Fix file delivery order (#3283)

Author: pzl

changelog/fragments/1708005256-file-order-fix.yaml

@@ -0,0 +1,32 @@
+# Kind can be one of:
+# - breaking-change: a change to previously-documented behavior
+# - deprecation: functionality that is being removed in a later release
+# - bug-fix: fixes a problem in a previous version
+# - enhancement: extends functionality but does not break or fix existing behavior
+# - feature: new functionality
+# - known-issue: problems that we are aware of in a given version
+# - security: impacts on the security of a product or a user’s deployment.
+# - upgrade: important information for someone upgrading from a prior version
+# - other: does not fit into any of the other categories
+kind: bug-fix
+
+# Change summary; a 80ish characters long description of the change.
+summary: fix file reassembly for large files
+
+# Long description; in case the summary is not enough to describe the change
+# this field accommodate a description without length limits.
+# NOTE: This field will be rendered only for breaking-change and known-issue kinds at the moment.
+#description:
+
+# Affected component; a word indicating the component this changeset affects.
+component:
+
+# PR URL; optional; the PR number that added the changeset.
+# If not present is automatically filled by the tooling finding the PR where this changelog fragment has been added.
+# NOTE: the tooling supports backports, so it's able to fill the original PR number instead of the backport PR number.
+# Please provide it if you are adding a fragment for a different PR.
+pr: 3283
+
+# Issue URL; optional; the GitHub issue related to this changeset (either closes or is part of).
+# If not present is automatically filled by the tooling with the issue linked to the PR number.
+#issue: https://github.com/owner/repo/1234

internal/pkg/file/delivery/delivery.go

@@ -10,6 +10,7 @@ import (
 	"errors"
 	"fmt"
 	"io"
+	"sort"
 
 	"github.com/elastic/fleet-server/v7/internal/pkg/bulk"
 	"github.com/elastic/fleet-server/v7/internal/pkg/file"
@@ -77,6 +78,9 @@ func (d *Deliverer) LocateChunks(ctx context.Context, zlog zerolog.Logger, fileI
 func (d *Deliverer) SendFile(ctx context.Context, zlog zerolog.Logger, w io.Writer, chunks []file.ChunkInfo, fileID string) error {
 	span, ctx := apm.StartSpan(ctx, "response", "write")
 	defer span.End()
+	sort.SliceStable(chunks, func(i, j int) bool {
+		return chunks[i].Pos < chunks[j].Pos
+	})
 	for _, chunkInfo := range chunks {
 		body, err := readChunkStream(ctx, d.client, chunkInfo.Index, chunkInfo.ID)
 		if err != nil {

internal/pkg/file/delivery/delivery_test.go

@@ -12,6 +12,7 @@ import (
 	"fmt"
 	"io"
 	"net/http"
+	"strconv"
 	"strings"
 	"testing"
 
@@ -252,6 +253,64 @@ func TestSendFileMultipleChunksUsesBackingIndex(t *testing.T) {
 	require.NoError(t, err)
 }
 
+func TestSendFileHandlesDisorderedChunks(t *testing.T) {
+	buf := bytes.NewBuffer(nil)
+
+	fakeBulk := itesting.NewMockBulk()
+	esClient, esMock := mockESClient(t)
+
+	const fileID = "xyz"
+	idx := fmt.Sprintf(FileDataIndexPattern, "endpoint") + "-0001"
+	sampleDocBody := hexDecode("A7665F696E64657878212E666C6565742D66696C6564656C69766572792D646174612D656E64706F696E74635F69646578797A2E30685F76657273696F6E01675F7365715F6E6F016D5F7072696D6172795F7465726D0165666F756E64F5666669656C6473A164646174618142ABCD")
+
+	chunks := []file.ChunkInfo{
+		{Index: idx, ID: fileID + ".20", Pos: 20},
+		{Index: idx, ID: fileID + ".21", Pos: 21},
+		{Index: idx, ID: fileID + ".22", Pos: 22},
+		{Index: idx, ID: fileID + ".9", Pos: 9},
+		{Index: idx, ID: fileID + ".10", Pos: 10},
+		{Index: idx, ID: fileID + ".11", Pos: 11},
+		{Index: idx, ID: fileID + ".12", Pos: 12},
+		{Index: idx, ID: fileID + ".13", Pos: 13},
+		{Index: idx, ID: fileID + ".14", Pos: 14},
+		{Index: idx, ID: fileID + ".15", Pos: 15},
+		{Index: idx, ID: fileID + ".16", Pos: 16},
+		{Index: idx, ID: fileID + ".17", Pos: 17},
+		{Index: idx, ID: fileID + ".18", Pos: 18},
+		{Index: idx, ID: fileID + ".19", Pos: 19},
+		{Index: idx, ID: fileID + ".0", Pos: 0},
+		{Index: idx, ID: fileID + ".1", Pos: 1},
+		{Index: idx, ID: fileID + ".2", Pos: 2},
+		{Index: idx, ID: fileID + ".3", Pos: 3},
+		{Index: idx, ID: fileID + ".4", Pos: 4},
+		{Index: idx, ID: fileID + ".5", Pos: 5},
+		{Index: idx, ID: fileID + ".6", Pos: 6},
+		{Index: idx, ID: fileID + ".7", Pos: 7},
+		{Index: idx, ID: fileID + ".8", Pos: 8},
+	}
+
+	expectedIdx := 0
+
+	esMock.RoundTripFn = func(req *http.Request) (*http.Response, error) {
+
+		// Parse out the chunk number requested
+		parts := strings.Split(req.URL.Path, "/") // ["", ".fleet-filedelivery-data-endpoint-0001", "_doc", "xyz.1"]
+		docIdx := strings.TrimPrefix(parts[3], fileID+".")
+		docnum, err := strconv.Atoi(docIdx)
+		require.NoError(t, err)
+
+		// should be our expected increasing counter
+		assert.Equal(t, expectedIdx, docnum)
+		expectedIdx += 1
+
+		return sendBodyBytes(sampleDocBody), nil
+	}
+
+	d := New(esClient, fakeBulk, -1)
+	err := d.SendFile(context.Background(), zerolog.Logger{}, buf, chunks, fileID)
+	require.NoError(t, err)
+}
+
 /*
 	Setup to convert a *elasticsearch.Client as a harmless mock
 	by replacing the Transport to nowhere