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|
package bonafide
import (
"errors"
"log"
"math/rand"
"sort"
"strconv"
"time"
)
const (
maxGateways = 3
)
// A Gateway is a representation of gateways that is independent of the api version.
// If a given physical location offers different transports, they will appear as separate gateways.
type Gateway struct {
Host string
IPAddress string
Location string
Ports []string
Protocols []string
Options map[string]string
Transport string
Label string
}
/* TODO add a String method with a human representation: Label (cc) */
/* For that, we should pass the locations to genLabels, and generate a string repr */
type gatewayDistance struct {
gateway Gateway
distance int
}
type gatewayPool struct {
available []Gateway
/* ranked is, for now, just an array of hostnames (fetched from the
geoip service). it should be a map in the future, to keep track of
quantitative metrics */
ranked []string
userChoice string
locations map[string]location
}
/* genLabels generates unique, human-readable labels for a gateway. It gives a serial
number to each gateway in the same location (paris-1, paris-2,...). The
current implementation will give a different label to each transport.
*/
func (p *gatewayPool) genLabels() {
acc := make(map[string]int)
for i, gw := range p.available {
if _, count := acc[gw.Location]; !count {
acc[gw.Location] = 1
} else {
acc[gw.Location] += 1
}
gw.Label = gw.Location + "-" + strconv.Itoa(acc[gw.Location])
p.available[i] = gw
}
/* skip suffix if only one occurence */
for i, gw := range p.available {
if acc[gw.Location] == 1 {
gw.Label = gw.Location
p.available[i] = gw
}
}
}
func (p *gatewayPool) getLabels() []string {
labels := make([]string, 0)
for _, gw := range p.available {
labels = append(labels, gw.Label)
}
/* TODO return error if called when no labels have been generated */
return labels
}
func (p *gatewayPool) isValidLabel(label string) bool {
labels := p.getLabels()
valid := stringInSlice(label, labels)
return valid
}
func (p *gatewayPool) getGatewayByLabel(label string) (Gateway, error) {
for _, gw := range p.available {
if gw.Label == label {
return gw, nil
}
}
return Gateway{}, errors.New("bonafide: not a valid label")
}
func (p *gatewayPool) getGatewayByIP(ip string) (Gateway, error) {
for _, gw := range p.available {
if gw.IPAddress == ip {
return gw, nil
}
}
return Gateway{}, errors.New("bonafide: not a valid ip address")
}
func (p *gatewayPool) setAutomaticChoice() {
p.userChoice = ""
}
func (p *gatewayPool) setUserChoice(label string) error {
if !p.isValidLabel(label) {
return errors.New("bonafide: not a valid label for gateway choice")
}
p.userChoice = label
return nil
}
func (p *gatewayPool) setRanking(hostnames []string) {
hosts := make([]string, 0)
for _, gw := range p.available {
hosts = append(hosts, gw.Host)
}
for _, host := range hostnames {
if !stringInSlice(host, hosts) {
log.Println("ERROR: invalid host in ranked hostnames", host)
return
}
}
p.ranked = hostnames
}
func (p *gatewayPool) getBest(transport string, tz, max int) ([]Gateway, error) {
gws := make([]Gateway, 0)
if len(p.userChoice) != 0 {
gw, err := p.getGatewayByLabel(p.userChoice)
gws = append(gws, gw)
return gws, err
} else if len(p.ranked) != 0 {
return p.getGatewaysByServiceRank(transport, max)
} else {
return p.getGatewaysByTimezone(transport, tz, max)
}
}
func (p *gatewayPool) getAll(transport string, tz int) ([]Gateway, error) {
if len(p.ranked) != 0 {
return p.getGatewaysByServiceRank(transport, 999)
} else {
return p.getGatewaysByTimezone(transport, tz, 999)
}
}
func (p *gatewayPool) getGatewaysByServiceRank(transport string, max int) ([]Gateway, error) {
gws := make([]Gateway, 0)
for _, host := range p.ranked {
for _, gw := range p.available {
if gw.Transport != transport {
continue
}
if gw.Host == host {
gws = append(gws, gw)
}
if len(gws) == max {
goto end
}
}
}
end:
return gws, nil
}
func (p *gatewayPool) getGatewaysByTimezone(transport string, tzOffsetHours, max int) ([]Gateway, error) {
gws := make([]Gateway, 0)
gwVector := []gatewayDistance{}
for _, gw := range p.available {
if gw.Transport != transport {
continue
}
distance := 13
gwOffset, err := strconv.Atoi(p.locations[gw.Location].Timezone)
if err != nil {
log.Printf("Error sorting gateways: %v", err)
return gws, err
} else {
distance = tzDistance(tzOffsetHours, gwOffset)
}
gwVector = append(gwVector, gatewayDistance{gw, distance})
}
rand.Seed(time.Now().UnixNano())
cmp := func(i, j int) bool {
if gwVector[i].distance == gwVector[j].distance {
return rand.Intn(2) == 1
}
return gwVector[i].distance < gwVector[j].distance
}
sort.Slice(gwVector, cmp)
for _, gw := range gwVector {
gws = append(gws, gw.gateway)
if len(gws) == max {
break
}
}
return gws, nil
}
func newGatewayPool(eip *eipService) *gatewayPool {
p := gatewayPool{}
p.available = eip.getGateways()
p.locations = eip.Locations
p.genLabels()
return &p
}
func tzDistance(offset1, offset2 int) int {
abs := func(x int) int {
if x < 0 {
return -x
}
return x
}
distance := abs(offset1 - offset2)
if distance > 12 {
distance = 24 - distance
}
return distance
}
func stringInSlice(a string, list []string) bool {
for _, b := range list {
if b == a {
return true
}
}
return false
}
|
