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Fix Auth Resnponse packet when cleartext is used #887

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merged 4 commits into from Nov 13, 2018
Merged

Fix Auth Resnponse packet when cleartext is used #887

merged 4 commits into from Nov 13, 2018

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@methane
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@methane methane commented Oct 30, 2018 •
edited

Fixes #884

Description

NUL shouldn't be after string[n] auth-response. It breaks following string[NUL] database.

https://dev.mysql.com/doc/internals/en/connection-phase-packets.html#packet-Protocol::HandshakeResponse41

So n should contain trailing NUL byte.

I confirmed cleartext is used in sha256_password. I can't confirm cleartext password.
Especially, there are no way to enable fast cleartext password in MySQL 5.7 and 8.0.
(default-authenticate-plugin can't be "cleartext_password".)

Checklist

  • Code compiles correctly
  • Created tests which fail without the change (if possible)
  • All tests passing
  • Extended the README / documentation, if necessary
  • Added myself / the copyright holder to the AUTHORS file
methane added 2 commits Oct 30, 2018
@methane
Fix Auth Resnponse packet when addNUL is true
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1dc3cd1 
Fixes #884
@methane
Remove addNUL
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c3870b2
@methane methane changed the title [wip] Fix Auth Resnponse packet when addNUL is true Fix Auth Resnponse packet when cleartext is used Oct 31, 2018
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@methane methane commented Oct 31, 2018

One problem is what should be returned for empty password: empty string or one byte NUL.

Whan I tested with sha256_password (which returns cleartext when secure connection), one byte NUL is required. I suppose cleartext password plugin is same.
@methane methane requested a review from julienschmidt Oct 31, 2018
@methane methane force-pushed the methane:fix-884 branch from ecaef0b to c3b9ee9 Oct 31, 2018
@methane
Fix tests
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5c20701
@methane methane force-pushed the methane:fix-884 branch from c3b9ee9 to 5c20701 Oct 31, 2018
@julienschmidt
julienschmidt reviewed Oct 31, 2018
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@julienschmidt julienschmidt left a comment

Why did you remove the addNUL?
It's there to avoid an allocation for a return value which is just copied again afterwards anyway.
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julienschmidt reviewed Oct 31, 2018
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@julienschmidt julienschmidt added this to the v1.4.1 milestone Oct 31, 2018
@julienschmidt julienschmidt added the bug label Oct 31, 2018
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@methane methane commented Nov 1, 2018

Why did you remove the addNUL?
It's there to avoid an allocation for a return value which is just copied again afterwards anyway.

Because I thought it's there to add NUL after string[n]. And appending it after n bytes was the bug.

I think both of []bytes(mc.cfg.Passwd) and append([]bytes(mc.cfg.Passwd), 0) are allocate once.

Anyway, code around addNUL looks ugly, and this code is used only for authentication, not query.
So performance difference should be ignorable.
@methane
Check writtenAuthRespLen in tests.
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@methane methane mentioned this pull request Nov 11, 2018
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@julienschmidt
julienschmidt approved these changes Nov 12, 2018
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@methane methane merged commit 369b5d6 into go-sql-driver:master Nov 13, 2018
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@methane methane deleted the methane:fix-884 branch Nov 13, 2018
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@jpeirson jpeirson commented Nov 13, 2018

I can confirm that the fixes in 369b5d6 fix the issue I was having.
julienschmidt added a commit that referenced this pull request Nov 14, 2018
@methane @julienschmidt
Fix Auth Resnponse packet for cleartext password (#887)
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fb9c42f 
Trailing NUL char should be in `string[n] auth-response`.
But NUL was after auth-response.
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