redbean demo with an xterm.js powershell/bash

tool/net/demo/hitcounter.lua

@@ -29,7 +29,9 @@ t = DecodeJson(s)
 Unlock()
 
 for k,v in pairs(t) do
+    if type(v) == 'number' then
         Write('<dt>%s<dd>%d\n' % {EscapeHtml(k), v})
+    end
 end
 
 Write('</dl>')

tool/net/demo/xterm.lua

@@ -0,0 +1,351 @@
+--[[
+XTERM Proof of concept
+This shows how redbean can be used to launch a powershell (windows)
+or bash (other OS) xterm session
+
+The demo loads an HTML page that loads https://xtermjs.org/ and
+defines a unique xtermid. An SSE EventSource is then defined which
+starts a SSEServer that takes care of starting the shell command
+As SSE is mostly a Server=>Client channel, the keyboard events/commands
+are sent via side-channel POST requests
+
+SSE Events :
+ - noname : stdout from the shell, encodeURIComponent encoded
+ - prompt : a way for the server to write a prompt on the client
+            (different shells can have different interactive behavior)
+ - exit   : a way to ask the client to stop its EventSource.
+            this will trigger a POST.exit to close the SSEServer
+
+POST Events :
+ - command : a command that was typed in the xterm.js
+ - exit : a way to ask the SSE server to shut down
+ - ping : a way to tell the server that the xterm.js session is still
+          alive. A vanished browser session will lead to the closing of
+	  the SSE server
+
+In order to share and reconcile the POSTed Events between the different
+processes (POST processes and SSE server), a json shm is used where
+the xtermid is used as a key to store the queue of commands.
+
+Notes:
+- security: Use at your own risk as it opens a shell on the server and
+  makes it available on the listening ip/ports
+- limitations: the demo does not use a real pty so there are certainly
+  a lot of limitations and it is not made to be keyboard spammed !
+- special chars are currently not handled. Things like CTRL-C to stop 
+  a command is not implemented
+- CTRL-V is not implemented
+- history is not implemented
+- tab completion is not implemented
+- some mechanisms have been put in place to try to garbage collect the
+  shm (tab closing, sending the 'exit' command, .. but there are probably
+  a lot of other corner cases that need to be tested and handled
+- the session state management and supervision could certainly be improved
+
+]]--
+
+ipcat = CategorizeIp(GetServerAddr())
+if ipcat ~= 'PRIVATE' and ipcat ~= 'LOOPBACK' then
+    Write('As a first level of security, the xterm/shell demo is only available on IPs categorized as private or loopback')
+    Write('The current category is ' .. ipcat)
+    return
+end
+
+
+
+
+function HTMLPage() 
+
+Write('<link rel="stylesheet" href="https://xtermjs.org/css/xterm.css" />\n')
+Write('<script src="https://xtermjs.org/js/xterm.js"></script>\n')
+Write('<script src="https://xtermjs.org/js/addon-webgl.js"></script>\n')
+Write('<h1>Redbean xterm.js/shell demo</h1>\n')
+Write('<p>you should be able to interact with powershell on windows or bash on other OSs</p>')
+Write('<span>Try usual commands like:</span>')
+Write('<ul>')
+Write('<li>ls</li>')
+Write('<li>whoami</li>')
+Write('<li>ps</li>')
+Write('<li>or any command you dare try ;-)</li>')
+
+Write('</ul>')
+Write('<div class="demo"><div class="inner"></div></div>\n')
+Write('<script>var xtermid = "'.. UuidV4() ..'"</script>\n')
+
+script = [[
+var baseTheme = {
+    foreground: '#F8F8F8',
+    background: '#2D2E2C',
+    selection: '#5DA5D533',
+    black: '#1E1E1D',
+    brightBlack: '#262625',
+    red: '#CE5C5C',
+    brightRed: '#FF7272',
+    green: '#5BCC5B',
+    brightGreen: '#72FF72',
