raw: optional IP version and next_header

[KingCol13]

Fixes #1064

Makes ip_version and ip_protocol fields of RawSocket into options, when None the socket will not check this field when sending or receiving.

[codecov]

Codecov Report

Attention: Patch coverage is 93.02326% with 3 lines in your changes missing coverage. Please review.

Project coverage is 81.16%. Comparing base (e2b75e3) to head (9779059).
Report is 5 commits behind head on main.

Files with missing lines	Patch %	Lines
src/socket/raw.rs	93.02%	3 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1067      +/-   ##
==========================================
- Coverage   81.17%   81.16%   -0.01%     
==========================================
  Files          81       81              
  Lines       28955    28974      +19     
==========================================
+ Hits        23503    23516      +13     
- Misses       5452     5458       +6     

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[whitequark]

I have two concerns.

1. This is a breaking change. @Dirbaio, do we just increment the minor? I'm not sure what the current policy is.
2. Should these be two individual options, or one option with a tuple of (IpVersion, IpProtocol)?

[KingCol13]

1. This is a breaking change. @Dirbaio, do we just increment the minor? I'm not sure what the current policy is.

Following Rust's modified semantic versioning we'd bump to 0.13.0. I don't know if that should be done in this PR or just before release though. Let me know if you want me to add to the changelog.

2. Should these be two individual options, or one option with a tuple of (IpVersion, IpProtocol)?

Two options gives users more flexibility, e.g. if I want to accept all Ipv4 packets without filtering on the protocol.

[whitequark]

Two options gives users more flexibility, e.g. if I want to accept all Ipv4 packets without filtering on the protocol.

Yes, good point. I'm fine with two options.

I haven't done release engineering on smoltcp in a while so I think we can just merge this, noting that the next release should be a minor bump.