feat(files): MinIO fallback for stale S3 downloads (#152)

storage_fallback.go

@@ -0,0 +1,200 @@
+package onlyoffice
+
+// MinIO download fallback for the portal's stale AWS S3 consumer.
+//
+// On the Fibu EDL portal some older Documents files live in S3/MinIO, but the
+// portal's storage consumer still points at s3.us-east-1.amazonaws.com with
+// access key "minio". Downloads of those files answer 403 InvalidAccessKeyId.
+// The bytes are present in the local MinIO store under a deterministic object
+// key, so the client retries the GET there.
+
+import (
+	"context"
+	"crypto/sha256"
+	"encoding/hex"
+	"fmt"
+	"io"
+	"net/http"
+	"net/url"
+	"os"
+	"strings"
+	"time"
+
+	"github.com/aws/aws-sdk-go-v2/aws"
+	"github.com/aws/aws-sdk-go-v2/aws/signer/v4"
+)
+
+const (
+	defaultMinioEndpoint = "http://192.168.188.10:9000"
+	defaultMinioBucket   = "office"
+	minioRegion          = "us-east-1"
+)
+
+// minioObjectKey is the fallback object key layout the portal's S3 consumer
+// writes for Documents files: 00/00/01/files/folder_<folderId>/file_<fileId>/v1/content.pdf.
+// Prefer minioObjectKeyFromURL: the portal stores all files below its storage
+// root folder, which is not the API folderId returned by GetFile.
+func minioObjectKey(fileID, folderID string) string {
+	return "00/00/01/files/folder_" + folderID + "/file_" + fileID + "/v1/content.pdf"
+}
+
+// minioObjectKeyFromURL extracts the object key from an S3 download URL. Path
+// style URLs (bucket as first path segment) have that segment removed; virtual
+// host style URLs are returned as-is. This is authoritative: the portal signs
+// the exact key, so no folder-id guessing is needed.
+func minioObjectKeyFromURL(rawURL, bucket string) (string, bool) {
+	u, err := url.Parse(strings.TrimSpace(rawURL))
+	if err != nil || u.Path == "" {
+		return "", false
+	}
+	segs := strings.Split(strings.Trim(u.Path, "/"), "/")
+	// Path-style URLs carry the bucket as leading segment; the portal's S3
+	// consumer can emit it twice (serviceurl already includes the bucket), so
+	// strip every leading segment equal to the bucket.
+	for len(segs) > 0 && bucket != "" && segs[0] == bucket {
+		segs = segs[1:]
+	}
+	if len(segs) == 0 {
+		return "", false
+	}
+	for _, s := range segs {
+		if s == "" || s == "." || s == ".." {
+			return "", false
+		}
+	}
+	return strings.Join(segs, "/"), true
+}
+
+// isStaleS3Redirect reports whether a download landed on the portal's stale AWS
+// S3 consumer. Such responses either carry an S3 InvalidAccessKeyId XML body or
+// point at amazonaws.com with the "minio" access key id in the query.
+func isStaleS3Redirect(rawURL string, body []byte) bool {
+	if strings.Contains(strings.ToLower(string(body)), "invalidaccesskeyid") {
+		return true
+	}
+	u, err := url.Parse(strings.TrimSpace(rawURL))
+	if err != nil || u.Host == "" {
+		return false
+	}
+	host := strings.ToLower(u.Host)
+	if !strings.Contains(host, "amazonaws.com") {
+		return false
+	}
+	q := strings.ToLower(u.RawQuery)
+	return strings.Contains(q, "accesskeyid=minio") || strings.Contains(q, "x-amz-credential=minio")
+}
+
+// minioConfig is the runtime configuration for the local MinIO fallback.
+type minioConfig struct {
+	Endpoint  string
+	Bucket    string
+	AccessKey string
+	SecretKey string
+}
+
+// loadMinioConfig reads the fallback configuration from the environment.
+// Secrets are never defaulted; without access/secret keys the fallback is off.
+func loadMinioConfig() minioConfig {
+	return minioConfig{
+		Endpoint:  strings.TrimRight(firstNonEmpty(os.Getenv("MINIO_ENDPOINT"), defaultMinioEndpoint), "/"),
+		Bucket:    firstNonEmpty(os.Getenv("MINIO_BUCKET"), defaultMinioBucket),
+		AccessKey: os.Getenv("MINIO_ACCESS_KEY"),
+		SecretKey: os.Getenv("MINIO_SECRET_KEY"),
+	}
+}
+
+// downloadFileEntry downloads f's bytes to dst. It transparently falls back to
+// the local MinIO store when the portal redirects the download to its stale AWS
+// S3 consumer.
