Fix crashes caused by regex characters in email signature

FlowCrypt/src/main/java/com/flowcrypt/email/jetpack/viewmodel/DraftViewModel.kt

@@ -156,14 +156,14 @@ class DraftViewModel(
 
     val isTextTheSame =
       if (outgoingMessageInfo.signature != null && !draftFingerprint.skipCheckingSignature) {
-      val textWithoutSignature = outgoingMessageInfo.msg?.replaceFirst(
-        regex = ("\n\n" + outgoingMessageInfo.signature).toRegex(RegexOption.MULTILINE),
-        replacement = ""
-      ) ?: ""
-      textWithoutSignature == draftFingerprint.msgText
-    } else {
-      (outgoingMessageInfo.msg ?: "") == draftFingerprint.msgText
-    }
+        val textWithoutSignature = removeSignature(
+          message = outgoingMessageInfo.msg,
+          signature = outgoingMessageInfo.signature
+        )
+        textWithoutSignature == draftFingerprint.msgText
+      } else {
+        (outgoingMessageInfo.msg ?: "") == draftFingerprint.msgText
+      }
 
     if (!isTextTheSame
       || outgoingMessageInfo.subject != draftFingerprint.msgSubject
@@ -343,5 +343,12 @@ class DraftViewModel(
 
   companion object {
     val DELAY_TIMEOUT = TimeUnit.SECONDS.toMillis(30)
+
+    internal fun removeSignature(message: String?, signature: String): String {
+      return message?.replaceFirst(
+        oldValue = "\n\n$signature",
+        newValue = ""
+      ) ?: ""
+    }
   }
 }

FlowCrypt/src/main/java/com/flowcrypt/email/ui/activity/fragment/CreateMessageFragment.kt

@@ -109,6 +109,7 @@ import com.flowcrypt.email.ui.adapter.AutoCompleteResultRecyclerViewAdapter
 import com.flowcrypt.email.ui.adapter.FromAddressesAdapter
 import com.flowcrypt.email.ui.adapter.RecipientChipRecyclerViewAdapter
 import com.flowcrypt.email.ui.adapter.recyclerview.itemdecoration.MarginItemDecoration
+import com.flowcrypt.email.util.EmailSignatureUtil
 import com.flowcrypt.email.util.FileAndDirectoryUtils
 import com.flowcrypt.email.util.GeneralUtil
 import com.flowcrypt.email.util.LogsUtil
@@ -2164,9 +2165,11 @@ class CreateMessageFragment : BaseFragment<FragmentCreateMessageBinding>(),
     val oldSignature = composeMsgViewModel.outgoingMessageInfoStateFlow.value.signature
     if (oldSignature == null && args.messageType == MessageType.DRAFT) {
       val extractedSignature = aliases.firstOrNull { alias ->
-        alias.plainTextSignature != null && binding?.editTextEmailMessage?.text?.contains(
-          ("^${alias.plainTextSignature}$").toRegex(RegexOption.MULTILINE)
-        ) == true
+        val aliasSignature = alias.plainTextSignature
+        aliasSignature != null && EmailSignatureUtil.containsSignature(
+          message = binding?.editTextEmailMessage?.text,
+          signature = aliasSignature
+        )
       }?.plainTextSignature
 
       if (!extractedSignature.isNullOrEmpty()) {
@@ -2180,19 +2183,18 @@ class CreateMessageFragment : BaseFragment<FragmentCreateMessageBinding>(),
       return
     }
 
-    val messageHasOldSignature =
-      oldSignature != null && binding?.editTextEmailMessage?.text?.contains(
-        ("^$oldSignature$").toRegex(RegexOption.MULTILINE)
-      ) == true
+    val messageText = binding?.editTextEmailMessage?.text?.toString() ?: ""
+    val messageWithUpdatedSignature = oldSignature?.let {
+      EmailSignatureUtil.replaceSignature(
+        message = messageText,
+        oldSignature = it,
+        newSignature = newSignature
+      )
+    }
 
