Usually we want no difference between the upstream project that we fork
via git-subtree, and our copy. However, for the subprojects, we need to
patch them. Do it.
If you know a better way, that allows to overwriting the subprojects
please send a patch.
Previously, during decline we would clear probe->current_lease,
however leave the state at GRANTED.
That is a wrong state, and can easily lead to a crash later.
For example, on the next timeout we will end up at
n_dhcp4_client_dispatch_timer(), then current-lease gets
accessed unconditionally:
case N_DHCP4_CLIENT_PROBE_STATE_GRANTED:
if (ns_now >= probe->current_lease->lifetime) {
Instead, return to INIT state and schedule a timer. As suggested
by RFC 2131, section 3.1, 5) ([1]).
[1] https://datatracker.ietf.org/doc/html/rfc2131#section-3.1
The lease list and the probe's state are strongly related. That is
evidenced by the fact that sometimes we check the state and then
access probe->current_lease without further checking.
The code in "n-dhcp4-c-probe.c" (select_lease, accept, decline) already
changes and maintains the state, it should also maintain the lease list.
Move the code.
The caller is supposed to call accept/decline/select with the lease that
was just announced. Calling it in the wrong state or with the wrong
lease is a user error.
Return an error when called in the wrong state, so that the user
notices they did something wrong.
If we have a lease and we get a NAK renewing/rebinding it, the lease
is lost.
Without this, probe->current_lease remains set and after the next
DISCOVER/OFFER round, any call to n_dhcp4_client_lease_select() will
fail at:
if (lease->probe->current_lease)
return -ENOTRECOVERABLE;
As in:
[5325.1313] dhcp4 (veth0): send REQUEST of 172.25.1.200 to 255.255.255.255
[5325.1434] dhcp4 (veth0): received NACK from 172.25.1.1
[5325.1435] dhcp4 (veth0): client event 3 (RETRACTED)
[5325.1436] dhcp4 (veth0): send DISCOVER to 255.255.255.255
[5325.1641] dhcp4 (veth0): received OFFER of 172.25.1.200 from 172.25.1.1
[5325.1641] dhcp4 (veth0): client event (OFFER)
[5325.1641] dhcp4 (veth0): selecting lease failed: -131 (ENOTRECOVERABLE)
Upstream: https://github.com/nettools/n-dhcp4/pull/33
Upstream: e4af93228ehttps://gitlab.freedesktop.org/NetworkManager/NetworkManager/-/issues/993e43b1791a3 ('Merge commit 'e23b3c9c3ac86b065eef002fa5c4321cc4a87df2' as 'shared/n-dhcp4'')
Each connection object includes a 64KiB scratch buffer used for
receiving packets. When many instances of the client are created,
those buffers use a significant amount of memory. For example, 500
clients take ~30MiB of memory constantly reserved only for those
buffers.
Since the buffer is used only in the function and is never passed
outside, a stack allocation would suffice; however, it's not wise to
do such large allocations on the stack; dynamically allocate it.
https://github.com/nettools/n-dhcp4/issues/26https://github.com/nettools/n-dhcp4/pull/2764513e31c0
I got a report of a scenario where multiple servers reply to a REQUEST
in SELECTING, and all servers send NAKs except the one which sent the
offer, which replies with a ACK. In that scenario, n-dhcp4 is not able
to obtain a lease because it restarts from INIT as soon as the first
NAK is received. For comparison, dhclient can get a lease because it
ignores all NAKs in SELECTING.
Arguably, the network is misconfigured there, but it would be great if
n-dhcp4 could still work in such scenario.
According to RFC 2131, ACK and NAK messages from server must contain a
server-id option. The RFC doesn't explicitly say that the client
should check the option, but I think it's a reasonable thing to do, at
least for NAKs.
This patch stores the server-id of the REQUEST in SELECTING, and
compares it with the server-id from NAKs, to discard other servers'
replies.
https://gitlab.freedesktop.org/NetworkManager/NetworkManager/-/merge_requests/1144
On RHEL-8.5, s390x with gcc-8.5.0-2.el8, we get a compiler warning:
$ CFLAGS='-O2 -Werror=maybe-uninitialized' meson build
...
cc -Isrc/libndhcp4-private.a.p -Isrc -I../src -Isubprojects/c-list/src -I../subprojects/c-list/src -Isubprojects/c-siphash/src -I../subprojects/c-siphash/src -Isubprojects/c-stdaux/src -I../subprojects/c-stdaux/src -fdiagnostics-color=always -pipe -D_FILE_OFFSET_BITS=64 -Wall -Winvalid-pch -std=c11 -g -D_GNU_SOURCE -O2 -Werror=maybe-uninitialized -fPIC -fvisibility=hidden -fno-common -MD -MQ src/libndhcp4-private.a.p/n-dhcp4-c-connection.c.o -MF src/libndhcp4-private.a.p/n-dhcp4-c-connection.c.o.d -o src/libndhcp4-private.a.p/n-dhcp4-c-connection.c.o -c ../src/n-dhcp4-c-connection.c
../src/n-dhcp4-c-connection.c: In function ‘n_dhcp4_c_connection_dispatch_io’:
../src/n-dhcp4-c-connection.c:1151:17: error: ‘type’ may be used uninitialized in this function [-Werror=maybe-uninitialized]
uint8_t type;
^~~~
https://github.com/nettools/n-dhcp4/pull/24
