net/ip/dhcpv4: Set source IP address for DHCP renewal requests #15179
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The source address in unicast DHCPv4 Request packets was found out to be all zeros address 0.0.0.0. This address is only acceptable if the destination is a multicast one, where the host in question is acquiring a DHCP address lease. This is true for the DHCP Discover and the initial DHCP Request message from the client towards the server. As subsequent DHCP Request renewal messages are sent as unicast to the server, the server will drop such packets. Fix this issue by explicitely specifying what source IP address is to be used, if none is specified, the all zeros address 0.0.0.0 is used in multicast addresses. The source address in the other unicast cases is identical to the 'ciaddr' in the DHCP message. Signed-off-by: Patrik Flykt <[email protected]>
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To clarify: Linux user space never sees the DHCP Request messages sent with source address 0.0.0.0. It will eventually work, as the Zephyr DHCP client restarts the address acquisition procedure with a DHCP Discover, but depending on the situation and DHCP servers involved, Zephyr might loose its address in between or get a new one assigned due to restarting of the DHCP procedure. |
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It would probably be a good idea to get this merged, I'd guess users would need this fix in the LTS anyway later. |
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This looks like a clean fix, and probably would (severely) affect production, long-running devices. @pfl, Please post a bug describing that case, and add "Fixes: " header to commit, to satisfy conditions for its inclusion in the release.
pfalcon
changed the title
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Bug is #16012 |
The source address in unicast DHCPv4 Request packets was found out
to be all zeros address 0.0.0.0. This address is only acceptable if
the destination is a multicast one, where the host in question is
acquiring a DHCP address lease. This is true for the DHCP Discover
and the initial DHCP Request message from the client towards the
server. As subsequent DHCP Request renewal messages are sent as
unicast to the server, the server will drop such packets.
Fix this issue by explicitely specifying what source IP address is
to be used, if none is specified, the all zeros address 0.0.0.0 is
used in multicast addresses. The source address in the other
unicast cases is identical to the 'ciaddr' in the DHCP message.
Signed-off-by: Patrik Flykt [email protected]