| 1 | package main |
| 2 | |
| 3 | import ( |
| 4 | "context" |
| 5 | "encoding/json" |
| 6 | "log" |
| 7 | "net/http" |
| 8 | "time" |
| 9 | |
| 10 | "github.com/coder/websocket" |
| 11 | ) |
| 12 | |
| 13 | // maxBlobBytes caps a single ciphertext payload. Plenty for a chat line plus |
| 14 | // AES-GCM overhead; keeps a misbehaving client from flooding the DB. |
| 15 | const maxBlobBytes = 64 * 1024 |
| 16 | |
| 17 | // client is one connected browser. send is the per-client outbound queue; the |
| 18 | // hub never blocks on a slow client — it drops them instead. userID lets the hub |
| 19 | // route a thread's traffic only to that thread's members. |
| 20 | type client struct { |
| 21 | userID string |
| 22 | send chan []byte |
| 23 | } |
| 24 | |
| 25 | // outbound is one fan-out: data delivered to every connected client whose user |
| 26 | // is in members (nil members = everyone, unused now that all traffic is |
| 27 | // thread-scoped). |
| 28 | type outbound struct { |
| 29 | members map[string]bool |
| 30 | data []byte |
| 31 | } |
| 32 | |
| 33 | // Hub fans out ciphertext blobs to connected clients. It only ever handles |
| 34 | // opaque bytes — it cannot read message contents — and routes each blob to the |
| 35 | // thread's members only. |
| 36 | type Hub struct { |
| 37 | register chan *client |
| 38 | unregister chan *client |
| 39 | broadcast chan outbound |
| 40 | control chan func() // runs fn on the hub goroutine (safe map access) |
| 41 | clients map[*client]bool |
| 42 | } |
| 43 | |
| 44 | func newHub() *Hub { |
| 45 | return &Hub{ |
| 46 | register: make(chan *client), |
| 47 | unregister: make(chan *client), |
| 48 | broadcast: make(chan outbound, 256), |
| 49 | control: make(chan func()), |
| 50 | clients: make(map[*client]bool), |
| 51 | } |
| 52 | } |
| 53 | |
| 54 | func (h *Hub) run() { |
| 55 | for { |
| 56 | select { |
| 57 | case fn := <-h.control: |
| 58 | fn() |
| 59 | case c := <-h.register: |
| 60 | h.clients[c] = true |
| 61 | case c := <-h.unregister: |
| 62 | if h.clients[c] { |
| 63 | delete(h.clients, c) |
| 64 | close(c.send) |
| 65 | } |
| 66 | case o := <-h.broadcast: |
| 67 | for c := range h.clients { |
| 68 | if o.members != nil && !o.members[c.userID] { |
| 69 | continue // not a member of this thread |
| 70 | } |
| 71 | select { |
| 72 | case c.send <- o.data: |
| 73 | default: |
| 74 | // Backed-up client: drop it. Its read loop will clean up. |
| 75 | delete(h.clients, c) |
| 76 | close(c.send) |
| 77 | } |
| 78 | } |
| 79 | } |
| 80 | } |
| 81 | } |
| 82 | |
| 83 | // shutdown closes every connected client so their browsers reconnect — to the |
| 84 | // new process, after a zero-downtime deploy (see docs/instance-router.md). It |
| 85 | // runs the close on the hub goroutine so it can't race broadcast/register. The |
| 86 | // closed send ends each client's writer, which closes the socket; the client's |
| 87 | // read loop then unregisters (a no-op, already removed). |
| 88 | func (h *Hub) shutdown() { |
| 89 | done := make(chan struct{}) |
| 90 | h.control <- func() { |
| 91 | for c := range h.clients { |
| 92 | delete(h.clients, c) |
| 93 | close(c.send) |
| 94 | } |
| 95 | close(done) |
| 96 | } |
| 97 | <-done |
| 98 | } |
| 99 | |
| 100 | // broadcastToThread fans data out to the members of threadID only. |
| 101 | func (s *Server) broadcastToThread(threadID string, data []byte) { |
| 102 | members, err := s.db.memberUserIDs(threadID) |
| 103 | if err != nil { |
| 104 | log.Println("broadcast: members:", err) |
| 105 | return |
| 106 | } |
| 107 | set := make(map[string]bool, len(members)) |
| 108 | for _, u := range members { |
| 109 | set[u] = true |
| 110 | } |
| 111 | s.hub.broadcast <- outbound{members: set, data: data} |
| 112 | } |
| 113 | |
| 114 | type wsIn struct { |
| 115 | Type string `json:"type"` |
| 116 | ThreadID string `json:"thread_id"` |
| 117 | Blob string `json:"blob"` |
