ESP32 Forum

I need a DHCP server on the Ethernet interface.
I have used the netif interface to add DHCP in a small worked example but I keep hitting stability issues when upgrading IDF on my application.

I am currently running with legacy GNU using toolchain 3.3.1 and IDF v4.0-dev-562-g2b301f53e. This seems quite stable. An unusual combo but the IDF was the first I found with CAN and have stuck with it.

I upgraded toolchain to xtensa-esp32-elf-gcc8_2_0-esp-2019r2-win32.zip and IDF v4.1-dev-1543-g431066f16
I then managed to create a simple DHCP server demonstration.
Unfortunately the full application was very unreliable.

I upgraded IDF to v4.2-dev-674-g640c7c510
The application is now reliable as a DHCP client but hangs during intialisation as a server.
The simple DHCP server example fails to assign an IP address when logging INFO but provides an IP address when logging DEBUG.
Probably a timing issue but weird.

So I am really looking for advice on the 'best' most stable IDF with DHCP support.
Or, maybe, a library which I could add to my original stable setup.

will allow the application to continue.

Adding the AUTOUP flag causes the application to hang around 50mS after esp_eth_start() call: As said, DHCPC client seems absolutely fine.
AUTOUP causes netif_set_up() to be called during setup rather than on interface event.

EDIT:
My application hangs because I have attached a UDP logger to ESP_LOG output. You would expect sendto() to return error rather than hang, but..
Removing my UDP logger allows the application to launch. The application launches a few services and starts periodic multicast. The multicast (sendto) fails:

Swapped cable and now works.
EDIT: 5 minutes latter no longer works.

There do seem to be issue(s) with netif, around AUTOUP, for example sendto() can block.
I am guessing that if you have a bad cable then AUTOUP may not work well. If you wait for driver detect then maybe the hardware is in the correct state and you bypass the bug.

Looking closer at the small worked example. The example was often not working. I had assumed that the example was working because the PC had a leased address. It seems that the PC will remember its last lease rather than use an auto local.

Understanding that the DHCP server was not actually working I dumped esp_netif_get_ip_info() which reveals that the ESP has address 0.0.0.0

To intitialise DHCP I use:
esp_netif_dhcps_stop(), esp_netif_set_ip_info(), esp_netif_dhcps_start()
but the assigned address does not stick when used early in the boot. Sometimes esp_netif_get_ip_info() will show the assigned IP but shortly later the address is 0.0.0.0 (when set used early in boot)
Using esp_netif_dhcps_stop(), esp_netif_set_ip_info(), esp_netif_dhcps_start() some seconds after boot seems to work.

Note that esp_netif_is_netif_up() returned true each time I perform the initialisation.
There is therefore some part of the initialisation which I do not understand.
When am I supposed to stop(), set_ip() and start()?
How can I test that its time to start?

EDIT: Additionally using sento() before the DHCPS is fully up (does not return 0.0.0.0) will hang. So it is vital that I can detect the condition.