Fix HEAD method in resources.GetRemote

Fixes #10604

2 files changed, 125 insertions, 33 deletions

diff --git a/resources/resource_factories/create/integration_test.go b/resources/resource_factories/create/integration_test.go
new file mode 100644
index 000000000..e3a41d335
--- /dev/null
+++ b/resources/resource_factories/create/integration_test.go
@@ -0,0 +1,56 @@
+// Copyright 2023 The Hugo Authors. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package create_test
+
+import (
+	"testing"
+
+	"github.com/gohugoio/hugo/hugolib"
+)
+
+func TestGetResourceHead(t *testing.T) {
+
+	files := `
+-- config.toml --
+[security]
+  [security.http]
+    methods = ['(?i)GET|POST|HEAD']
+    urls = ['.*gohugo\.io.*']
+
+-- layouts/index.html --
+{{ $url := "https://gohugo.io/img/hugo.png" }}
+{{ $opts := dict "method" "head" }}
+{{ with resources.GetRemote $url $opts }}
+  {{ with .Err }}
+    {{ errorf "Unable to get remote resource: %s" . }}
+  {{ else }}
+    Head Content: {{ .Content }}.
+  {{ end }}
+{{ else }}
+  {{ errorf "Unable to get remote resource: %s" $url }}
+{{ end }}
+`
+
+	b := hugolib.NewIntegrationTestBuilder(
+		hugolib.IntegrationTestConfig{
+			T:           t,
+			TxtarString: files,
+		},
+	)
+
+	b.Build()
+
+	b.AssertFileContent("public/index.html", "Head Content: .")
+
+}
diff --git a/resources/resource_factories/create/remote.go b/resources/resource_factories/create/remote.go
index fa5533d7b..5216fff79 100644
--- a/resources/resource_factories/create/remote.go
+++ b/resources/resource_factories/create/remote.go
@@ -45,7 +45,29 @@ type HTTPError struct {
 	Body       string
 }
 
-func toHTTPError(err error, res *http.Response) *HTTPError {
+func responseToData(res *http.Response, readBody bool) map[string]any {
+	var body []byte
+	if readBody {
+		body, _ = ioutil.ReadAll(res.Body)
+	}
+
+	m := map[string]any{
+		"StatusCode":       res.StatusCode,
+		"Status":           res.Status,
+		"TransferEncoding": res.TransferEncoding,
+		"ContentLength":    res.ContentLength,
+		"ContentType":      res.Header.Get("Content-Type"),
+	}
+
+	if readBody {
+		m["Body"] = string(body)
+	}
+
+	return m
+
+}
+
+func toHTTPError(err error, res *http.Response, readBody bool) *HTTPError {
 	if err == nil {
 		panic("err is nil")
 	}
@@ -56,19 +78,9 @@ func toHTTPError(err error, res *http.Response) *HTTPError {
 		}
 	}
 
-	var body []byte
-	body, _ = ioutil.ReadAll(res.Body)
-
 	return &HTTPError{
 		error: err,
-		Data: map[string]any{
-			"StatusCode":       res.StatusCode,
-			"Status":           res.Status,
-			"Body":             string(body),
-			"TransferEncoding": res.TransferEncoding,
-			"ContentLength":    res.ContentLength,
-			"ContentType":      res.Header.Get("Content-Type"),
-		},
+		Data:  responseToData(res, readBody),
 	}
 }
 
@@ -80,6 +92,12 @@ func (c *Client) FromRemote(uri string, optionsm map[string]any) (resource.Resou
 		return nil, fmt.Errorf("failed to parse URL for resource %s: %w", uri, err)
 	}
 
+	method := "GET"
+	if s, ok := maps.LookupEqualFold(optionsm, "method"); ok {
+		method = strings.ToUpper(s.(string))
+	}
+	isHeadMethod := method == "HEAD"
+
 	resourceID := calculateResourceID(uri, optionsm)
 