-    if (messageHasOldSignature) {
+    if (messageWithUpdatedSignature != null) {
       useNewSignature = true
-      binding?.editTextEmailMessage?.setText(
-        binding?.editTextEmailMessage?.text?.replaceFirst(
-          regex = oldSignature.toRegex(RegexOption.MULTILINE),
-          replacement = newSignature
-        )
-      )
+      binding?.editTextEmailMessage?.setText(messageWithUpdatedSignature)
     } else if (oldSignature == null) {
       useNewSignature = true
       if (binding?.editTextEmailMessage?.text?.isEmpty() == true) {

FlowCrypt/src/main/java/com/flowcrypt/email/util/EmailSignatureUtil.kt

@@ -0,0 +1,26 @@
+/*
+ * © 2016-present FlowCrypt a.s. Limitations apply. Contact human@flowcrypt.com
+ * Contributors: denbond7
+ */
+
+package com.flowcrypt.email.util
+
+internal object EmailSignatureUtil {
+  fun containsSignature(message: CharSequence?, signature: String): Boolean {
+    return message != null && findSignature(message, signature) != null
+  }
+
+  fun replaceSignature(
+    message: String,
+    oldSignature: String,
+    newSignature: String
+  ): String? {
+    val signatureMatch = findSignature(message, oldSignature) ?: return null
+    return message.replaceRange(signatureMatch.range, newSignature)
+  }
+
+  private fun findSignature(message: CharSequence, signature: String): MatchResult? {
+    val signatureRegex = ("^${Regex.escape(signature)}$").toRegex(RegexOption.MULTILINE)
+    return signatureRegex.find(message)
+  }
+}

FlowCrypt/src/test/java/com/flowcrypt/email/jetpack/viewmodel/DraftViewModelTest.kt

@@ -0,0 +1,24 @@
+/*
+ * © 2016-present FlowCrypt a.s. Limitations apply. Contact human@flowcrypt.com
+ * Contributors: denbond7
+ */
+
+package com.flowcrypt.email.jetpack.viewmodel
+
+import org.junit.Assert.assertEquals
+import org.junit.Test
+
+class DraftViewModelTest {
+  @Test
+  fun testRemoveSignatureWithRegexMetaCharacters() {
+    val signature = """
+      Kind regards
+
+      (123 456
+      [example].*+?\
+    """.trimIndent()
+    val message = "Message body\n\n$signature"
+
+    assertEquals("Message body", DraftViewModel.removeSignature(message, signature))
+  }
+}

FlowCrypt/src/test/java/com/flowcrypt/email/util/EmailSignatureUtilTest.kt

@@ -0,0 +1,32 @@
+/*
+ * © 2016-present FlowCrypt a.s. Limitations apply. Contact human@flowcrypt.com
+ * Contributors: denbond7
+ */
+
+package com.flowcrypt.email.util
+
+import org.junit.Assert.assertEquals
+import org.junit.Assert.assertTrue
+import org.junit.Test
+
+class EmailSignatureUtilTest {
+  @Test
+  fun testMatchingAndReplacementWithRegexMetaCharacters() {
+    val oldSignature = """
+      Best regards,
+      (111 222 333).*+?\
+      $100 \path
+    """.trimIndent()
+    val newSignature = """
+      Sincerely,
+      $500 & \path\to\file
+    """.trimIndent()
+    val message = "Hello World\n\n$oldSignature"
+
+    assertTrue(EmailSignatureUtil.containsSignature(message, oldSignature))
+    assertEquals(
+      "Hello World\n\n$newSignature",
+      EmailSignatureUtil.replaceSignature(message, oldSignature, newSignature)
+    )
+  }
+}

gradle/wrapper/gradle-wrapper.properties

@@ -1,6 +1,6 @@
 distributionBase=GRADLE_USER_HOME
 distributionPath=wrapper/dists
-distributionUrl=https\://services.gradle.org/distributions/gradle-9.6.1-bin.zip
+distributionUrl=https\://services.gradle.org/distributions/gradle-9.7.0-bin.zip
 networkTimeout=10000
 validateDistributionUrl=true
 zipStoreBase=GRADLE_USER_HOME