[nrf fromtree] net: dhcpv4: Accept unicast replies #1257
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Some DHCPv4 servers do not respect BROADCAST flag set on DHCP Discover,
replying with unicast packet, making it impossible to obtain DHCP
address by Zephyr in such cases.
RFC1542 chapter 3.1.1 makes the following statement about the BROADCAST
flag:
This addition to the protocol is a workaround for old host
implementations. Such implementations SHOULD be modified so
that they may receive unicast BOOTREPLY messages, thus making
use of this workaround unnecessary. In general, the use of
this mechanism is discouraged.
Making it clear that being able to process unicast replies from the DHCP
server is not only an optional behavior, but a recommended solution.
Therefore, introduce a support for unicast DHCPv4 in Zephyr. To achieve
this, add additional filtering rule at the IPv4 level - in case DHCPv4
is enabled, there is an active query and the packet is destined for the
DHCPv4 module, let it through for the DHCPv4 module to process,
regardless of the destination IP address.
Signed-off-by: Robert Lubos <robert.lubos@nordicsemi.no>
(cherry picked from commit a22f7e7)
krish2718
requested review from
rado17,
sachinthegreen,
ajayparida,
krga2022 and
VivekUppunda
rlubos
approved these changes
Jul 27, 2023
rado17
approved these changes
Jul 28, 2023
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Some DHCPv4 servers do not respect BROADCAST flag set on DHCP Discover, replying with unicast packet, making it impossible to obtain DHCP address by Zephyr in such cases.
RFC1542 chapter 3.1.1 makes the following statement about the BROADCAST flag:
This addition to the protocol is a workaround for old host
implementations. Such implementations SHOULD be modified so
that they may receive unicast BOOTREPLY messages, thus making
use of this workaround unnecessary. In general, the use of
this mechanism is discouraged.
Making it clear that being able to process unicast replies from the DHCP server is not only an optional behavior, but a recommended solution.
Therefore, introduce a support for unicast DHCPv4 in Zephyr. To achieve this, add additional filtering rule at the IPv4 level - in case DHCPv4 is enabled, there is an active query and the packet is destined for the DHCPv4 module, let it through for the DHCPv4 module to process, regardless of the destination IP address.
Signed-off-by: Robert Lubos robert.lubos@nordicsemi.no
(cherry picked from commit a22f7e7)