From 8e516a1b4cdc36e6d4f5acb1ab662d7e41886bab Mon Sep 17 00:00:00 2001
From: Lucas Bremgartner <lucas.bremgartner@futurfusion.io>
Date: Tue, 26 Nov 2024 16:15:27 +0100
Subject: [PATCH] client: invalidate simple streams cache

if download by hash fails with 404 not found.

Signed-off-by: Lucas Bremgartner <lucas.bremgartner@futurfusion.io>
---
 client/simplestreams_images.go        | 6 ++++++
 shared/simplestreams/simplestreams.go | 4 ++++
 shared/util/net.go                    | 8 ++++++++
 3 files changed, 18 insertions(+)

diff --git a/client/simplestreams_images.go b/client/simplestreams_images.go
index 32260698293..bffbdda899c 100644
--- a/client/simplestreams_images.go
+++ b/client/simplestreams_images.go
@@ -3,6 +3,7 @@ package incus
 import (
 	"context"
 	"crypto/sha256"
+	"errors"
 	"fmt"
 	"io"
 	"net/http"
@@ -13,6 +14,7 @@ import (
 	"time"
 
 	"github.com/lxc/incus/v6/shared/api"
+	"github.com/lxc/incus/v6/shared/logger"
 	"github.com/lxc/incus/v6/shared/subprocess"
 	"github.com/lxc/incus/v6/shared/util"
 )
@@ -121,6 +123,10 @@ func (r *ProtocolSimpleStreams) GetImageFile(fingerprint string, req ImageFileRe
 
 			size, err = util.DownloadFileHash(context.TODO(), &httpClient, r.httpUserAgent, req.ProgressHandler, req.Canceler, filename, uri, hash, sha256.New(), target)
 			if err != nil {
+				if errors.Is(err, util.ErrNotFound) {
+					logger.Info("Unable to download file by hash, invalidate potentially outdated cache", logger.Ctx{"filename": filename, "uri": uri, "hash": hash})
+					r.ssClient.InvalidateCache()
+				}
 				return -1, err
 			}
 		}
diff --git a/shared/simplestreams/simplestreams.go b/shared/simplestreams/simplestreams.go
index d91c5fe5fda..1ee3ba312cf 100644
--- a/shared/simplestreams/simplestreams.go
+++ b/shared/simplestreams/simplestreams.go
@@ -92,6 +92,10 @@ func (s *SimpleStreams) readCache(path string) ([]byte, bool) {
 	return body, expired
 }
 
+func (s *SimpleStreams) InvalidateCache() {
+	_ = os.RemoveAll(s.cachePath)
+}
+
 func (s *SimpleStreams) cachedDownload(path string) ([]byte, error) {
 	fields := strings.Split(path, "/")
 	fileName := fields[len(fields)-1]
diff --git a/shared/util/net.go b/shared/util/net.go
index 74bbef1c1df..21d88ff80e4 100644
--- a/shared/util/net.go
+++ b/shared/util/net.go
@@ -2,6 +2,7 @@ package util
 
 import (
 	"context"
+	"errors"
 	"fmt"
 	"hash"
 	"io"
@@ -12,6 +13,10 @@ import (
 	"github.com/lxc/incus/v6/shared/units"
 )
 
+// ErrNotFound is used to explicitly signal error cases, where a resource
+// can not be found (404 HTTP status code).
+var ErrNotFound = errors.New("resource not found")
+
 func DownloadFileHash(ctx context.Context, httpClient *http.Client, useragent string, progress func(progress ioprogress.ProgressData), canceler *cancel.HTTPRequestCanceller, filename string, url string, hash string, hashFunc hash.Hash, target io.WriteSeeker) (int64, error) {
 	// Always seek to the beginning
 	_, _ = target.Seek(0, io.SeekStart)
@@ -44,6 +49,9 @@ func DownloadFileHash(ctx context.Context, httpClient *http.Client, useragent st
 	defer close(doneCh)
 
 	if r.StatusCode != http.StatusOK {
+		if r.StatusCode == http.StatusNotFound {
+			return -1, fmt.Errorf("Unable to fetch %s: %w", url, ErrNotFound)
+		}
 		return -1, fmt.Errorf("Unable to fetch %s: %s", url, r.Status)
 	}