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balancer.go
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balancer.go
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/*
* VC5 load balancer. Copyright (C) 2021-present David Coles
*
* 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 2 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, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
package kernel
import (
"fmt"
"net"
"sort"
"sync"
"time"
"github.com/davidcoles/vc5/kernel/bpf"
"github.com/davidcoles/vc5/kernel/xdp"
"github.com/davidcoles/vc5/types"
)
const (
A = false
B = true
)
type l4Service struct {
vip IP4
svc L4
}
type Counter struct {
Octets uint64
Packets uint64
Flows uint64
Concurrent uint64
Blocked uint64
Latency uint64 // global only
QueueFailed uint64 // global only
DEFCON uint8 // global only
}
func (c *Counter) Add(n Counter) {
c.Octets += n.Octets
c.Packets += n.Packets
c.Flows += n.Flows
c.Concurrent += n.Concurrent
c.Blocked += n.Blocked
}
type Balancer struct {
maps *maps
checks chan Healthchecks
stats map[Target]bool
conns map[Target]bpf_active
mutex sync.Mutex
logger types.Logger
}
func (m *maps) Balancer(c Healthchecks, l types.Logger) *Balancer {
b := &Balancer{maps: m, logger: l, checks: make(chan Healthchecks)}
go b.balancer()
b.checks <- c
return b
}
func (b *Balancer) Close() {
close(b.checks)
}
func (b *Balancer) Configure(r Healthchecks) {
b.checks <- r
}
func (b *Balancer) Stats() map[Target]Counter {
// local copies of stats to fill in
stats := map[Target]Counter{}
conns := map[Target]bpf_active{}
b.mutex.Lock()
for k, _ := range b.stats {
stats[k] = Counter{}
}
for k, v := range b.conns {
conns[k] = v
}
b.mutex.Unlock()
for k, _ := range stats {
var bc bpf_counter
vrrp := bpf_vrpp{vip: k.VIP, rip: k.RIP, port: htons(k.Port), protocol: k.Protocol}
b.maps.lookup_vrpp_counter(&vrrp, &bc)
stats[k] = Counter{Octets: bc.octets, Packets: bc.packets, Flows: bc.flows, Concurrent: uint64(conns[k].current)}
}
return stats
}
func (b *Balancer) StoreFlow(fs []byte) {
if len(fs) != bpf.FLOW_S+bpf.STATE_S {
return
}
flow := uP(&fs[0])
state := uP(&fs[bpf.FLOW_S])
time := (*uint32)(state)
*time = uint32(xdp.KtimeGet()) // set first 4 bytes of state to the local kernel time
xdp.BpfMapUpdateElem(b.maps.flow_shared(), flow, state, xdp.BPF_ANY)
}
func (b *Balancer) FlowQueue() []byte {
var entry [bpf.FLOW_S + bpf.STATE_S]byte
if xdp.BpfMapLookupAndDeleteElem(b.maps.flow_queue(), nil, uP(&entry)) != 0 {
return nil
}
return entry[:]
}
func (b *Balancer) BlockList(list [PREFIXES]bool) {
var table [PREFIXES / 64]uint64
for n := 0; n < PREFIXES/64; n++ {
var val uint64
for m := 0; m < 64; m++ {
if list[(n*64)+m] {
val |= pow(m)
}
}
table[n] = val
}
b.maps.update_drop_map(table)
b.maps.features.BLOCKLIST = true
b.maps.write_settings()
}
func (b *Balancer) NoBlockList() {
var table [PREFIXES / 64]uint64
b.maps.update_drop_map(table)
b.maps.features.BLOCKLIST = false
b.maps.write_settings()
}
func (b *Balancer) Global() Counter {
g := b.maps.lookup_globals()
return Counter{Octets: g.rx_octets, Packets: g.rx_packets, Flows: g.new_flows, QueueFailed: g.qfailed, Latency: g.latency(), DEFCON: b.maps.defcon, Blocked: g.blocked}
}
func (b *Balancer) balancer() {
FACILITY := "balancer"
b.stats = map[Target]bool{} // list of stats to collect - not values!
