mirror of
https://github.com/GNS3/gns3-server.git
synced 2026-10-18 17:02:26 +03:00
21b866aeed
Cross-compute links can ride kernel VXLAN tunnels instead of the uBridge
UDP relay: each endpoint creates one VXLAN device (uBridge's rtnetlink
vxlan module) enslaved into the same per-link Linux bridge the same-host
datapath uses, so filters, markers, capture and suspend keep running on
the anchor unchanged. Opt-in (Server.enable_vxlan_cross_compute, default
off) because the tunnel caps the usable MTU at the underlay minus the
outer headers; the relay stays the default and the fallback.
The controller derives what the pair must agree on: one VNI per link
(upper VNI space, per-link random salt) and deterministic device names
(gvl{link}{node}) that make crashed-run leftovers claimable
(show -> delete -> create). Same-host compute pairs, switch endpoints
and serial/unix-socket containers stay on the relay.
A VNI the kernel refuses self-heals on every path it can surface:
interactive create retries a fresh salt then degrades to the relay;
project open re-dispatches refused batch entries the same way; node
start recognises the refused device, stops the half-started node,
re-wires both ends on a fresh VNI (or degrades the link) and retries
the start. The device MTU is derived from the lower device (dev=) and
the per-link bridge inherits it - no configuration. The capability
probe (ubridge_vxlan in /capabilities) runs one scratch create/delete
on a scratch port that never equals the configured dstport.
The e2e scenario runs two computes on one machine (a network namespace
joined by a veth pair as the fabric) and needs root.
87 lines
3.6 KiB
Python
87 lines
3.6 KiB
Python
#
|
|
# Copyright (C) 2026 GNS3 Technologies Inc.
|
|
#
|
|
# This program is free software: you can redistribute it and/or modify
|
|
# it under the terms of the GNU General Public License as published by
|
|
# the Free Software Foundation, either version 3 of the License, or
|
|
# (at your option) any later version.
|
|
#
|
|
# This program is distributed in the hope that it will be useful,
|
|
# but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
|
# GNU General Public License for more details.
|
|
#
|
|
# You should have received a copy of the GNU General Public License
|
|
# along with this program. If not, see <http://www.gnu.org/licenses/>.
|
|
|
|
"""
|
|
Identity of a cross-compute VXLAN link: the device name and VNI the
|
|
controller derives and ships in both endpoints' NIOs.
|
|
|
|
A cross-compute kernel link is carried by one VXLAN device per endpoint
|
|
(uBridge's ``vxlan`` module, rtnetlink), enslaved into the link's per-link
|
|
kernel bridge next to the node's anchor. Each device is local to its own
|
|
host, but the VNI is the kernel's demux key for received frames on the
|
|
deployment-wide shared dstport socket — both ends must agree on it while
|
|
neither can ask the other, so the controller is the single source for both
|
|
values.
|
|
|
|
* the device name is a pure function of the link id plus the endpoint's
|
|
node id: unique per (link, endpoint), within IFNAMSIZ, and outside the
|
|
``gns3``/anchor name spaces (``gvl`` prefix). Determinism is what makes
|
|
a crashed run's leftover device recognisable — the compute deletes a
|
|
device it finds under the name before re-creating it;
|
|
* the VNI is a pure function of the link id and a controller-side salt —
|
|
a random base per link object, bumped when a retry needs a fresh VNI —
|
|
drawn from the upper half of the VNI space so it cannot collide with the
|
|
low well-known VNIs other software uses (Flannel's 1, Docker overlay
|
|
networks from 256, ...).
|
|
|
|
The kernel refuses a second device registering a VNI already taken on the
|
|
same (dstport, socket) pair with EEXIST — a check that doubles as the
|
|
collision detector: the controller retries with a bumped salt and falls
|
|
back to the UDP relay when the space stays occupied (the relay needs no
|
|
VNI at all).
|
|
"""
|
|
|
|
import hashlib
|
|
|
|
# The VNI range derived links draw from: at or above 0x100000 (1M) to stay
|
|
# clear of the low VNIs other VXLAN software commonly registers, at or below
|
|
# 0xFFFFFE so every derived value is valid for the module's 1..16777215
|
|
# (0xFFFFFF) check with one value of headroom.
|
|
VXLAN_VNI_MIN = 0x100000
|
|
VXLAN_VNI_MAX = 0xFFFFFE
|
|
|
|
# IFNAMSIZ (16) - 1 for the terminator: "gvl" (3) + 8 (link) + 4 (node) = 15.
|
|
VXLAN_NAME_PREFIX = "gvl"
|
|
|
|
|
|
def derive_vni(link_id, salt=0):
|
|
"""
|
|
The VNI both endpoints of *link_id* tunnel through.
|
|
|
|
:param link_id: link UUID (or str)
|
|
:param salt: controller-side retry counter — bumped when the kernel
|
|
refuses the previous VNI as already registered on the shared
|
|
dstport socket; 0 for the first attempt
|
|
:returns: VNI in [VXLAN_VNI_MIN, VXLAN_VNI_MAX]
|
|
"""
|
|
|
|
digest = hashlib.sha256(f"{link_id}:{salt}".encode()).digest()
|
|
span = VXLAN_VNI_MAX - VXLAN_VNI_MIN + 1
|
|
return VXLAN_VNI_MIN + int.from_bytes(digest[:8], "big") % span
|
|
|
|
|
|
def vxlan_device_name(link_id, node_id):
|
|
"""
|
|
The VXLAN device name one endpoint of *link_id* creates on its own host,
|
|
deterministic from the link id plus the endpoint's node id (the pair
|
|
normally lives on two hosts, but a forced same-host pair must not name
|
|
both its devices identically).
|
|
"""
|
|
|
|
link = str(link_id).replace("-", "")[:8]
|
|
node = str(node_id).replace("-", "")[:4]
|
|
return f"{VXLAN_NAME_PREFIX}{link}{node}"
|