Connected clients admin API (#217)

* Add support for ending the inbound stream. Closes #191

* Add a simple success response to API requests

* Connected clients API with geo details

* Post-rebase cleanup

* Make setting and reading geo details separate operations to unblock and speed up

* Rename file

* Fire geoip api call behind goroutine

* Add comment

* Post-rebase fixes

* Add support for the MaxMind GeoLite2 GeoIP database

geoip/geoip.go

@@ -0,0 +1,84 @@
+// This package utilizes the MaxMind GeoLite2 GeoIP database https://dev.maxmind.com/geoip/geoip2/geolite2/.
+// You must provide your own copy of this database for it to work.
+// Read more about how this works at http://owncast.online/docs/geoip
+
+package geoip
+
+import (
+	"net"
+
+	"github.com/oschwald/geoip2-golang"
+	"github.com/owncast/owncast/config"
+	log "github.com/sirupsen/logrus"
+)
+
+var _geoIPCache = map[string]GeoDetails{}
+var _enabled = true // Try to use GeoIP support it by default.
+
+// GeoDetails stores details about a location
+type GeoDetails struct {
+	CountryCode string `json:"countryCode"`
+	RegionName  string `json:"regionName"`
+	TimeZone    string `json:"timeZone"`
+}
+
+// GetGeoFromIP returns geo details associated with an IP address if we
+// have previously fetched it.
+func GetGeoFromIP(ip string) *GeoDetails {
+	if cachedGeoDetails, ok := _geoIPCache[ip]; ok {
+		return &cachedGeoDetails
+	}
+
+	return nil
+}
+
+// FetchGeoForIP makes an API call to get geo details for an IP address.
+func FetchGeoForIP(ip string) {
+	// If GeoIP has been disabled then don't try to access it.
+	if !_enabled {
+		return
+	}
+
+	// Don't re-fetch if we already have it.
+	if _, ok := _geoIPCache[ip]; ok {
+		return
+	}
+
+	go func() {
+		db, err := geoip2.Open(config.GeoIPDatabasePath)
+		if err != nil {
+			log.Traceln("GeoIP support is disabled. visit http://owncast.online/docs/geoip to learn how to enable.", err)
+			_enabled = false
+			return
+		}
+
+		defer db.Close()
+
+		ipObject := net.ParseIP(ip)
+
+		record, err := db.City(ipObject)
+		if err != nil {
+			log.Warnln(err)
+			return
+		}
+
+		// If no country is available then exit
+		if record.Country.IsoCode == "" {
+			return
+		}
+
+		// If we believe this IP to be anonymous then no reason to report it
+		if record.Traits.IsAnonymousProxy {
+			return
+		}
+
+		response := GeoDetails{
+			CountryCode: record.Country.IsoCode,
+			RegionName:  record.Subdivisions[0].Names["en"],
+			TimeZone:    record.Location.TimeZone,
+		}
+
+		_geoIPCache[ip] = response
+	}()
+
+}