b.conns = map[Target]bpf_active{}
done := make(chan bool)
defer close(done)
go b.connections(done)
state := map[l4Service]*be_state{}
vips := map[IP4]bool{}
for h := range b.checks {
b.logger.DEBUG(FACILITY, "Configuration update")
if false {
fmt.Println(h.JSON())
}
services := map[l4Service]bool{}
targets := map[Target]bool{}
interfaces := scanifs()
for vlanid, prefix := range h.VLANs() {
iface, _ := interfaces[prefix]
b.logger.DEBUG("Writing redirect map", vlanid, prefix, iface.mac.String(), iface.index)
_vlanid := uint32(vlanid)
_ifindex := uint32(iface.index)
xdp.BpfMapUpdateElem(b.maps.redirect_mac(), uP(&_vlanid), uP(&(iface.mac)), xdp.BPF_ANY)
xdp.BpfMapUpdateElem(b.maps.redirect_map(), uP(&_vlanid), uP(&(_ifindex)), xdp.BPF_ANY)
}
for k, service := range h.Services__() {
vip := k.VIP
l4 := k.L4()
b.update_backend_service(vip, l4, service, state)
b.create_counters(vip, l4, service.Reals(), targets)
services[l4Service{vip: vip, svc: l4}] = true // add to log of active services
b.maps.update_vrpp_counter(&bpf_vrpp{vip: vip}, &bpf_counter{}, xdp.BPF_NOEXIST) // ICMP responder
vips[vip] = true
}
b.remove_stale_stats(targets)
b.remove_stale_l4(state, services)
for vip, _ := range vips {
if _, ok := h.Virtual[vip]; !ok {
fmt.Println(xdp.BpfMapDeleteElem(b.maps.vrpp_counter(), uP(&bpf_vrpp{vip: vip}))) // remove ICMP responder
delete(vips, vip)
}
}
}
}
func (b *Balancer) update_backend_service(vip IP4, l4 L4, s Service, state map[l4Service]*be_state) {
l4service := l4Service{vip: vip, svc: l4}
bpf_reals := map[IP4]bpf_real{}
//for ip, real := range s.Reals_() {
for _, real := range s.Reals() {
ip := real.RIP
if real.Probe().Passed {
bpf_reals[ip] = bpf_real{rip: ip, mac: real.MAC, vid: htons(real.VID)}
}
}
key := &bpf_service{vip: vip, port: l4.NP(), protocol: l4.PN()}
val := &be_state{
fallback: false,
sticky: s.Sticky,
bpf_reals: bpf_reals,
}
if s.Leastconns {
val.leastconns = s.LeastconnsIP
val.weight = s.LeastconnsWeight
}
now := time.Now()
if update_backend(val, state[l4service], b.logger) {
b.maps.update_service_backend(key, &(val.bpf_backend), xdp.BPF_ANY)
b.logger.INFO("balancer", "Updated table for ", vip, l4, val.bpf_backend.hash[:32], time.Now().Sub(now))
state[l4service] = val
}
}
func (b *Balancer) connections(done chan bool) {
ticker := time.NewTicker(30 * time.Second)
defer ticker.Stop()
var era uint8
for {
select {
case <-done:
return
case <-ticker.C:
stats := map[Target]bool{}
conns := map[Target]bpf_active{}
// grab a copy of the list stats that we're interested in
b.mutex.Lock()
for k, v := range b.stats {
stats[k] = v
}
b.mutex.Unlock()
era++
old := era%2 == 0
b.maps.Era(era) // write back new setting to kernel
// iterate over the selection reading counters at our leisure
for v, _ := range stats {
var a bpf_active
vrrp := bpf_vrpp{vip: v.VIP, rip: v.RIP, port: htons(v.Port), protocol: v.Protocol}
b.maps.lookup_vrpp_concurrent(old, &vrrp, &a) // lookup previous counter
b.maps.update_vrpp_concurrent(old, &vrrp, nil, xdp.BPF_EXIST) // clear previous counter
conns[v] = a
}
// write counters back to the visible copy
b.mutex.Lock()
b.conns = conns
b.mutex.Unlock()
}
}
}
func (b *Balancer) create_counters(vip IP4, l4 L4, reals []Real, targets map[Target]bool) {
m := b.maps
// ensure that backend counters for the service exists
//for rip, _ := range reals {
for _, real := range reals {
rip := real.RIP
vr := bpf_vrpp{vip: vip, rip: rip, port: htons(l4.Port), protocol: l4.Protocol.Number()}
