chore(publicip): internal/publicip/ipinfo package

internal/publicip/ipinfo/fetch.go

@@ -0,0 +1,74 @@
+package ipinfo
+
+import (
+	"context"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"net"
+	"net/http"
+	"strings"
+
+	"github.com/qdm12/gluetun/internal/constants"
+)
+
+type Fetch struct {
+	client *http.Client
+}
+
+func New(client *http.Client) *Fetch {
+	return &Fetch{
+		client: client,
+	}
+}
+
+var (
+	ErrTooManyRequests = errors.New("too many requests sent for this month")
+	ErrBadHTTPStatus   = errors.New("bad HTTP status received")
+)
+
+// FetchInfo obtains information on the ip address provided
+// using the ipinfo.io API. If the ip is nil, the public IP address
+// of the machine is used as the IP.
+func (f *Fetch) FetchInfo(ctx context.Context, ip net.IP) (
+	result Response, err error) {
+	const baseURL = "https://ipinfo.io/"
+	url := baseURL
+	if ip != nil {
+		url += ip.String()
+	}
+
+	request, err := http.NewRequestWithContext(ctx, http.MethodGet, url, nil)
+	if err != nil {
+		return result, err
+	}
+
+	response, err := f.client.Do(request)
+	if err != nil {
+		return result, err
+	}
+	defer response.Body.Close()
+
+	switch response.StatusCode {
+	case http.StatusOK:
+	case http.StatusTooManyRequests:
+		return result, fmt.Errorf("%w from %s: %d %s",
+			ErrTooManyRequests, url, response.StatusCode, response.Status)
+	default:
+		return result, fmt.Errorf("%w from %s: %d %s",
+			ErrBadHTTPStatus, url, response.StatusCode, response.Status)
+	}
+
+	decoder := json.NewDecoder(response.Body)
+	if err := decoder.Decode(&result); err != nil {
+		return result, fmt.Errorf("cannot decode response: %w", err)
+	}
+
+	countryCode := strings.ToLower(result.Country)
+	country, ok := constants.CountryCodes()[countryCode]
+	if ok {
+		result.Country = country
+	}
+
+	return result, nil
+}