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A complete yet simple Web server (with login & logout system) written in Shell Script
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| #!/bin/bash | |
| ## Create the response FIFO | |
| rm -f response | |
| mkfifo response | |
| function handle_GET_home() { | |
| RESPONSE=$(cat home.html | \ | |
| sed "s/{{$COOKIE_NAME}}/$COOKIE_VALUE/") | |
| } | |
| function handle_GET_login() { | |
| RESPONSE=$(cat login.html) | |
| } | |
| function handle_POST_login() { | |
| RESPONSE=$(cat post-login.http | \ | |
| sed "s/{{cookie_name}}/$INPUT_NAME/" | \ | |
| sed "s/{{cookie_value}}/$INPUT_VALUE/") | |
| } | |
| function handle_POST_logout() { | |
| RESPONSE=$(cat post-logout.http | \ | |
| sed "s/{{cookie_name}}/$COOKIE_NAME/" | \ | |
| sed "s/{{cookie_value}}/$COOKIE_VALUE/") | |
| } | |
| function handle_not_found() { | |
| RESPONSE=$(cat 404.html) | |
| } | |
| function handleRequest() { | |
| ## Read the HTTP request until \r\n | |
| while read line; do | |
| echo $line | |
| trline=$(echo $line | tr -d '[\r\n]') ## Removes the \r\n from the EOL | |
| ## Breaks the loop when line is empty | |
| [ -z "$trline" ] && break | |
| ## Parses the headline | |
| ## e.g GET /login HTTP/1.1 -> GET /login | |
| HEADLINE_REGEX='(.*?)\s(.*?)\sHTTP.*?' | |
| [[ "$trline" =~ $HEADLINE_REGEX ]] && | |
| REQUEST=$(echo $trline | sed -E "s/$HEADLINE_REGEX/\1 \2/") | |
| ## Parses the Content-Length header | |
| ## e.g Content-Length: 42 -> 42 | |
| CONTENT_LENGTH_REGEX='Content-Length:\s(.*?)' | |
| [[ "$trline" =~ $CONTENT_LENGTH_REGEX ]] && | |
| CONTENT_LENGTH=$(echo $trline | sed -E "s/$CONTENT_LENGTH_REGEX/\1/") | |
| ## Parses the Cookie header | |
| ## e.g Cookie: name=John -> name John | |
| COOKIE_REGEX='Cookie:\s(.*?)\=(.*?).*?' | |
| [[ "$trline" =~ $COOKIE_REGEX ]] && | |
| read COOKIE_NAME COOKIE_VALUE <<< $(echo $trline | sed -E "s/$COOKIE_REGEX/\1 \2/") | |
| done | |
| ## Read the remaining HTTP request body | |
| if [ ! -z "$CONTENT_LENGTH" ]; then | |
| BODY_REGEX='(.*?)=(.*?)' | |
| while read -n$CONTENT_LENGTH -t1 line; do | |
| echo $line | |
| trline=`echo $line | tr -d '[\r\n]'` | |
| [ -z "$trline" ] && break | |
| read INPUT_NAME INPUT_VALUE <<< $(echo $trline | sed -E "s/$BODY_REGEX/\1 \2/") | |
| done | |
| fi | |
| ## Route request to the response handler | |
| case "$REQUEST" in | |
| "GET /login") handle_GET_login ;; | |
| "GET /") handle_GET_home ;; | |
| "POST /login") handle_POST_login ;; | |
| "POST /logout") handle_POST_logout ;; | |
| *) handle_not_found ;; | |
| esac | |
| echo -e "$RESPONSE" > response | |
| } | |
| echo 'Listening on 3000...' | |
| ## Keep the server running forever | |
| while true; do | |
| ## 1. wait for FIFO | |
| ## 2. creates a socket and listens to the port 3000 | |
| ## 3. as soon as a request message arrives to the socket, pipes it to the handleRequest function | |
| ## 4. the handleRequest function processes the request message and routes it to the response handler, which writes to the FIFO | |
| ## 5. as soon as the FIFO receives a message, it's sent to the socket | |
| ## 6. closes the connection (`-N`), closes the socket and repeat the loop | |
| cat response | nc -lN 3000 | handleRequest | |
| done |
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| HTTP/1.1 404 NotFound | |
| Content-Type: text/html | |
| <h1>Sorry, not found</h1> |
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| HTTP/1.1 200 | |
| Content-Type: text/html | |
| <html> | |
| <head> | |
| <style> | |
| section { | |
| display: inline-block; | |
| margin-left: 40%; | |
| margin-top: 10%; | |
| } | |
| section p { | |
| color: black; | |
| } | |
| </style> | |
| </head> | |
| <body> | |
| <section> | |
| <p>Hello, {{name}}</p> | |
| <form method="POST" action="/logout"> | |
| <input type="submit" value="Logout" /> | |
| </form> | |
| <a href="javascript:void(0)">Blue theme</a> | |
| </section> | |
| </body> | |
| <footer> | |
| <script> | |
| let themeElem = document.querySelector('a'); | |
| let nameElem = document.querySelector('section > p'); | |
| themeElem.addEventListener('click', function(evt) { | |
| if (nameElem.style.color == 'blue') { | |
| nameElem.style.color = 'black'; | |
| themeElem.text = 'Blue theme'; | |
| } else { | |
| nameElem.style.color = 'blue'; | |
| themeElem.text = 'Black theme'; | |
| } | |
| }) | |
| </script> | |
| </footer> | |
| </html> |
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| HTTP/1.1 200 | |
| Content-Type: text/html | |
| <html> | |
| <head> | |
| <style> | |
| section { | |
| display: inline-block; | |
| margin-left: 40%; | |
| margin-top: 10%; | |
| } | |
| input[name="name"] { | |
| height: 30px; | |
| margin-top: 20%; | |
| border: 1px solid #999; | |
| border-radius: 4px; | |
| } | |
| </style> | |
| </head> | |
| <body> | |
| <section> | |
| <form method="POST" action="/login"> | |
| <input type="text" name="name" /> | |
| <input type="submit" value="Login" /> | |
| </form> | |
| </section> | |
| </body> | |
| </html> |
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| HTTP/1.1 301 | |
| Location: http://localhost:3000/ | |
| Set-Cookie: {{cookie_name}}={{cookie_value}}; path=/; HttpOnly |
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| HTTP/1.1 301 | |
| Location: http://localhost:3000/login | |
| Set-Cookie: {{cookie_name}}={{cookie_value}}; path=/; HttpOnly; Expires=Thu, 01 Jan 1970 00:00:00 GMT |
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crlf tips!
nc -Cwill automatically translate lf to crlf.read -d $'\r\n'to simplify header parsing.