Implement stream management requesting ACKs

package.json

@@ -52,7 +52,7 @@
   "bundlesize": [
     {
       "path": "./packages/client/dist/xmpp.min.js",
-      "maxSize": "16 KB"
+      "maxSize": "17 KB"
     }
   ],
   "lint-staged": {

packages/stream-management/index.js

@@ -1,6 +1,7 @@
 "use strict";
 
 const xml = require("@xmpp/xml");
+const time = require("@xmpp/time");
 
 // https://xmpp.org/extensions/xep-0198.html
 
@@ -46,24 +47,34 @@ module.exports = function streamManagement({
   middleware,
 }) {
   let address = null;
+  let timeoutTimeout = null;
 
   const sm = {
     allowResume: true,
     preferredMaximum: null,
     enabled: false,
     id: "",
+    outbound_q: [],
     outbound: 0,
     inbound: 0,
     max: null,
+    timeout: 60000,
   };
 
   entity.on("online", (jid) => {
     address = jid;
+    if (sm.outbound_q.length > 0) {
+      throw "Stream Management assertion failure, queue should be empty during online";
+    }
     sm.outbound = 0;
     sm.inbound = 0;
   });
 
   entity.on("offline", () => {
+    let stanza;
+    while ((stanza = sm.outbound_q.shift())) {
+      entity.emit("stream-management/fail", stanza);
+    }
     sm.outbound = 0;
     sm.inbound = 0;
     sm.enabled = false;
@@ -72,35 +83,92 @@ module.exports = function streamManagement({
 
   middleware.use((context, next) => {
     const { stanza } = context;
+    if (timeoutTimeout) clearTimeout(timeoutTimeout);
     if (["presence", "message", "iq"].includes(stanza.name)) {
       sm.inbound += 1;
     } else if (stanza.is("r", NS)) {
       // > When an <r/> element ("request") is received, the recipient MUST acknowledge it by sending an <a/> element to the sender containing a value of 'h' that is equal to the number of stanzas handled by the recipient of the <r/> element.
       entity.send(xml("a", { xmlns: NS, h: sm.inbound })).catch(() => {});
     } else if (stanza.is("a", NS)) {
       // > When a party receives an <a/> element, it SHOULD keep a record of the 'h' value returned as the sequence number of the last handled outbound stanza for the current stream (and discard the previous value).
-      sm.outbound = stanza.attrs.h;
+      const oldOutbound = sm.outbound;
+      for (let i = 0; i < stanza.attrs.h - oldOutbound; i++) {
+        let stanza = sm.outbound_q.shift();
+        sm.outbound++;
+        entity.emit("stream-management/ack", stanza);
+      }
     }
 
     return next();
   });
 
+  let requestAckTimeout = null;
+  function requestAck() {
+    if (timeoutTimeout) clearTimeout(timeoutTimeout);
+    if (sm.timeout) {
+      timeoutTimeout = setTimeout(() => entity.disconnect(), sm.timeout);
+    }
+    entity.send(xml("r", { xmlns: NS })).catch(() => {});
+    // Periodically send r to check the connection
+    // If a stanza goes out it will cancel this and set a sooner timer
+    requestAckTimeout = setTimeout(requestAck, 300000);
+  }
+
+  middleware.filter((context, next) => {
+    const { stanza } = context;
+    if (sm.enabled && ["presence", "message", "iq"].includes(stanza.name)) {
+      let qStanza = stanza;
+      if (
+        qStanza.name === "message" &&
+        !qStanza.getChild("delay", "urn:xmpp:delay")
+      ) {
+        qStanza = xml.clone(stanza);
+        qStanza.c("delay", {
+          xmlns: "urn:xmpp:delay",
+          from: entity.jid.toString(),
+          stamp: time.datetime(),
+        });
+      }
+      sm.outbound_q.push(qStanza);
+      // Debounce requests so we send only one after a big run of stanza together
+      if (requestAckTimeout) clearTimeout(requestAckTimeout);
+      requestAckTimeout = setTimeout(requestAck, 100);
+    }
+    return next();
+  });
+
   // https://xmpp.org/extensions/xep-0198.html#enable
   // For client-to-server connections, the client MUST NOT attempt to enable stream management until after it has completed Resource Binding unless it is resuming a previous session
 
   streamFeatures.use("sm", NS, async (context, next) => {
     // Resuming
     if (sm.id) {
       try {
-        await resume(entity, sm.inbound, sm.id);
+        let resumed = await resume(entity, sm.inbound, sm.id);
         sm.enabled = true;
-        entity.jid = address;
+        if (address) entity.jid = address;
         entity.status = "online";
+        const oldOutbound = sm.outbound;
+        for (let i = 0; i < resumed.attrs.h - oldOutbound; i++) {
+          let stanza = sm.outbound_q.shift();
+          sm.outbound++;
+          entity.emit("stream-management/ack", stanza);
+        }
+        let q = sm.outbound_q;
+        sm.outbound_q = [];
+        for (const item of q) {
+          entity.send(item); // This will trigger the middleware and re-add to the queue
+        }
+        entity.emit("stream-management/resumed");
         return true;
         // If resumption fails, continue with session establishment
       } catch {
         sm.id = "";
         sm.enabled = false;
+        let stanza;
+        while ((stanza = sm.outbound_q.shift())) {
+          entity.emit("stream-management/fail", stanza);
+        }
         sm.outbound = 0;
       }
     }
@@ -113,6 +181,9 @@ module.exports = function streamManagement({
     const promiseEnable = enable(entity, sm.allowResume, sm.preferredMaximum);
 
     // > The counter for an entity's own sent stanzas is set to zero and started after sending either <enable/> or <enabled/>.
+    if (sm.outbound_q.length > 0) {
+      throw "Stream Management assertion failure, queue should be empty after enable";
+    }
     sm.outbound = 0;
 
     try {

packages/stream-management/package.json

@@ -12,7 +12,8 @@
     "management"
   ],
   "dependencies": {
-    "@xmpp/xml": "^0.13.2"
+    "@xmpp/xml": "^0.13.2",
+    "@xmpp/time": "^0.13.2"
   },
   "engines": {
     "node": ">= 14"

packages/xml/index.js

@@ -2,6 +2,7 @@
 
 const Element = require("ltx/lib/Element");
 const createElement = require("ltx/lib/createElement");
+const clone = require("ltx/lib/clone");
 const Parser = require("./lib/Parser");
 const {
   escapeXML,
@@ -19,6 +20,7 @@ module.exports = xml;
 
 Object.assign(module.exports, {
   Element,
+  clone,
   createElement,
   Parser,
   escapeXML,