Consume the eBPF impairment classifier delivered in uBridge
feature/tc-precision: frequency_drop becomes the exact every-Nth mode
(tc nth_drop; -1 = drop everything maps to every 1st) and the new
kernel-only quota type is the byte-cap mode (tc quota_drop, 100 = hard
cutoff). KERNEL_UNSUPPORTED_FILTERS is gone entirely — kernel/relay
eligibility is now purely topological. Both modes gate on ebpf=1 from
the per-process tc capabilities probe (error names the setcap fix); the
cleanup path (modes off) only talks to the eBPF commands when the probe
reported them. Reconcile is a plain re-set: the netem reset-before-set
already detaches the program and clears uBridge's per-interface
registry, so a mode set after it is a fresh load+attach.
Documented semantic difference: the relay counts both directions
through one bridge counter, the kernel counts per direction — N=3
round-trip loss is 1-(2/3)^2 = 55.6% on kernel vs ~1/N on relay
(measured 57%). window_drop is NOT exposed: the delivered
implementation advances the window with no gap, making 'outside the
window packets pass' unreachable (needs outage/period fields —
recorded in the spec); flow_drop awaits a parameter-shape decision.
Also fixes a pre-existing restart bug the e2e exposed: _bridges (relay
bridge names) was never cleared on stop, so restarting a node with a
relay link skipped 'bridge create' and failed on add_nio_udp.
e2e (isolated instance): 13/13 — pref-1 tc_impair classifier on both
veths, 57% round-trip for N=3, -1 = exact 100%, quota hard cutoff,
delay coexistence, clean teardown, suspend/resume, node restart,
relay-leg frequency_drop regression through an Ethernet switch. Full
suite: 1925 passed.
Surface the netem extensions delivered in uBridge feature/tc-netem-ext
as GNS3 filter types: rate (tc-style bandwidth string), reorder (needs
delay), gemodel (Gilbert-Elliot bursty loss, exclusive with
packet_loss), duplicate, seed and limit, plus the delay jitter
distribution and the loss/dup correlation parameters. All are
kernel-datapath only — the relay's packet-filter registry has no
equivalent, so available_filters hides them on relay links, setting one
on a created relay link returns 409, and the project-load path drops
them with a warning (update_filters runs before the datapath is
decided, so it cannot reject there). Validation mirrors the tc grammar:
reorder requires delay, gemodel and packet_loss are mutually exclusive,
a distribution requires jitter > 0, rate is integer+unit capped at
100gbit.
The translation in DockerVM._netem_command_parts emits the frozen
grammar order and gates extension keywords on the 'tc capabilities'
netem token list (probed once per uBridge process; a plain
delay/loss/corrupt/dup filter never probes, keeping old uBridge builds
untouched; the correl suffix has no token and gates on 'rate' as the
extension-build marker).
Reconcile became reset-before-set: the kernel's netem change merges
optional attributes (rate, correlation, reorder, corrupt, gemodel,
distribution, seed keep their previous value when the new message omits
them), so removing a parameter needs an explicit 'tc reset' — the
bpf_drop filters are re-added right after in the same flow, so the
clsact churn is invisible. The capability check runs before the reset
so a failed update leaves the previous qdisc in place.
e2e (isolated instance, kernel link): 24/24 — rate 512kbit adds exactly
2x the per-packet serialization to the RTT (45.5 ms for 1400-byte
pings), paretonormal jitter + rate-cleared leak check, reorder gap 5,
gemodel 50% bursty loss, duplicate, loss 30% correl 50%, seed 42 +
limit 5000 visible in the qdisc dump, suspend/resume and node restart
keep the filters, relay link rejects rate with 409, teardown leaves no
netem. Full unit suite: 1916 passed.
Impairment filters with a netem equivalent (delay, packet_loss, corrupt)
now run on the kernel datapath as one tc netem qdisc per veth host end,
pushed through uBridge's netlink tc module (tc netem set / tc reset).
This removes the relay delay filter's nanosleep bottleneck (upstream
Both link endpoints carry the filters: each end's qdisc egress covers
the traffic entering that container, so every direction is impaired
exactly once -- the same net effect as the relay, where both directions
cross the single filtered bridge.
