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cafaa63ec6
If the server sends a packet with multiple instances of the same
option, they are concatenated during n_dhcp4_incoming_linearize() and
evaluated as a single option as per section 7 of RFC 3396.
However, there are broken server implementations that send
self-contained options in multiple copies. They are reassembled to
form a single instance by the nettools client, which then fails to
parse them because they have a length greater than the expected one.
This problem can be reproduced by starting a server with:
dnsmasq --bind-interfaces --interface veth1 -d
--dhcp-range=172.25.1.100,172.25.1.200,1m
--dhcp-option=54,172.25.1.1
In this way dnsmasq sends a duplicate option 54 (server-id) when the
client requests it in the 'parameter request list' option, as
dhcp=systemd and dhcp=nettools currently do.
While this is a violation of the RFC by the server, both isc-dhcp and
systemd-networkd client implementations have mechanisms to deal with
this situation. dhclient simply takes the first bytes of the
aggregated option. systemd-networkd doesn't follow RFC 3396 and
doesn't aggregate multiple options; it considers only the last
occurrence of each option.
Change the parsing code to accept options that are longer than
necessary.
https://gitlab.freedesktop.org/NetworkManager/NetworkManager/issues/324
(cherry picked from commit
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| .. | ||
| c-list | ||
| c-rbtree | ||
| c-siphash | ||
| c-stdaux | ||
| n-acd | ||
| n-dhcp4 | ||
| nm-glib-aux | ||
| nm-libnm-core-aux | ||
| nm-libnm-core-intern | ||
| nm-std-aux | ||
| nm-udev-aux | ||
| nm-utils | ||
| systemd | ||
| meson.build | ||
| nm-default.h | ||
| nm-meta-setting.c | ||
| nm-meta-setting.h | ||
| nm-test-libnm-utils.h | ||
| nm-test-utils-impl.c | ||
| nm-version-macros.h.in | ||