 	_, httpResponse, err := c.cacheGetResource.GetOrCreate(resourceID, func() (io.ReadCloser, error) {
@@ -100,15 +118,16 @@ func (c *Client) FromRemote(uri string, optionsm map[string]any) (resource.Resou
 		if err != nil {
 			return nil, err
 		}
+		defer res.Body.Close()
 
 		httpResponse, err := httputil.DumpResponse(res, true)
 		if err != nil {
-			return nil, toHTTPError(err, res)
+			return nil, toHTTPError(err, res, !isHeadMethod)
 		}
 
 		if res.StatusCode != http.StatusNotFound {
 			if res.StatusCode < 200 || res.StatusCode > 299 {
-				return nil, toHTTPError(fmt.Errorf("failed to fetch remote resource: %s", http.StatusText(res.StatusCode)), res)
+				return nil, toHTTPError(fmt.Errorf("failed to fetch remote resource: %s", http.StatusText(res.StatusCode)), res, !isHeadMethod)
 
 			}
 		}
@@ -124,15 +143,24 @@ func (c *Client) FromRemote(uri string, optionsm map[string]any) (resource.Resou
 	if err != nil {
 		return nil, err
 	}
+	defer res.Body.Close()
 
 	if res.StatusCode == http.StatusNotFound {
 		// Not found. This matches how looksup for local resources work.
 		return nil, nil
 	}
 
-	body, err := ioutil.ReadAll(res.Body)
-	if err != nil {
-		return nil, fmt.Errorf("failed to read remote resource %q: %w", uri, err)
+	var (
+		body      []byte
+		mediaType media.Type
+	)
+	// A response to a HEAD method should not have a body. If it has one anyway, that body must be ignored.
+	// See https://developer.mozilla.org/en-US/docs/Web/HTTP/Methods/HEAD
+	if !isHeadMethod && res.Body != nil {
+		body, err = ioutil.ReadAll(res.Body)
+		if err != nil {
+			return nil, fmt.Errorf("failed to read remote resource %q: %w", uri, err)
+		}
 	}
 
 	filename := path.Base(rURL.Path)
@@ -142,30 +170,38 @@ func (c *Client) FromRemote(uri string, optionsm map[string]any) (resource.Resou
 		}
 	}
 
-	var extensionHints []string
-
 	contentType := res.Header.Get("Content-Type")
 
-	// mime.ExtensionsByType gives a long list of extensions for text/plain,
-	// just use ".txt".
-	if strings.HasPrefix(contentType, "text/plain") {
-		extensionHints = []string{".txt"}
+	if isHeadMethod {
+		// We have no body to work with, so we need to use the Content-Type header.
+		mediaType, _ = media.FromString(contentType)
 	} else {
-		exts, _ := mime.ExtensionsByType(contentType)
-		if exts != nil {
-			extensionHints = exts
+
+		var extensionHints []string
+
+		// mime.ExtensionsByType gives a long list of extensions for text/plain,
+		// just use ".txt".
+		if strings.HasPrefix(contentType, "text/plain") {
+			extensionHints = []string{".txt"}
+		} else {
+			exts, _ := mime.ExtensionsByType(contentType)
+			if exts != nil {
+				extensionHints = exts
+			}
 		}
-	}
 
-	// Look for a file extension. If it's .txt, look for a more specific.
-	if extensionHints == nil || extensionHints[0] == ".txt" {
-		if ext := path.Ext(filename); ext != "" {
-			extensionHints = []string{ext}
+		// Look for a file extension. If it's .txt, look for a more specific.
+		if extensionHints == nil || extensionHints[0] == ".txt" {
+			if ext := path.Ext(filename); ext != "" {
+				extensionHints = []string{ext}
+			}
 		}
+
+		// Now resolve the media type primarily using the content.
+		mediaType = media.FromContent(c.rs.MediaTypes, extensionHints, body)
+
 	}
 
-	// Now resolve the media type primarily using the content.
-	mediaType := media.FromContent(c.rs.MediaTypes, extensionHints, body)
 	if mediaType.IsZero() {
 		return nil, fmt.Errorf("failed to resolve media type for remote resource %q", uri)
 	}