Obtain PIA v4 server information from API (#257)

- Obtain CN for port forwarding https verification
- Obtain for each server if they support port forwarding
- Obtain for each server their IP address for openvpn UDP and openvpn TCP (one for each)
- Updater program updated to use API
- Hardcoded values updated for PIA v3 and v4 servers
- Clearer separation between pia v3 and v4
- Fixes #250

internal/provider/pia.go

@@ -8,68 +8,6 @@ import (
 	"github.com/qdm12/gluetun/internal/models"
 )
 
-func filterPIAServers(servers []models.PIAServer, region string) (filtered []models.PIAServer) {
-	if len(region) == 0 {
-		return servers
-	}
-	for _, server := range servers {
-		if strings.EqualFold(server.Region, region) {
-			return []models.PIAServer{server}
-		}
-	}
-	return nil
-}
-
-func getPIAOpenVPNConnections(allServers []models.PIAServer, selection models.ServerSelection) (connections []models.OpenVPNConnection, err error) {
-	servers := filterPIAServers(allServers, selection.Region)
-	if len(servers) == 0 {
-		return nil, fmt.Errorf("no server found for region %q", selection.Region)
-	}
-
-	var port uint16
-	switch selection.Protocol {
-	case constants.TCP:
-		switch selection.EncryptionPreset {
-		case constants.PIAEncryptionPresetNormal:
-			port = 502
-		case constants.PIAEncryptionPresetStrong:
-			port = 501
-		}
-	case constants.UDP:
-		switch selection.EncryptionPreset {
-		case constants.PIAEncryptionPresetNormal:
-			port = 1198
-		case constants.PIAEncryptionPresetStrong:
-			port = 1197
-		}
-	}
-	if port == 0 {
-		return nil, fmt.Errorf("combination of protocol %q and encryption %q does not yield any port number", selection.Protocol, selection.EncryptionPreset)
-	}
-
-	for _, server := range servers {
-		for _, IP := range server.IPs {
-			if selection.TargetIP != nil {
-				if selection.TargetIP.Equal(IP) {
-					return []models.OpenVPNConnection{{IP: IP, Port: port, Protocol: selection.Protocol}}, nil
-				}
-			} else {
-				connections = append(connections, models.OpenVPNConnection{IP: IP, Port: port, Protocol: selection.Protocol})
-			}
-		}
-	}
-
-	if selection.TargetIP != nil {
-		return nil, fmt.Errorf("target IP %s not found in IP addresses", selection.TargetIP)
-	}
-
-	if len(connections) > 64 {
-		connections = connections[:64]
-	}
-
-	return connections, nil
-}
-
 func buildPIAConf(connections []models.OpenVPNConnection, verbosity int, root bool, cipher, auth string, extras models.ExtraConfigOptions) (lines []string) {
 	var X509CRL, certificate string
 	if extras.EncryptionPreset == constants.PIAEncryptionPresetNormal {