forked from Qortal/qortal
48 lines
2.3 KiB
Markdown
48 lines
2.3 KiB
Markdown
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# Auto Updates
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## Theory
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* Using a specific git commit (e.g. abcdef123) we produce a determinstic JAR with consistent hash.
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* To avoid issues with over-eager anti-virus / firewalls we obfuscate JAR using very simplistic XOR-based method.
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* Obfuscated JAR is uploaded to various well-known locations, usually including github itself, referenced in settings.
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* An `ARBITRARY` transaction is published by a **non-admin** member of the "dev" group (groupID 1) with:
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+ 'service' set to 1
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+ txGroupId set to dev groupID, i.e. 1
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and containing this data:
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+ git commit's timestamp in milliseconds (8 bytes)
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+ git commit's SHA1 hash (20 bytes)
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+ SHA256 hash of *obfuscated* JAR (32 bytes)
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* Admins of dev group approve above transaction until it reaches, or exceeds, dev group's approval threshold (e.g. 60%).
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* Nodes notice approved transaction and begin auto-update process of:
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+ checking transaction's timestamp is greater than node's current build timestamp
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+ checking git commit timestamp (in data payload) is greater than node's current build timestamp
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+ downloading update (obfuscated JAR) from various locations using git commit SHA1 hash
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+ checking downloaded update's SHA256 hash matches hash in transaction's data payload
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+ calling ApplyUpdate Java class to shutdown, update and restart node
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## Obfuscation method
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The same method is used to obfuscate and de-obfuscate:
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* XOR each byte of the file with 0x5A
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## Typical download locations
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The git SHA1 commit hash is used to replace `%s` in various download locations, e.g.:
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* https://github.com/QORT/qortal/raw/%s/qortal.update
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* https://raw.githubusercontent.com@151.101.16.133/QORT/qortal/%s/qortal.update
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These locations are part of the org.qortal.settings.Settings class and can be overriden in settings.json like:
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```
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"autoUpdateRepos": [
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"http://mirror.qortal.org/auto-updates/%s",
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"https://server.host.name@1.2.3.4/Qortal/%s"
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]
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```
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The latter entry is an example where the IP address is provided, bypassing name resolution, for situations where DNS is unreliable or unavailable.
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## XOR tool
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To help with manual verification of auto-updates, there is a XOR tool included in the Qortal JAR.
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It can be used thus:
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```
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$ java -cp qortal.jar org.qortal.XorUpdate
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usage: XorUpdate <input-file> <output-file>
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$ java -cp qortal.jar org.qortal.XorUpdate qortal.jar qortal.update
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$
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```
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