Default to use an IPV4 address (#25668)

* Default to use an IPV4 address

On some devices it appears that the commissioner may not have an
appropriate IPV6 address and attempts to send a user directed
commissioning request to a device using its IPV6 address.

Its a bit unclear how this situation happens but in theory it could
occur. In most cases this should be safe to default to an ipv4 address
if it is available.

The implementation of the user directed commissioning server does
something similar.

* Expand on the error messaging to clarify ipv4 selection

Author: cliffamzn

examples/tv-casting-app/tv-casting-common/include/CastingServer.h

@@ -430,6 +430,19 @@ class CastingServer
     static void DeviceEventCallback(const chip::DeviceLayer::ChipDeviceEvent * event, intptr_t arg);
     void ReadServerClusters(chip::EndpointId endpointId);
 
+    /**
+     * @brief Retrieve the IP Address to use for the UDC request.
+     * This function will look for an IPv4 address in the list of IPAddresses passed in if available and return
+     * that address if found. If there are no available IPv4 addresses, it will default to the first available address.
+     * This logic is similar to the one used by the UDC server that prefers IPv4 addresses.
+     *
+     * @param ipAddresses - The list of ip addresses available to use
+     * @param numIPs - The number of ip addresses available in the array
+     *
+     * @returns The IPv4 address in the array if available, otherwise will return the first address in the list.
+     */
+    static chip::Inet::IPAddress * getIpAddressForUDCRequest(chip::Inet::IPAddress ipAddresses[], const size_t numIPs);
+
     PersistenceManager mPersistenceManager;
     bool mInited        = false;
     bool mUdcInProgress = false;

examples/tv-casting-app/tv-casting-common/src/CastingServer.cpp

@@ -145,13 +145,35 @@ CHIP_ERROR CastingServer::SendUserDirectedCommissioningRequest(chip::Transport::
     return Server::GetInstance().SendUserDirectedCommissioningRequest(commissioner);
 }
 
+chip::Inet::IPAddress * CastingServer::getIpAddressForUDCRequest(chip::Inet::IPAddress ipAddresses[], const size_t numIPs)
+{
+    size_t ipIndexToUse = 0;
+    for (size_t i = 0; i < numIPs; i++)
+    {
+        if (ipAddresses[i].IsIPv4())
+        {
+            ipIndexToUse = i;
+            ChipLogProgress(AppServer, "Found IPv4 address at index: %lu - prioritizing use of IPv4", ipIndexToUse);
+            break;
+        }
+
+        if (i == (numIPs - 1))
+        {
+            ChipLogProgress(AppServer, "Could not find an IPv4 address, defaulting to the first address in IP list");
+        }
+    }
+
+    return &ipAddresses[ipIndexToUse];
+}
+
 CHIP_ERROR CastingServer::SendUserDirectedCommissioningRequest(Dnssd::DiscoveredNodeData * selectedCommissioner)
 {
     mUdcInProgress = true;
     // Send User Directed commissioning request
+    chip::Inet::IPAddress * ipAddressToUse =
+        getIpAddressForUDCRequest(selectedCommissioner->resolutionData.ipAddress, selectedCommissioner->resolutionData.numIPs);
     ReturnErrorOnFailure(SendUserDirectedCommissioningRequest(chip::Transport::PeerAddress::UDP(
-        selectedCommissioner->resolutionData.ipAddress[0], selectedCommissioner->resolutionData.port,
-        selectedCommissioner->resolutionData.interfaceId)));
+        *ipAddressToUse, selectedCommissioner->resolutionData.port, selectedCommissioner->resolutionData.interfaceId)));
     mTargetVideoPlayerVendorId   = selectedCommissioner->commissionData.vendorId;
     mTargetVideoPlayerProductId  = selectedCommissioner->commissionData.productId;
     mTargetVideoPlayerDeviceType = selectedCommissioner->commissionData.deviceType;