esp_netif_set_ip_info doesn't always trigger an IP_CHANGED event. (IDFGH-11836)

[karlp]

Answers checklist.

• I have read the documentation ESP-IDF Programming Guide and the issue is not addressed there.
• I have updated my IDF branch (master or release) to the latest version and checked that the issue is present there.
• I have searched the issue tracker for a similar issue and not found a similar issue.

IDF version.

v5.1.2-2-g11f9b315f7 (2 commits are unrelated phy changes, separate PR)

Espressif SoC revision.

ESP32

Operating System used.

Linux

How did you build your project?

Command line with idf.py

If you are using Windows, please specify command line type.

None

Development Kit.

custom

Power Supply used.

External 3.3V

What is the expected behavior?

When I use esp_netif_set_ip_info() to change to a different static IP address, I expect the IP_EVENT_ETH_GOT_IP (as appropriate for interface) to be published. This is required so that (for instance) mDNS can update automatically.

What is the actual behavior?

Instead, the event is not published. Note, this only fails when the gateway portion of a static IP is null.

Steps to reproduce.

	esp_netif_ip_info_t ip;
        ip.ip.addr = ipaddr_addr("10.1.1.1");
        ip.netmask.addr = ipaddr_addr("255.255.0.0");
        ip.gw.addr = ipaddr_addr("0.0.0.0");
        esp_netif_set_ip_info(netif, ip))

2. No event will be produced.

Debug Logs.

No response

More Information.

The problem is here: https://github.com/espressif/esp-idf/blob/master/components/esp_netif/lwip/esp_netif_lwip.c#L1836:

The new IP address is checked, and if any of ip/mask/gw are null, the actual check on whether the IP has changed is just skipped entirely, regardless of what changes have taken place. Given that a null gateway is perfectly legitimate, I propose at least removing the ip4_addr_isany_val(ip_info->gw) check. This does fix the problem for me, and makes the system behave much more predictably.

Arguably, the entire triple check should be dropped though. The memcmp check below, that actually checks whether the addresses have changed at all should already completely cover this.

[david-cermak]

Hi @karlp

Thanks for reporting this problem. I agree that we don't have to check the default gateway nor the mask. I would however leave the IP address condition there, due to historic reasons (setting an IP to IP4_ANY meant loosing the IP) and to be in line with other parts of the code, e.g. here (called directly from lwip):

esp-idf/components/esp_netif/lwip/esp_netif_lwip.c

Line 1281 in 6b9c2fc

if ( !ip4_addr_cmp(ip_2_ip4(&netif->ip_addr), IP4_ADDR_ANY4) ) {

I'll replace this line:

esp-idf/components/esp_netif/lwip/esp_netif_lwip.c

Line 1835 in 6b9c2fc

if (!(ip4_addr_isany_val(ip_info->ip) || ip4_addr_isany_val(ip_info->netmask) || ip4_addr_isany_val(ip_info->gw))) {

with checking ip4_addr_isany_val(ip_info->ip) only. Please keep this open, we'll close it after it's fixed in IDF.