implement reading comment from openssh private key

[topia]

Reading key comment from an openssh private key, Because it's encrypted, added callback on Decrypt.
https://github.com/openssh/openssh-portable/blob/4a1805d532616233dd6072e5cd273b96dd3062e6/PROTOCOL.key#L38-L39

See also: dlech/KeeAgent#375

[dlech]

Thanks for the PR.

Instead of adding a callback for the comment, could we just add a property for it like we already have for all of the other info parsed from the private key?

[topia]

Instead of adding a callback for the comment, could we just add a property for it like we already have for all of the other info parsed from the private key?

Thanks for your comment. I want to make sure which method you said; I think two options for that:

1. drop callback for SshPrivateKey.Decrypt only

• keep callback for internal DecryptFunc. it makes short diff and simple changes but might be confusing for implementors.

2. drop callback for Decrypt and DecryptFunc

• closure needs to keep a reference for SshPrivateKey to update its property, or maybe we can pass this to the delegate.

Also, How about the type of that property? I consider string? because I think it has three states - (not loaded/private key doesn't have any comment), (loaded but empty comment), (loaded and some comment).
Sometimes we want to distinguish between not loaded and loaded but no comment field for telling the caller a behavior of that property.

[dlech]

Apparently, I didn't think about it enough. 😄

A property that we have to update doesn't seem right since we want the object to be immutable.

Instead of a callback in the decrypt function though, it seems like it would be simpler to just have an out paramter (or modify the return value to return a ValueTuple).

[topia]

I started with the callback design to keep source-level compatibility for them.
But now I changed all callers for some reason. I'll consider the out parameter for that.

[codecov-commenter]

Codecov Report

Merging #23 (d12cce6) into master (1dcb0ed) will decrease coverage by 0.05%.
The diff coverage is 75.00%.

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@@            Coverage Diff             @@
##           master      #23      +/-   ##
==========================================
- Coverage   51.83%   51.79%   -0.05%     
==========================================
  Files          37       37              
  Lines        5533     5553      +20     
  Branches      503      504       +1     
==========================================
+ Hits         2868     2876       +8     
- Misses       2482     2493      +11     
- Partials      183      184       +1     

Impacted Files	Coverage Δ
SshAgentLib/IAgent.cs	0.00% <0.00%> (ø)
SshAgentLib/Keys/OpensshPrivateKey.cs	75.48% <100.00%> (+0.48%)	⬆️
SshAgentLib/Keys/PemPrivateKey.cs	82.00% <100.00%> (+2.45%)	⬆️
SshAgentLib/Keys/PuttyPrivateKey.cs	79.60% <100.00%> (+0.49%)	⬆️
SshAgentLib/Keys/SshPrivateKey.cs	80.00% <100.00%> (ø)
SshAgentLib/WslSocket.cs	83.51% <0.00%> (-7.70%)	⬇️

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