Formed in 2009, the Archive Team (not to be confused with the archive.org Archive-It Team) is a rogue archivist collective dedicated to saving copies of rapidly dying or deleted websites for the sake of history and digital heritage. The group is 100% composed of volunteers and interested parties, and has expanded into a large amount of related projects for saving online and digital history.
xdp
Package github.com/asavie/xdp allows one to use XDP sockets from the Go programming language.
Here is a minimal example of a program which receives network frames, modifies their destination MAC address in-place to broadcast address and transmits them back out the same network link:
package main
import (
"github.com/asavie/xdp"
"github.com/vishvananda/netlink"
)
func main() {
const NetworkDevice = "enp3s0"
const QueueID = 0
link, err := netlink.LinkByName(NetworkDevice)
if err != nil {
panic(err)
}
xsk, err := xdp.NewSocket(link.Attrs().Index, QueueID)
if err != nil {
panic(err)
}
for {
xsk.Fill(xsk.GetDescs(xsk.NumFreeFillSlots()))
numRx, _, err := xsk.Poll(-1)
if err != nil {
panic(err)
}
rxDescs := xsk.Receive(numRx)
for i := 0; i < len(rxDescs); i++ {
// Set destination MAC address to
// ff:ff:ff:ff:ff:ff
frame := xsk.GetFrame(rxDescs[i])
for i := 0; i < 6; i++ {
frame[i] = byte(0xff)
}
}
xsk.Transmit(rxDescs)
}
}Performance
examples/sendudp
With the default UDP payload size of 1400 bytes, running on Linux kernel 5.1.20, on a tg3 (so no native XDP support) gigabit NIC, sendudp.go does around 980 Mb/s, so practically line rate.
examples/senddnsqueries
TL;DR: in the same environment, sending a pre-generated DNS query using an ordinary UDP socket yields around 30 MiB/s whereas sending it using the senddnsqueries.go example program yields around 77 MiB/s.
Connecting a PC with Intel Core i7-7700 CPU running Linux kernel 5.0.17 and igb driver to a laptop with Intel Core i7-5600U CPU running Linux kernel 5.0.9 with e1000e with a cat 5E gigabit ethernet cable and using the following program
package main
import (
"net"
"github.com/miekg/dns"
)
func main() {
query := new(dns.Msg)
query.SetQuestion(dns.Fqdn("asavie.com"), dns.TypeA)
payload, err := query.Pack()
if err != nil {
panic(err)
}
conn, err := net.ListenPacket("udp", ":0")
if err != nil {
panic(err)
}
defer conn.Close()
dst, err := net.ResolveUDPAddr("udp", "192.168.111.10:53")
if err != nil {
panic(err)
}
for {
_, err = conn.WriteTo(payload, dst)
if err != nil {
panic(err)
}
}
}which uses an ordinary UDP socket to send a pre-generated DNS query from PC to laptop as quickly as possible - I get about 30 MiB/s at laptop side.
Using the senddnsqueries.go example program - I get about 77 MiB/s at laptop side.