Fix - handle reordering of fragments in multipart reply #319

In case when reordering detected - try to search in all requested
fragments for provided data range.
Will not work if server creates more fragments than requested.
Coalesing should be OK.

Special situation of EOS server

Author: linev

modules/io.mjs

@@ -2896,7 +2896,7 @@ class TFile {
          // multipart messages requires special handling
 
          const indx = hdr.indexOf('boundary=');
-         let boundary = '', n = first, o = 0;
+         let boundary = '', n = first, o = 0, normal_order = true;
          if (indx > 0) {
             boundary = hdr.slice(indx + 9);
             if ((boundary[0] === '"') && (boundary[boundary.length - 1] === '"'))
@@ -2950,12 +2950,34 @@ class TFile {
                blobs.push(new DataView(res, o, place[n + 1]));
                o += place[n + 1];
                n += 2;
-            } else {
+            } else if (normal_order) {
+               const n0 = n;
                while ((n < last) && (place[n] >= segm_start) && (place[n] + place[n + 1] - 1 <= segm_last)) {
                   blobs.push(new DataView(res, o + place[n] - segm_start, place[n + 1]));
                   n += 2;
                }
 
+               if (n > n0)
+                  o += (segm_last - segm_start + 1);
+               else
+                  normal_order = false;
+            }
+
+            if (!normal_order) {
+               // special situation when server reorder segments in the reply
+               let isany = false;
+               for (let n1 = n; n1 < last; n1 += 2) {
+                  if ((place[n1] >= segm_start) && (place[n1] + place[n1 + 1] - 1 <= segm_last)) {
+                     blobs[n1/2] = new DataView(res, o + place[n1] - segm_start, place[n1 + 1]);
+                     isany = true;
+                  }
+               }
+               if (!isany)
+                  return rejectFunc(Error(`Provided fragment ${segm_start} - ${segm_last} out of requested multi-range request`));
+
+               while (blobs[n/2])
+                  n += 2;
+
                o += (segm_last - segm_start + 1);
             }
          }