rproxy: read the rest of a Connection: close visitor's body after an early answer (closes #373)

Go's server reads up to 256 KiB of a body left unread once the handler
returns, but not a body with a declared length from a visitor that sent
Connection: close. It closes that connection with the rest unread, and
the visitor, still sending, gets a reset. rproxy now reads that rest
itself, until the deadline already set on the connection, through a
MaxBytesReader made with Go's own ResponseWriter. With more than 256 KiB
left, that has Go's server tell the visitor it sends no more and wait
500 ms before it closes. rproxy reads the rest only after an answer with
a Content-Length, because Go's server ends any other answer only once
the handler returns.

Model: opus-5-5

SPEC.md

@@ -1773,6 +1773,10 @@ member. A staff user's address skips them too: `username` when signing in, and
 `email` when creating the first staff user, asking for a password reset or
 saving a profile.
 
+The `canonical_url` of a post or a page skips 930120 and 932120, as `url` does.
+A post's skips them under `/ghost/api/admin/posts/`, and a page's under
+`/ghost/api/admin/pages/`.
+
 The articles carry HTML on purpose. These fields on the Admin API hold them:
 
 - `lexical`, which the editor saves, and `mobiledoc` and `html`, which
@@ -1813,7 +1817,7 @@ fields, on the Admin API:
 (941170 and 941210). Path traversal and SQL injection are still refused in every
 field above. Script injection is too, outside the articles and code injection.
 `; wget http://example.com/x.sh` is still refused in the query fields, the plain
-text and the addresses.
+text, the addresses and the canonical URLs.
 
 Coraza names a staff user's `profile_image` field `json.users.0.profile_image`.
 That name holds `.profile`, a file on the list of system files, so the name

internal/coreruleset/ghost.conf

@@ -216,6 +216,23 @@ SecRule REQUEST_FILENAME "@beginsWith /ghost/api/admin/" \
     SecRule &ARGS_GET:/^json\.(?:(?:posts|pages)\.\d+\.(?:lexical|mobiledoc|html|codeinjection_(?:head|foot))|settings\.\d+\.value)$/ "@eq 0" \
         "ctl:ruleRemoveTargetById=941110;ARGS:/^json\.(?:(?:posts|pages)\.\d+\.(?:lexical|mobiledoc|html|codeinjection_(?:head|foot))|settings\.\d+\.value)$/"
 
+# The canonical URL of a post or a page skips the two rules that url skips:
+#   930120: https://example.com/blog/.htaccess/
+#   932120: https://example.com/blog/powershell/
+# Each of these fields skips them only on its own path:
+#   posts.<n>.canonical_url, under /ghost/api/admin/posts/
+#   pages.<n>.canonical_url, under /ghost/api/admin/pages/
+SecRule REQUEST_FILENAME "@beginsWith /ghost/api/admin/posts/" \
+    "id:900383,phase:1,pass,nolog,chain"
+    SecRule &ARGS_GET:/^json\.posts\.\d+\.canonical_url$/ "@eq 0" \
+        "ctl:ruleRemoveTargetById=930120;ARGS:/^json\.posts\.\d+\.canonical_url$/,\
+        ctl:ruleRemoveTargetById=932120;ARGS:/^json\.posts\.\d+\.canonical_url$/"
+SecRule REQUEST_FILENAME "@beginsWith /ghost/api/admin/pages/" \
+    "id:900384,phase:1,pass,nolog,chain"
+    SecRule &ARGS_GET:/^json\.pages\.\d+\.canonical_url$/ "@eq 0" \
+        "ctl:ruleRemoveTargetById=930120;ARGS:/^json\.pages\.\d+\.canonical_url$/,\
+        ctl:ruleRemoveTargetById=932120;ARGS:/^json\.pages\.\d+\.canonical_url$/"
+
 # Saving a staff user's profile sends the field profile_image, whose name holds
 # .profile, a file the list of system files names (930120).
 SecRule REQUEST_FILENAME "@rx ^/ghost/api/admin/users/[0-9a-f]{24}/$" \

internal/coreruleset/ghost_test.go

@@ -143,6 +143,16 @@ var ghostAddressFields = []ghostField{
 	{http.MethodPut, ghostUser, `{"users":[{"email":"VALUE"}]}`},
 }
 
+// ghostCanonicalURLFields hold the canonical URL of a post or a page, and skip
+// 930120 and 932120, as url does.
+//
+//nolint:gochecknoglobals // a constant cannot be a list
+var ghostCanonicalURLFields = []ghostField{
+	{http.MethodPut, ghostPost, `{"posts":[{"canonical_url":"VALUE"}]}`},
+	{http.MethodPost, ghostPosts, `{"posts":[{"canonical_url":"VALUE"}]}`},
+	{http.MethodPut, ghostPage, `{"pages":[{"canonical_url":"VALUE"}]}`},
+}
+
 // ghostPostFields hold a post or a page, skip the rules of 900355, and take a
 // <script> element by 900366.
 //
@@ -220,13 +230,16 @@ var ghostQueryFields = []string{
 	ghostAdminFilter, ghostContentFilter, ghostSearch, ghostEmbed,
 }
 
