From 44f31b1f27c2a53cf8a4e053a50c245e379558b0 Mon Sep 17 00:00:00 2001
From: Hsieh Chin Fan <pham@topo.tw>
Date: Wed, 26 Jun 2024 12:18:32 +0800
Subject: Update

---
 snippets/bash_server | 90 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 snippets/dot_example | 27 ++++++++++++++++
 2 files changed, 117 insertions(+)
 create mode 100644 snippets/bash_server
 create mode 100644 snippets/dot_example

(limited to 'snippets')

diff --git a/snippets/bash_server b/snippets/bash_server
new file mode 100644
index 0000000..f008d11
--- /dev/null
+++ b/snippets/bash_server
@@ -0,0 +1,90 @@
+#!/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 request
+  while read line; do
+    echo $line
+    trline=$(echo $line | tr -d '[\r\n]')
+
+    [ -z "$trline" ] && break
+
+    HEADLINE_REGEX='(.*?)\s(.*?)\sHTTP.*?'
+    [[ "$trline" =~ $HEADLINE_REGEX ]] &&
+      REQUEST=$(echo $trline | sed -E "s/$HEADLINE_REGEX/\1 \2/")
+
+    CONTENT_LENGTH_REGEX='Content-Length:\s(.*?)'
+    [[ "$trline" =~ $CONTENT_LENGTH_REGEX ]] &&
+      CONTENT_LENGTH=$(echo $trline | sed -E "s/$CONTENT_LENGTH_REGEX/\1/")
+
+    COOKIE_REGEX='Cookie:\s(.*?)\=(.*?).*?'
+    [[ "$trline" =~ $COOKIE_REGEX ]] &&
+      read COOKIE_NAME COOKIE_VALUE <<< $(echo $trline | sed -E "s/$COOKIE_REGEX/\1 \2/")
+  done
+
+  ## Read 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 to the response handlers
+  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 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
diff --git a/snippets/dot_example b/snippets/dot_example
new file mode 100644
index 0000000..fa95abc
--- /dev/null
+++ b/snippets/dot_example
@@ -0,0 +1,27 @@
+digraph G {
+
+  subgraph cluster_0 {
+    style=filled;
+    color=lightgrey;
+    node [style=filled,color=white];
+    a0 -> a1 -> a2 -> a3;
+    label = "process #1";
+  }
+
+  subgraph cluster_1 {
+    node [style=filled];
+    b0 -> b1 -> b2 -> b3;
+    label = "process #2";
+    color=blue
+  }
+  start -> a0;
+  start -> b0;
+  a1 -> b3;
+  b2 -> a3;
+  a3 -> a0;
+  a3 -> end;
+  b3 -> end;
+
+  start [shape=Mdiamond];
+  end [shape=Msquare];
+}
-- 
cgit v1.2.3-70-g09d2