An HTTP server in BASH

2023-03-25 00:58:38 +03:00 · 2023-03-25 00:58:38 +03:00 · 97e32564b3
commit 97e32564b3
1 changed files with 112 additions and 0 deletions
--- a/server.sh
+++ b/server.sh
@ -0,0 +1,112 @@
+#!/bin/bash
+
+set -e
+
+ADDR=127.0.0.1
+PORT=1234
+ROOT="$(realpath "${1:-$PWD}")"
+
+LF=$'\n'
+
+tmpdir="$(mktemp -d)"
+trap 'rm -r "$tmpdir"' EXIT
+trap 'exit' INT
+
+stdhead() {
+	code="$1"
+	head="$2"
+	echo "HTTP/1.0 $code $head"
+	echo "Content-Type: text/plain"
+	echo "Connection: close"
+}
+
+error() {
+	code="$1"
+	head="$2"
+	message="$3"
+	echo "HTTP/1.0 $code $head"
+	echo "Content-Type: text/plain"
+	echo "Connection: close"
+	echo
+	echo "$code $head"
+	echo
+	echo "$message"
+	exit
+}
+
+handle() {
+	connection_id="$1"
+	response_pipe="$tmpdir/response-$connection_id.pipe"
+	event_pipe="$tmpdir/event-$connection_id.pipe"
+	mkfifo -m 0600 "$response_pipe" "$event_pipe"
+	gnetcat -c -l "$ADDR" -p "$PORT" < "$response_pipe" | sed -E -u 's/\r$//' | (
+		read method url version || {
+			echo "Connection broken" > "$event_pipe"
+			exit
+		}
+		cat >& /dev/null & # read but ignore headers and whatever else
+		echo "$method $url" > "$event_pipe"
+		if ! [ "$version" = "HTTP/1.0" -o "$version" = "HTTP/1.1" ]; then
+			error 505 'HTTP Version Not Supported' "Version $version is not supported.${LF}Only 1.0 is really supported."
+		fi
+		if ! [ "$method" = "GET" ]; then
+			error 501 'Not Implemented' "Method $method is not implemented.${LF}Only GET is supported."
+		fi
+		if ! echo "$url" | grep -q '^/'; then
+			error 400 'Bad Request' "URL must be host-relative"
+		fi
+		if echo "$url" | grep -q '/\.'; then
+			error 403 'Forbidden' "Dot-files are forbidden"
+		fi
+		target="$ROOT$url"
+		name=$(basename "$url")
+		if [ -f "$target" ]; then
+			echo "HTTP/1.0 200 OK"
+			echo "Connection: close"
+			echo
+			cat "$target"
+			exit
+		fi
+		if [ -d "$target" ]; then
+			if ! echo "$url" | grep -q '/$'; then
+				echo "HTTP/1.0 307 Temporary Redirect"
+				echo "Connection: close"
+				echo "Location: $url/"
+				exit
+			fi
+			ls "$target" 2>/dev/null | {
+				echo "HTTP/1.0 200 OK"
+				echo "Content-Type: text/html; charset=utf-8"
+				echo "Connection: close"
+				echo
+				echo "<!DOCTYPE html>"
+				echo "<title>Directory listing for $url</title>"
+				echo "<h1>$name</h1>"
+				echo "<p><a href=\"..\">up</a>"
+				echo "<ul>"
+				while read entry; do
+					if [ -d "$target$entry" ]; then
+						entry="$entry/";
+					elif [ -f "$target$entry" ]; then
+						true
+					else
+						continue
+					fi
+					echo "<li><a href=\"$entry\">$entry</a>"
+				done
+				echo "</ul>"
+			} || error 403 'Forbidden' "Permission denied for $url"
+			exit
+		fi
+		error 404 'Not Found' "Requested file $url is not found"
+	) > "$response_pipe" &
+	rm "$response_pipe"
+	cat "$event_pipe"
+	rm "$event_pipe"
+}
+
+echo "Serving $ROOT"
+
+for((i=0;;i++)); do
+	handle $i
+done