-// ghostURLs are addresses 930120 and 932120 refused in url.
+// ghostURLs are addresses 930120 and 932120 refused in url and in a canonical
+// URL.
 //
 //nolint:gochecknoglobals // a constant cannot be a list
 var ghostURLs = []string{
 	"https://github.com/example/site/blob/main/.htaccess",
 	"https://example.com/blog/powershell-tips?ref=ghost",
 	"https://example.com/docs/python3/",
+	"https://example.com/blog/powershell/",
+	"https://example.com/blog/.htaccess/",
 }
 
 // ghostAddresses are addresses 930120, 932120 and 932260 refused.
@@ -327,6 +340,10 @@ func TestGhostOrdinaryValuesPassInTheExcludedFields(t *testing.T) {
 
 	for _, address := range ghostURLs {
 		wantGhostQuery(t, ghostEmbed+url.QueryEscape(address), false)
+
+		for _, f := range ghostCanonicalURLFields {
+			wantGhostField(t, f, address, false)
+		}
 	}
 
 	for _, address := range ghostAddresses {
@@ -395,7 +412,7 @@ func TestGhostAttacksAreRefusedInTheExcludedFields(t *testing.T) {
 
 	for _, attack := range ghostAttacks {
 		for _, f := range slices.Concat(ghostTextFields, ghostAddressFields,
-			ghostArticleFields, ghostCodeFields) {
+			ghostCanonicalURLFields, ghostArticleFields, ghostCodeFields) {
 			wantGhostField(t, f, attack, true)
 		}
 
@@ -407,7 +424,7 @@ func TestGhostAttacksAreRefusedInTheExcludedFields(t *testing.T) {
 	// A script injection stays refused in every field that does not take a
 	// <script> element.
 	for _, f := range slices.Concat(ghostTextFields, ghostAddressFields,
-		ghostSnippetAndNewsletterFooterFields) {
+		ghostCanonicalURLFields, ghostSnippetAndNewsletterFooterFields) {
 		wantGhostField(t, f, scriptTag, true)
 	}
 
@@ -416,8 +433,10 @@ func TestGhostAttacksAreRefusedInTheExcludedFields(t *testing.T) {
 	}
 
 	// A command after a separator stays refused wherever its rules do not
-	// misfire: in the query fields, the plain text and the addresses.
+	// misfire: in the query fields, the plain text, the addresses and the
-	for _, f := range slices.Concat(ghostTextFields, ghostAddressFields) {
+	// canonical URLs.
+	for _, f := range slices.Concat(ghostTextFields, ghostAddressFields,
+		ghostCanonicalURLFields) {
 		wantGhostField(t, f, commandAfterASeparator, true)
 	}
 
@@ -462,6 +481,8 @@ func TestGhostExclusionsAreNarrow(t *testing.T) {
 		setupEmail         = `{"setup":[{"email":"python3.dev@example.com"}]}`
 		passwordResetEmail = `{"password_reset":[{"email":"python3.dev@example.com"}]}`
 		userEmail          = `{"users":[{"email":"python3.dev@example.com"}]}`
+		postURL            = `{"posts":[{"canonical_url":"https://example.com/powershell/"}]}`
+		pageURL            = `{"pages":[{"canonical_url":"https://example.com/powershell/"}]}`
 	)
 
 	for _, refused := range []struct{ target, body string }{
@@ -498,6 +519,12 @@ func TestGhostExclusionsAreNarrow(t *testing.T) {
 		{ghostPasswordReset + "?json.password_reset.0.email=x", passwordResetEmail},
 		{ghostPosts, userEmail},
 		{ghostUser + "?json.users.0.email=x", userEmail},
+		{"/api/posts/1/", postURL},
+		{ghostMembers, postURL},
+		{ghostPage, postURL},
+		{ghostPost + "?json.posts.0.canonical_url=x", postURL},
+		{ghostPost, pageURL},
+		{ghostPage + "?json.pages.0.canonical_url=x", pageURL},
 		{ghostSession, `{"username":"x","pass":"' OR '1'='1"}`},
 		{"/ghost/api/admin/users/me/", `{"password":"' OR '1'='1"}`},
 		{"/ghost/api/admin/posts/1/", `{"users":[{"profile_image":null}]}`},

