feat(providers): add AirVPN support (#1145)

internal/provider/airvpn/updater/api.go

@@ -0,0 +1,65 @@
+package updater
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"net"
+	"net/http"
+
+	"github.com/qdm12/gluetun/internal/provider/common"
+)
+
+type apiData struct {
+	Servers []apiServer `json:"servers"`
+}
+
+type apiServer struct {
+	PublicName  string `json:"public_name"`
+	CountryName string `json:"country_name"`
+	CountryCode string `json:"country_code"`
+	Location    string `json:"location"`
+	Continent   string `json:"continent"`
+	IPv4In1     net.IP `json:"ip_v4_in1"`
+	IPv4In2     net.IP `json:"ip_v4_in2"`
+	IPv4In3     net.IP `json:"ip_v4_in3"`
+	IPv4In4     net.IP `json:"ip_v4_in4"`
+	IPv6In1     net.IP `json:"ip_v6_in1"`
+	IPv6In2     net.IP `json:"ip_v6_in2"`
+	IPv6In3     net.IP `json:"ip_v6_in3"`
+	IPv6In4     net.IP `json:"ip_v6_in4"`
+	Health      string `json:"health"`
+}
+
+func fetchAPI(ctx context.Context, client *http.Client) (
+	data apiData, err error) {
+	const url = "https://airvpn.org/api/status/"
+
+	request, err := http.NewRequestWithContext(ctx, http.MethodGet, url, nil)
+	if err != nil {
+		return data, fmt.Errorf("creating HTTP request: %w", err)
+	}
+
+	response, err := client.Do(request)
+	if err != nil {
+		return data, fmt.Errorf("doing HTTP request: %w", err)
+	}
+
+	if response.StatusCode != http.StatusOK {
+		_ = response.Body.Close()
+		return data, fmt.Errorf("%w: %d %s",
+			common.ErrHTTPStatusCodeNotOK, response.StatusCode, response.Status)
+	}
+
+	decoder := json.NewDecoder(response.Body)
+	if err := decoder.Decode(&data); err != nil {
+		_ = response.Body.Close()
+		return data, fmt.Errorf("unmarshaling response body: %w", err)
+	}
+
+	if err := response.Body.Close(); err != nil {
+		return data, fmt.Errorf("closing response body: %w", err)
+	}
+
+	return data, nil
+}