0cabbfd · skrepka · git.iko.soy

git.iko.soy/skrepka

Fix 7 server.knot bugs: offline gossip peer loss, missing hex validation, clock skew intolerance, fromServer validation, senderServers overfitting, poll unauthorized ambiguity, and FederationAck message scope

Fixes: 1. broadcastOfflineGossip now captures peer servers before pruning to avoid missing servers whose entries were pruned 2. Add isValidHex helper and validation before bytesFromHex in VerifyAuth 3. Add clockSkewTolerance config with 5s tolerance for clock skew in gossip timestamp checks 4. Add fromServer length validation in RecvGossip (matching FederationAck pattern) 5. Fix senderServers to use effectiveEvents instead of validEvents to avoid excluding uninvolved servers 6. Poll now returns cursor -1 for unauthorized requests (signals re-authentication needed) 7. FederationAck message deletion now scoped to originServer == "" (locally-originated messages only)

commit0cabbfd1cce0895e74d61dafaa38b659bd838507 authoriko <mail@iko.soy> dateThu 26 Mar 2026, 18:03 (7 months ago) parent242926b

1 file changed+50−46

compare with master

unifiedsplit

server.knot+50−46

server.knot+50−46

@@ -16,6 +16,7 @@ maxBlobLen = 65536

1616maxSignatureLen = 256

1717maxMessageIds = 100

1818maxGossipEvents = 100

19+clockSkewTolerance = 5000 -- 5 seconds tolerance for clock skew between federated servers

1920

2021-- ============================================

2122-- Types

@@ -94,6 +95,8 @@ genToken = do

9495

9596tooLong = \s maxLen -> not (drop maxLen s == "")

9697

98+isValidHex = \s -> not (s == "") && bytesToHex (bytesFromHex s) == s

99+

97100lookupSession = \sessions token t ->

98101 single (do

99102 s <- sessions

@@ -148,6 +151,10 @@ pruneExpired = \t -> do

148151 where s.expiresAt > t

149152 yield s

150153 presenceBefore <- *presence

154+ let peerServersBefore = fold (\acc p ->

155+ if p.server == serverHost then acc

156+ else if count (do a <- acc; where a == p.server; yield a) > 0 then acc

157+ else union acc [p.server]) [] presenceBefore

151158 let presenceAfter = do

152159 p <- presenceBefore

153160 where p.expiresAt > t

@@ -158,7 +165,7 @@ pruneExpired = \t -> do

158165 m <- messages

159166 where m.timestamp >= t - messageMaxAge

160167 yield m

161− yield (do

168+ yield {expiredLocal: (do

162169 p <- presenceBefore

163170 where p.expiresAt <= t

164171 where p.server == serverHost

@@ -167,20 +174,14 @@ pruneExpired = \t -> do

167174 where q.pubkey == p.pubkey

168175 where q.server == serverHost

169176 yield q) == 0

170− yield p)

177+ yield p), peerServers: peerServersBefore}

171178

172−broadcastOfflineGossip = \t expiredLocal -> do

179+broadcastOfflineGossip = \t peerServers expiredLocal -> do

173180 let expiredPubkeys = fold (\acc p ->

174181 if count (do a <- acc; where a == p.pubkey; yield a) > 0 then acc

175182 else union acc [p.pubkey]) [] expiredLocal

176− if not (federationSecret == "") && count expiredPubkeys > 0

183+ if not (federationSecret == "") && count expiredPubkeys > 0 && count peerServers > 0

177184 then do

178− peerServers <- atomic do

179− presence <- *presence

180− yield (fold (\acc p ->

181− if p.server == serverHost then acc

182− else if count (do a <- acc; where a == p.server; yield a) > 0 then acc

183− else union acc [p.server]) [] presence)

184185 let gossipEvents = do

185186 pk <- expiredPubkeys

186187 yield {eventType: "offline", pubkey: pk, server: serverHost, timestamp: t, ttl: 3600}

@@ -202,21 +203,21 @@ serve = \req -> case req of

202203 else do

203204 challenge <- genToken

204205 t <- now

205− expiredLocal <- atomic do

206− el <- pruneExpired t

206+ pruneResult <- atomic do

207+ pr <- pruneExpired t

207208 challenges <- *challenges

208209 set *challenges = union challenges

209210 [{pubkey: pubkey, challenge: challenge, expiresAt: t + 60000}]