internal/coreruleset/testdata/ghost-requests.txt

@@ -533,6 +533,8 @@
 {"method": "GET", "target": "/ghost/api/admin/pages/6af45d34d281b00001a599a0/?formats=mobiledoc%2Clexical&include=tags%2Cauthors%2Cauthors.roles%2Cemail%2Ctiers%2Cnewsletter%2Ccount.clicks%2Cpost_revisions%2Cpost_revisions.author", "headers": ["Host: example.com", "User-Agent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/156.0.8078.4 Safari/537.36", "app-pragma: no-cache", "Accept: */*", "Referer: http://example.com/ghost/", "Accept-Encoding: gzip, deflate", "Cookie: ghost-admin-api-session=s%3ApyQuEYuuhAK8u18lU0bDl1kAjTTCtLBe.fHhgUS7MTBvPYpROnyCJjqXG%2BzBuicl%2Bw6WGQi%2Brq5Q"], "body": ""}
 {"method": "PUT", "target": "/ghost/api/admin/pages/6af45d34d281b00001a599a0/?formats=mobiledoc%2Clexical&include=tags%2Cauthors%2Cauthors.roles%2Cemail%2Ctiers%2Cnewsletter%2Ccount.clicks%2Cpost_revisions%2Cpost_revisions.author", "headers": ["Host: example.com", "Content-Length: 3980", "User-Agent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/156.0.8078.4 Safari/537.36", "content-type: application/json", "app-pragma: no-cache", "Accept: */*", "Origin: http://example.com", "Referer: http://example.com/ghost/", "Accept-Encoding: gzip, deflate", "Cookie: ghost-admin-api-session=s%3ApyQuEYuuhAK8u18lU0bDl1kAjTTCtLBe.fHhgUS7MTBvPYpROnyCJjqXG%2BzBuicl%2Bw6WGQi%2Brq5Q"], "body": "{\"pages\":[{\"title\":\"About: python3, powershell & .htaccess\",\"slug\":\"about-python3-powershell-htaccess\",\"lexical\":\"{\\\"root\\\":{\\\"children\\\":[{\\\"children\\\":[{\\\"detail\\\":0,\\\"format\\\":0,\\\"mode\\\":\\\"normal\\\",\\\"style\\\":\\\"\\\",\\\"text\\\":\\\"Who writes here, and why.\\\",\\\"type\\\":\\\"extended-text\\\",\\\"version\\\":1}],\\\"direction\\\":\\\"ltr\\\",\\\"format\\\":\\\"\\\",\\\"indent\\\":0,\\\"type\\\":\\\"paragraph\\\",\\\"version\\\":1},{\\\"children\\\":[{\\\"detail\\\":0,\\\"format\\\":0,\\\"mode\\\":\\\"normal\\\",\\\"style\\\":\\\"\\\",\\\"text\\\":\\\"About this site\\\",\\\"type\\\":\\\"extended-text\\\",\\\"version\\\":1}],\\\"direction\\\":\\\"ltr\\\",\\\"format\\\":\\\"\\\",\\\"indent\\\":0,\\\"type\\\":\\\"extended-heading\\\",\\\"version\\\":1,\\\"tag\\\":\\\"h2\\\"},{\\\"children\\\":[{\\\"detail\\\":0,\\\"format\\\":0,\\\"mode\\\":\\\"normal\\\",\\\"style\\\":\\\"\\\",\\\"text\\\":\\\"Notes on \\\",\\\"type\\\":\\\"extended-text\\\",\\\"version\\\":1},{\\\"detail\\\":0,\\\"format\\\":1,\\\"mode\\\":\\\"normal\\\",\\\"style\\\":\\\"\\\",\\\"text\\\":\\\"python3\\\",\\\"type\\\":\\\"extended-text\\\",\\\"version\\\":1},{\\\"detail\\\":0,\\\"format\\\":0,\\\"mode\\\":\\\"normal\\\",\\\"style\\\":\\\"\\\",\\\"text\\\":\\\", \\\",\\\"type\\\":\\\"extended-text\\\",\\\"version\\\":1},{\\\"detail\\\":0,\\\"format\\\":2,\\\"mode\\\":\\\"normal\\\",\\\"style\\\":\\\"\\\",\\\"text\\\":\\\"powershell\\\",\\\"type\\\":\\\"extended-text\\\",\\\"version\\\":1},{\\\"detail\\\":0,\\\"format\\\":0,\\\"mode\\\":\\\"normal\\\",\\\"style\\\":\\\"\\\",\\\"text\\\":\\\" and the shell. Start with \\\",\\\"type\\\":\\\"extended-text\\\",\\\"version\\\":1},{\\\"detail\\\":0,\\\"format\\\":16,\\\"mode\\\":\\\"normal\\\",\\\"style\\\":\\\"\\\",\\\"text\\\":\\\"ls -la ~/.ssh\\\",\\\"type\\\":\\\"extended-text\\\",\\\"version\\\":1},{\\\"detail\\\":0,\\\"format\\\":0,\\\"mode\\\":\\\"normal\\\",\\\"style\\\":\\\"\\\",\\\"text\\\":\\\" and read \\\",\\\"type\\\":\\\"extended-text\\\",\\\"version\\\":1},{\\\"children\\\":[{\\\"detail\\\":0,\\\"format\\\":0,\\\"mode\\\":\\\"normal\\\",\\\"style\\\":\\\"\\\",\\\"text\\\":\\\"the .htaccess primer\\\",\\\"type\\\":\\\"extended-text\\\",\\\"version\\\":1}],\\\"direction\\\":\\\"ltr\\\",\\\"format\\\":\\\"\\\",\\\"indent\\\":0,\\\"type\\\":\\\"link\\\",\\\"version\\\":1,\\\"rel\\\":null,\\\"target\\\":null,\\\"title\\\":null,\\\"url\\\":\\\"https://example.com/htaccess\\\"},{\\\"detail\\\":0,\\\"format\\\":0,\\\"mode\\\":\\\"normal\\\",\\\"style\\\":\\\"\\\",\\\"text\\\":\\\".