| 118 | MessageID int64 `json:"message_id"` |
| 119 | Emoji string `json:"emoji"` |
| 120 | // BlobIDs are the attachment blob ids a deleted message referenced. The server |
| 121 | // can't read them from the (encrypted) message body, so the client — which can |
| 122 | // — reports them on delete, and the server GCs those blobs scoped to the thread |
| 123 | // (a client can only drop its own thread's blobs). See the "delete" case. |
| 124 | BlobIDs []string `json:"blob_ids,omitempty"` |
| 125 | // Ephemeral asks for relay-only delivery: fan the blob out to the thread's |
| 126 | // members without storing or pushing it (presence-style traffic — typing, |
| 127 | // live cursors). The flag lives on the envelope, not the ciphertext, so the |
| 128 | // server can honour it while staying blind to the content. |
| 129 | Ephemeral bool `json:"ephemeral,omitempty"` |
| 130 | } |
| 131 | |
| 132 | type wsOut struct { |
| 133 | Type string `json:"type"` |
| 134 | ThreadID string `json:"thread_id,omitempty"` |
| 135 | ID int64 `json:"id"` |
| 136 | CreatedAt int64 `json:"created_at,omitempty"` |
| 137 | Blob string `json:"blob"` |
| 138 | EditedAt int64 `json:"edited_at,omitempty"` |
| 139 | Ephemeral bool `json:"ephemeral,omitempty"` |
| 140 | } |
| 141 | |
| 142 | // editWindow is how long after sending a message its author may still edit it. |
| 143 | // Enforced server-side against the message's created_at (see editMessage). |
| 144 | const editWindow = 15 * time.Minute |
| 145 | |
| 146 | // activeWindow: a device counts as "active" (open + focused) if it signalled within |
| 147 | // this window. New messages skip push to a person active on ANY of their devices, so |
| 148 | // a chat you're reading on one device doesn't also notify your others. |
| 149 | const activeWindow = 45 * time.Second |
| 150 | |
| 151 | func (s *Server) markActive(token string) { |
| 152 | now := time.Now().Unix() |
| 153 | s.active.Store(token, now) |
| 154 | // Roll the signal up to the owner so suppression is per-person, not per-device. |
| 155 | if uid, ok := s.db.deviceTokenUser(token); ok && uid != "" { |
| 156 | s.activeUsers.Store(uid, now) |
| 157 | // Fresh activity may flip an idle-away member back online (presence.go); |
| 158 | // a pinned-away one stays away — presenceChanged resolves that. |
| 159 | s.presenceChanged(uid) |
| 160 | } |
| 161 | } |
| 162 | |
| 163 | func (s *Server) isActive(token string) bool { |
| 164 | if v, ok := s.active.Load(token); ok { |
| 165 | return time.Since(time.Unix(v.(int64), 0)) < activeWindow |
| 166 | } |
| 167 | return false |
| 168 | } |
| 169 | |
| 170 | // isUserActive reports whether the user is reading on any of their devices right now. |
| 171 | func (s *Server) isUserActive(uid string) bool { |
| 172 | if uid == "" { |
| 173 | return false |
| 174 | } |
| 175 | if v, ok := s.activeUsers.Load(uid); ok { |
| 176 | return time.Since(time.Unix(v.(int64), 0)) < activeWindow |
| 177 | } |
| 178 | return false |
| 179 | } |
| 180 | |
| 181 | // wsTypingOut relays a typing indicator. Like everything else it carries only an |
| 182 | // opaque blob (the sender's name + expiry ride encrypted inside) — the server |
| 183 | // never stores it and never pushes it; it's a transient presence hint. |
| 184 | type wsTypingOut struct { |
| 185 | Type string `json:"type"` |
| 186 | ThreadID string `json:"thread_id,omitempty"` |
| 187 | Blob string `json:"blob"` |
| 188 | } |
| 189 | |
| 190 | // wsReadOut tells a user's other devices their read watermark for a thread |
| 191 | // advanced, so their unread dots clear live. Routed only to that user's own |
| 192 | // connections — never to other members; reading habits aren't shared. |
| 193 | type wsReadOut struct { |
| 194 | Type string `json:"type"` |
| 195 | ThreadID string `json:"thread_id"` |
| 196 | LastReadAt int64 `json:"last_read_at"` |
| 197 | } |
| 198 | |
