From 9804c6cf5ea6ab5d570f6b9df2a0d3c5c9d7e761 Mon Sep 17 00:00:00 2001
From: Greyson Parrelli <greyson@signal.org>
Date: Fri, 24 Jul 2026 11:44:38 -0400
Subject: [PATCH] Improve call message validations.

---
 .../api/messages/EnvelopeContentValidator.kt  | 11 +++++-
 .../messages/EnvelopeContentValidatorTest.kt  | 37 +++++++++++++++++++
 2 files changed, 47 insertions(+), 1 deletion(-)

diff --git a/lib/libsignal-service/src/main/java/org/whispersystems/signalservice/api/messages/EnvelopeContentValidator.kt b/lib/libsignal-service/src/main/java/org/whispersystems/signalservice/api/messages/EnvelopeContentValidator.kt
index 94fef3b7ea..b6ec0c655b 100644
--- a/lib/libsignal-service/src/main/java/org/whispersystems/signalservice/api/messages/EnvelopeContentValidator.kt
+++ b/lib/libsignal-service/src/main/java/org/whispersystems/signalservice/api/messages/EnvelopeContentValidator.kt
@@ -11,6 +11,7 @@ import org.signal.libsignal.zkgroup.groups.GroupMasterKey
 import org.signal.libsignal.zkgroup.receipts.ReceiptCredentialPresentation
 import org.whispersystems.signalservice.internal.push.AttachmentPointer
 import org.whispersystems.signalservice.internal.push.BodyRange
+import org.whispersystems.signalservice.internal.push.CallMessage
 import org.whispersystems.signalservice.internal.push.Content
 import org.whispersystems.signalservice.internal.push.DataMessage
 import org.whispersystems.signalservice.internal.push.EditMessage
@@ -61,7 +62,7 @@ object EnvelopeContentValidator {
       envelope.story == true && !content.meetsStoryFlagCriteria() -> Result.Invalid("Envelope was flagged as a story, but it did not have any story-related content!")
       content.dataMessage != null -> validateDataMessage(envelope, content.dataMessage)
       content.syncMessage != null -> validateSyncMessage(envelope, content.syncMessage, localAci)
-      content.callMessage != null -> Result.Valid
+      content.callMessage != null -> validateCallMessage(content.callMessage)
       content.nullMessage != null -> Result.Valid
       content.receiptMessage != null -> validateReceiptMessage(content.receiptMessage)
       content.typingMessage != null -> validateTypingMessage(envelope, content.typingMessage)
@@ -207,6 +208,14 @@ object EnvelopeContentValidator {
     return this.options.size < MIN_POLL_OPTIONS || this.options.any { option -> option.length > MAX_POLL_CHARACTER_LENGTH }
   }
 
+  private fun validateCallMessage(callMessage: CallMessage): Result {
+    if (callMessage.hangup != null && callMessage.hangup.type == null) {
+      return Result.Invalid("[CallMessage] Missing type on CallMessage.hangup!")
+    }
+
+    return Result.Valid
+  }
+
   private fun validateSyncMessage(envelope: Envelope, syncMessage: SyncMessage, localAci: ACI): Result {
     // Source serviceId was already determined to be a valid serviceId in general
     val sourceServiceId = ServiceId.parseOrThrow(envelope.sourceServiceId, envelope.sourceServiceIdBinary)
diff --git a/lib/libsignal-service/src/test/java/org/whispersystems/signalservice/api/messages/EnvelopeContentValidatorTest.kt b/lib/libsignal-service/src/test/java/org/whispersystems/signalservice/api/messages/EnvelopeContentValidatorTest.kt
index 545241bf9a..14cc4be3f0 100644
--- a/lib/libsignal-service/src/test/java/org/whispersystems/signalservice/api/messages/EnvelopeContentValidatorTest.kt
+++ b/lib/libsignal-service/src/test/java/org/whispersystems/signalservice/api/messages/EnvelopeContentValidatorTest.kt
@@ -12,6 +12,7 @@ import org.signal.libsignal.protocol.message.CiphertextMessage
 import org.signal.libsignal.protocol.message.DecryptionErrorMessage
 import org.whispersystems.signalservice.internal.push.AttachmentPointer
 import org.whispersystems.signalservice.internal.push.BodyRange
+import org.whispersystems.signalservice.internal.push.CallMessage
 import org.whispersystems.signalservice.internal.push.Content
 import org.whispersystems.signalservice.internal.push.DataMessage
 import org.whispersystems.signalservice.internal.push.EditMessage
@@ -1102,4 +1103,40 @@ class EnvelopeContentValidatorTest {
     val result = EnvelopeContentValidator.validate(envelope, content, SELF_ACI, CiphertextMessage.WHISPER_TYPE)
     assert(result is EnvelopeContentValidator.Result.Valid)
   }
+
+  @Test
+  fun `validate - ensure call message hangup without a type is marked invalid`() {
+    val content = Content(
+      callMessage = CallMessage(
+        hangup = CallMessage.Hangup(id = 1)
+      )
+    )
+
+    val result = EnvelopeContentValidator.validate(Envelope(), content, SELF_ACI, CiphertextMessage.WHISPER_TYPE)
+    assert(result is EnvelopeContentValidator.Result.Invalid)
+  }
+
+  @Test
+  fun `validate - ensure call message hangup with a type is marked valid`() {
+    val content = Content(
+      callMessage = CallMessage(
+        hangup = CallMessage.Hangup(id = 1, type = CallMessage.Hangup.Type.HANGUP_NORMAL)
+      )
+    )
+
+    val result = EnvelopeContentValidator.validate(Envelope(), content, SELF_ACI, CiphertextMessage.WHISPER_TYPE)
+    assert(result is EnvelopeContentValidator.Result.Valid)
+  }
+
+  @Test
+  fun `validate - ensure call message without a hangup is marked valid`() {
+    val content = Content(
+      callMessage = CallMessage(
+        busy = CallMessage.Busy(id = 1)
+      )
+    )
+
+    val result = EnvelopeContentValidator.validate(Envelope(), content, SELF_ACI, CiphertextMessage.WHISPER_TYPE)
+    assert(result is EnvelopeContentValidator.Result.Valid)
+  }
 }