From 3bdffed8c990801cbe4f2e662ca4aba728d3e17d Mon Sep 17 00:00:00 2001
From: Alex Hart <alex@signal.org>
Date: Fri, 16 Jun 2023 09:54:19 -0300
Subject: [PATCH] Add call link scrubbing for logs.

---
 .../org/signal/core/util/logging/Scrubber.java  | 17 +++++++++++++++++
 .../signal/core/util/logging/ScrubberTest.java  | 12 ++++++++++++
 2 files changed, 29 insertions(+)

diff --git a/core-util/src/main/java/org/signal/core/util/logging/Scrubber.java b/core-util/src/main/java/org/signal/core/util/logging/Scrubber.java
index e46c2b8bd8..6ac9c3a994 100644
--- a/core-util/src/main/java/org/signal/core/util/logging/Scrubber.java
+++ b/core-util/src/main/java/org/signal/core/util/logging/Scrubber.java
@@ -89,6 +89,12 @@ public final class Scrubber {
                                                                                 "mobi", "by", "cat", "wiki", "la", "ga", "xxx", "cf", "hr", "ng", "jobs", "online", "kz", "ug", "gq", "ae", "is",
                                                                                 "lv", "pro", "fm", "tips", "ms", "sa", "app"));
 
+  /**
+   * Base16 Call Link Key Pattern
+   */
+  private static final Pattern      CALL_LINK_PATTERN       = Pattern.compile("([bBcCdDfFgGhHkKmMnNpPqQrRsStTxXzZ]{4})(-[bBcCdDfFgGhHkKmMnNpPqQrRsStTxXzZ]{4}){7}");
+  private static final String       CALL_LINK_CENSOR_SUFFIX = "-XXXX-XXXX-XXXX-XXXX-XXXX-XXXX-XXXX";
+
   public static CharSequence scrub(@NonNull CharSequence in) {
 
     in = scrubE164(in);
@@ -98,6 +104,7 @@ public final class Scrubber {
     in = scrubUuids(in);
     in = scrubDomains(in);
     in = scrubIpv4(in);
+    in = scrubCallLinkKeys(in);
 
     return in;
   }
@@ -171,6 +178,16 @@ public final class Scrubber {
                  (matcher, output) -> output.append(IPV4_CENSOR));
   }
 
+  private static CharSequence scrubCallLinkKeys(@NonNull CharSequence in) {
+    return scrub(in,
+                 CALL_LINK_PATTERN,
+                 ((matcher, output) -> {
+                   String match = matcher.group(1);
+                   output.append(match);
+                   output.append(CALL_LINK_CENSOR_SUFFIX);
+                 }));
+  }
+
 
   private static CharSequence scrub(@NonNull CharSequence in, @NonNull Pattern pattern, @NonNull ProcessMatch processMatch) {
     final StringBuilder output  = new StringBuilder(in.length());
diff --git a/core-util/src/test/java/org/signal/core/util/logging/ScrubberTest.java b/core-util/src/test/java/org/signal/core/util/logging/ScrubberTest.java
index b907dccb2f..6898fd3ddc 100644
--- a/core-util/src/test/java/org/signal/core/util/logging/ScrubberTest.java
+++ b/core-util/src/test/java/org/signal/core/util/logging/ScrubberTest.java
@@ -113,6 +113,18 @@ public final class ScrubberTest {
 
     { "Not an ipv4 3.141",
       "Not an ipv4 3.141"
+    },
+
+    { "A Call Link Root Key BCDF-FGHK-MNPQ-RSTX-ZRQH-BCDF-FGHM-STXZ",
+      "A Call Link Root Key BCDF-XXXX-XXXX-XXXX-XXXX-XXXX-XXXX-XXXX"
+    },
+
+    { "Not a Call Link Root Key (Invalid Characters) BCAF-FGHK-MNPQ-RSTX-ZRQH-BCDF-FGHM-STXZ",
+      "Not a Call Link Root Key (Invalid Characters) BCAF-FGHK-MNPQ-RSTX-ZRQH-BCDF-FGHM-STXZ"
+    },
+
+    { "Not a Call Link Root Key (Missing Quartet) BCAF-FGHK-MNPQ-RSTX-ZRQH-BCDF-STXZ",
+      "Not a Call Link Root Key (Missing Quartet) BCAF-FGHK-MNPQ-RSTX-ZRQH-BCDF-STXZ"
     }
 
     });