feat(cache): add Cloudflare SigV4 S3 signature compatibility fix and compile locally

go-cache-plugin-src/lib/s3util/s3util_test.go

@@ -0,0 +1,42 @@
+// Copyright (c) Tailscale Inc & AUTHORS
+// SPDX-License-Identifier: BSD-3-Clause
+
+package s3util_test
+
+import (
+	"bytes"
+	"crypto/md5"
+	"encoding/hex"
+	"io"
+	"strings"
+	"testing"
+
+	"github.com/tailscale/go-cache-plugin/lib/s3util"
+)
+
+func TestETagReader(t *testing.T) {
+	const testInput = "the once and future kitten"
+
+	want := md5.Sum([]byte(testInput))
+	t.Logf("MD5(%q) = %x", testInput, want)
+
+	r := s3util.NewETagReader(strings.NewReader(testInput))
+
+	nr, err := io.Copy(io.Discard, r)
+	if err != nil {
+		t.Fatalf("Copy failed; %v", err)
+	} else if nr != int64(len(testInput)) {
+		t.Errorf("Copied %d bytes, want %d", nr, len(testInput))
+	}
+
+	etag := r.ETag()
+	t.Logf("Got etag %s for input %q", etag, testInput)
+
+	got, err := hex.DecodeString(r.ETag())
+	if err != nil {
+		t.Fatalf("Result is not valid hex: %s", r.ETag())
+	}
+	if !bytes.Equal(got, want[:]) {
+		t.Errorf("Wrong result: got %x, want %x", got, want)
+	}
+}