210− yield el

211+ yield pr

211212 respond {challenge: challenge}

212− broadcastOfflineGossip t expiredLocal

213+ broadcastOfflineGossip t pruneResult.peerServers pruneResult.expiredLocal

213214

214215 VerifyAuth {pubkey, challenge, signature, respond} -> do

215216 t <- now

216217 token <- genToken

217218 let expiry = t + 3600000

218219 result <- atomic do

219− expiredLocal <- pruneExpired t

220+ pr <- pruneExpired t

220221 challenges <- *challenges

221222 sessions <- *sessions

222223 presence <- *presence

@@ -229,6 +230,8 @@ serve = \req -> case req of

229230 let sigValid = case matched of

230231 Nothing {} -> False {}

231232 _ -> if tooLong signature maxSignatureLen

233+ then False {}

234+ else if not (isValidHex pubkey) || not (isValidHex signature)

232235 then False {}

233236 else verify (bytesFromHex pubkey) (textToBytes challenge) (bytesFromHex signature)

234237 set *challenges = if sigValid

@@ -268,7 +271,7 @@ serve = \req -> case req of

268271 else if count (do a <- acc; where a == p.server; yield a) > 0 then acc

269272 else union acc [p.server]) [] updatedPresence

270273 else []

271− yield {sigValid: sigValid, peerServers: peerServers, expiredLocal: expiredLocal}

274+ yield {sigValid: sigValid, peerServers: peerServers, expiredLocal: pr.expiredLocal, offlinePeers: pr.peerServers}

272275 if result.sigValid

273276 then respond {token: token, expiresAt: expiry}

274277 else respond {token: "", expiresAt: 0}

@@ -278,13 +281,13 @@ serve = \req -> case req of

278281 {authorization: "Bearer " ++ federationSecret}

279282 {events: [{eventType: "online", pubkey: pubkey, server: serverHost, timestamp: t, ttl: 3600}], hopsRemaining: 2, fromServer: serverHost})

280283 else yield {}

281− broadcastOfflineGossip t result.expiredLocal

284+ broadcastOfflineGossip t result.offlinePeers result.expiredLocal

282285

283286 Poll {cursor, authorization, respond} -> do

284287 t <- now

285288 let token = extractToken authorization

286289 result <- atomic do

287− expiredLocal <- pruneExpired t

290+ pr <- pruneExpired t

288291 sessions <- *sessions

289292 messages <- *messages

290293 seqCounter <- *seqCounter

@@ -301,11 +304,11 @@ serve = \req -> case req of

301304 encryptedBlob: m.encryptedBlob,

302305 timestamp: m.timestamp}}

303306 let newCursor = case session of

304− Nothing {} -> 0

307+ Nothing {} -> -1

305308 _ -> if seqCounter > cursor then seqCounter else cursor

306− yield {events: evts, cursor: newCursor, expiredLocal: expiredLocal}

309+ yield {events: evts, cursor: newCursor, expiredLocal: pr.expiredLocal, peerServers: pr.peerServers}

307310 respond {events: result.events, cursor: result.cursor}

308− broadcastOfflineGossip t result.expiredLocal

311+ broadcastOfflineGossip t result.peerServers result.expiredLocal

309312

310313 SendMessage {to, encryptedBlob, timestamp, authorization, respond} -> do

311314 t <- now

@@ -313,7 +316,7 @@ serve = \req -> case req of

313316 let clampedTs = if timestamp > t then t else if timestamp < t - messageMaxAge then t else timestamp

314317 let validInput = not (to == "") && not (encryptedBlob == "") && not (tooLong to maxPubkeyLen) && not (tooLong encryptedBlob maxBlobLen)

315318 result <- atomic do

316− expiredLocal <- pruneExpired t

319+ pr <- pruneExpired t

317320 sessions <- *sessions

318321 messages <- *messages

319322 presence <- *presence

@@ -356,7 +359,7 @@ serve = \req -> case req of

356359 else if localOnline then "delivered"

357360 else if count remoteServers > 0 then "federated"

358361 else "queued"

359− yield {status: status, remoteServers: remoteServers, fromKey: fromKey, expiredLocal: expiredLocal}

362+ yield {status: status, remoteServers: remoteServers, fromKey: fromKey, expiredLocal: pr.expiredLocal, peerServers: pr.peerServers}

360363 finalStatus <- if result.status == "federated" && not (federationSecret == "")

361364 then do

362365 anyOk <- forwardToAll result.remoteServers "/federation/forward"

@@ -366,7 +369,7 @@ serve = \req -> case req of

366369 yield (if anyOk then "federated" else "queued")

367370 else yield result.status

368371 respond {status: finalStatus, messageId: (if result.status == "unauthorized" then "" else if result.status == "invalid" then "" else msgId)}

