feat(nordvpn): new API endpoint and wireguard support (#1380)

Co-authored-by: Quentin McGaw <quentin.mcgaw@gmail.com>

internal/provider/nordvpn/updater/models.go

@@ -0,0 +1,131 @@
+package updater
+
+import (
+	"encoding/base64"
+	"errors"
+	"fmt"
+	"net/netip"
+)
+
+// Check out the JSON data from https://api.nordvpn.com/v1/servers?limit=10
+type serverData struct {
+	// Name is the server name, for example 'Poland #128'
+	Name string `json:"name"`
+	// Stations is, it seems, the entry IP address.
+	// However it is ignored in favor of the 'ips' entry field.
+	Station netip.Addr `json:"station"`
+	// IPv6Station is mostly empty, so we ignore it for now.
+	IPv6Station netip.Addr `json:"station_ipv6"`
+	// Hostname is the server hostname, for example 'pl128.nordvpn.com'
+	Hostname string
+	// Status is the server status, for example 'online'
+	Status string `json:"status"`
+	// Locations is the list of locations for the server.
+	// Only the first location is taken into account for now.
+	Locations []struct {
+		Country struct {
+			// Name is the country name, for example 'Poland'.
+			Name string `json:"name"`
+			City struct {
+				// Name is the city name, for example 'Warsaw'.
+				Name string `json:"name"`
+			} `json:"city"`
+		} `json:"country"`
+	} `json:"locations"`
+	Technologies []struct {
+		// Identifier is the technology id name, it can notably be:
+		// - openvpn_udp
+		// - openvpn_tcp
+		// - wireguard_udp
+		Identifier string `json:"identifier"`
+		// Metadata is notably useful for the Wireguard public key.
+		Metadata []struct {
+			// Name can notably be 'public_key'.
+			Name string `json:"name"`
+			// Value can notably the Wireguard public key value.
+			Value string `json:"value"`
+		} `json:"metadata"`
+	} `json:"technologies"`
+	Groups []struct {
+		// Title can notably be the region name, for example 'Europe',
+		// if the group's type/identifier is 'regions'.
+		Title string `json:"title"`
+		Type  struct {
+			// Identifier can be 'regions'.
+			Identifier string `json:"identifier"`
+		} `json:"type"`
+	} `json:"groups"`
+	// IPs is the list of IP addresses for the server.
+	IPs []struct {
+		// Type can notably be 'entry'.
+		Type string `json:"type"`
+		IP   struct {
+			IP netip.Addr `json:"ip"`
+		} `json:"ip"`
+	} `json:"ips"`
+}
+
+// country returns the country name of the server.
+func (s *serverData) country() (country string) {
+	if len(s.Locations) == 0 {
+		return ""
+	}
+	return s.Locations[0].Country.Name
+}
+
+// region returns the region name of the server.
+func (s *serverData) region() (region string) {
+	for _, group := range s.Groups {
+		if group.Type.Identifier == "regions" {
+			return group.Title
+		}
+	}
+	return ""
+}
+
+// city returns the city name of the server.
+func (s *serverData) city() (city string) {
+	if len(s.Locations) == 0 {
+		return ""
+	}
+	return s.Locations[0].Country.City.Name
+}
+
+// ips returns the list of IP addresses for the server.
+func (s *serverData) ips() (ips []netip.Addr) {
+	ips = make([]netip.Addr, 0, len(s.IPs))
+	for _, ipObject := range s.IPs {
+		if ipObject.Type != "entry" {
+			continue
+		}
+		ips = append(ips, ipObject.IP.IP)
+	}
+	return ips
+}
+
+var (
+	ErrWireguardPublicKeyMalformed = errors.New("wireguard public key is malformed")
+	ErrWireguardPublicKeyNotFound  = errors.New("wireguard public key not found")
+)
+
+// wireguardPublicKey returns the Wireguard public key for the server.
+func (s *serverData) wireguardPublicKey() (wgPubKey string, err error) {
+	for _, technology := range s.Technologies {
+		if technology.Identifier != "wireguard_udp" {
+			continue
+		}
+		for _, metadata := range technology.Metadata {
+			if metadata.Name != "public_key" {
+				continue
+			}
+			wgPubKey = metadata.Value
+			_, err = base64.StdEncoding.DecodeString(wgPubKey)
+			if err != nil {
+				return "", fmt.Errorf("%w: %s cannot be decoded: %s",
+					ErrWireguardPublicKeyMalformed, wgPubKey, err)
+			}
+			return metadata.Value, nil
+		}
+	}
+	return "", fmt.Errorf("%w", ErrWireguardPublicKeyNotFound)
+}