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espressif / esp-lwip

Fork of lwIP (https://savannah.nongnu.org/projects/lwip/) with ESP-IDF specific patches
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ARP checking not testing for it's own IP (IDFGH-11117) #60

Closed phildimond closed 8 months ago

phildimond commented 1 year ago

https://github.com/espressif/esp-lwip/blob/3b88e84f9b05e76a1ad96e6650a795df74af23aa/src/core/ipv4/dhcp.c#L976

Device responds to it's own ARP check, detects itself and then rejects the ip address offered for DHCP. The device should check that the respondent's MAC is not it's own or (better) disable ARP responses before the check and re-enable afterward.

espressif-abhikroy commented 11 months ago

If the device already have an IP address, the ip4_addr_cmp() function should not be executed due to the preceding check:

  /* Is a DHCP client performing an ARP check? */
  if ((dhcp != NULL) && (dhcp->state == DHCP_STATE_CHECKING)) {

In this scenario, any ARP reply should be discarded.

If you have a different observation, kindly provide details about your network setup and all relevant logs.

david-cermak commented 8 months ago

feel free to reopen with more details/comments.