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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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The dhcp client behaviour is not standard compliant for DHCP clients (RFC2131) (IDFGH-5139) #30

Closed mitec-embedded closed 3 years ago

mitec-embedded commented 3 years ago

Starting from commit 2117f049dca64d15a12e81a308c27f36ac6e6272 which adds option 61 (Client identifiers) the dhcp is no more complaining for standard RFC2131, since the standard says If the client supplies a 'client identifier', the client MUST use the same 'client identifier' in all subsequent messages, and the server MUST use that identifier to identify the client.

The option 61 was only included in "discover" and "select" messages, but not in the dhcp_renew() or other methods. This is causing a big issue:

When the esp32 first boot, it sends both the DISCOVER and DHCP_REQUEST containing the option "client id". But then, after a while, when the ESP try to renew its IP, it sends a DHCP_REQUEST messages WITHOUT the "client id". This is causing that "professional DHCPs" like zyxell firewalls that slavishly follow the DHCP standard, sends a NACK.

This cause the ESP stack to drop all connections and restart a DHCP negotiation. And this cycles over forever, since some requests has the client_id, and some others has not.

david-cermak commented 3 years ago

@mitec-embedded Thanks for reporting this bug!

Indeed this option should be added to other packets as well. This needs to be fixed. Please find a quick patch below: dhcp-Fix-client-identifier-to-be-added-to-relevant-p.patch.txt