+    yellow: '#CCCC5B',
+    brightYellow: '#FFFF72',
+    blue: '#5D5DD3',
+    brightBlue: '#7279FF',
+    magenta: '#BC5ED1',
+    brightMagenta: '#E572FF',
+    cyan: '#5DA5D5',
+    brightCyan: '#72F0FF',
+    white: '#F8F8F8',
+    brightWhite: '#FFFFFF'
+  };
+var isBaseTheme = true;
+var term = new window.Terminal({
+    fontFamily: '"Cascadia Code", Menlo, monospace',
+    theme: baseTheme,
+    cursorBlink: true,
+    allowProposedApi: true,
+    cols: 150,
+    convertEol: true
+  });
+term.open(document.querySelector('.demo .inner'));
+var isWebglEnabled = false;
+try {
+    const webgl = new window.WebglAddon.WebglAddon();
+    term.loadAddon(webgl);
+    isWebglEnabled = true;
+} catch (e) {
+    console.warn('WebGL addon threw an exception during load', e);
+}
+
+
+prompt_str = 'redbean shell \ud83e\udd9e  > '
+function prompt(term, str) {
+    command = '';
+    prompt_str = str || prompt_str;
+    term.write(prompt_str);
+  }
+
+var command = '';
+var running = true;
+
+function sendCommand(type, data) {
+    return fetch('xterm.lua?xtermid='+xtermid, {
+        method: "POST",
+        body: JSON.stringify({ type: type, data: data })
+    });
+}
+
+function runCommand(term, text) {
+    const command = text.trim();
+    if (command.length > 0) {
+        term.writeln('');
+        sendCommand("command", command);
+    } else {
+        term.write("\r\n");
+        prompt(term);
+    }
+}
+  
+term.onData(e => {
+    if (!running) return;
+    switch (e) {
+        case '\u0003': // Ctrl+C
+            term.write('^C');
+            prompt(term);
+            break;
+        case '\r': // Enter
+            runCommand(term, command);
+            command = '';
+            break;
+        case '\u007F': // Backspace (DEL)
+            // Do not delete the prompt
+            if (term._core.buffer.x > 2) {
+                term.write('\b \b');
+                if (command.length > 0) {
+                    command = command.substr(0, command.length - 1);
+                }
+            }
+            break;
+        default: // Print all other characters for demo
+            if (e >= String.fromCharCode(0x20) && e <= String.fromCharCode(0x7E) || e >= '\u00a0') {
+              command += e;
+              term.write(e);
+            }
+    }
+});
+
+
+
+var evtSource = new EventSource('xterm.lua?xtermid='+xtermid+'&sse');
+evtSource.onmessage = (event) => {
+    term.write(decodeURIComponent(event.data))
+}; 
+evtSource.addEventListener("prompt", (event) => {
+    prompt(term, decodeURIComponent(event.data))
+});
+evtSource.addEventListener("exit", (event) => {
+    console.log("exit", event.data);
+    evtSource.close();
+    running = false;
+    term.write('..TERMINATED..');
+    sendCommand('exit', null);
+});
+
+
+function ping() {
+    if (running) {
+        sendCommand('ping', null);
+    }
+}
+
+// we ping the SSE server to avoid a dangling a SSE process on the server
+window.addEventListener('load', function () {
+  var fetchInterval = 2000;
+  setInterval(ping, fetchInterval);
+});
+
+]]
+
+Write('<script>'..script..'</script><body>')
+
+end
+
+-- SSE Events needs yielding to be sent as event-stream
+local function streamWrap(func)
+  return function(...) return coroutine.yield(func(...)) or true end
+end
+local function writeEvent(event, data)
+    if event then Write("event: " .. event .. "\n") end
+    if data then Write("data: " .. EscapeParam(data) .. "\n") end
+    Write("\n")
+end
+local streamEvent = streamWrap(writeEvent)
+
+function SSEServer()
+    xtermid = GetParam('xtermid')
+    if GetHostOs() == 'WINDOWS' then
+        cmd = { 'pwsh.exe', "-Interactive", "-Command", "-" }
