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* SB/PC: use 4-character hash in request

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* use hash prefix as the cache key

Squashed commit of the following:

commit d719a84ee9b9cf43aaab4f53d07451645ea836db
Merge: d9d6d443 97df1989
Author: Simon Zolin <s.zolin@adguard.com>
Date:   Thu Aug 13 11:41:28 2020 +0300

    Merge remote-tracking branch 'origin/master' into sbpc

commit d9d6d44376c44959f2216b08e577d8e5c5f65bff
Merge: 0a8b2483 de92c852
Author: Simon Zolin <s.zolin@adguard.com>
Date:   Thu Aug 13 11:23:14 2020 +0300

    Merge remote-tracking branch 'origin/master' into sbpc

commit 0a8b24839683683a9d327ecf57a7d182b3996b1d
Merge: 0255a24a 9b9902f0
Author: Simon Zolin <s.zolin@adguard.com>
Date:   Wed Aug 12 20:21:22 2020 +0300

    Merge remote-tracking branch 'origin/master' into sbpc

commit 0255a24a191efd2e4ef23d6a00a7a9fed8831730
Author: Simon Zolin <s.zolin@adguard.com>
Date:   Wed Aug 12 17:16:57 2020 +0300

    - TestServerCustomClientUpstream(): fix

commit d2311902f887be9621a9d9312c73f899dd269440
Author: Simon Zolin <s.zolin@adguard.com>
Date:   Wed Aug 12 17:07:12 2020 +0300

    * SB/PC: hard-code Family server IP addresses to prevent from requesting them at runtime

commit ee340108f11f98d49a7af2a7e8a228c25ab1537a
Author: Simon Zolin <s.zolin@adguard.com>
Date:   Wed Aug 12 17:05:57 2020 +0300

    * dnsproxy v0.30.1

commit f5f53ba7116ad525204d00b80352202eee88b78c
Author: Simon Zolin <s.zolin@adguard.com>
Date:   Wed Aug 12 14:53:23 2020 +0300

    minor

commit fb4631e2cd570b0fd5ae26ec2b1890361275a5a8
Author: Simon Zolin <s.zolin@adguard.com>
Date:   Mon Aug 10 20:07:27 2020 +0300

    * SB/PC: implement new cache

commit f9f58461a6efbcfacd798f7640a4645cf1971cb2
Author: Simon Zolin <s.zolin@adguard.com>
Date:   Fri Aug 7 19:31:05 2020 +0300

    doc

commit ed69626a6c119ab1a3b187f5afbd4cef708c3159
Author: Simon Zolin <s.zolin@adguard.com>
Date:   Fri Aug 7 18:25:57 2020 +0300

    * SB/PC: use hostname prefix for cache

commit afa8040c8c0836c7e59e6fb9aaf1caccd132ea8f
Author: Simon Zolin <s.zolin@adguard.com>
Date:   Fri Jul 31 11:19:49 2020 +0300

    * SB/PC: use 4-character hash in request
This commit is contained in:
Simon Zolin
2020-08-13 11:49:42 +03:00
parent 97df19898f
commit 705a9d909d
9 changed files with 469 additions and 185 deletions
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38
AGHTechDoc.md
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@@ -64,6 +64,7 @@ Contents:
* API: Log in
* API: Log out
* API: Get current user info
* Safe services
## Relations between subsystems
@@ -1747,3 +1748,40 @@ Response:
}
If no client is configured then authentication is disabled and server sends an empty response.
### Safe services
Check if host name is blocked by SB/PC service:
* For each host name component, search for the result in cache by the first 2 bytes of SHA-256 hashes of host name components (max. is 4, i.e. sub2.sub1.host.com), excluding TLD:
hashes[] = cache_search(sha256(host.com)[0..1])
...
If hash prefix is found, search for a full hash sum in the cached data.
If found, the host is blocked.
If not found, the host is not blocked - don't request data for this prefix from the Family server again.
If hash prefix is not found, request data for this prefix from the Family server.
* Prepare query string which is generated from the first 2 bytes (converted to a 4-character string) of SHA-256 hashes of host name components (max. is 4, i.e. sub2.sub1.host.com), excluding TLD:
qs = ... + string(sha256(sub.host.com)[0..1]) + "." + string(sha256(host.com)[0..1]) + ".sb.dns.adguard.com."
For PC `.pc.dns.adguard.com` suffix is used.
* Send TXT query to Family server, receive response which contains the array of complete hash sums of the blocked hosts
* Check if one of received hash sums (`hashes[]`) matches hash sums for our host name
hashes[0] <> sha256(host.com)
hashes[0] <> sha256(sub.host.com)
hashes[1] <> sha256(host.com)
hashes[1] <> sha256(sub.host.com)
...
* Store all received hash sums in cache:
sha256(host.com)[0..1] -> hashes[0],hashes[1],...
sha256(sub.host.com)[0..1] -> hashes[2],...
...