PIA port forwarding final fixes (#259)

- Returns an error if the server does not support port forwarding
- TLS verification using the server common name obtained through the API
- Updated readme
- Fixes #236

Dockerfile

@@ -113,4 +113,6 @@ RUN apk add -q --progress --no-cache --update openvpn ca-certificates iptables i
     deluser tinyproxy && \
     deluser unbound && \
     mkdir /gluetun
+# TODO remove once SAN is added to PIA servers certificates, see https://github.com/pia-foss/manual-connections/issues/10
+ENV GODEBUG=x509ignoreCN=0
 COPY --from=builder /tmp/gobuild/entrypoint /entrypoint

README.md

@@ -352,11 +352,11 @@ There are various ways to achieve this, depending on your use case.
 
 ## Private Internet Access port forwarding
 
-Note that [not all regions support port forwarding](https://www.privateinternetaccess.com/helpdesk/kb/articles/how-do-i-enable-port-forwarding-on-my-vpn).
-
-When `PORT_FORWARDING=on`, a port will be forwarded on the VPN server side and written to the file specified by `PORT_FORWARDING_STATUS_FILE=/forwarded_port`.
+When `PORT_FORWARDING=on`, a port will be forwarded on the VPN server side and written to the file specified by `PORT_FORWARDING_STATUS_FILE=/tmp/gluetun/forwarded_port`.
 It can be useful to mount this file as a volume to read it from other containers, for example to configure a torrenting client.
 
+For `VPNSP=private internet access` (default), you will keep the same forwarded port for 60 days as long as you bind mount the `/gluetun` directory.
+
 You can also use the HTTP control server (see below) to get the port forwarded.
 
 ## HTTP control server

internal/provider/piav4.go

@@ -24,9 +24,11 @@ import (
 )
 
 type piaV4 struct {
-	servers    []models.PIAServer
-	timeNow    timeNowFunc
-	randSource rand.Source
+	servers        []models.PIAServer
+	timeNow        timeNowFunc
+	randSource     rand.Source
+	activeServer   models.PIAServer
+	activeProtocol models.NetworkProtocol
 }
 
 func newPrivateInternetAccessV4(servers []models.PIAServer, timeNow timeNowFunc) *piaV4 {
@@ -79,7 +81,29 @@ func (p *piaV4) GetOpenVPNConnection(selection models.ServerSelection) (connecti
 		}
 	}
 
-	return pickRandomConnection(connections, p.randSource), nil
+	connection = pickRandomConnection(connections, p.randSource)
+
+	// Reverse lookup server from picked connection
+	found := false
+	for _, server := range servers {
+		IPs := server.OpenvpnUDP.IPs
+		if selection.Protocol == constants.TCP {
+			IPs = server.OpenvpnTCP.IPs
+		}
+		for _, IP := range IPs {
+			if connection.IP.Equal(IP) {
+				p.activeServer = server
+				found = true
+				break
+			}
+		}
+		if found {
+			break
+		}
+	}
+	p.activeProtocol = selection.Protocol
+
+	return connection, nil
 }
 
 func (p *piaV4) BuildConf(connection models.OpenVPNConnection, verbosity, uid, gid int, root bool, cipher, auth string, extras models.ExtraConfigOptions) (lines []string) {
@@ -90,11 +114,19 @@ func (p *piaV4) BuildConf(connection models.OpenVPNConnection, verbosity, uid, g
 func (p *piaV4) PortForward(ctx context.Context, client *http.Client,
 	fileManager files.FileManager, pfLogger logging.Logger, gateway net.IP, fw firewall.Configurator,
 	syncState func(port uint16) (pfFilepath models.Filepath)) {
+	if !p.activeServer.PortForward {
+		pfLogger.Error("The server %s does not support port forwarding", p.activeServer.Region)
+		return
+	}
 	if gateway == nil {
 		pfLogger.Error("aborting because: VPN gateway IP address was not found")
 		return
 	}
-	client, err := newPIAv4HTTPClient()
+	commonName := p.activeServer.OpenvpnUDP.CN
+	if p.activeProtocol == constants.TCP {
+		commonName = p.activeServer.OpenvpnTCP.CN
+	}
+	client, err := newPIAv4HTTPClient(commonName)
 	if err != nil {
 		pfLogger.Error("aborting because: %s", err)
 		return
@@ -225,7 +257,7 @@ func filterPIAServers(servers []models.PIAServer, region string) (filtered []mod
 	return nil
 }
 
-func newPIAv4HTTPClient() (client *http.Client, err error) {
+func newPIAv4HTTPClient(serverName string) (client *http.Client, err error) {
 	certificateBytes, err := base64.StdEncoding.DecodeString(constants.PIACertificateStrong)
 	if err != nil {
 		return nil, fmt.Errorf("cannot decode PIA root certificate: %w", err)
@@ -237,10 +269,10 @@ func newPIAv4HTTPClient() (client *http.Client, err error) {
 	rootCAs := x509.NewCertPool()
 	rootCAs.AddCert(certificate)
 	TLSClientConfig := &tls.Config{
-		RootCAs:            rootCAs,
-		MinVersion:         tls.VersionTLS12,
-		InsecureSkipVerify: true, //nolint:gosec
-	} // TODO fix and remove InsecureSkipVerify
+		RootCAs:    rootCAs,
+		MinVersion: tls.VersionTLS12,
+		ServerName: serverName,
+	}
 	transport := http.Transport{
 		TLSClientConfig: TLSClientConfig,
 		Proxy:           http.ProxyFromEnvironment,
@@ -267,9 +299,6 @@ func refreshPIAPortForwardData(client *http.Client, gateway net.IP, fileManager
 	}
 	data.Port, data.Signature, data.Expiration, err = fetchPIAPortForwardData(client, gateway, data.Token)
 	if err != nil {
-		if strings.HasSuffix(err.Error(), "connection refused") {
-			return data, fmt.Errorf("cannot obtain port forwarding data: connection was refused, are you sure the region you are using supports port forwarding ;)")
-		}
 		return data, fmt.Errorf("cannot obtain port forwarding data: %w", err)
 	}
 	if err := writePIAPortForwardData(fileManager, data); err != nil {