Add v4.ident.me resolver

public_resolvers/base_resolver.go

@@ -0,0 +1,44 @@
+package public_resolvers
+
+import (
+	"context"
+	"fmt"
+	"io"
+	"net"
+	"net/http"
+)
+
+type Doer interface {
+	Do(*http.Request) (*http.Response, error)
+}
+
+type baseResolver struct {
+	client Doer
+	url    string
+}
+
+func (i baseResolver) ResolvePublicIp(ctx context.Context) (net.IP, error) {
+	req, err := http.NewRequestWithContext(ctx, http.MethodGet, i.url, nil)
+	if err != nil {
+		return net.IP{}, fmt.Errorf("error creating ifconfig request: %w", err)
+	}
+
+	resp, err := i.client.Do(req)
+	if err != nil {
+		return net.IP{}, err
+	}
+	defer func() {
+		_ = resp.Body.Close()
+	}()
+
+	if resp.StatusCode != http.StatusOK {
+		return net.IP{}, fmt.Errorf("unexpected response code %d", resp.StatusCode)
+	}
+
+	ipText, err := io.ReadAll(resp.Body)
+	if err != nil {
+		return net.IP{}, fmt.Errorf("error reading body: %w", err)
+	}
+
+	return net.ParseIP(string(ipText)), nil
+}