+// tailnet is the globally unique identifier for a Tailscale network, such
+// as "example.com" or "user@gmail.com".
+func NewNoiseClient(tailnet string, noiseRoundTripper http.RoundTripper, nk key.NodePublic) *Client {
+	return &Client{
+		tailnet:    tailnet,
+		auth:       nodeKeyAuth(nk),
+		HTTPClient: &http.Client{Transport: noiseRoundTripper},
+	}
+}
+
 // NewClient is a convenience method for instantiating a new Client.
 //
 // tailnet is the globally unique identifier for a Tailscale network, such

ipn/ipnlocal/local.go

@@ -3736,6 +3736,20 @@ func (b *LocalBackend) magicConn() (*magicsock.Conn, error) {
 	return mc, nil
 }
 
+type noiseRoundTripper struct {
+	*LocalBackend
+}
+
+func (n noiseRoundTripper) RoundTrip(req *http.Request) (*http.Response, error) {
+	return n.LocalBackend.DoNoiseRequest(req)
+}
+
+// NoiseRoundTripper returns an http.RoundTripper that uses the LocalBackend's
+// DoNoiseRequest method.
+func (b *LocalBackend) NoiseRoundTripper() http.RoundTripper {
+	return noiseRoundTripper{b}
+}
+
 // DoNoiseRequest sends a request to URL over the control plane
 // Noise connection.
 func (b *LocalBackend) DoNoiseRequest(req *http.Request) (*http.Response, error) {

tsnet/tsnet.go

@@ -9,6 +9,7 @@ package tsnet
 
 import (
 	"context"
+	"errors"
 	"fmt"
 	"io"
 	"log"
@@ -481,6 +482,25 @@ func getTSNetDir(logf logger.Logf, confDir, prog string) (string, error) {
 	return newPath, nil
 }
 
+// APIClient returns a tailscale.Client that can be used to make authenticated
+// requests to the Tailscale control server.
+// It requires the user to set tailscale.I_Acknowledge_This_API_Is_Unstable.
+func (s *Server) APIClient() (*tailscale.Client, error) {
+	if !tailscale.I_Acknowledge_This_API_Is_Unstable {
+		return nil, errors.New("use of Client without setting I_Acknowledge_This_API_Is_Unstable")
+	}
+	if err := s.Start(); err != nil {
+		return nil, err
+	}
+
+	nm := s.lb.NetMap()
+	if nm == nil {
+		return nil, errors.New("no netmap, not logged in?")
+	}
+	c := tailscale.NewNoiseClient(nm.Domain, s.lb.NoiseRoundTripper(), nm.NodeKey)
+	return c, nil
+}
+
 // Listen announces only on the Tailscale network.
 // It will start the server if it has not been started yet.
 func (s *Server) Listen(network, addr string) (net.Listener, error) {