From 2043d29fa12ad5f58cc288f49818028f5fefd363 Mon Sep 17 00:00:00 2001
From: =?utf8?q?cat=20=C3=A6scling?=
 <11325618-aescling@users.noreply.gitlab.com>
Date: Tue, 25 Jul 2023 19:33:07 -0400
Subject: [PATCH] Implement Content-Type override

Document accordingly

Ignore any Content-Type headers in
`configuration/override/${resource}/headers`

* Remove empty line comments
---
 README.md                                             | 10 +++++++---
 .../binaries/http-print-header-files.execline         | 11 +++++++++++
 visible-to-httpd/binaries/httpd.execline              | 10 ++++++----
 3 files changed, 24 insertions(+), 7 deletions(-)

diff --git a/README.md b/README.md
index 7b51078..a209adc 100644
--- a/README.md
+++ b/README.md
@@ -96,7 +96,7 @@ will be served with a `Content-Type` of `{1}/${2}` (with colons in
 `index.text=x:market` will always be served with a `Content-Type` of
 `text/x.market`.
 2. using the per-resource `overrides` folder (see below) to specify a
-`Content-Type` header explicitly.
+`Content-Type` header explicitly (but not in the `headers` subdirectory).
 
 #### `./visible-to-httpd/configuration/default_headers/` ###
 
@@ -147,9 +147,13 @@ this directory allows you to override the extra headers sent along
 with a resource, and attach a status code other than 200 with them. a
 folder named after the specific resource (including a prepended
 hostname) should may contain a `status_code` file containing a
-numerical status code and optional textual message, as well as a
+numerical status code and optional textual message, a
 `headers` folder, which specifies headers using the `default_headers`
-scheme.
+scheme, and a `Content-Type` file, to override any other mechanism for
+determining the Content-Type to send to the client.
+
+Note that a `Content-Type` file in the `headers` folder is always
+ignored.
 
 a former official website for `httpd-execline.eerie.garden`
 used to redirect to this github repository, thanks to
diff --git a/visible-to-httpd/binaries/http-print-header-files.execline b/visible-to-httpd/binaries/http-print-header-files.execline
index 230d976..9886081 100755
--- a/visible-to-httpd/binaries/http-print-header-files.execline
+++ b/visible-to-httpd/binaries/http-print-header-files.execline
@@ -6,6 +6,8 @@
 # instances of ${hostname} and ${resource} are substituted with the provided
 # host and resource from the request
 #
+# the script will refuse to override the Content-Type header
+#
 # execs into self in order to retain an environment variable which marks
 # whether a certain header has been overridden or not
 
@@ -31,6 +33,15 @@ backtick -E -n header_name {
 	sed "s@.*/([^/]*)@\\1@"
 }
 
+ifelse {
+	pipeline { s6-echo -n -- \${header_name} }
+	grep -s -i '^[ 	]*Content-Type[ 	]*$' # paranoid whitespace matching
+}
+{
+	foreground { log.execline "refusing to override Content-Type header" }
+	http-print-header-directories.execline ${@}
+}
+
 # short circuit on overridden header
 ifelse { s6-test -v http_print_header_directories_${header_name} }
 {
diff --git a/visible-to-httpd/binaries/httpd.execline b/visible-to-httpd/binaries/httpd.execline
index b38f3dd..2860e6e 100755
--- a/visible-to-httpd/binaries/httpd.execline
+++ b/visible-to-httpd/binaries/httpd.execline
@@ -147,8 +147,13 @@ if -X -n -t {
 
 	#### 4. send response ###
 	##### 4.1. determine found resource's Content-Type ###
-	#
 	backtick -i -n Content-Type {
+		define Content_Type_override_file configuration/overrides/${resourse}/Content-Type
+		ifelse { s6-test -f ${Content_Type_override_file} -a -r ${Content_Type_override_file} }
+		{
+			cat ${Content_Type_override_file}
+		}
+
 		backtick -D "no.extension" -n extension {
 			pipeline { printenv resource }
 			# strip everything up to the non-periods after the final
@@ -162,12 +167,9 @@ if -X -n -t {
 		# with `Content-Type` `${1}/${2}`. colons in the extension are
 		# transformed into periods, allowing files like
 		# `index.text=x:market` being served as `text/x.market`
-		#
-		# this overrides any other Content-Type determination mechanism
 		ifelse {
 			pipeline { printenv extension }
 			# this regex matches exactly what `publicfile` does
-			#
 			grep -s "[a-zA-Z0-9]+=[^=]+$"
 		}
 		{
-- 
2.47.3