RDKCOM-5616: RDKBDEV-3470, RDKBACCL-1485: Verify configurable wan interface in BPI R4

[anatar818]

Reason for change: Verify configurable wan interface in BPI R4 (ethagent functionality)
Test Procedure: Build and flash the image ,Validate wan functionality for the customized interface name
Risks: None
Priority : P1

[Copilot]

Pull request overview

Adds platform-specific initialization logic to support a configurable WAN interface name on BPI R4 (and related platforms) during Ethernet agent startup.

Changes:

• Introduces a RaspberryPi/Turris/BPI-R4 init path (when FEATURE_RDKB_VLAN_MANAGER is not defined) that reads wan_physical_ifname, persists/reads it via /nvram/wan_name.txt, and configures a bridge using ip link.
• Sets the resulting WAN bridge/interface MAC and enslaves ETHWAN_DEF_INTF_NAME under the configured bridge name.

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[Copilot]

Pull request overview

Copilot reviewed 1 out of 1 changed files in this pull request and generated 4 comments.

[Copilot]

Pull request overview

Copilot reviewed 1 out of 1 changed files in this pull request and generated no new comments.

Comments suppressed due to low confidence (3)

source/TR-181/board_sbapi/cosa_ethernet_apis.c:3519

• getInterfaceMacAddress() is called with wanPhyName before the bridge/interface named wanPhyName is created. If wanPhyName doesn't already exist, this leaves macAddr as 00:00:00:00:00:00 and then programs the bridge MAC to all-zero, which can break networking.

       memset(&macAddr,0,sizeof(macaddr_t));
       getInterfaceMacAddress(&macAddr,wanPhyName);
       memset(wan_mac,0,sizeof(wan_mac));
       snprintf(wan_mac, sizeof(wan_mac), "%02x:%02x:%02x:%02x:%02x:%02x", macAddr.hw[0], macAddr.hw[1], macAddr.hw[2],
                    macAddr.hw[3], macAddr.hw[4], macAddr.hw[5]);

source/TR-181/board_sbapi/cosa_ethernet_apis.c:3521

• This command writes wan_physical_ifname to /tmp/wan_name.txt but the file is not read anywhere in this function, so it looks like leftover debug/bring-up code and adds an unnecessary side effect at boot.

       v_secure_system("syscfg get wan_physical_ifname > /tmp/wan_name.txt");

source/TR-181/board_sbapi/cosa_ethernet_apis.c:3468

• The new RaspberryPi/Turris/BananaPi-R4 init path adds non-trivial logic (syscfg + /nvram persistence + bridge creation). There are gtests for this module, but no coverage for this new branch, making regressions (e.g., bad interface names, missing /nvram, bridge already exists) harder to catch.

   #if (defined(_PLATFORM_RASPBERRYPI_) || defined(_PLATFORM_TURRIS_) || defined(_PLATFORM_BANANAPI_R4_)) && !defined(FEATURE_RDKB_VLAN_MANAGER)

	   char wanPhyName[20] = {0},out_value[20] = {0},fileValue[20] = {0};
       FILE *fp = NULL;
       macaddr_t macAddr;