Fix 'panic: runtime error: slice bounds out of range'

[richardwilkes]

Description

The code added in commit f557730 introduced a bug that prevents access to some databases by failing to check to see if the data it is looking for was actually present. This corrects that.

Discovered using MemSQL 5.5.8.

The data in the packet that was received in the readInitPacket() function was:

[10 53 46 53 46 56 0 165 0 0 0 60 70 63 58 68 104 34 97 0 223 247 33 2 0 15 128 21 0 0 0 0 0 0 0 0 0 0 98 120 114 47 85 75 109 99 51 77 50 64 0 109 121 115 113 108 95 110 97 116 105 118 101 95 112 97 115 115 119 111 114 100]

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

[julienschmidt]

The TODO section right below seems to be about the plugin name. If no NUL byte is found it should use data[pos:] instead (end-of-file / packet), I think.

Edit: Please also use our pull-request template.

[richardwilkes]

Made the suggested change and updated the initial description to use your template. Did not mark each section with a check as I didn't touch those areas -- not clear whether they should be checked despite this.

[julienschmidt]

Do you mind moving the

// EOF if version (>= 5.5.7 and < 5.5.10) or (>= 5.6.0 and < 5.6.2)
// \NUL otherwise

above the pluginName code and remove the TODO and other commented-out code? It was there because we didn't read the plugin name so far.

[julienschmidt]

Can you also tell use how you ran into that bug, i.e. what database server and version you are using?
Even better, but not mandatory, would be a packet dump, which we could use in a regression test.

[julienschmidt]

I meant moving the comment here (add an extra blank line above). Besides that, the changes LGTM.

[richardwilkes]

Ah... ok, will do

[julienschmidt]

Thanks!

[collinalexbell]

I am getting the following error with this new code:

unknown authentication plugin name ''

With the old code, I get the slice bounds out of range error.