\\\",\\\"type\\\":\\\"extended-text\\\",\\\"version\\\":1}],\\\"direction\\\":\\\"ltr\\\",\\\"format\\\":\\\"\\\",\\\"indent\\\":0,\\\"type\\\":\\\"paragraph\\\",\\\"version\\\":1},{\\\"type\\\":\\\"codeblock\\\",\\\"version\\\":1,\\\"code\\\":\\\"Get-ChildItem -Force | Where-Object { $_.Name -like '.htaccess' }\\\\nInvoke-WebRequest -Uri https://example.com/feed.xml -OutFile feed.xml\\\",\\\"language\\\":\\\"powershell\\\",\\\"caption\\\":\\\"\\\"},{\\\"children\\\":[{\\\"detail\\\":0,\\\"format\\\":0,\\\"mode\\\":\\\"normal\\\",\\\"style\\\":\\\"\\\",\\\"text\\\":\\\"Contact\\\",\\\"type\\\":\\\"extended-text\\\",\\\"version\\\":1}],\\\"direction\\\":\\\"ltr\\\",\\\"format\\\":\\\"\\\",\\\"indent\\\":0,\\\"type\\\":\\\"extended-heading\\\",\\\"version\\\":1,\\\"tag\\\":\\\"h3\\\"},{\\\"children\\\":[{\\\"detail\\\":0,\\\"format\\\":0,\\\"mode\\\":\\\"normal\\\",\\\"style\\\":\\\"\\\",\\\"text\\\":\\\"Write to \\\",\\\"type\\\":\\\"extended-text\\\",\\\"version\\\":1},{\\\"children\\\":[{\\\"detail\\\":0,\\\"format\\\":0,\\\"mode\\\":\\\"normal\\\",\\\"style\\\":\\\"\\\",\\\"text\\\":\\\"alice@example.com\\\",\\\"type\\\":\\\"extended-text\\\",\\\"version\\\":1}],\\\"direction\\\":\\\"ltr\\\",\\\"format\\\":\\\"\\\",\\\"indent\\\":0,\\\"type\\\":\\\"link\\\",\\\"version\\\":1,\\\"rel\\\":null,\\\"target\\\":null,\\\"title\\\":null,\\\"url\\\":\\\"mailto:alice@example.com\\\"},{\\\"detail\\\":0,\\\"format\\\":0,\\\"mode\\\":\\\"normal\\\",\\\"style\\\":\\\"\\\",\\\"text\\\":\\\".\\\",\\\"type\\\":\\\"extended-text\\\",\\\"version\\\":1}],\\\"direction\\\":\\\"ltr\\\",\\\"format\\\":\\\"\\\",\\\"indent\\\":0,\\\"type\\\":\\\"paragraph\\\",\\\"version\\\":1},{\\Line truncated
 {"method": "PUT", "target": "/ghost/api/admin/pages/6af45d34d281b00001a599a0/?formats=mobiledoc%2Clexical&include=tags%2Cauthors%2Cauthors.roles%2Cemail%2Ctiers%2Cnewsletter%2Ccount.clicks%2Cpost_revisions%2Cpost_revisions.author", "headers": ["Host: example.com", "Content-Length: 3984", "User-Agent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/156.0.8078.4 Safari/537.36", "content-type: application/json", "app-pragma: no-cache", "Accept: */*", "Origin: http://example.com", "Referer: http://example.com/ghost/", "Accept-Encoding: gzip, deflate", "Cookie: ghost-admin-api-session=s%3ApyQuEYuuhAK8u18lU0bDl1kAjTTCtLBe.fHhgUS7MTBvPYpROnyCJjqXG%2BzBuicl%2Bw6WGQi%2Brq5Q"], "body": "{\"pages\":[{\"title\":\"About: python3, powershell & .htaccess\",\"slug\":\"about-python3-powershell-htaccess\",\"lexical\":\"{\\\"root\\\":{\\\"children\\\":[{\\\"children\\\":[{\\\"detail\\\":0,\\\"format\\\":0,\\\"mode\\\":\\\"normal\\\",\\\"style\\\":\\\"\\\",\\\"text\\\":\\\"Who writes here, and why.\\\",\\\"type\\\":\\\"extended-text\\\",\\\"version\\\":1}],\\\"direction\\\":\\\"ltr\\\",\\\"format\\\":\\\"\\\",\\\"indent\\\":0,\\\"type\\\":\\\"paragraph\\\",\\\"version\\\":1},{\\\"children\\\":[{\\\"detail\\\":0,\\\"format\\\":0,\\\"mode\\\":\\\"normal\\\",\\\"style\\\":\\\"\\\",\\\"text\\\":\\\"About this site\\\",\\\"type\\\":\\\"extended-text\\\",\\\"version\\\":1}],\\\"direction\\\":\\\"ltr\\\",\\\"format\\\":\\\"\\\",\\\"indent\\\":0,\\\"type\\\":\\\"extended-heading\\\",\\\"version\\\":1,\\\"tag\\\":\\\"h2\\\"},{\\\"children\\\":[{\\\"detail\\\":0,\\\"format\\\":0,\\\"mode\\\":\\\"normal\\\",\\\"style\\\":\\\"\\\",\\\"text\\\":\\\"Notes on \\\",\\\"type\\\":\\\"extended-text\\\",\\\"version\\\":1},{\\\"detail\\\":0,\\\"format\\\":1,\\\"mode\\\":\\\"normal\\\",\\\"style\\\":\\\"\\\",\\\"text\\\":\\\"python3\\\",\\\"type\\\":\\\"extended-text\\\",\\\"version\\\":1},{\\\"detail\\\":0,\\\"format\\\":0,\\\"mode\\\":\\\"normal\\\",\\\"style\\\":\\\"\\\",\\\"text\\\":\\\", \\\",\\\"type\\\":\\\"extended-text\\\",\\\"version\\\":1},{\\\"detail\\\":0,\\\"format\\\":2,\\\"mode\\\":\\\"normal\\\",\\\"style\\\":\\\"\\\",\\\"text\\\":\\\"powershell\\\",\\\"type\\\":\\\"extended-text\\\",\\\"version\\\":1},{\\\"detail\\\":0,\\\"format\\\":0,\\\"mode\\\":\\\"normal\\\",\\\"style\\\":\\\"\\\",\\\"text\\\":\\\" and the shell. Start with \\\",\\\"type\\\":\\\"extended-text\\\",\\\"version\\\":1},{\\\"detail\\\":0,\\\"format\\\":16,\\\"mode\\\":\\\"normal\\\",\\\"style\\\":\\\"\\\",\\\"text\\\":\\\"ls -la ~/.ssh\\\",\\\"type\\\":\\\"extended-text\\\",\\\"version\\\":1},{\\\"detail\\\":0,\\\"format\\\":0,\\\"mode\\\":\\\"normal\\\",\\\"style\\\":\\\"\\\",\\\"text\\\":\\\" and read \\\",\\\"type\\\":\\\"extended-text\\\",\\\"version\\\":1},{\\\"children\\\":[{\\\"detail\\\":0,\\\"format\\\":0,\\\"mode\\\":\\\"normal\\\",\\\"style\\\":\\\"\\\",\\\"text\\\":\\\"the .htaccess primer\\\",\\\"type\\\":\\\"extended-text\\\",\\\"version\\\":1}],\\\"direction\\\":\\\"ltr\\\",\\\"format\\\":\\\"\\\",\\\"indent\\\":0,\\\"type\\\":\\\"link\\\",\\\"version\\\":1,\\\"rel\\\":null,\\\"target\\\":null,\\\"title\\\":null,\\\"url\\\":\\\"https://example.com/htaccess\\\"},{\\\"detail\\\":0,\\\"format\\\":0,\\\"mode\\\":\\\"normal\\\",\\\"style\\\":\\\"\\\",\\\"text\\\":\\\".\\\",\\\"type\\\":\\\"extended-text\\\",\\\"version\\\":1}],\\\"direction\\\":\\\"ltr\\\",\\\"format\\\":\\\"\\\",\\\"indent\\\":0,\\\"type\\\":\\\"paragraph\\\",\\\"version\\\":1},{\\\"type\\\":\\\"codeblock\\\",\\\"version\\\":1,\\\"code\\\":\\\"Get-ChildItem -Force | Where-Object { $_.Name -like '.htaccess' }\\\\nInvoke-WebRequest -Uri https://example.com/feed.xml -OutFile feed.xml\\\",\\\"language\\\":\\\"powershell\\\",\\\"caption\\\":\\\"\\\"},{\\\"children\\\":[{\\\"detail\\\":0,\\\"format\\\":0,\\\"mode\\\":\\\"normal\\\",\\\"style\\\":\\\"\\\",\\\"text\\\":\\\"Contact\\\",\\\"type\\\":\\\"extended-text\\\",\\\"version\\\":1}],\\\"direction\\\":\\\"ltr\\\",\\\"format\\\":\\\"\\\",\\\"indent\\\":0,\\\"type\\\":\\\"extended-heading\\\",\\\"version\\\":1,\\\"tag\\\":\\\"h3\\\"},{\\\"children\\\":[{\\\"detail\\\":0,\\\"format\\\":0,\\\"mode\\\":\\\"normal\\\",\\\"style\\\":\\\"\\\",\\\"text\\\":\\\"Write to \\\",\\\"type\\\":\\\"extended-text\\\",\\\"version\\\":1},{\\\"children\\\":[{\\\"detail\\\":0,\\\"format\\\":0,\\\"mode\\\":\\\"normal\\\",\\\"style\\\":\\\"\\\",\\\"text\\\":\\\"alice@example.com\\\",\\\"type\\\":\\\"extended-text\\\",\\\"version\\\":1}],\\\"direction\\\":\\\"ltr\\\",\\\"format\\\":\\\"\\\",\\\"indent\\\":0,\\\"type\\\":\\\"link\\\",\\\"version\\\":1,\\\"rel\\\":null,\\\"target\\\":null,\\\"title\\\":null,\\\"url\\\":\\\"mailto:alice@example.com\\\"},{\\\"detail\\\":0,\\\"format\\\":0,\\\"mode\\\":\\\"normal\\\",\\\"style\\\":\\\"\\\",\\\"text\\\":\\\".\\\",\\\"type\\\":\\\"extended-text\\\",\\\"version\\\":1}],\\\"direction\\\":\\\"ltr\\\",\\\"format\\\":\\\"\\\",\\\"indent\\\":0,\\\"type\\\":\\\"paragraph\\\",\\\"version\\\":1},{\\Line truncated
+{"method": "PUT", "target": "/ghost/api/admin/posts/6af5659a6dde5d0001d3d72e/?formats=mobiledoc%2Clexical&include=tags%2Cauthors%2Cauthors.roles%2Cemail%2Ctiers%2Cnewsletter%2Ccount.clicks%2Cpost_revisions%2Cpost_revisions.author", "headers": ["Host: example.com", "Content-Length: 713", "User-Agent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/156.0.8078.4 Safari/537.36", "content-type: application/json", "app-pragma: no-cache", "Accept: */*", "Origin: http://example.com", "Referer: http://example.com/ghost/", "Accept-Encoding: gzip, deflate", "Cookie: ghost-admin-api-session=s%3AoIVlIxucaQas8uV_V0tI2mNyxYEoOjBC.ajmnN2F%2BNe0IFunZWICXaJjQpUSV75M6lrkP5I0svVs"], "body": "{\"posts\":[{\"title\":\"Getting started with PowerShell\",\"slug\":\"getting-started-with-powershell\",\"lexical\":\"{\\\"root\\\":{\\\"children\\\":[{\\\"children\\\":[{\\\"detail\\\":0,\\\"format\\\":0,\\\"mode\\\":\\\"normal\\\",\\\"style\\\":\\\"\\\",\\\"text\\\":\\\"First published on the old blog.