+func (c *Client) downloadFileEntry(ctx context.Context, f *FileEntry, dst io.Writer) (int64, error) {
+	if f == nil {
+		return 0, fmt.Errorf("onlyoffice: download: nil file entry")
+	}
+	if f.ViewURL == nil || *f.ViewURL == "" {
+		return 0, fmt.Errorf("onlyoffice: file has no viewUrl")
+	}
+	downloadURL := c.resolveAPIURL(*f.ViewURL)
+	auth, err := c.authHeader()
+	if err != nil {
+		return 0, err
+	}
+	req, err := http.NewRequestWithContext(ctx, http.MethodGet, downloadURL, nil)
+	if err != nil {
+		return 0, err
+	}
+	req.Header.Set("Authorization", auth)
+	resp, err := c.client.Do(req)
+	if err != nil {
+		return 0, err
+	}
+	defer resp.Body.Close()
+
+	if resp.StatusCode >= 400 {
+		b, _ := io.ReadAll(io.LimitReader(resp.Body, 4096))
+		finalURL := downloadURL
+		if resp.Request != nil && resp.Request.URL != nil {
+			finalURL = resp.Request.URL.String()
+		}
+		if isStaleS3Redirect(finalURL, b) {
+			key, ok := minioObjectKeyFromURL(finalURL, loadMinioConfig().Bucket)
+			if !ok {
+				fileID := ""
+				if f.ID != nil {
+					fileID = f.ID.String()
+				}
+				key = minioObjectKey(fileID, FileFolderID(f))
+			}
+			n, merr := c.downloadFromMinio(ctx, key, dst)
+			if merr == nil {
+				return n, nil
+			}
+			return 0, fmt.Errorf("GET viewUrl: %d (stale S3) and minio fallback: %w", resp.StatusCode, merr)
+		}
+		return 0, fmt.Errorf("GET viewUrl: %d %s", resp.StatusCode, truncate(string(b), 400))
+	}
+	return io.Copy(dst, resp.Body)
+}
+
+// downloadFromMinio streams objectKey from the configured MinIO bucket.
+func (c *Client) downloadFromMinio(ctx context.Context, objectKey string, dst io.Writer) (int64, error) {
+	if objectKey == "" {
+		return 0, fmt.Errorf("onlyoffice: minio fallback: empty object key")
+	}
+	cfg := loadMinioConfig()
+	if cfg.AccessKey == "" || cfg.SecretKey == "" {
+		return 0, fmt.Errorf("onlyoffice: minio fallback: MINIO_ACCESS_KEY/MINIO_SECRET_KEY not set")
+	}
+	base, err := url.Parse(cfg.Endpoint)
+	if err != nil || base.Host == "" {
+		return 0, fmt.Errorf("onlyoffice: minio fallback: bad MINIO_ENDPOINT %q", cfg.Endpoint)
+	}
+	u := *base
+	u.Path = "/" + cfg.Bucket + "/" + objectKey
+	req, err := http.NewRequestWithContext(ctx, http.MethodGet, u.String(), nil)
+	if err != nil {
+		return 0, err
+	}
+	if err := signMinioRequest(ctx, cfg, req); err != nil {
+		return 0, err
+	}
+	resp, err := c.client.Do(req)
+	if err != nil {
+		return 0, fmt.Errorf("onlyoffice: minio fallback: %w", err)
+	}
+	defer resp.Body.Close()
+	if resp.StatusCode >= 400 {
+		b, _ := io.ReadAll(io.LimitReader(resp.Body, 512))
+		return 0, fmt.Errorf("onlyoffice: minio fallback: %d %s", resp.StatusCode, truncate(string(b), 300))
+	}
+	return io.Copy(dst, resp.Body)
+}
+
+// signMinioRequest signs req with AWS Signature V4 for the S3 service.
+func signMinioRequest(ctx context.Context, cfg minioConfig, req *http.Request) error {
+	sum := sha256.Sum256(nil)
+	creds := aws.Credentials{AccessKeyID: cfg.AccessKey, SecretAccessKey: cfg.SecretKey}
+	if err := v4.NewSigner().SignHTTP(ctx, creds, req, hex.EncodeToString(sum[:]), "s3", minioRegion, time.Now()); err != nil {
+		return fmt.Errorf("onlyoffice: minio fallback: sign: %w", err)
+	}
+	return nil
+}