Initial

internal/client/fetch_status.go

@@ -0,0 +1,102 @@
+package client
+
+import (
+	"bytes"
+	"compress/gzip"
+	"context"
+	"encoding/base64"
+	"errors"
+	"fmt"
+	"io"
+	"net/http"
+	"strings"
+	"time"
+
+	"netisjwt/internal/jws"
+)
+
+// PridobiInPreveriStatus poklice GET endpoint, preveri JWS in vrne status.
+func PridobiInPreveriStatus(ctx context.Context, targetURL string) (bool, error) {
+	req, err := http.NewRequestWithContext(ctx, http.MethodGet, targetURL, nil)
+	if err != nil {
+		return false, err
+	}
+
+	resp, err := http.DefaultClient.Do(req)
+	if err != nil {
+		return false, err
+	}
+	defer resp.Body.Close()
+
+	if resp.StatusCode != http.StatusOK {
+		return false, fmt.Errorf("unexpected status code: %d", resp.StatusCode)
+	}
+
+	rawToken, err := io.ReadAll(resp.Body)
+	if err != nil {
+		return false, err
+	}
+	token := strings.TrimSpace(string(rawToken))
+
+	claims, err := jws.PreveriZeton(token)
+	if err != nil {
+		return false, err
+	}
+	if err := jws.PreveriTrditve(claims, izdajateljIzURL(targetURL), time.Now()); err != nil {
+		return false, err
+	}
+
+	values, err := dekodirajKodiranSeznam(claims.Status.EncodedList)
+	if err != nil {
+		return false, err
+	}
+	return preberiBit(values, claims.Status.Index)
+}
+
+// izdajateljIzURL vrne url brez zadnjega segmenta index.
+func izdajateljIzURL(url string) string {
+	parts := strings.Split(url, "/")
+	if len(parts) < 5 {
+		return ""
+	}
+	return strings.Join(parts[:len(parts)-1], "/")
+}
+
+// dekodirajKodiranSeznam pretvori base64+gzip seznam v surove bajte.
+func dekodirajKodiranSeznam(encoded string) ([]byte, error) {
+	compressed, err := base64.StdEncoding.DecodeString(encoded)
+	if err != nil {
+		return nil, err
+	}
+
+	reader, err := newGzipBralnik(compressed)
+	if err != nil {
+		return nil, err
+	}
+	defer reader.Close()
+
+	return io.ReadAll(reader)
+}
+
+// preberiBit prebere en bit iz podanega bajtnega zaporedja.
+func preberiBit(data []byte, index int) (bool, error) {
+	if index < 0 {
+		return false, errors.New("index must be >= 0")
+	}
+	byteIdx := index / 8
+	if byteIdx >= len(data) {
+		return false, errors.New("index is out of encoded list range")
+	}
+	mask := byte(1 << (index % 8))
+	return data[byteIdx]&mask != 0, nil
+}
+
+type gzipReader interface {
+	io.Reader
+	Close() error
+}
+
+// newGzipBralnik ustvari gzip reader iz podanih bajtov.
+func newGzipBralnik(input []byte) (gzipReader, error) {
+	return gzip.NewReader(bytes.NewReader(input))
+}