tailcfg, control/controlclient: add PingRequest.URLIsNoise [capver 38]

Change-Id: I19bb63b6d99e96b2f9fd2c440afcc31d38137ded
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>

control/controlclient/direct.go

@@ -885,7 +885,7 @@ func (c *Direct) sendMapRequest(ctx context.Context, maxPolls int, readOnly bool
 
 		if pr := resp.PingRequest; pr != nil && c.isUniquePingRequest(pr) {
 			metricMapResponsePings.Add(1)
-			go answerPing(c.logf, c.httpc, pr, c.pinger)
+			go c.answerPing(pr)
 		}
 		if u := resp.PopBrowserURL; u != "" && u != sess.lastPopBrowserURL {
 			sess.lastPopBrowserURL = u
@@ -1203,21 +1203,30 @@ func (c *Direct) isUniquePingRequest(pr *tailcfg.PingRequest) bool {
 	return true
 }
 
-func answerPing(logf logger.Logf, c *http.Client, pr *tailcfg.PingRequest, pinger Pinger) {
+func (c *Direct) answerPing(pr *tailcfg.PingRequest) {
+	httpc := c.httpc
+	if pr.URLIsNoise {
+		nc, err := c.getNoiseClient()
+		if err != nil {
+			c.logf("failed to get noise client for ping request: %v", err)
+			return
+		}
+		httpc = nc.Client
+	}
 	if pr.URL == "" {
-		logf("invalid PingRequest with no URL")
+		c.logf("invalid PingRequest with no URL")
 		return
 	}
 	if pr.Types == "" {
-		answerHeadPing(logf, c, pr)
+		answerHeadPing(c.logf, httpc, pr)
 		return
 	}
 	for _, t := range strings.Split(pr.Types, ",") {
 		switch pt := tailcfg.PingType(t); pt {
 		case tailcfg.PingTSMP, tailcfg.PingDisco, tailcfg.PingICMP, tailcfg.PingPeerAPI:
-			go doPingerPing(logf, c, pr, pinger, pt)
+			go doPingerPing(c.logf, httpc, pr, c.pinger, pt)
 		default:
-			logf("unsupported ping request type: %q", t)
+			c.logf("unsupported ping request type: %q", t)
 		}
 	}
 }

tailcfg/tailcfg.go

@@ -72,7 +72,8 @@ type CapabilityVersion int
 //	34: 2022-08-02: client understands CapabilityFileSharingTarget
 //	36: 2022-08-02: added PeersChangedPatch.{Key,DiscoKey,Online,LastSeen,KeyExpiry,Capabilities}
 //	37: 2022-08-09: added Debug.{SetForceBackgroundSTUN,SetRandomizeClientPort}; Debug are sticky
-const CurrentCapabilityVersion CapabilityVersion = 37
+//	38: 2022-08-11: added PingRequest.URLIsNoise
+const CurrentCapabilityVersion CapabilityVersion = 38
 
 type StableID string
 
@@ -1151,6 +1152,10 @@ type PingRequest struct {
 	// If Types and IP are defined, then URL is the URL to send a POST request to.
 	URL string
 
+	// URLIsNoise, if true, means that the client should hit URL over the Noise
+	// transport instead of TLS.
+	URLIsNoise bool `json:",omitempty"`
+
 	// Log is whether to log about this ping in the success case.
 	// For failure cases, the client will log regardless.
 	Log bool `json:",omitempty"`