From: cat æscling <aescling@cat.family>
Date: Tue, 30 Apr 2024 00:11:53 +0000 (-0400)
Subject: Add optional support for gzip'd `Content-Encoding`
X-Git-Url: https://git.xn--scling-oua.cat.family/?a=commitdiff_plain;h=7249172d4d0686cab73585dd54bd3fd6a1c67a9a;p=httpd-execline.git

Add optional support for gzip'd `Content-Encoding`

If the client accepts gzip, and if the server is configured to use it,
gzip(1p) the resource on tranfur. otherwise, just cat(1p)

* Simplify regexp fur testing
	- Revert
* Fix eltest syntax
* Import `output_executable`
* Correct Content-Encoding logic
* Add log lines fur debugging
	- Revert
* Look fur the correct header
* Fix envvar name
* Fix missing sequencing command on logging
* Use input redirection fur output

* Update README
---

diff --git a/README.md b/README.md
index 8abfb16..f330ed0 100644
--- a/README.md
+++ b/README.md
@@ -107,6 +107,8 @@ feasible configuration is to place statically linked dependencies into
 + [toybox](http://www.landley.net/toybox/): `wc(1)`,
 `date(1p)`, `stat(1)`, `cat(1)`, `timeout(1)`
   - toybox&#x2019;s `tr(1)` is pending but seems to work
++ [busybox](https://www.busybox.net/): `gzip(1)` (optional; required for gzip
+  encoding)
 + etc.: presumably, your system already has `chroot(1)`
 
 note that if you build execline and s6-portable-utils with slashpackage
@@ -203,3 +205,9 @@ containing the text `301 moved permanently`; and
 + the file
 `./visible-to-httpd/configuration/overrides/httpd-execline.eerie.garden/index.xhtml/headers/Location`
 containing `https://github.com/single-right-quote/httpd.execline`
+
+### environment variables
+
++ `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.
diff --git a/visible-to-httpd/binaries/http-header-parse.execline b/visible-to-httpd/binaries/http-header-parse.execline
index 9d1a09c..8560e8e 100755
--- a/visible-to-httpd/binaries/http-header-parse.execline
+++ b/visible-to-httpd/binaries/http-header-parse.execline
@@ -94,6 +94,31 @@ case -N -- ${current_line_stripped} {
 			tr A-Z a-z
 		}
 
+		#### special case: content-encoding header
+		#
+		# test that the client accepts a gzip-encoded body, setting the
+		# variable HTTPD_EXECLINE_CLIENT_WANTS_GZIP if they do
+		ifelse {
+			eltest -v HTTPD_EXECLINE_GZIP
+				-a ${header_name} = accept-encoding
+		}
+		{
+			backtick -x HTTPD_EXECLINE_CLIENT_WANTS_GZIP {
+				backtick -E -i -n header_contents_lowercase {
+					pipeline { s6-echo -n -- ${header_contents} }
+					tr A-Z a-z
+				}
+				# TODO: is there a single regexp fur this?
+				eltest ${header_contents_lowercase} =~ "[, \t](x-)?gzip[, \t]"
+					-o ${header_contents_lowercase} =~ "[, \t](x-)?gzip$"
+					-o ${header_contents_lowercase} =~ "^(x-)?gzip[, \t]"
+					-o ${header_contents_lowercase} =~ "^(x-)?gzip$"
+			}
+			${0}
+				${supported_hostname_test}
+				${@}
+		}
+
 		#### special case: host header
 		#
 		# short circuits the program
diff --git a/visible-to-httpd/binaries/httpd.execline b/visible-to-httpd/binaries/httpd.execline
index ace93e0..27ec66f 100755
--- a/visible-to-httpd/binaries/httpd.execline
+++ b/visible-to-httpd/binaries/httpd.execline
@@ -91,6 +91,29 @@ if -X -n -t {
 	}
 
 	#### 4. send response ###
+	backtick -i output_executable {
+		ifelse {
+			eltest -v HTTPD_EXECLINE_GZIP
+				-a -v HTTPD_EXECLINE_CLIENT_WANTS_GZIP
+		}
+		{
+			if { log.execline "info: client wants gzip" }
+			s6-echo -n -- gzip
+		}
+		s6-echo -n -- cat
+	}
+
+	backtick -i -n Content-Encoding {
+		ifelse {
+			eltest -v HTTPD_EXECLINE_GZIP
+				-a -v HTTPD_EXECLINE_CLIENT_WANTS_GZIP
+		 }
+		 {
+			s6-echo -n -- gzip
+		 }
+		s6-echo -n -- identity
+	}
+
 	##### 4.1. determine found resource's Content-Type ###
 	backtick -i -n Content-Type {
 		define Content_Type_override_file configuration/overrides/${resource}/Content-Type
@@ -167,7 +190,9 @@ if -X -n -t {
 
 	##### 4.3. send the response ###
 	multisubstitute {
+		importas -i -u output_executable output_executable
 		importas -i -u status_code_and_message status_code_and_message
+		importas -i -u Content-Encoding Content-Encoding
 		importas -i -u Content-Length Content-Length
 		importas -i -u Content-Type Content-Type
 		importas -i -u Date Date
@@ -176,6 +201,7 @@ if -X -n -t {
 	}
 	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: "${Last-Modified}"\r
@@ -185,7 +211,8 @@ Date: "${Date}${extra_headers}"
 	}
 	foreground {
 		if -t { eltest \${method} = GET }
-			cat supported_domains/${resource}
+			redirfd -r 0 supported_domains/${resource}
+			${output_executable}
 	}
 	# hack: write(3p) does not guarantee that all the
 	# content actually gets written before this process