From c216cf551dcbd2de1da1b9fe8a7e179b76827753 Mon Sep 17 00:00:00 2001
From: Francis Lavoie <lavofr@gmail.com>
Date: Fri, 20 Dec 2024 13:16:34 -0500
Subject: [PATCH] caddyhttp: Allow matching Transfer-Encoding, add to access
 logs (#6629)

* caddyhttp: Allow matching Transfer-Encoding

* Log transfer_encoding on the request

---------

Co-authored-by: Matt Holt <mholt@users.noreply.github.com>
---
 modules/caddyhttp/marshalers.go       |  3 +++
 modules/caddyhttp/matchers.go         | 18 +++++++++++-------
 modules/caddyhttp/responsematchers.go |  2 +-
 3 files changed, 15 insertions(+), 8 deletions(-)

diff --git a/modules/caddyhttp/marshalers.go b/modules/caddyhttp/marshalers.go
index c985bb92..9bce377f 100644
--- a/modules/caddyhttp/marshalers.go
+++ b/modules/caddyhttp/marshalers.go
@@ -51,6 +51,9 @@ func (r LoggableHTTPRequest) MarshalLogObject(enc zapcore.ObjectEncoder) error {
 		Header:               r.Header,
 		ShouldLogCredentials: r.ShouldLogCredentials,
 	})
+	if r.TransferEncoding != nil {
+		enc.AddArray("transfer_encoding", LoggableStringArray(r.TransferEncoding))
+	}
 	if r.TLS != nil {
 		enc.AddObject("tls", LoggableTLSConnState(*r.TLS))
 	}
diff --git a/modules/caddyhttp/matchers.go b/modules/caddyhttp/matchers.go
index 25fdc1fe..e5ca28b9 100644
--- a/modules/caddyhttp/matchers.go
+++ b/modules/caddyhttp/matchers.go
@@ -978,7 +978,7 @@ func (m MatchHeader) Match(r *http.Request) bool {
 // MatchWithError returns true if r matches m.
 func (m MatchHeader) MatchWithError(r *http.Request) (bool, error) {
 	repl := r.Context().Value(caddy.ReplacerCtxKey).(*caddy.Replacer)
-	return matchHeaders(r.Header, http.Header(m), r.Host, repl), nil
+	return matchHeaders(r.Header, http.Header(m), r.Host, r.TransferEncoding, repl), nil
 }
 
 // CELLibrary produces options that expose this matcher for use in CEL
@@ -1004,22 +1004,26 @@ func (MatchHeader) CELLibrary(_ caddy.Context) (cel.Library, error) {
 }
 
 // getHeaderFieldVals returns the field values for the given fieldName from input.
-// The host parameter should be obtained from the http.Request.Host field since
-// net/http removes it from the header map.
-func getHeaderFieldVals(input http.Header, fieldName, host string) []string {
+// The host parameter should be obtained from the http.Request.Host field, and the
+// transferEncoding from http.Request.TransferEncoding, since net/http removes them
+// from the header map.
+func getHeaderFieldVals(input http.Header, fieldName, host string, transferEncoding []string) []string {
 	fieldName = textproto.CanonicalMIMEHeaderKey(fieldName)
 	if fieldName == "Host" && host != "" {
 		return []string{host}
 	}
+	if fieldName == "Transfer-Encoding" && input[fieldName] == nil {
+		return transferEncoding
+	}
 	return input[fieldName]
 }
 
 // matchHeaders returns true if input matches the criteria in against without regex.
 // The host parameter should be obtained from the http.Request.Host field since
 // net/http removes it from the header map.
-func matchHeaders(input, against http.Header, host string, repl *caddy.Replacer) bool {
+func matchHeaders(input, against http.Header, host string, transferEncoding []string, repl *caddy.Replacer) bool {
 	for field, allowedFieldVals := range against {
-		actualFieldVals := getHeaderFieldVals(input, field, host)
+		actualFieldVals := getHeaderFieldVals(input, field, host, transferEncoding)
 		if allowedFieldVals != nil && len(allowedFieldVals) == 0 && actualFieldVals != nil {
 			// a non-nil but empty list of allowed values means
 			// match if the header field exists at all
@@ -1119,7 +1123,7 @@ func (m MatchHeaderRE) Match(r *http.Request) bool {
 // MatchWithError returns true if r matches m.
 func (m MatchHeaderRE) MatchWithError(r *http.Request) (bool, error) {
 	for field, rm := range m {
-		actualFieldVals := getHeaderFieldVals(r.Header, field, r.Host)
+		actualFieldVals := getHeaderFieldVals(r.Header, field, r.Host, r.TransferEncoding)
 		match := false
 	fieldVal:
 		for _, actualFieldVal := range actualFieldVals {
diff --git a/modules/caddyhttp/responsematchers.go b/modules/caddyhttp/responsematchers.go
index cf96b00c..a6b34c76 100644
--- a/modules/caddyhttp/responsematchers.go
+++ b/modules/caddyhttp/responsematchers.go
@@ -41,7 +41,7 @@ func (rm ResponseMatcher) Match(statusCode int, hdr http.Header) bool {
 	if !rm.matchStatusCode(statusCode) {
 		return false
 	}
-	return matchHeaders(hdr, rm.Headers, "", nil)
+	return matchHeaders(hdr, rm.Headers, "", []string{}, nil)
 }
 
 func (rm ResponseMatcher) matchStatusCode(statusCode int) bool {