369− broadcastOfflineGossip t result.expiredLocal

372+ broadcastOfflineGossip t result.peerServers result.expiredLocal

370373

371374 AckMessages {messageIds, authorization, respond} -> do

372375 t <- now

@@ -376,7 +379,7 @@ serve = \req -> case req of

376379 else if count (do a <- acc; where a == mid; yield a) > 0 then acc

377380 else union acc [mid]) [] messageIds

378381 result <- atomic do

379− expiredLocal <- pruneExpired t

382+ pr <- pruneExpired t

380383 sessions <- *sessions

381384 messages <- *messages

382385 let session = lookupSession sessions (extractToken authorization) t

@@ -394,7 +397,7 @@ serve = \req -> case req of

394397 let ok = case session of

395398 Nothing {} -> False {}

396399 _ -> True {}

397− yield {ok: ok, ackedMessages: ackedMessages, expiredLocal: expiredLocal}

400+ yield {ok: ok, ackedMessages: ackedMessages, expiredLocal: pr.expiredLocal, peerServers: pr.peerServers}

398401 let fedMessages = do

399402 m <- result.ackedMessages

400403 where not (m.originServer == "")

@@ -411,12 +414,12 @@ serve = \req -> case req of

411414 originServer: server, fromServer: serverHost})

412415 else yield {}

413416 respond {ok: result.ok}

414− broadcastOfflineGossip t result.expiredLocal

417+ broadcastOfflineGossip t result.peerServers result.expiredLocal

415418

416419 LookupPresence {pubkey, authorization, respond} -> do

417420 t <- now

418421 result <- atomic do

419− expiredLocal <- pruneExpired t

422+ pr <- pruneExpired t

420423 sessions <- *sessions

421424 presence <- *presence

422425 let session = lookupSession sessions (extractToken authorization) t

@@ -439,15 +442,15 @@ serve = \req -> case req of

439442 yield p) of

440443 Just {value: p} -> p.server

441444 Nothing {} -> fold (\_ p -> p.server) "" valid

442− yield {foundServer: foundServer, authorized: authorized, expiredLocal: expiredLocal}

445+ yield {foundServer: foundServer, authorized: authorized, expiredLocal: pr.expiredLocal, peerServers: pr.peerServers}

443446 respond {online: not (result.foundServer == ""), server: result.foundServer, authorized: result.authorized}

444− broadcastOfflineGossip t result.expiredLocal

447+ broadcastOfflineGossip t result.peerServers result.expiredLocal

445448

446449 RecvGossip {events, hopsRemaining, fromServer, authorization, respond} -> do

447450 t <- now

448451 let authorized = verifyFederationAuth authorization

449452 let cappedHops = if hopsRemaining > 5 then 5 else hopsRemaining

450− let validRequest = authorized && cappedHops >= 1 && not (fromServer == "") && count events <= maxGossipEvents

453+ let validRequest = authorized && cappedHops >= 1 && not (fromServer == "") && not (tooLong fromServer maxPubkeyLen) && count events <= maxGossipEvents

451454 let onlineEntries = do

452455 e <- events

453456 where validRequest

@@ -457,7 +460,7 @@ serve = \req -> case req of

457460 where not (tooLong e.pubkey maxPubkeyLen)

458461 where not (tooLong e.server maxPubkeyLen)

459462 where not (e.server == serverHost)

460− where e.timestamp <= t

463+ where e.timestamp <= t + clockSkewTolerance

461464 where e.timestamp + (clampTtl e.ttl) * 1000 > t

462465 yield {pubkey: e.pubkey, server: e.server, expiresAt: e.timestamp + (clampTtl e.ttl) * 1000, timestamp: e.timestamp}

463466 let offlineEntries = do

@@ -469,7 +472,7 @@ serve = \req -> case req of

469472 where not (tooLong e.pubkey maxPubkeyLen)

470473 where not (tooLong e.server maxPubkeyLen)

471474 where not (e.server == serverHost)

472− where e.timestamp <= t

475+ where e.timestamp <= t + clockSkewTolerance

473476 where t - e.timestamp < (clampTtl e.ttl) * 1000

474477 yield {pubkey: e.pubkey, server: e.server, timestamp: e.timestamp}

475478 let filteredOnline = do

@@ -503,7 +506,7 @@ serve = \req -> case req of

503506 yield a)

504507 [e]) [] filteredOnline

505508 gossipResult <- atomic do

506− expiredLocal <- pruneExpired t

509+ pr <- pruneExpired t

507510 presence <- *presence

508511 let appliedOnline = do

509512 e <- deduped

@@ -561,7 +564,7 @@ serve = \req -> case req of

561564 set *presence = if validRequest

562565 then afterOffline

563566 else presence

564− yield {appliedKeys: (union appliedOnline appliedOffline), expiredLocal: expiredLocal}

