From b31707098acdece3e9f3f091960e0b08a0efac12 Mon Sep 17 00:00:00 2001
From: yflory <yann.flory@xwiki.com>
Date: Fri, 18 Sep 2020 12:42:09 +0200
Subject: [PATCH] Improve getHistoryRange to support 'toHash'

---
 lib/hk-util.js                    | 5 +++--
 lib/workers/db-worker.js          | 8 ++++++++
 lib/workers/index.js              | 3 ++-
 www/common/outer/async-store.js   | 5 +++--
 www/common/sframe-common-outer.js | 1 +
 5 files changed, 17 insertions(+), 5 deletions(-)

diff --git a/lib/hk-util.js b/lib/hk-util.js
index ed5f43297..14263e481 100644
--- a/lib/hk-util.js
+++ b/lib/hk-util.js
@@ -662,10 +662,11 @@ const handleGetHistoryRange = function (Env, Server, seq, userId, parsed) {
     }
 
     var oldestKnownHash = map.from;
+    var untilHash = map.to;
     var desiredMessages = map.count;
     var desiredCheckpoint = map.cpCount;
     var txid = map.txid;
-    if (typeof(desiredMessages) !== 'number' && typeof(desiredCheckpoint) !== 'number') {
+    if (typeof(desiredMessages) !== 'number' && typeof(desiredCheckpoint) !== 'number' && !untilHash) {
         return void Server.send(userId, [seq, 'ERROR', 'UNSPECIFIED_COUNT', HISTORY_KEEPER_ID]);
     }
 
@@ -674,7 +675,7 @@ const handleGetHistoryRange = function (Env, Server, seq, userId, parsed) {
     }
 
     Server.send(userId, [seq, 'ACK']);
-    Env.getOlderHistory(channelName, oldestKnownHash, desiredMessages, desiredCheckpoint, function (err, toSend) {
+    Env.getOlderHistory(channelName, oldestKnownHash, untilHash, desiredMessages, desiredCheckpoint, function (err, toSend) {
         if (err && err.code !== 'ENOENT') {
             Env.Log.error("HK_GET_OLDER_HISTORY", err);
         }
diff --git a/lib/workers/db-worker.js b/lib/workers/db-worker.js
index d80c2dc21..87b8fe93a 100644
--- a/lib/workers/db-worker.js
+++ b/lib/workers/db-worker.js
@@ -221,6 +221,7 @@ const computeMetadata = function (data, cb) {
 
 const getOlderHistory = function (data, cb) {
     const oldestKnownHash = data.hash;
+    const untilHash = data.toHash;
     const channelName = data.channel;
     const desiredMessages = data.desiredMessages;
     const desiredCheckpoint = data.desiredCheckpoint;
@@ -251,6 +252,13 @@ const getOlderHistory = function (data, cb) {
         var toSend = [];
         if (typeof (desiredMessages) === "number") {
             toSend = messages.slice(-desiredMessages);
+        } else if (untilHash) {
+            for (var i = messages.length - 1; i >= 0; i--) {
+                toSend.unshift(messages[i]);
+                if (Array.isArray(messages[i]) && HK.getHash(messages[i][4], Log) === untilHash) {
+                    break;
+                }
+            }
         } else {
             let cpCount = 0;
             for (var i = messages.length - 1; i >= 0; i--) {
diff --git a/lib/workers/index.js b/lib/workers/index.js
index a77de5437..1033aad0b 100644
--- a/lib/workers/index.js
+++ b/lib/workers/index.js
@@ -281,12 +281,13 @@ Workers.initialize = function (Env, config, _cb) {
             });
         };
 
-        Env.getOlderHistory = function (channel, oldestKnownHash, desiredMessages, desiredCheckpoint, cb) {
+        Env.getOlderHistory = function (channel, oldestKnownHash, toHash, desiredMessages, desiredCheckpoint, cb) {
             Env.store.getWeakLock(channel, function (next) {
                 sendCommand({
                     channel: channel,
                     command: "GET_OLDER_HISTORY",
                     hash: oldestKnownHash,
+                    toHash: toHash,
                     desiredMessages: desiredMessages,
                     desiredCheckpoint: desiredCheckpoint,
                 }, Util.both(next, cb));
diff --git a/www/common/outer/async-store.js b/www/common/outer/async-store.js
index 7c8793893..f07378d64 100644
--- a/www/common/outer/async-store.js
+++ b/www/common/outer/async-store.js
@@ -2069,7 +2069,7 @@ define([
                     if (first) {
                         // If the first message if not a checkpoint, it means it is the first
                         // message of the pad, so we have the full history!
-                        if (!/^cp\|/.test(msg)) { fullHistory = true; }
+                        if (!/^cp\|/.test(msg) && !data.toHash) { fullHistory = true; }
                         lastKnownHash = msg.slice(0,64);
                         first = false;
                     }
@@ -2086,7 +2086,8 @@ define([
             network.on('message', onMsg);
             network.sendto(hk, JSON.stringify(['GET_HISTORY_RANGE', data.channel, {
                 from: data.lastKnownHash,
-                cpCount: data.cpCount || 2,
+                to: data.toHash,
+                cpCount: data.cpCount || 2, // Ignored if "to" is provided
                 txid: txid
             }]));
         };
diff --git a/www/common/sframe-common-outer.js b/www/common/sframe-common-outer.js
index 28d6678a1..a08ecb0f2 100644
--- a/www/common/sframe-common-outer.js
+++ b/www/common/sframe-common-outer.js
@@ -1108,6 +1108,7 @@ define([
                 Cryptpad.getHistoryRange({
                     channel: channel,
                     validateKey: validate,
+                    toHash: data.toHash,
                     lastKnownHash: data.lastKnownHash
                 }, function (data) {
                     cb({