block creation or sending of duplicate channels. (#3913)

core/model/src/main/kotlin/org/meshtastic/core/model/util/ChannelSet.kt

@@ -89,3 +89,21 @@ fun ChannelSet.qrCode(shouldAdd: Boolean): Bitmap? = try {
     Timber.e("URL was too complex to render as barcode")
     null
 }
+
+/**
+ * Check if the ChannelSet contains any duplicate PSKs.
+ *
+ * @return true if there are duplicate PSKs, false otherwise
+ */
+fun ChannelSet.hasDuplicateKeys(): Boolean {
+    val pskList = mutableListOf<ByteArray>()
+    for (setting in settingsList) {
+        val channel = Channel(setting, loraConfig)
+        val pskBytes = channel.psk.toByteArray()
+        if (pskList.any { it contentEquals pskBytes }) {
+            return true
+        }
+        pskList.add(pskBytes)
+    }
+    return false
+}

core/strings/src/commonMain/composeResources/values/strings.xml

@@ -218,6 +218,7 @@
     <string name="meshtastic_service_notifications">Service notifications</string>
     <string name="about">About</string>
     <string name="channel_invalid">This Channel URL is invalid and can not be used</string>
+    <string name="channel_key_already_in_use">A channel with this key is already in use</string>
     <string name="contact_invalid">This contact is invalid and can not be added</string>
     <string name="debug_panel">Debug Panel</string>
     <string name="debug_decoded_payload">Decoded Payload:</string>

core/ui/src/main/kotlin/org/meshtastic/core/ui/qr/ScannedQrCodeDialog.kt

@@ -40,9 +40,11 @@ import androidx.compose.runtime.getValue
 import androidx.compose.runtime.mutableStateListOf
 import androidx.compose.runtime.mutableStateOf
 import androidx.compose.runtime.remember
+import androidx.compose.runtime.rememberCoroutineScope
 import androidx.compose.runtime.setValue
 import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
+import androidx.compose.ui.platform.LocalContext
 import androidx.compose.ui.text.style.TextOverflow
 import androidx.compose.ui.tooling.preview.PreviewScreenSizes
 import androidx.compose.ui.unit.dp
@@ -50,15 +52,19 @@ import androidx.compose.ui.window.Dialog
 import androidx.compose.ui.window.DialogProperties
 import androidx.hilt.lifecycle.viewmodel.compose.hiltViewModel
 import androidx.lifecycle.compose.collectAsStateWithLifecycle
+import kotlinx.coroutines.launch
 import org.jetbrains.compose.resources.stringResource
 import org.meshtastic.core.model.Channel
+import org.meshtastic.core.model.util.hasDuplicateKeys
 import org.meshtastic.core.strings.Res
 import org.meshtastic.core.strings.accept
 import org.meshtastic.core.strings.add
 import org.meshtastic.core.strings.cancel
+import org.meshtastic.core.strings.channel_key_already_in_use
 import org.meshtastic.core.strings.new_channel_rcvd
 import org.meshtastic.core.strings.replace
 import org.meshtastic.core.ui.component.ChannelSelection
+import org.meshtastic.core.ui.util.showToast
 import org.meshtastic.proto.AppOnlyProtos.ChannelSet
 import org.meshtastic.proto.ConfigProtos.Config.LoRaConfig.ModemPreset
 import org.meshtastic.proto.channelSet
@@ -290,10 +296,16 @@ fun ScannedQrCodeDialog(
                             )
                         }
 
+                        val context = LocalContext.current
+                        val coroutineScope = rememberCoroutineScope()
                         TextButton(
                             onClick = {
-                                onDismiss()
-                                onConfirm(selectedChannelSet)
+                                if (selectedChannelSet.hasDuplicateKeys()) {
+                                    coroutineScope.launch { context.showToast(Res.string.channel_key_already_in_use) }
+                                } else {
+                                    onDismiss()
+                                    onConfirm(selectedChannelSet)
+                                }
                             },
                             enabled = selectedChannelSet.settingsCount in 1..8,
                         ) {