Add drain and close function

Signed-off-by: Philip Laine <philip.laine@gmail.com>

.golangci.yaml

@@ -2,7 +2,6 @@ version: "2"
 linters:
   default: none
   enable:
-    - bodyclose
     - errcheck
     - gocritic
     - govet

CHANGELOG.md

@@ -11,6 +11,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 - [#905](https://github.com/spegel-org/spegel/pull/905) Change mirror type to url and add byte range parameter.
 - [#909](https://github.com/spegel-org/spegel/pull/909) Add base http client and transport.
+- [#910](https://github.com/spegel-org/spegel/pull/910) Add drain and close function.
 
 ### Changed
 

internal/cleanup/cleanup.go

@@ -3,7 +3,6 @@ package cleanup
 import (
 	"context"
 	"errors"
-	"io"
 	"net"
 	"net/http"
 	"net/url"
@@ -130,11 +129,7 @@ func probeIPs(ctx context.Context, client *http.Client, ips []net.IPAddr, port s
 			if err != nil {
 				return err
 			}
-			defer resp.Body.Close()
-			_, err = io.Copy(io.Discard, resp.Body)
-			if err != nil {
-				return err
-			}
+			defer httpx.DrainAndClose(resp.Body)
 			err = httpx.CheckResponseStatus(resp, http.StatusOK)
 			if err != nil {
 				return err

pkg/httpx/httpx.go

@@ -1,6 +1,8 @@
 package httpx
 
 import (
+	"errors"
+	"io"
 	"net"
 	"net/http"
 	"time"
@@ -41,3 +43,25 @@ func BaseTransport() *http.Transport {
 		ExpectContinueTimeout: 1 * time.Second,
 	}
 }
+
+const (
+	// MaxReadBytes is the maximum amount of bytes read when draining a response or reading error message.
+	MaxReadBytes = 512 * 1024
+)
+
+// DrainAndCloses empties the body buffer before closing the body.
+func DrainAndClose(rc io.ReadCloser) error {
+	errs := []error{}
+	n, err := io.Copy(io.Discard, io.LimitReader(rc, MaxReadBytes+1))
+	if err != nil {
+		errs = append(errs, err)
+	}
+	if n > MaxReadBytes {
+		errs = append(errs, errors.New("reader has more data than max read bytes"))
+	}
+	err = rc.Close()
+	if err != nil {
+		errs = append(errs, err)
+	}
+	return errors.Join(errs...)
+}

pkg/httpx/httpx_test.go

@@ -1,6 +1,8 @@
 package httpx
 
 import (
+	"bytes"
+	"io"
 	"net/http"
 	"testing"
 	"time"
@@ -22,3 +24,22 @@ func TestBaseTransport(t *testing.T) {
 
 	BaseTransport()
 }
+
+func TestDrainAndClose(t *testing.T) {
+	t.Parallel()
+
+	buf := bytes.NewBuffer(nil)
+	err := DrainAndClose(io.NopCloser(buf))
+	require.NoError(t, err)
+	require.Empty(t, buf.Bytes())
+
+	buf = bytes.NewBuffer(make([]byte, MaxReadBytes))
+	err = DrainAndClose(io.NopCloser(buf))
+	require.NoError(t, err)
+	require.Empty(t, buf.Bytes())
+
+	buf = bytes.NewBuffer(make([]byte, MaxReadBytes+10))
+	err = DrainAndClose(io.NopCloser(buf))
+	require.EqualError(t, err, "reader has more data than max read bytes")
+	require.Len(t, buf.Bytes(), 9)
+}

pkg/httpx/status.go

@@ -55,9 +55,11 @@ func getErrorMessage(resp *http.Response) (string, error) {
 		"application/xml",
 	}
 	if !slices.Contains(contentTypes, resp.Header.Get(HeaderContentType)) {
-		_, err := io.Copy(io.Discard, resp.Body)
+		return "", nil
+	}
+	b, err := io.ReadAll(io.LimitReader(resp.Body, MaxReadBytes))
+	if err != nil {
 		return "", err
 	}
-	b, err := io.ReadAll(resp.Body)
 	return string(b), err
 }

pkg/oci/client.go

@@ -63,66 +63,74 @@ func (c *Client) Pull(ctx context.Context, img Image, mirror *url.URL) ([]PullMe
 		queue = queue[1:]
 
 		start := time.Now()
-		rc, desc, err := c.Get(ctx, dist, mirror, nil)
-		if err != nil {
-			return nil, err
-		}
+		desc, err := func() (ocispec.Descriptor, error) {
+			rc, desc, err := c.Get(ctx, dist, mirror, nil)
+			if err != nil {
+				return ocispec.Descriptor{}, err
+			}
+			defer httpx.DrainAndClose(rc)
 