m.update_vrpp_counter(&vr, &bpf_counter{}, xdp.BPF_NOEXIST)
m.update_vrpp_concurrent(A, &vr, nil, xdp.BPF_NOEXIST) // create 'A' counter if it does not exist
m.update_vrpp_concurrent(B, &vr, nil, xdp.BPF_NOEXIST) // create 'B' counter if it does not exist
target := Target{VIP: vip, RIP: rip, Port: l4.Port, Protocol: l4.Protocol.Number()}
b.mutex.Lock()
b.stats[target] = true
targets[target] = true
b.mutex.Unlock()
}
}
func (b *Balancer) remove_stale_stats(targets map[Target]bool) {
m := b.maps
for k, _ := range b.stats {
if _, ok := targets[k]; !ok {
vr := bpf_vrpp{vip: k.VIP, rip: k.RIP, port: htons(k.Port), protocol: k.Protocol}
xdp.BpfMapDeleteElem(m.vrpp_counter(), uP(&vr))
xdp.BpfMapDeleteElem(m.vrpp_concurrent(), uP(&vr))
vr.pad = 1
xdp.BpfMapDeleteElem(m.vrpp_concurrent(), uP(&vr))
b.mutex.Lock()
delete(b.stats, k)
b.mutex.Unlock()
}
}
}
func (b *Balancer) remove_stale_l4(state map[l4Service]*be_state, services map[l4Service]bool) {
for k, _ := range state {
if _, ok := services[k]; !ok {
s := bpf_service{vip: k.vip, port: k.svc.NP(), protocol: k.svc.PN()}
xdp.BpfMapDeleteElem(b.maps.service_backend(), uP(&s))
delete(state, k)
}
}
}
func update_backend(curr, prev *be_state, l types.Logger) bool {
if !curr.diff(prev) {
return false
}
var flag [4]byte
//const F_STICKY = 0x01
//const F_FALLBACK = 0x02
if curr.sticky {
flag[0] |= bpf.F_STICKY
}
if curr.fallback {
flag[0] |= bpf.F_FALLBACK
}
mapper := map[[4]byte]uint8{}
list := IP4s(make([]IP4, 0, len(curr.bpf_reals)))
for ip, _ := range curr.bpf_reals {
list = append(list, ip)
}
sort.Sort(list)
var real [256]bpf_real
for i, ip := range list {
if i < 255 {
idx := uint8(i) + 1
mapper[ip] = idx
real[idx] = curr.bpf_reals[ip]
} else {
fmt.Println("more than 255 hosts", ip, i)
}
}
curr.bpf_backend.real = real
curr.bpf_backend.hash, _ = maglev8192(mapper)
var rip IP4
var mac MAC
var vid [2]byte
if !curr.leastconns.IsNil() {
if n, ok := mapper[curr.leastconns]; ok {
flag[1] = curr.weight
rip = real[n].rip
mac = real[n].mac
vid = real[n].vid
}
}
curr.bpf_backend.real[0] = bpf_real{rip: rip, mac: mac, vid: vid, flag: flag}
return true
}
type be_state struct {
sticky bool
fallback bool
leastconns IP4
weight uint8
bpf_backend bpf_backend
bpf_reals map[IP4]bpf_real
}
func bpf_reals_differ(a, b map[IP4]bpf_real) bool {
for k, v := range a {
if x, ok := b[k]; !ok {
return true
} else {
if x != v {
return true
}
}
}
for k, _ := range b {
if _, ok := a[k]; !ok {
return true
}
}
return false
}
func (curr *be_state) diff(prev *be_state) bool {
if prev == nil {
return true
}
if curr.sticky != prev.sticky ||
curr.fallback != prev.fallback ||
curr.leastconns != prev.leastconns ||
curr.weight != prev.weight {
return true
}
if bpf_reals_differ(curr.bpf_reals, prev.bpf_reals) {
return true
}
return false
}
type iface struct {
index int
mac MAC
}
func scanifs() (ret map[string]iface) {
ret = map[string]iface{}
ifaces, err := net.Interfaces()
if err != nil {
return
}
for _, i := range ifaces {
if i.Flags&net.FlagLoopback != 0 {
continue
}
if i.Flags&net.FlagUp == 0 {
continue
}
if i.Flags&net.FlagBroadcast == 0 {
continue
}
if len(i.HardwareAddr) != 6 {
continue
}
var mac MAC
copy(mac[:], i.HardwareAddr[:])
addr, err := i.Addrs()
if err == nil {
for _, a := range addr {
cidr := a.String()
ip, ipnet, err := net.ParseCIDR(cidr)
if err == nil && ip.To4() != nil {
ret[ipnet.String()] = iface{index: i.Index, mac: mac}
}
}
}
}
return
}