144 lines
3.3 KiB
Go
144 lines
3.3 KiB
Go
package main
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import (
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log "github.com/sirupsen/logrus"
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"math"
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"net"
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"net/http"
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"runtime"
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"strings"
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"sync"
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"time"
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)
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var (
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checkClient = &http.Client{
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Timeout: 10 * time.Second,
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}
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)
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type Server struct {
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Available bool
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Host string
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Path string
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Latitude float64
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Longitude float64
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}
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type ServerList []*Server
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func (s ServerList) checkLoop() {
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t := time.NewTicker(60 * time.Second)
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for {
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<-t.C
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s.Check()
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}
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}
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// Check will request the index from all servers
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// If a server does not respond in 10 seconds, it is considered offline.
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// This will wait until all checks are complete.
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func (s ServerList) Check() {
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var wg sync.WaitGroup
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for _, server := range s {
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wg.Add(1)
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go func(server *Server) {
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req, err := http.NewRequest(http.MethodGet, "https://"+server.Host+"/"+strings.TrimLeft(server.Path, "/"), nil)
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req.Header.Set("User-Agent", "ArmbianRouter/1.0 (Go "+runtime.Version()+")")
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if err != nil {
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// This should never happen.
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log.WithError(err).Warning("Invalid request! This should not happen, please check config.")
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wg.Done()
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return
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}
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res, err := checkClient.Do(req)
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if err != nil {
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if server.Available {
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log.WithField("server", server.Host).Info("Server went offline")
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server.Available = false
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}
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wg.Done()
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return
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}
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if (res.StatusCode == http.StatusOK || res.StatusCode == http.StatusMovedPermanently || res.StatusCode == http.StatusFound) &&
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!server.Available {
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server.Available = true
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log.WithField("server", server.Host).Info("Server is online")
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}
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wg.Done()
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}(server)
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}
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wg.Wait()
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}
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// Closest will use GeoIP on the IP provided and find the closest server.
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// Return values are the closest server, the distance, and if an error occurred.
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func (s ServerList) Closest(ip net.IP) (*Server, float64, error) {
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var city City
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err := db.Lookup(ip, &city)
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if err != nil {
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return nil, -1, err
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}
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var closest *Server
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var closestDistance float64 = -1
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for _, server := range s {
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if !server.Available {
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continue
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}
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distance := Distance(city.Location.Latitude, city.Location.Longitude, server.Latitude, server.Longitude)
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if closestDistance == -1 || distance < closestDistance {
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closestDistance = distance
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closest = server
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}
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}
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return closest, closestDistance, nil
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}
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// haversin(θ) function
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func hsin(theta float64) float64 {
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return math.Pow(math.Sin(theta/2), 2)
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}
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// Distance function returns the distance (in meters) between two points of
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// a given longitude and latitude relatively accurately (using a spherical
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// approximation of the Earth) through the Haversin Distance Formula for
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// great arc distance on a sphere with accuracy for small distances
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//
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// point coordinates are supplied in degrees and converted into rad. in the func
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//
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// distance returned is METERS!!!!!!
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// http://en.wikipedia.org/wiki/Haversine_formula
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func Distance(lat1, lon1, lat2, lon2 float64) float64 {
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// convert to radians
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// must cast radius as float to multiply later
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var la1, lo1, la2, lo2, r float64
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la1 = lat1 * math.Pi / 180
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lo1 = lon1 * math.Pi / 180
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la2 = lat2 * math.Pi / 180
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lo2 = lon2 * math.Pi / 180
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r = 6378100 // Earth radius in METERS
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// calculate
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h := hsin(la2-la1) + math.Cos(la1)*math.Cos(la2)*hsin(lo2-lo1)
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return 2 * r * math.Asin(math.Sqrt(h))
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}
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