dandelion/main.go

// TODO
// 1. Convery network messages to flatbuffers so we don't need to parse JSON in Go.
// Use binary WS messages. Generate for Go and JS and use that everywhere. We can
// also use this for WebRTC messages.
// 2. Keep a list of all nodes that bootstrapped in the last N minutes.
// 3. When a node bootstraps, send it a random list of the nodes we know about.
// 4. Do the signalling to connect those nodes.
// 5. Each node will know about N other nodes. To find get the data for a feed,
// a node will need to find another node that has that data. To do that we'll need to
// implement a search message that is sent to all currently connected nodes, and they
// forward to all their nodes, passing back the address of the node that has the data.
// Once we find it, we'll do the signalling to connect to it via Web RTC via our existing connected nodes.
// -----
// Feeds. People can curate feeds which can be any combination of hashtags, serch terms and users.
// Invite-only communities. Just block everyone else even if they post to it.
// Limit to friends and friends of friends

// MVP
// You connect to the person you want to get the post from to get the post
// they give you the post
// If they're offline, you can't get their updates.
// This is very stupid, but it's simplest thing.
// The bootstrap server connects you to them directly via WebRTC
// This will make the thing actually function as a little toy for people to play with.
// This will let us test whether background tabs respond to webrtc requests.

// THEN
// Need to have identity sorted out
// When you read someone's posts, you also cache them locally
// cache priority goes mutuals->people you follow->people who you folllow, follow, so you're always
// caching your mutual's posts
// Posts are samll, so caching per-post will work fine.
// Then the process is for the bootstrap server to remember all nodes and what they're caching
// This will allow distributed content delivery but put a memory and bendwidth strain on the
// bootstrap sever. Look into Web Transport for the raspberry pi overhead. Could buy a few more RPIs
// and make a little cluster

// ✅ Domain name so we can get a certificate and serve HTTPS / HTTP3

// Think about compiling Typescript on initial access and caching the JS in a service worker
// so you don't need a build system to change things.
// Think about self-hosting the client so the system can be completely self-hosted

package main

import (
	"encoding/json"
	"fmt"
	"io"
	"log"
	"net/http"
	"os"
	"path/filepath"
	"strconv"
	"strings"

	"github.com/andybalholm/brotli"
	"github.com/gorilla/websocket"
)

var upgrader = websocket.Upgrader{
	CheckOrigin: func(r *http.Request) bool {
		origin := r.Header.Get("Origin")
		return origin == "https://ddlion.net"
	},
}

func websocketCloseHandler(code int, text string) error {
	log.Print("Client closed websocket.")
	return nil
}

type Message struct {
	Type string `json:"type"`
}

type MessageHandler func([]byte, *websocket.Conn) error

var messageHandlers = make(map[string]MessageHandler)

func registerHandler(messageType string, handler MessageHandler) {
	messageHandlers[messageType] = handler
}

func dispatchMessage(message []byte, conn *websocket.Conn) error {
	var msg Message
	if err := json.Unmarshal(message, &msg); err != nil {
		return err
	}

	handler, ok := messageHandlers[msg.Type]
	if !ok {
		log.Printf("No handler registered for message type: %s", msg.Type)
		return nil
	}

	return handler(message, conn)
}

func handleWebSocket(w http.ResponseWriter, r *http.Request) {
	log.Println("Websocket connection!", r.RemoteAddr)

	conn, err := upgrader.Upgrade(w, r, nil)
	if err != nil {
		log.Println("Upgrade error:", err)
		return
	}
	defer conn.Close()

	conn.SetCloseHandler(websocketCloseHandler)

	for {
		_, message, err := conn.ReadMessage()
		if err != nil {
			log.Println("ReadMessage error:", err)
			break
		}
		log.Printf("recv: %s", message)

		if err := dispatchMessage(message, conn); err != nil {
			log.Printf("Error dispatching message: %v", err)
		}
	}
}