\\\",\\\"type\\\":\\\"extended-text\\\",\\\"version\\\":1}],\\\"direction\\\":\\\"ltr\\\",\\\"format\\\":\\\"\\\",\\\"indent\\\":0,\\\"type\\\":\\\"paragraph\\\",\\\"version\\\":1}],\\\"direction\\\":\\\"ltr\\\",\\\"format\\\":\\\"\\\",\\\"indent\\\":0,\\\"type\\\":\\\"root\\\",\\\"version\\\":1}}\",\"feature_image\":null,\"feature_image_alt\":null,\"feature_image_caption\":null,\"status\":\"draft\",\"published_at\":null,\"canonical_url\":\"https://example.com/blog/powershell/\",\"id\":\"6af5659a6dde5d0001d3d72e\",\"updated_at\":\"2026-11-12T07:07:12.000Z\"}]}"}
+{"method": "PUT", "target": "/ghost/api/admin/pages/6af565b96dde5d0001d3d735/?formats=mobiledoc%2Clexical&include=tags%2Cauthors%2Cauthors.roles%2Cemail%2Ctiers%2Cnewsletter%2Ccount.clicks%2Cpost_revisions%2Cpost_revisions.author", "headers": ["Host: example.com", "Content-Length: 701", "User-Agent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/156.0.8078.4 Safari/537.36", "content-type: application/json", "app-pragma: no-cache", "Accept: */*", "Origin: http://example.com", "Referer: http://example.com/ghost/", "Accept-Encoding: gzip, deflate", "Cookie: ghost-admin-api-session=s%3AoIVlIxucaQas8uV_V0tI2mNyxYEoOjBC.ajmnN2F%2BNe0IFunZWICXaJjQpUSV75M6lrkP5I0svVs"], "body": "{\"pages\":[{\"title\":\"Rewrite rules in .htaccess\",\"slug\":\"rewrite-rules-in-htaccess\",\"lexical\":\"{\\\"root\\\":{\\\"children\\\":[{\\\"children\\\":[{\\\"detail\\\":0,\\\"format\\\":0,\\\"mode\\\":\\\"normal\\\",\\\"style\\\":\\\"\\\",\\\"text\\\":\\\"First published on the old blog.\\\",\\\"type\\\":\\\"extended-text\\\",\\\"version\\\":1}],\\\"direction\\\":\\\"ltr\\\",\\\"format\\\":\\\"\\\",\\\"indent\\\":0,\\\"type\\\":\\\"paragraph\\\",\\\"version\\\":1}],\\\"direction\\\":\\\"ltr\\\",\\\"format\\\":\\\"\\\",\\\"indent\\\":0,\\\"type\\\":\\\"root\\\",\\\"version\\\":1}}\",\"feature_image\":null,\"feature_image_alt\":null,\"feature_image_caption\":null,\"status\":\"draft\",\"published_at\":null,\"canonical_url\":\"https://example.com/blog/.htaccess/\",\"id\":\"6af565b96dde5d0001d3d735\",\"updated_at\":\"2026-11-12T07:07:42.000Z\"}]}"}
 {"method": "GET", "target": "/ghost/assets/pages-route-Bx4g0rd3.js", "headers": ["Host: example.com", "User-Agent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/156.0.8078.4 Safari/537.36", "Origin: http://example.com", "Accept: */*", "Referer: http://example.com/ghost/", "Accept-Encoding: gzip, deflate", "Cookie: ghost-admin-api-session=s%3ApyQuEYuuhAK8u18lU0bDl1kAjTTCtLBe.fHhgUS7MTBvPYpROnyCJjqXG%2BzBuicl%2Bw6WGQi%2Brq5Q"], "body": ""}
 {"method": "GET", "target": "/ghost/api/admin/pages/?filter=status%3Ascheduled&order=published_at+desc&limit=30", "headers": ["Host: example.com", "User-Agent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/156.0.8078.4 Safari/537.36", "app-pragma: no-cache", "Accept: */*", "Referer: http://example.com/ghost/", "Accept-Encoding: gzip, deflate", "Cookie: ghost-admin-api-session=s%3ApyQuEYuuhAK8u18lU0bDl1kAjTTCtLBe.fHhgUS7MTBvPYpROnyCJjqXG%2BzBuicl%2Bw6WGQi%2Brq5Q"], "body": ""}
 {"method": "GET", "target": "/ghost/api/admin/pages/?filter=status%3Adraft&order=updated_at+desc&limit=30", "headers": ["Host: example.com", "User-Agent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/156.0.8078.4 Safari/537.36", "app-pragma: no-cache", "Accept: */*", "Referer: http://example.com/ghost/", "Accept-Encoding: gzip, deflate", "Cookie: ghost-admin-api-session=s%3ApyQuEYuuhAK8u18lU0bDl1kAjTTCtLBe.fHhgUS7MTBvPYpROnyCJjqXG%2BzBuicl%2Bw6WGQi%2Brq5Q"], "body": ""}

