Nikolay Aleksandrov says:
====================
This set tries to help with an old ask that we've had for some time
which is to print nexthop information while monitoring or dumping routes.
The core problem is that people cannot follow nexthop changes while
monitoring route changes, by the time they check the nexthop it could be
deleted or updated to something else. In order to help them out I've
added a nexthop cache which is populated (only used if -d / show_details
is specified) while decoding routes and kept up to date while monitoring.
The nexthop information is printed on its own line starting with the
"nh_info" attribute and its embedded inside it if printing JSON. To
cache the nexthop entries I parse them into structures, in order to
reuse most of the code the print helpers have been altered so they rely
on prepared structures. Nexthops are now always parsed into a structure,
even if they won't be cached, that structure is later used to print the
nexthop and destroyed if not going to be cached. New nexthops (not found
in the cache) are retrieved from the kernel using a private netlink
socket so they don't disrupt an ongoing dump, similar to how interfaces
are retrieved and cached.
I have tested the set with the kernel forwarding selftests and also by
stressing it with nexthop create/update/delete in loops while monitoring.
Comments are very welcome as usual. :)
Changes since RFC:
- reordered parse/print splits, in order to do that I have to parse
resilient groups first, then add nh entry parsing so code has been
reordered as well and patch order has changed, but there have been
no functional changes (as before refactoring of old code is done in
the first 8 patches and then patches 9-12 add the new cache and use it)
- re-run all tests above
Patch breakdown:
Patches 1-2: update current route helpers to take parsed arguments so we
can directly pass them from the nh_entry structure later
Patch 3: adds new nha_res_grp structure which describes a resilient
nexhtop group
Patch 4: splits print_nh_res_group into a parse and print parts
which use the new nha_res_grp structure
Patch 5: adds new nh_entry structure which describes a nexthop
Patch 6: factors out print_nexthop's attribute parsing into nh_entry
structure used before printing
Patch 7: factors out print_nexthop's nh_entry structure printing
Patch 8: factors out ipnh_get's rtnl talk part and allows to use a
different rt handle for the communication
Patch 9: adds nexthop cache and helpers to manage it, it uses the
new __ipnh_get to retrieve nexthops
Patch 10: adds a new helper print_cache_nexthop_id that prints nexthop
information from its id, if the nexthop is not found in the
cache it fetches it
Patch 11: the new print_cache_nexthop_id helper is used when printing
routes with show_details (-d) to output detailed nexthop
information, the format after nh_info is the same as
ip nexthop show
Patch 12: changes print_nexthop into print_cache_nexthop which always
outputs the nexthop information and can also update the cache
(based on process_cache argument), it's used to keep the
cache up to date while monitoring
Example outputs (monitor):
[NEXTHOP]id 101 via 169.254.2.22 dev veth2 scope link proto unspec
[NEXTHOP]id 102 via 169.254.3.23 dev veth4 scope link proto unspec
[NEXTHOP]id 103 group 101/102 type resilient buckets 512 idle_timer 0 unbalanced_timer 0 unbalanced_time 0 scope global proto unspec
[ROUTE]unicast 192.0.2.0/24 nhid 203 table 4 proto boot scope global
nh_info id 203 group 201/202 type resilient buckets 512 idle_timer 0 unbalanced_timer 0 unbalanced_time 0 scope global proto unspec
nexthop via 169.254.2.12 dev veth3 weight 1
nexthop via 169.254.3.13 dev veth5 weight 1
[NEXTHOP]id 204 via fe80:2::12 dev veth3 scope link proto unspec
[NEXTHOP]id 205 via fe80:3::13 dev veth5 scope link proto unspec
[NEXTHOP]id 206 group 204/205 type resilient buckets 512 idle_timer 0 unbalanced_timer 0 unbalanced_time 0 scope global proto unspec
[ROUTE]unicast 2001:db8:1::/64 nhid 206 table 4 proto boot scope global metric 1024 pref medium
nh_info id 206 group 204/205 type resilient buckets 512 idle_timer 0 unbalanced_timer 0 unbalanced_time 0 scope global proto unspec
nexthop via fe80:2::12 dev veth3 weight 1
nexthop via fe80:3::13 dev veth5 weight 1
[NEXTHOP]id 2 encap mpls 200/300 via 10.1.1.1 dev ens20 scope link proto unspec onlink
[ROUTE]unicast 2.3.4.10 nhid 2 table main proto boot scope global
nh_info id 2 encap mpls 200/300 via 10.1.1.1 dev ens20 scope link proto unspec onlink
JSON:
{
"type": "unicast",
"dst": "198.51.100.0/24",
"nhid": 103,
"table": "3",
"protocol": "boot",
"scope": "global",
"flags": [ ],
"nh_info": {
"id": 103,
"group": [ {
"id": 101,
"weight": 11
},{
"id": 102,
"weight": 45
} ],
"type": "resilient",
"resilient_args": {
"buckets": 512,
"idle_timer": 0,
"unbalanced_timer": 0,
"unbalanced_time": 0
},
"scope": "global",
"protocol": "unspec",
"flags": [ ]
},
"nexthops": [ {
"gateway": "169.254.2.22",
"dev": "veth2",
"weight": 11,
"flags": [ ]
},{
"gateway": "169.254.3.23",
"dev": "veth4",
"weight": 45,
"flags": [ ]
} ]
}
====================
Signed-off-by: David Ahern <dsahern@kernel.org>
This is a set of utilities for Linux networking.
Information:
https://wiki.linuxfoundation.org/networking/iproute2
Download:
http://www.kernel.org/pub/linux/utils/net/iproute2/
Stable version repository:
git://git.kernel.org/pub/scm/network/iproute2/iproute2.git
Development repository:
git://git.kernel.org/pub/scm/network/iproute2/iproute2-next.git
How to compile this.
--------------------
1. libdbm
arpd needs to have the berkeleydb development libraries. For Debian
users this is the package with a name like libdbX.X-dev.
DBM_INCLUDE points to the directory with db_185.h which
is the include file used by arpd to get to the old format Berkeley
database routines. Often this is in the db-devel package.
2. make
The makefile will automatically build a config.mk file which
contains definitions of libraries that may or may not be available
on the system such as: ATM, ELF, MNL, and SELINUX.
3. include/uapi
This package includes matching sanitized kernel headers because
the build environment may not have up to date versions. See Makefile
if you have special requirements and need to point at different
kernel include files.
Stephen Hemminger
stephen@networkplumber.org
Alexey Kuznetsov
kuznet@ms2.inr.ac.ru
ec703e0629