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check incoming hash when present

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This commit is contained in:
Brian Gough 2019-04-08 13:43:24 +01:00
parent 1052e9e000
commit cc1f3fce5b
1 changed files with 11 additions and 0 deletions
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11
services/document-updater/app/coffee/ShareJsUpdateManager.coffee
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@ -6,6 +6,7 @@ Keys = require "./UpdateKeys"
{EventEmitter} = require "events"
util = require "util"
RealTimeRedisManager = require "./RealTimeRedisManager"
crypto = require "crypto"
ShareJsModel:: = {}
util.inherits ShareJsModel, EventEmitter
@ -42,6 +43,10 @@ module.exports = ShareJsUpdateManager =
logger.log project_id: project_id, doc_id: doc_id, error: error, "applied update"
model.getSnapshot doc_key, (error, data) =>
return callback(error) if error?
# only check hash when present and no other updates have been applied
if update.hash? and update.v == version
ourHash = ShareJsUpdateManager._computeHash(data.snapshot)
return callback(new Error("Invalid hash")) if ourHash != update.hash
docLines = data.snapshot.split(/\r\n|\n|\r/)
callback(null, docLines, data.v, model.db.appliedOps[doc_key] or [])
@ -53,3 +58,9 @@ module.exports = ShareJsUpdateManager =
_sendOp: (project_id, doc_id, op) ->
RealTimeRedisManager.sendData {project_id, doc_id, op}
_computeHash: (content) ->
return crypto.createHash('sha1')
.update("blob " + content.length + "\x00")
.update(content, 'utf8')
.digest('hex')