SignatureV4 validation with Metadata in the presignedUrl (#5894)

The `X-Amz-Meta-`/`X-Minio-Meta-` will now be recognized in query string also.

Fixes #5857 #5950

cmd/handler-utils.go

@@ -114,40 +114,54 @@ var userMetadataKeyPrefixes = []string{
 	"X-Minio-Meta-",
 }
 
-// extractMetadataFromHeader extracts metadata from HTTP header.
-func extractMetadataFromHeader(ctx context.Context, header http.Header) (map[string]string, error) {
-	if header == nil {
-		logger.LogIf(ctx, errInvalidArgument)
-		return nil, errInvalidArgument
+// extractMetadata extracts metadata from HTTP header and HTTP queryString.
+func extractMetadata(ctx context.Context, r *http.Request) (metadata map[string]string, err error) {
+	query := r.URL.Query()
+	header := r.Header
+	metadata = make(map[string]string)
+	// Extract all query values.
+	err = extractMetadataFromMap(ctx, query, metadata)
+	if err != nil {
+		return nil, err
 	}
-	metadata := make(map[string]string)
 
+	// Extract all header values.
+	err = extractMetadataFromMap(ctx, header, metadata)
+	if err != nil {
+		return nil, err
+	}
+
+	// Success.
+	return metadata, nil
+}
+
+// extractMetadata extracts metadata from map values.
+func extractMetadataFromMap(ctx context.Context, v map[string][]string, m map[string]string) error {
+	if v == nil {
+		logger.LogIf(ctx, errInvalidArgument)
+		return errInvalidArgument
+	}
 	// Save all supported headers.
 	for _, supportedHeader := range supportedHeaders {
-		canonicalHeader := http.CanonicalHeaderKey(supportedHeader)
-		// HTTP headers are case insensitive, look for both canonical
-		// and non canonical entries.
-		if _, ok := header[canonicalHeader]; ok {
-			metadata[supportedHeader] = header.Get(canonicalHeader)
-		} else if _, ok := header[supportedHeader]; ok {
-			metadata[supportedHeader] = header.Get(supportedHeader)
+		if value, ok := v[http.CanonicalHeaderKey(supportedHeader)]; ok {
+			m[supportedHeader] = value[0]
+		} else if value, ok := v[supportedHeader]; ok {
+			m[supportedHeader] = value[0]
 		}
 	}
-
-	// Go through all other headers for any additional headers that needs to be saved.
-	for key := range header {
-		if key != http.CanonicalHeaderKey(key) {
-			logger.LogIf(ctx, errInvalidArgument)
-			return nil, errInvalidArgument
-		}
+	for key := range v {
 		for _, prefix := range userMetadataKeyPrefixes {
-			if strings.HasPrefix(key, prefix) {
-				metadata[key] = header.Get(key)
+			if !strings.HasPrefix(strings.ToLower(key), strings.ToLower(prefix)) {
+				continue
+			}
+			value, ok := v[key]
+			if ok {
+				m[key] = value[0]
 				break
 			}
 		}
 	}
-	return metadata, nil
+	return nil
 }
 
 // The Query string for the redirect URL the client is