Added Mullvad configuration builder

internal/mullvad/conf.go

@@ -0,0 +1,71 @@
+package mullvad
+
+import (
+	"fmt"
+
+	"github.com/qdm12/golibs/files"
+	"github.com/qdm12/private-internet-access-docker/internal/constants"
+	"github.com/qdm12/private-internet-access-docker/internal/models"
+)
+
+func (c *configurator) GetOpenVPNConnections(country models.MullvadCountry, city models.MullvadCity, provider models.MullvadProvider, protocol models.NetworkProtocol, customPort uint16) (connections []models.OpenVPNConnection, err error) {
+	servers := constants.MullvadServerFilter(country, city, provider)
+	if len(servers) == 0 {
+		return nil, fmt.Errorf("no server found for country %q, city %q and ISP %q", country, city, provider)
+	}
+	for _, server := range servers {
+		port := server.DefaultPort
+		if customPort > 0 {
+			port = customPort
+		}
+		for _, IP := range server.IPs {
+			connections = append(connections, models.OpenVPNConnection{IP: IP, Port: port, Protocol: protocol})
+		}
+	}
+	return connections, nil
+}
+
+func (c *configurator) BuildConf(connections []models.OpenVPNConnection, uid, gid int) (err error) {
+	if len(connections) == 0 {
+		return fmt.Errorf("at least one connection string is expected")
+	}
+	lines := []string{
+		"client",
+		"dev tun",
+		"nobind",
+		"persist-key",
+		"persist-tun",
+		"remote-cert-tls server",
+		"ping 300",
+		"verb 1", // TODO env variable
+
+		// Mullvad specific
+		// "sndbuf 524288"
+		// "rcvbuf 524288"
+		"cipher AES-256-CBC",
+		"tls-cipher TLS-DHE-RSA-WITH-AES-256-GCM-SHA384:TLS-DHE-RSA-WITH-AES-256-CBC-SHA",
+
+		// Added constant values
+		"mute-replay-warnings",
+		"user nonrootuser",
+		"pull-filter ignore \"auth-token\"", // prevent auth failed loops
+		"auth-retry nointeract",
+		"remote-random",
+
+		// Modified variables
+		fmt.Sprintf("auth-user-pass %s", constants.OpenVPNAuthConf),
+		fmt.Sprintf("proto %s", string(connections[0].Protocol)),
+	}
+	for _, connection := range connections {
+		lines = append(lines, fmt.Sprintf("remote %s %d", connection.IP.String(), connection.Port))
+	}
+	lines = append(lines, []string{
+		"<ca>",
+		"-----BEGIN CERTIFICATE-----",
+		constants.MullvadCertificate,
+		"-----END CERTIFICATE-----",
+		"</ca>",
+		"",
+	}...)
+	return c.fileManager.WriteLinesToFile(string(constants.OpenVPNConf), lines, files.Ownership(uid, gid), files.Permissions(0400))
+}