| 199 | func (s *Server) handleWS(w http.ResponseWriter, r *http.Request) { |
| 200 | token := r.URL.Query().Get("token") |
| 201 | if !s.tokenOK(token) { |
| 202 | http.Error(w, "invalid invite", http.StatusForbidden) |
| 203 | return |
| 204 | } |
| 205 | |
| 206 | conn, err := websocket.Accept(w, r, nil) // same-origin check is on by default |
| 207 | if err != nil { |
| 208 | return |
| 209 | } |
| 210 | conn.SetReadLimit(maxBlobBytes + 1024) |
| 211 | |
| 212 | // The hub routes a thread's traffic to its members, so each client carries the |
| 213 | // user it belongs to (empty for legacy non-device tokens — they receive nothing |
| 214 | // thread-scoped until migrated). |
| 215 | userID, _ := s.db.deviceTokenUser(token) |
| 216 | cl := &client{userID: userID, send: make(chan []byte, 32)} |
| 217 | s.hub.register <- cl |
| 218 | // Presence: connecting counts as activity (a device that never sends |
| 219 | // "active" frames — native, today — still reads online, then idles out). |
| 220 | s.presence.addConn(userID) |
| 221 | s.markActive(token) |
| 222 | |
| 223 | ctx := r.Context() |
| 224 | |
| 225 | // Writer: drains this client's queue. Closing send (by the hub) ends it. |
| 226 | go func() { |
| 227 | defer conn.CloseNow() |
| 228 | for b := range cl.send { |
| 229 | wctx, cancel := context.WithTimeout(context.Background(), 10*time.Second) |
| 230 | err := conn.Write(wctx, websocket.MessageText, b) |
| 231 | cancel() |
| 232 | if err != nil { |
| 233 | return |
| 234 | } |
| 235 | } |
| 236 | }() |
| 237 | |
| 238 | // Reader: accepts new ciphertext, stores it, and broadcasts to everyone. |
| 239 | // However the socket dies — clean close, error, or the hub dropping a |
| 240 | // backed-up client — this defer runs, so the presence count stays true. |
| 241 | defer func() { |
| 242 | s.hub.unregister <- cl |
| 243 | conn.CloseNow() |
| 244 | s.presence.dropConn(userID) |
| 245 | s.presenceChanged(userID) |
| 246 | }() |
| 247 | for { |
| 248 | _, data, err := conn.Read(ctx) |
| 249 | if err != nil { |
| 250 | return |
| 251 | } |
| 252 | var in wsIn |
| 253 | if json.Unmarshal(data, &in) != nil { |
| 254 | continue |
| 255 | } |
| 256 | if in.Type == "active" { |
| 257 | s.markActive(token) // this device is open + focused; mute its siblings' push |
| 258 | continue |
| 259 | } |
| 260 | if in.Type != "msg" && in.Type != "edit" && in.Type != "delete" && in.Type != "typing" { |
| 261 | continue |
| 262 | } |
| 263 | // Re-check the credential so a revoked invite / removed device can't keep |
| 264 | // posting or reacting. |
| 265 | if !s.tokenOK(token) { |
| 266 | return |
| 267 | } |
| 268 | // All traffic is thread-scoped: you must be a member of the thread you're |
| 269 | // posting/reacting to. This is the server-side gate on the social graph. |
| 270 | if in.ThreadID == "" || !s.db.threadMember(in.ThreadID, userID) { |
| 271 | continue |
| 272 | } |
| 273 | // A closed DM (issue #578) accepts no new traffic — messages, edits, |
| 274 | // and typing are all communication. Deletes still pass: taking your |
| 275 | // own words back is always allowed. |
| 276 | if in.Type != "delete" { |
| 277 | if closed, _ := s.db.dmClosed(in.ThreadID); closed { |
| 278 | continue |
| 279 | } |
| 280 | } |
| 281 | |
| 282 | switch in.Type { |
| 283 | case "typing": |
| 284 | // Transient presence hint: relay the opaque blob to the thread's other |
| 285 | // members (the sender ignores its own echo) without storing or pushing |
| 286 | // it. The receiver decrypts the name + expiry and shows it briefly. |
| 287 | // |
| 288 | // This is a dedicated relay-only frame, like "active"/"ping" — typing |
| 289 | // isn't message-shaped (no id, created_at, reactions). If more |
| 290 | // ephemeral kinds appear later, consider generalising to a plaintext |
| 291 | // `ephemeral` flag on the frame (read by the server to skip storage — |