internal/rproxy/limits_test.go

@@ -26,6 +26,10 @@ import (
 // post is the start of a POST whose headers end with what follows it.
 const post = "POST / HTTP/1.1\r\nHost: site.example\r\n"
 
+// limitPastFirstPart is a SWW_RPROXY_MAX_REQUEST_SIZE past the first part of a
+// body, the 64 KiB rproxy reads before it asks waf.
+const limitPastFirstPart = "128K"
+
 // announcedLength is the header that announces a body of size bytes, and the
 // end of the headers.
 func announcedLength(size int) string {
@@ -75,7 +79,10 @@ func TestABodyAnnouncedOverItsLimitIsRefusedOnceWAFAllowsIt(t *testing.T) {
 		size, asked int
 	}{
 		{"with the limit within the first part", "1K", 1025, 1024},
-		{"with the limit past the first part", "128K", 129 << 10, questionBodyMaxBytes},
+		{
+			"with the limit past the first part", limitPastFirstPart, 129 << 10,
+			questionBodyMaxBytes,
+		},
 	} {
 		t.Run(tc.name, func(t *testing.T) {
 			t.Parallel()
@@ -136,6 +143,134 @@ func TestADenyOutranksTheBodySizeLimit(t *testing.T) {
 	}
 }
 
+func TestAVisitorSendingConnectionCloseReadsAnAnswerBeforeTheRestOfItsBody(
+	t *testing.T,
+) {
+	t.Parallel()
+
+	for _, tc := range []struct {
+		name   string
+		waf    http.HandlerFunc
+		rest   int
+		status int
+	}{
+		{"over the size limit", allow, 65 << 10, http.StatusRequestEntityTooLarge},
+		{"denied", deny, 65 << 10, http.StatusForbidden},
+		// rproxy reads 256 KiB of this rest. What it leaves unread must fit in the
+		// connection's buffers. Otherwise the visitor is still sending when the
+		// connection closes, and gets a reset.
+		{
+			"with more than 256 KiB left", allow, 272 << 10,
+			http.StatusRequestEntityTooLarge,
+		},
+	} {
+		t.Run(tc.name, func(t *testing.T) {
+			t.Parallel()
+
+			standIn := startWAF(t, tc.waf)
+			app := startApp(t, func(http.ResponseWriter, *http.Request) {
+				t.Error("the app was asked")
+			})
+			addr, _ := startRProxy(t, standIn.URL, app.URL,
+				map[string]string{maxRequestSize: limitPastFirstPart})
+
+			conn := dial(t, addr)
+			send(t, conn, post+"Connection: close\r\n"+
+				announcedLength(questionBodyMaxBytes+tc.rest)+
+				strings.Repeat("x", questionBodyMaxBytes))
+
+			reader := bufio.NewReader(conn)
+
+			res, err := http.ReadResponse(reader, nil)
+			if err != nil {
+				t.Fatalf("read the answer: %v", err)
+			}
+
+			_, _ = io.Copy(io.Discard, res.Body)
+			_ = res.Body.Close()
+
+			if res.StatusCode != tc.status {
+				t.Errorf("status %d, want %d", res.StatusCode, tc.status)
+			}
+
+			// The rest goes in small parts, so that a reset fails a later one.
+			for sent := 0; sent < tc.rest; sent += 1 << 10 {
+				send(t, conn, strings.Repeat("x", 1<<10))
+			}
+
+			got, err := io.ReadAll(reader)
+			if err != nil || len(got) != 0 {
+				t.Errorf(
+					"after the answer, read %q and %v, want the end",
+					got,
+					err,
+				)
+			}
+		})
+	}
+}
+
+func TestCloseDoesNotWaitForTheRestOfTheBodyOfAVisitorSendingConnectionClose(
+	t *testing.T,
+) {
+	t.Parallel()
+
+	standIn := startWAF(t, func(w http.ResponseWriter, _ *http.Request) {
+		w.Header().Set(dispositionHeader, dispositionClose)
+		w.WriteHeader(http.StatusOK)
+	})
+	app := startApp(t, func(http.ResponseWriter, *http.Request) {
+		t.Error("the app was asked")
+	})
+	// The request time limit is far longer than dial's deadline.
+	addr, _ := startRProxy(t, standIn.URL, app.URL, map[string]string{
+		maxRequestTime: "120000",
+	})
+
+	conn := dial(t, addr)
+	send(t, conn, post+"Connection: close\r\n"+
+		announcedLength(2*questionBodyMaxBytes)+
+		strings.Repeat("x", questionBodyMaxBytes))
+
+	// If the connection stays open, dial's deadline ends this read with a timeout.
+	text, err := io.ReadAll(conn)
+	if err != nil || len(text) != 0 {
+		t.Errorf(
+			"read %q (%v), want the connection closed without an answer",
+			text,
+			err,
+		)
+	}
+}
+
+func TestAVisitorSendingConnectionCloseGetsTheEndOfAnAnswerWithoutContentLengthAtOnce(
+	t *testing.T,
+) {
+	t.Parallel()
+
+	standIn := startWAF(t, allow)
+	// The flush has the app's server send greeting in chunks instead of adding a
+	// Content-Length.
+	app := startApp(t, func(w http.ResponseWriter, _ *http.Request) {
+		rc := http.NewResponseController(w)
+		_ = rc.EnableFullDuplex()
+
+		_, _ = io.WriteString(w, greeting)
+		_ = rc.Flush()
+	})
+	// The request time limit is far longer than dial's deadline.
+	addr, _ := startRProxy(t, standIn.URL, app.URL, map[string]string{
+		maxRequestTime: "120000",
+	})
+
+	conn := dial(t, addr)
+	send(t, conn, post+"Connection: close\r\n"+
+		announcedLength(2*questionBodyMaxBytes)+
+		strings.Repeat("x", questionBodyMaxBytes+1))
+
+	wantGreeting(t, readAnswer(t, conn))
+}
+
 func TestABodyNotAnnouncedOverItsLimitIsRefused(t *testing.T) {
 	t.Parallel()
 
