From: cat æscling <aescling@cat.family>
Date: Tue, 30 Apr 2024 02:00:51 +0000 (-0400)
Subject: Add minimal cacheing support
X-Git-Url: https://git.xn--scling-oua.cat.family/?a=commitdiff_plain;h=88944f026bfb5030c038ec26a3cdf49861af477e;p=httpd-execline.git

Add minimal cacheing support

If configured to do so, generate ETags on the fly fur every successfully
found resource with `cksum(1)`.

* Typos
* Fix strange syntax error
* Fix missing `"`
* Typos
* Wrap ETag generation in a conditional
---

diff --git a/README.md b/README.md
index f330ed0..315acdb 100644
--- a/README.md
+++ b/README.md
@@ -105,7 +105,8 @@ feasible configuration is to place statically linked dependencies into
   - some 9base commands do not build on my system, but thankfully none of the
   tools required by httpd.execline fail.
 + [toybox](http://www.landley.net/toybox/): `wc(1)`,
-`date(1p)`, `stat(1)`, `cat(1)`, `timeout(1)`
+`date(1p)`, `stat(1)`, `cat(1)`, `timeout(1)`, `cksum(1)` (optional; used to
+generate ETags)
   - toybox&#x2019;s `tr(1)` is pending but seems to work
 + [busybox](https://www.busybox.net/): `gzip(1)` (optional; required for gzip
   encoding)
@@ -211,3 +212,7 @@ containing `https://github.com/single-right-quote/httpd.execline`
 + `httpd_execline_default_index`: the file to default to if a resource matches
   a directory. defaults to `index.html`
 + `HTTPD_EXECLINE_GZIP`: if set, use `gzip(1)` to compress found resources.
++ `HTTPD_EXECLINE_GENERATE_ETAGS`: if set, use `cksum(1)` to generate `ETag`s
+  for all resources on the fly
++ `HTTPD_EXECLINE_MAX_AGE`: if `HTTPD_EXECLINE_CACHE` is set, this variable
+  controls the max-age directive. defaults to `604800`
\ No newline at end of file
diff --git a/visible-to-httpd/binaries/httpd.execline b/visible-to-httpd/binaries/httpd.execline
index 27ec66f..cf55de1 100755
--- a/visible-to-httpd/binaries/httpd.execline
+++ b/visible-to-httpd/binaries/httpd.execline
@@ -114,6 +114,27 @@ if -X -n -t {
 		s6-echo -n -- identity
 	}
 
+	backtick -D "no-cache" Cache-Control {
+		if { eltest -v HTTPD_EXECLINE_GENERATE_ETAGS }
+			importas -D "604800" -u HTTPD_EXECLINE_MAX_AGE HTTPD_EXECLINE_MAX_AGE
+			s6-echo -n -- ${HTTPD_EXECLINE_MAX_AGE}
+	}
+
+	backtick -D "" optional_etag_line {
+		if { eltest -v HTTPD_EXECLINE_GENERATE_ETAGS }
+			backtick -i -E -n cksum {
+				redirfd -r 0 supported_domains/${resource}
+				cksum
+			}
+			case -N -- ${cksum} {
+				"^([^ ]+) .*$" {
+					importas -i -u actual_cksum 1
+					s6-echo -n -- "Etag: "${actual_cksum}"\r\n"
+				}
+			}
+			s6-echo -n -- ''
+	}
+
 	##### 4.1. determine found resource's Content-Type ###
 	backtick -i -n Content-Type {
 		define Content_Type_override_file configuration/overrides/${resource}/Content-Type
@@ -192,19 +213,23 @@ if -X -n -t {
 	multisubstitute {
 		importas -i -u output_executable output_executable
 		importas -i -u status_code_and_message status_code_and_message
+		importas -i -u Cache-Control Cache-Control
 		importas -i -u Content-Encoding Content-Encoding
 		importas -i -u Content-Length Content-Length
 		importas -i -u Content-Type Content-Type
+		importas -i -u optional_etag_line optional_etag_line
 		importas -i -u Date Date
 		importas -i -u Last-Modified Last-Modified
 		importas -i -u extra_headers extra_headers
 	}
+	if { log.execline line is ${optional_etag_line} }
 	if {
 		s6-echo -n -- "HTTP/1.1 "${status_code_and_message}"\r
 Content-Encoding: "${Content-Encoding}"\r
 Content-Type: "${Content-Type}"\r
 Content-Length: "${Content-Length}"\r
-Last-Modified: "${Last-Modified}"\r
+Cache-Control: "${Cache-Control}"\r
+"${optional_etag_line}"\r\nLast-Modified: "${Last-Modified}"\r
 Date: "${Date}${extra_headers}"
 \r
 "