refactor(backend): service http ports

backend/internal/repository/github_release_service.go

@@ -0,0 +1,116 @@
+package repository
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"io"
+	"net/http"
+	"os"
+	"time"
+
+	"sub2api/internal/service"
+)
+
+type githubReleaseClient struct {
+	httpClient *http.Client
+}
+
+func NewGitHubReleaseClient() service.GitHubReleaseClient {
+	return &githubReleaseClient{
+		httpClient: &http.Client{
+			Timeout: 30 * time.Second,
+		},
+	}
+}
+
+func (c *githubReleaseClient) FetchLatestRelease(ctx context.Context, repo string) (*service.GitHubRelease, error) {
+	url := fmt.Sprintf("https://api.github.com/repos/%s/releases/latest", repo)
+
+	req, err := http.NewRequestWithContext(ctx, http.MethodGet, url, nil)
+	if err != nil {
+		return nil, err
+	}
+	req.Header.Set("Accept", "application/vnd.github.v3+json")
+	req.Header.Set("User-Agent", "Sub2API-Updater")
+
+	resp, err := c.httpClient.Do(req)
+	if err != nil {
+		return nil, err
+	}
+	defer resp.Body.Close()
+
+	if resp.StatusCode != http.StatusOK {
+		return nil, fmt.Errorf("GitHub API returned %d", resp.StatusCode)
+	}
+
+	var release service.GitHubRelease
+	if err := json.NewDecoder(resp.Body).Decode(&release); err != nil {
+		return nil, err
+	}
+
+	return &release, nil
+}
+
+func (c *githubReleaseClient) DownloadFile(ctx context.Context, url, dest string, maxSize int64) error {
+	req, err := http.NewRequestWithContext(ctx, http.MethodGet, url, nil)
+	if err != nil {
+		return err
+	}
+
+	client := &http.Client{Timeout: 10 * time.Minute}
+	resp, err := client.Do(req)
+	if err != nil {
+		return err
+	}
+	defer resp.Body.Close()
+
+	if resp.StatusCode != http.StatusOK {
+		return fmt.Errorf("download returned %d", resp.StatusCode)
+	}
+
+	// SECURITY: Check Content-Length if available
+	if resp.ContentLength > maxSize {
+		return fmt.Errorf("file too large: %d bytes (max %d)", resp.ContentLength, maxSize)
+	}
+
+	out, err := os.Create(dest)
+	if err != nil {
+		return err
+	}
+	defer out.Close()
+
+	// SECURITY: Use LimitReader to enforce max download size even if Content-Length is missing/wrong
+	limited := io.LimitReader(resp.Body, maxSize+1)
+	written, err := io.Copy(out, limited)
+	if err != nil {
+		return err
+	}
+
+	// Check if we hit the limit (downloaded more than maxSize)
+	if written > maxSize {
+		os.Remove(dest) // Clean up partial file
+		return fmt.Errorf("download exceeded maximum size of %d bytes", maxSize)
+	}
+
+	return nil
+}
+
+func (c *githubReleaseClient) FetchChecksumFile(ctx context.Context, url string) ([]byte, error) {
+	req, err := http.NewRequestWithContext(ctx, http.MethodGet, url, nil)
+	if err != nil {
+		return nil, err
+	}
+
+	resp, err := c.httpClient.Do(req)
+	if err != nil {
+		return nil, err
+	}
+	defer resp.Body.Close()
+
+	if resp.StatusCode != http.StatusOK {
+		return nil, fmt.Errorf("HTTP %d", resp.StatusCode)
+	}
+
+	return io.ReadAll(resp.Body)
+}