@@ -148,7 +283,7 @@ func TestABodyNotAnnouncedOverItsLimitIsRefused(t *testing.T) {
 		mayReachApp bool
 	}{
 		{"within the first part", "1K", 2 << 10, false},
-		{"past the first part", "128K", 129 << 10, true},
+		{"past the first part", limitPastFirstPart, 129 << 10, true},
 	} {
 		t.Run(tc.name, func(t *testing.T) {
 			t.Parallel()

internal/rproxy/request.go

@@ -38,6 +38,10 @@ const plainText = "text/plain; charset=utf-8"
 // and the visitor then gets a closed connection and no answer.
 const minSendTime = 10 * time.Second
 
+// maxBodyReadAfterAnswer is the most of a body left unread that Go's server
+// reads once the handler returns, for a visitor without Connection: close.
+const maxBodyReadAfterAnswer = 256 << 10
+
 // errResponseTooLate refuses an app's answer that arrives once
 // SWW_RPROXY_MAX_RESPONSE_TIME_MS has run out.
 var errResponseTooLate = errors.New(
@@ -338,8 +342,8 @@ func (rq *request) answer(status int) {
 	}
 
 	// A visitor found too slow is read no more; any other may go on sending until
-	// its time is up, so that Go's server can read the rest of the body and end
+	// its time is up, so that the rest of the body is read and the request ends
-	// the request cleanly.
+	// cleanly: by Go's server, or by readRestOfBody.
 	deadline := rq.requestDeadline()
 	if status == http.StatusRequestTimeout {
 		deadline = time.Now()
@@ -523,10 +527,35 @@ func (rq *request) stopReadingBody(deadline time.Time) {
 	_ = rq.rc.SetReadDeadline(deadline)
 }
 
+// readRestOfBody reads up to 256 KiB of the rest of the body once the visitor
+// has been answered with a Content-Length, until the read deadline already set on
+// the connection. It does this only for a body with a declared length from a
+// visitor that sent Connection: close, because Go's server reads none of that
+// rest. Without the read, the visitor, still sending, gets a reset and may never
+// read the answer. Go's server ends an answer without a Content-Length only once
+// the handler returns, so reading first would hold back the end of that answer.
+// Past 256 KiB, the MaxBytesReader made with Go's own ResponseWriter has Go's
+// server tell the visitor it sends no more, then wait 500 ms before it closes
+// the connection.
+func (rq *request) readRestOfBody() {
+	if !rq.in.Close || rq.in.ContentLength <= 0 || rq.body.received.Load() ||
+		rq.out.Header().Get("Content-Length") == "" ||
+		rq.out.status == http.StatusSwitchingProtocols {
+		return
+	}
+
+	rest := http.MaxBytesReader(
+		rq.out.ResponseWriter,
+		rq.in.Body,
+		maxBodyReadAfterAnswer,
+	)
+	_, _ = io.Copy(io.Discard, rest)
+}
+
 // stopPassingOnBody ends the transport's reading of a visitor's body that has
-// not arrived whole, and lets Go's server read the rest until deadline. Go's
+// not arrived whole, and lets Go's server, or readRestOfBody, read the rest until
-// server reads it once the handler returns, but with no deadline at all if
+// deadline. Go's server reads it once the handler returns, but with no deadline
-// another read of it is still waiting.
+// at all if another read of it is still waiting.
 func (rq *request) stopPassingOnBody(deadline time.Time) {
 	if rq.body == nil || rq.body.received.Load() {
 		return

internal/rproxy/rproxy.go

@@ -169,6 +169,7 @@ func newWAFTransport() *http.Transport {
 // it writes the request's log line and sends its report.
 func (h *handler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 	rq := h.newRequest(w, r)
+	defer rq.readRestOfBody()
 	defer rq.finish(r.Context())
 
 	if r.Method == http.MethodGet && r.URL.Path == waf.HealthPath {