From af931dcccd24564adebafaa8794563c620a9bcda Mon Sep 17 00:00:00 2001
From: Tom DNetto <tom@tailscale.com>
Date: Wed, 7 Feb 2024 13:15:43 -0800
Subject: [PATCH] tsweb: replace domains/emails in paths when bucketing stats

Signed-off-by: Tom DNetto <tom@tailscale.com>
Updates: corp#17075
---
 tsweb/tsweb.go      | 22 ++++++++++++++--------
 tsweb/tsweb_test.go |  3 +++
 2 files changed, 17 insertions(+), 8 deletions(-)

diff --git a/tsweb/tsweb.go b/tsweb/tsweb.go
index 5ce45226a..a45e6ebc7 100644
--- a/tsweb/tsweb.go
+++ b/tsweb/tsweb.go
@@ -192,24 +192,30 @@ type BucketedStatsOptions struct {
 	Finished *expvar.Map
 }
 
-var (
-	hexSequenceRegex = regexp.MustCompile("[a-fA-F0-9]{9,}")
-)
+// normalizePathRegex matches components in a HTTP request path
+// that should be replaced.
+//
+// See: https://regex101.com/r/WIfpaR/1 for the explainer and test cases.
+var normalizePathRegex = regexp.MustCompile("([a-fA-F0-9]{9,}|([^\\/])+\\.([^\\/]){2,})")
 
-// NormalizedPath returns the given path with any query parameters
-// removed, and any hex strings of 9 or more characters replaced
-// with an ellipsis.
+// NormalizedPath returns the given path with the following modifications:
+//
+//   - any query parameters are removed
+//   - any path component with a hex string of 9 or more characters is
+//     replaced by an ellipsis
+//   - any path component containing a period with at least two characters
+//     after the period (i.e. an email or domain)
 func NormalizedPath(p string) string {
 	// Fastpath: No hex sequences in there we might have to trim.
 	// Avoids allocating.
-	if hexSequenceRegex.FindStringIndex(p) == nil {
+	if normalizePathRegex.FindStringIndex(p) == nil {
 		b, _, _ := strings.Cut(p, "?")
 		return b
 	}
 
 	// If we got here, there's at least one hex sequences we need to
 	// replace with an ellipsis.
-	replaced := hexSequenceRegex.ReplaceAllString(p, "…")
+	replaced := normalizePathRegex.ReplaceAllString(p, "…")
 	b, _, _ := strings.Cut(replaced, "?")
 	return b
 }
diff --git a/tsweb/tsweb_test.go b/tsweb/tsweb_test.go
index 3a97191fb..0ace46236 100644
--- a/tsweb/tsweb_test.go
+++ b/tsweb/tsweb_test.go
@@ -681,6 +681,9 @@ func TestBucket(t *testing.T) {
 		{"/map/a87e865a9d1c7", "/map/…"},
 		{"/machine/37fc1acb57f256b69b0d76749d814d91c68b241057c6b127fee3df37e4af111e", "/machine/…"},
 		{"/machine/37fc1acb57f256b69b0d76749d814d91c68b241057c6b127fee3df37e4af111e/map", "/machine/…/map"},
+		{"/api/v2/tailnet/jeremiah@squish.com/devices", "/api/v2/tailnet/…/devices"},
+		{"/machine/ssh/wait/5227109621243650/to/7111899293970143/a/a9e4e04cc01b", "/machine/ssh/wait/…/to/…/a/…"},
+		{"/a/831a4bf39856?refreshed=true", "/a/…"},
 	}
 
 	for _, tc := range tcs {