// Example handlers
func handlePing(message []byte, conn *websocket.Conn) error {
	var pingMsg struct {
		Type   string `json:"type"`
		PeerID string `json:"peer_id"`
	}
	if err := json.Unmarshal(message, &pingMsg); err != nil {
		return err
	}
	log.Printf("Received ping from peer: %s", pingMsg.PeerID)
	return nil
}

type PeerSet map[string]struct{}

var userPeers = make(map[string]PeerSet)
var peerConnections = make(map[string]*websocket.Conn)

func handleHello(message []byte, conn *websocket.Conn) error {

	var m struct {
		Type   string `json:"type"`
		UserID string `json:"user_id"`
		PeerID string `json:"peer_id"`
	}

	if err := json.Unmarshal(message, &m); err != nil {
		return err
	}

	if userPeers[m.UserID] == nil {
		userPeers[m.UserID] = make(PeerSet)
	}

	userPeers[m.UserID][m.PeerID] = struct{}{}
	peerConnections[m.PeerID] = conn

	jsonData, _ := json.MarshalIndent(userPeers, "", "  ")
	fmt.Println(string(jsonData), peerConnections)

	log.Printf("Received connect from peer: %s, user:%s", m.PeerID, m.UserID)
	return nil
}

// LoggingHandler logs requests and delegates them to the underlying handler.
// type LoggingHandler struct {
// 	handler http.Handler
// }

// func (lh *LoggingHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
// 	log.Printf("Serving file: %s", r.URL.Path)
// 	lh.handler.ServeHTTP(w, r)
// }

// BrotliResponseWriter wraps http.ResponseWriter to support Brotli compression
type brotliResponseWriter struct {
	http.ResponseWriter
	Writer io.Writer
}

func (w *brotliResponseWriter) Write(b []byte) (int, error) {
	return w.Writer.Write(b)
}

// noDirListing wraps an http.FileServer handler to prevent directory listings
func noDirListing(h http.Handler, root string) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {

		// Serve index.html when root is requested
		if r.URL.Path == "/" {
			http.ServeFile(w, r, filepath.Join(root, "index.html"))
			return
		}

		path := filepath.Join(root, r.URL.Path)
		info, err := os.Stat(path)
		if err != nil || info.IsDir() {
			log.Printf("404 File not found/dir serving: %s to ip %s, useragent %s", r.URL.Path, r.RemoteAddr, r.UserAgent())
			http.NotFound(w, r)
			return
		}

		log.Printf("Serving: %s to ip %s, useragent %s", r.URL.Path, r.RemoteAddr, r.UserAgent())

		// Check if client supports Brotli encoding
		if strings.Contains(r.Header.Get("Accept-Encoding"), "br") {
			w.Header().Set("Content-Encoding", "br")
			w.Header().Del("Content-Length") // Cannot know content length with compressed data

			// Wrap the ResponseWriter with Brotli writer
			brWriter := brotli.NewWriter(w)
			defer brWriter.Close()

			// Create a ResponseWriter that writes to brWriter
			bw := &brotliResponseWriter{
				ResponseWriter: w,
				Writer:         brWriter,
			}

			// Serve the file using http.ServeFile
			http.ServeFile(bw, r, path)
			return
		}

		h.ServeHTTP(w, r)
	}
}

func main() {
	dir := "./"
	port := 6789

	addr := ":" + strconv.Itoa(port)
	log.Printf("Starting server on %s", addr)

	// Register handlers
	registerHandler("hello", handleHello)
	registerHandler("ping", handlePing)

	// Set up file server and WebSocket endpoint
	fs := http.FileServer(http.Dir(dir))
	// loggingHandler := &LoggingHandler{handler: fs}
	// http.Handle("/", loggingHandler)
	http.Handle("/", noDirListing(fs, dir))

	http.HandleFunc("/ws", handleWebSocket)

	// Configure and start the HTTP server
	server := &http.Server{
		Addr:    addr,
		Handler: nil, // nil uses the default ServeMux, which we configured above
	}

	log.Printf("Server is configured and serving on port %d...", port)
	log.Fatal(server.ListenAndServeTLS("/etc/letsencrypt/live/ddlion.net/fullchain.pem", "/etc/letsencrypt/live/ddlion.net/privkey.pem"))
}