-		switch dist.Kind {
-		case DistributionKindBlob:
-			_, copyErr := io.Copy(io.Discard, rc)
-			closeErr := rc.Close()
-			err := errors.Join(copyErr, closeErr)
-			if err != nil {
-				return nil, err
-			}
-		case DistributionKindManifest:
-			b, readErr := io.ReadAll(rc)
-			closeErr := rc.Close()
-			err = errors.Join(readErr, closeErr)
-			if err != nil {
-				return nil, err
-			}
-			switch desc.MediaType {
-			case images.MediaTypeDockerSchema2ManifestList, ocispec.MediaTypeImageIndex:
-				var idx ocispec.Index
-				if err := json.Unmarshal(b, &idx); err != nil {
-					return nil, err
-				}
-				for _, m := range idx.Manifests {
-					// TODO: Add platform option.
-					//nolint: staticcheck // Simplify in the future.
-					if !(m.Platform.OS == runtime.GOOS && m.Platform.Architecture == runtime.GOARCH) {
-						continue
-					}
-					queue = append(queue, DistributionPath{
-						Kind:     DistributionKindManifest,
-						Name:     dist.Name,
-						Digest:   m.Digest,
-						Registry: dist.Registry,
-					})
-				}
-			case images.MediaTypeDockerSchema2Manifest, ocispec.MediaTypeImageManifest:
-				var manifest ocispec.Manifest
-				err := json.Unmarshal(b, &manifest)
+			switch dist.Kind {
+			case DistributionKindBlob:
+				// Right now we are just discarding the contents because we do not have a writable store.
+				_, copyErr := io.Copy(io.Discard, rc)
+				closeErr := rc.Close()
+				err := errors.Join(copyErr, closeErr)
 				if err != nil {
-					return nil, err
+					return ocispec.Descriptor{}, err
 				}
-				queue = append(queue, DistributionPath{
-					Kind:     DistributionKindBlob,
-					Name:     dist.Name,
-					Digest:   manifest.Config.Digest,
-					Registry: dist.Registry,
-				})
-				for _, layer := range manifest.Layers {
+			case DistributionKindManifest:
+				b, readErr := io.ReadAll(rc)
+				closeErr := rc.Close()
+				err = errors.Join(readErr, closeErr)
+				if err != nil {
+					return ocispec.Descriptor{}, err
+				}
+				switch desc.MediaType {
+				case images.MediaTypeDockerSchema2ManifestList, ocispec.MediaTypeImageIndex:
+					var idx ocispec.Index
+					if err := json.Unmarshal(b, &idx); err != nil {
+						return ocispec.Descriptor{}, err
+					}
+					for _, m := range idx.Manifests {
+						// TODO: Add platform option.
+						//nolint: staticcheck // Simplify in the future.
+						if !(m.Platform.OS == runtime.GOOS && m.Platform.Architecture == runtime.GOARCH) {
+							continue
+						}
+						queue = append(queue, DistributionPath{
+							Kind:     DistributionKindManifest,
+							Name:     dist.Name,
+							Digest:   m.Digest,
+							Registry: dist.Registry,
+						})
+					}
+				case images.MediaTypeDockerSchema2Manifest, ocispec.MediaTypeImageManifest:
+					var manifest ocispec.Manifest
+					err := json.Unmarshal(b, &manifest)
+					if err != nil {
+						return ocispec.Descriptor{}, err
+					}
 					queue = append(queue, DistributionPath{
 						Kind:     DistributionKindBlob,
 						Name:     dist.Name,
-						Digest:   layer.Digest,
+						Digest:   manifest.Config.Digest,
 						Registry: dist.Registry,
 					})
+					for _, layer := range manifest.Layers {
+						queue = append(queue, DistributionPath{
+							Kind:     DistributionKindBlob,
+							Name:     dist.Name,
+							Digest:   layer.Digest,
+							Registry: dist.Registry,
+						})
+					}
 				}
 			}
+			return desc, nil
+		}()
+		if err != nil {
+			return nil, err
 		}
 
 		metric := PullMetric{
@@ -142,11 +150,7 @@ func (c *Client) Head(ctx context.Context, dist DistributionPath, mirror *url.UR
 	if err != nil {
 		return ocispec.Descriptor{}, err
 	}
-	defer rc.Close()
-	_, err = io.Copy(io.Discard, rc)
-	if err != nil {
-		return ocispec.Descriptor{}, err
-	}
+	defer httpx.DrainAndClose(rc)
 	return desc, nil
 }
 

pkg/registry/registry.go

@@ -364,16 +364,10 @@ func forwardRequest(client *http.Client, bufferPool *sync.Pool, req *http.Reques
 	if err != nil {
 		return err
 	}
-	defer forwardResp.Body.Close()
-
-	// Clear body and try next if non 200 response.
-	//nolint:staticcheck // Keep things readable.
-	if !(forwardResp.StatusCode == http.StatusOK || forwardResp.StatusCode == http.StatusPartialContent) {
-		_, err = io.Copy(io.Discard, forwardResp.Body)
-		if err != nil {
-			return err
-		}
-		return fmt.Errorf("expected mirror to respond with 200 OK but received: %s", forwardResp.Status)
+	defer httpx.DrainAndClose(forwardResp.Body)
+	err = httpx.CheckResponseStatus(forwardResp, http.StatusOK, http.StatusPartialContent)
+	if err != nil {
+		return err
 	}
 
 	// TODO (phillebaba): Is it possible to retry if copy fails half way through?