567+ yield {appliedKeys: (union appliedOnline appliedOffline), expiredLocal: pr.expiredLocal, peerServers: pr.peerServers}

565568 let validEvents = do

566569 e <- events

567570 where validRequest

@@ -570,7 +573,7 @@ serve = \req -> case req of

570573 where not (tooLong e.pubkey maxPubkeyLen)

571574 where not (tooLong e.server maxPubkeyLen)

572575 where not (e.server == serverHost)

573− where e.timestamp <= t

576+ where e.timestamp <= t + clockSkewTolerance

574577 where e.timestamp + (clampTtl e.ttl) * 1000 > t

575578 where not (e.eventType == "online" && count (do

576579 o <- offlineEntries

@@ -593,7 +596,7 @@ serve = \req -> case req of

593596 else union acc [p.server]) [] presence)

594597 let senderServers = fold (\acc e ->

595598 if count (do a <- acc; where a == e.server; yield a) > 0 then acc

596− else union acc [e.server]) (if fromServer == "" then [] else [fromServer]) validEvents

599+ else union acc [e.server]) (if fromServer == "" then [] else [fromServer]) effectiveEvents

597600 let targets = do

598601 s <- peerServers

599602 where count (do ss <- senderServers; where ss == s; yield ss) == 0

@@ -604,7 +607,7 @@ serve = \req -> case req of

604607 {events: effectiveEvents, hopsRemaining: cappedHops - 1, fromServer: serverHost})

605608 else yield {}

606609 respond {ok: validRequest}

607− broadcastOfflineGossip t gossipResult.expiredLocal

610+ broadcastOfflineGossip t gossipResult.peerServers gossipResult.expiredLocal

608611

609612 ForwardMessage {toKey, fromKey, encryptedBlob, timestamp, originServer, messageId, authorization, respond} -> do

610613 t <- now

@@ -612,8 +615,8 @@ serve = \req -> case req of

612615 let validOrigin = not (originServer == "") && not (originServer == serverHost)

613616 let validFields = not (toKey == "") && not (fromKey == "") && not (encryptedBlob == "") && not (messageId == "") && not (tooLong toKey maxPubkeyLen) && not (tooLong fromKey maxPubkeyLen) && not (tooLong encryptedBlob maxBlobLen) && not (tooLong messageId maxPubkeyLen)

614617 let clampedTs = if timestamp > t then t else if timestamp < t - messageMaxAge then t else timestamp

615− expiredLocal <- atomic do

616− el <- pruneExpired t

618+ pruneResult <- atomic do

619+ pr <- pruneExpired t

617620 messages <- *messages

618621 seqCounter <- *seqCounter

619622 let seqTs = if t > seqCounter then t else seqCounter + 1

@@ -629,9 +632,9 @@ serve = \req -> case req of

629632 [{messageId: messageId, toKey: toKey, fromKey: fromKey,

630633 encryptedBlob: encryptedBlob, timestamp: clampedTs, originServer: originServer, receivedAt: seqTs}]

631634 else messages

632− yield el

635+ yield pr

633636 respond {ok: authorized && validOrigin && validFields}

634− broadcastOfflineGossip t expiredLocal

637+ broadcastOfflineGossip t pruneResult.peerServers pruneResult.expiredLocal

635638

636639 FederationAck {messageIds, originServer, fromServer, authorization, respond} -> do

637640 t <- now

@@ -642,8 +645,8 @@ serve = \req -> case req of

642645 else if count (do a <- acc; where a == mid; yield a) > 0 then acc

643646 else union acc [mid]) [] messageIds

644647 let validAck = authorized && originServer == serverHost && not (fromServer == "") && not (fromServer == serverHost) && not (tooLong fromServer maxPubkeyLen) && count messageIds <= maxMessageIds

645− expiredLocal <- atomic do

646− el <- pruneExpired t

648+ pruneResult <- atomic do

649+ pr <- pruneExpired t

647650 messages <- *messages

648651 presence <- *presence

649652 set *messages = if validAck

@@ -651,6 +654,7 @@ serve = \req -> case req of

651654 m <- messages

652655 mid <- dedupedIds

653656 where m.messageId == mid

657+ where m.originServer == ""

654658 where count (do

655659 p <- presence

656660 where p.pubkey == m.toKey

@@ -659,9 +663,9 @@ serve = \req -> case req of

659663 yield p) == 0

660664 yield m)

661665 else messages

662− yield el

666+ yield pr

663667 respond {ok: validAck}

664− broadcastOfflineGossip t expiredLocal

668+ broadcastOfflineGossip t pruneResult.peerServers pruneResult.expiredLocal

665669

666670-- ============================================

667671-- Entry Point