| 292 | // it must live on the envelope, not the ciphertext, which stays E2E). |
| 293 | if in.Blob == "" || len(in.Blob) > maxBlobBytes { |
| 294 | continue |
| 295 | } |
| 296 | out, _ := json.Marshal(wsTypingOut{Type: "typing", ThreadID: in.ThreadID, Blob: in.Blob}) |
| 297 | s.broadcastToThread(in.ThreadID, out) |
| 298 | |
| 299 | case "msg": |
| 300 | if in.Blob == "" || len(in.Blob) > maxBlobBytes { |
| 301 | continue |
| 302 | } |
| 303 | // The content-blind message brake (issue #578): far above any |
| 304 | // human pace; a flood just stops landing. Admins exempt. |
| 305 | if s.db.userRole(userID) != "admin" && !s.brake().messages.allow(userID) { |
| 306 | continue |
| 307 | } |
| 308 | // Ephemeral: relay to the thread's members and forget — no store, no |
| 309 | // push. This generalises the dedicated "typing" frame below for |
| 310 | // mini-app presence traffic (the client marks the frame; content |
| 311 | // stays opaque). Delivered with no id, so clients can't confuse it |
| 312 | // with a stored message. |
| 313 | if in.Ephemeral { |
| 314 | out, _ := json.Marshal(wsOut{Type: "msg", ThreadID: in.ThreadID, Blob: in.Blob, Ephemeral: true}) |
| 315 | s.broadcastToThread(in.ThreadID, out) |
| 316 | continue |
| 317 | } |
| 318 | m, err := s.db.insertMessage(in.ThreadID, in.Blob, userID) |
| 319 | if err != nil { |
| 320 | log.Println("insert message:", err) |
| 321 | continue |
| 322 | } |
| 323 | out, _ := json.Marshal(wsOut{Type: "msg", ThreadID: in.ThreadID, ID: m.ID, CreatedAt: m.CreatedAt, Blob: m.Blob}) |
| 324 | s.broadcastToThread(in.ThreadID, out) |
| 325 | // Notify the thread's other members (not the sender), best-effort, async. |
| 326 | go s.pushNewMessage(m.Blob, in.ThreadID, token, m.ID, m.CreatedAt) |
| 327 | |
| 328 | case "edit": |
| 329 | if in.MessageID <= 0 || in.Blob == "" || len(in.Blob) > maxBlobBytes || |
| 330 | !s.db.messageInThread(in.MessageID, in.ThreadID) { |
| 331 | continue |
| 332 | } |
| 333 | // Edits share the message bucket — each one broadcasts to the whole |
| 334 | // thread, so edit-churn is just message spam wearing a hat. (Typing |
| 335 | // and ephemeral relays stay unthrottled on purpose: never stored, |
| 336 | // never pushed, and burning message tokens on typing beats would |
| 337 | // starve real sends.) |
| 338 | if s.db.userRole(userID) != "admin" && !s.brake().messages.allow(userID) { |
| 339 | continue |
| 340 | } |
| 341 | m, ok, err := s.db.editMessage(in.MessageID, in.Blob, userID, editWindow) |
| 342 | if err != nil { |
| 343 | log.Println("edit message:", err) |
| 344 | continue |
| 345 | } |
| 346 | if !ok { |
| 347 | continue // wrong author, too old, or unknown id — silently ignore |
| 348 | } |
| 349 | out, _ := json.Marshal(wsOut{Type: "edit", ThreadID: in.ThreadID, ID: m.ID, Blob: m.Blob, EditedAt: m.EditedAt}) |
| 350 | s.broadcastToThread(in.ThreadID, out) |
| 351 | |
| 352 | case "delete": |
| 353 | if in.MessageID <= 0 || !s.db.messageInThread(in.MessageID, in.ThreadID) { |
| 354 | continue |
| 355 | } |
| 356 | ok, err := s.db.deleteMessage(in.MessageID, userID) |
| 357 | if err != nil { |
| 358 | log.Println("delete message:", err) |
| 359 | continue |
| 360 | } |
| 361 | if !ok { |
| 362 | continue // not the author, or unknown id — silently ignore |
| 363 | } |
| 364 | // Reclaim the message's attachment blobs (scoped to this thread, so a |
| 365 | // client can't drop another thread's blobs). Best-effort — a failure |
| 366 | // here shouldn't block the delete fan-out. |
| 367 | if len(in.BlobIDs) > 0 { |
| 368 | if err := s.db.deleteBlobs(in.ThreadID, in.BlobIDs); err != nil { |
| 369 | log.Println("gc attachment blobs:", err) |
| 370 | } |
| 371 | } |
| 372 | out, _ := json.Marshal(wsOut{Type: "delete", ThreadID: in.ThreadID, ID: in.MessageID}) |
| 373 | s.broadcastToThread(in.ThreadID, out) |
| 374 | |
| 375 | } |
| 376 | } |
| 377 | } |
| 378 | |
amadan