+        eol = '\r\n'
+    else
+        cmd = { '/bin/bash' }
+        eol = '\n'
+    end
+    cmd[1] = assert(unix.commandv(cmd[1]))
+
+    readerIn, writerIn = assert(unix.pipe(unix.O_CLOEXEC))
+    readerOut, writerOut = assert(unix.pipe(unix.O_CLOEXEC))
+    child = assert(unix.fork())
+    
+    if child == 0 then
+        unix.close(0)
+        unix.dup(readerIn)
+        unix.close(1)
+        unix.dup(writerOut)
+        unix.close(2)
+        unix.dup(writerOut)
+        unix.close(writerIn)
+        unix.close(readerOut)
+        unix.execve(cmd[1], cmd)
+        unix.exit(127)
+    else
+        SetHeader('Content-Type', 'text/event-stream')
+        SetHeader('Connection','Close')
+        unix.close(readerIn)
+        unix.close(writerOut)
+
+        pollfds = {}
+        pollfds[readerOut] = unix.POLLIN
+        polling = true
+        promptblock = GetTime()
+        needprompt = true
+        lastping = GetTime()
+  
+        while polling do
+            evs, errno = unix.poll(pollfds, 100)
+            if not evs then
+              break
+            end
+
+            hasStdout = false
+            for fd,revents in pairs(evs) do
+                if fd == readerOut then
+                    hasStdout =true
+                    data, errno = unix.read(fd)
+                    if data ~= '' then
+                        streamEvent(nil, data)
+                        promptblock = GetTime() + 0.1
+                    end
+                end
+            end
+            command = nextCommand(xtermid)
+            if command then lastping = GetTime() end
+            if command and command.type == "command" then
+                if command.data == 'exit' then
+                    -- ask browser to close its SSE EventSource
+                    streamEvent('exit', '')
+                end
+                unix.write(writerIn, command.data .. eol)
+                promptblock = GetTime() + 1
+                needprompt = true
+            end
+            if (command and command.type == "exit") or lastping < GetTime() - 5 then
+                polling = false
+            end
+            if needprompt and not hasStdout and GetTime() > promptblock then
+                streamEvent('prompt', 'redbean shell '..utf8.char(129438)..'  > ')
+                needprompt = false
+            end
+        end
+        unix.close(readerOut)
+        unix.close(writerIn)
+        deleteSession(xtermid)
+        unix.wait(-1)
+        Log(kLogWarn, 'xterm SSE server '..xtermid.. 'has been closed')
+        return
+    end
+end
+
+function registerCommand(xtermid)
+    posted = GetPayload()
+    local s, t, k
+    Lock()
+    s = shm:read(SHM_JSON)
+    if s == '' then s = '{}' end
+    t = DecodeJson(s)
+    k = xtermid
+    if not t[k] then t[k] = {} end
+    table.insert(t[k], 1, DecodeJson(posted))
+    shm:write(SHM_JSON, EncodeJson(t))
+    Unlock()
+end
+function nextCommand(xtermid)
+    local s, t, k
+    Lock()
+    s = shm:read(SHM_JSON)
+    if s == '' then s = '{}' end
+    t = DecodeJson(s)
+    k = xtermid
+    if not t[k] then t[k] = {} end
+    command = table.remove(t[k])
+    shm:write(SHM_JSON, EncodeJson(t))
+    Unlock()
+    return command
+end
+function deleteSession(xtermid)
+    local s, t, k
+    Lock()
+    s = shm:read(SHM_JSON)
+    if s == '' then s = '{}' end
+    t = DecodeJson(s)
+    k = xtermid
+    t[k] = nil
+    shm:write(SHM_JSON, EncodeJson(t))
+    Unlock()
+end
+
+
+if HasParam('sse') then
+    SSEServer()
+elseif GetMethod() == "POST" then
+    registerCommand(GetParam('xtermid'))
+else
+    HTMLPage()
+end
+
+