Add initial prototype (#1)

* Add survey library to select server

* Add speedtest

* Add --random flag to connect

* Add list command

* Cache server list

* Tail the openvpn logs so that it appears in vpngate logs

* Add goreleaser action

* Add golangci-lint action

pkg/vpn/list.go

@@ -0,0 +1,104 @@
+package vpn
+
+import (
+	"net/http"
+
+	"bytes"
+	"io"
+
+	"github.com/jszwec/csvutil"
+	"github.com/rs/zerolog/log"
+
+	"github.com/juju/errors"
+)
+
+const (
+	vpnList = "https://www.vpngate.net/api/iphone/"
+)
+
+// Server holds in formation about a vpn relay server
+type Server struct {
+	HostName          string `csv:"#HostName"`
+	CountryLong       string `csv:"CountryLong"`
+	CountryShort      string `csv:"CountryShort"`
+	Score             int    `csv:"Score"`
+	IPAddr            string `csv:"IP"`
+	OpenVpnConfigData string `csv:"OpenVPN_ConfigData_Base64"`
+	Ping              string `csv:"Ping"`
+}
+
+func streamToBytes(stream io.Reader) []byte {
+	buf := new(bytes.Buffer)
+	_, err := buf.ReadFrom(stream)
+	if err != nil {
+		log.Error().Msg("Unable to stream bytes")
+	}
+	return buf.Bytes()
+}
+
+// parse csv
+func parseVpnList(r io.Reader) (*[]Server, error) {
+
+	var servers []Server
+
+	serverList := streamToBytes(r)
+
+	// Trim known invalid rows
+	serverList = bytes.TrimPrefix(serverList, []byte("*vpn_servers\r\n"))
+	serverList = bytes.TrimSuffix(serverList, []byte("*\r\n"))
+
+	if err := csvutil.Unmarshal(serverList, &servers); err != nil {
+		return nil, errors.Annotatef(err, "Unable to parse CSV")
+	}
+
+	return &servers, nil
+
+}
+
+// GetList returns a list of vpn servers
+func GetList() (*[]Server, error) {
+
+	cacheExpired := vpnListCacheIsExpired()
+
+	var servers *[]Server
+
+	if !cacheExpired {
+		servers, err := getVpnListCache()
+
+		if err != nil {
+			log.Info().Msg("Unable to retrieve vpn list from cache")
+		} else {
+			return servers, nil
+		}
+
+	} else {
+		log.Info().Msg("The vpn server list cache has expired")
+	}
+
+	log.Info().Msg("Fetching the latest server list")
+	r, err := http.Get(vpnList)
+
+	if err != nil {
+		return nil, errors.Annotate(err, "Unable to retrieve vpn list")
+	}
+
+	defer r.Body.Close()
+
+	if r.StatusCode != 200 {
+		return nil, errors.Annotatef(err, "Unexpected status code when retrieving vpn list: %d", r.StatusCode)
+	}
+
+	servers, err = parseVpnList(r.Body)
+
+	if err != nil {
+		return nil, errors.Annotate(err, "unable to parse vpn list")
+	}
+
+	err = writeVpnListToCache(*servers)
+
+	if err != nil {
+		log.Warn().Msgf("Unable to write servers to cache: %s", err)
+	}
+
+	return servers, nil
+}