- controller: eligibility keys on relay-only types (frequency_drop, bpf)
instead of any filter; kernel links push the real filters (the
synthetic suspend frequency_drop no longer flips a suspended link to
relay on reopen/reset); update_filters 409s only relay-only types;
available_filters hides them on kernel links
- compute: create_nio whitelists netem-capable filter types; the NIO
update path keeps its own guard (PUT mutates the NIO in place);
_ubridge_apply_netem translates the filter dict into one atomic
netem-set (full re-apply IS the reconcile); node restart restores the
qdisc, link deletion detaches it (the veth survives the link)
- e2e (27/27): delay 100 -> 200.2 ms RTT, atomic replace 50 -> 100.2 ms,
clear -> baseline, packet_loss 30 -> 48 % round-trip (expected 51 %),
suspend/resume and node restart keep the qdisc, link delete leaves no
residual impairment
Markers no longer disqualify the kernel datapath. They ride the NIO like
on the relay path and attach to the veth host end through uBridge's
marker add_kernel/delete_kernel/enable_kernel commands (AF_PACKET taps,
same BPF/direction/signal semantics as the relay mark filter).
- base_node: marker anchors are now polymorphic (relay bridge name or
kernel veth host interface); the reconcile loop is datapath-agnostic
and DockerVM overrides the add/delete/enable primitives to translate
the commands. Marker-name validation extracted for both add paths.
- docker_vm: kernel NIO connect/update apply markers on the veth anchor;
link deletion tears markers down explicitly (the veth survives the
link, unlike a relay bridge whose death drops its filters).
- controller: eligibility and start_marker no longer exclude markers or
project-level marker definitions; the kernel NIO carries the capture
node's marker specs.
- NIO creation accepts markers on kernel NIOs (filters still rejected).
Eligible links (both endpoints Docker, same compute, no filters/markers,
stopped nodes, no unix-socket NIO containers) are wired as veth pairs
enslaved into a per-link Linux kernel bridge (gns3 + 11 hex of the link
id, filling IFNAMSIZ) instead of the uBridge UDP relay, so frames flow
entirely in the kernel.
- NIOBridge NIO type: the controller decides the datapath in
UDPLink._prepare and both computes enslave their deterministic gv*/gc*
veth pair via uBridge's docker/brctl modules
- carrier/suspend = host-end admin state; both endpoints race-safely
create/delete the bridge (EEXIST/EBUSY/ENOENT tolerated)
- veth adapters can still attach relay (UDP) links on a running node:
lazy relay bridge over AF_PACKET on the host end (add_nio_ethernet)
- filters/markers/capture are rejected with explicit errors on this
datapath (they live in the uBridge relay); vendor unix-socket
containers are excluded; Server.enable_kernel_datapath is the
kill-switch (default on)
- host-end veths survive container death and are removed on stop plus
swept by name on the next start (crash/stale recovery)
Mirror the packet-filter lifecycle: marker specs now live on the NIO
(next to filters), ride in link_data from controller to compute on
every NIO create/update, and are reapplied by _ubridge_apply_markers
in add_ubridge_udp_connection (bridge creation / node restart) and
update_ubridge_udp_connection (NIO update — following the preceding
reset_packet_filters so markers survive filter changes).
Changes:
- NIO / NIOUDP: _markers property + asdict
- schemas/compute/nios.py: UDPNIO.markers field
- base_manager.create_nio: nio.markers from settings
- PUT /nio routes (vpcs/qemu/docker): nio.markers update
- base_node: _ubridge_apply_markers(bridge_name, nio) iterates
nio.markers, computes pcap path, calls _ubridge_add_marker_filter
+ MarkerManager.register; called after _ubridge_apply_filters
- controller udp_link: _get_node_markers + _markers_for_node (route
by capture_node_id); markers in create() and update() link_data
- /markers/start,stop endpoints: mirror spec onto nio.markers so
the marker survives a subsequent node stop/start without a PUT
- tests: add markers field to NIO data expectations
This covers:
- Node restart: NIO persists, add_ubridge_udp_connection re-applies
- Filter update: reset wipes markers, _ubridge_apply_markers re-adds
- Project reload: create() carries markers in link_data → create_nio
- Immediate create: endpoint sets nio.markers immediately
* The PCAP file is directly accessed if controller and client are on the same host.
* The PCAP file is streamed from the compute server to the client with the controller as a proxy when the controller is remote for the client.
