Protocols v2 no_std support

[Georges760]

Here are a couple of change to avoid getrandom which is not compatible with no_std.

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 2 lines in your changes missing coverage. Please review.

Project coverage is 19.08%. Comparing base (757b9ef) to head (1694832).
Report is 12 commits behind head on main.

Files with missing lines	Patch %	Lines
protocols/v2/codec-sv2/src/encoder.rs	0.00%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1394      +/-   ##
==========================================
- Coverage   19.08%   19.08%   -0.01%     
==========================================
  Files         166      166              
  Lines       11066    11068       +2     
==========================================
  Hits         2112     2112              
- Misses       8954     8956       +2     

Flag	Coverage Δ
binary_codec_sv2-coverage	0.00% <0.00%> (ø)
binary_serde_sv2-coverage	3.55% <0.00%> (-0.01%)	⬇️
binary_sv2-coverage	5.34% <0.00%> (-0.01%)	⬇️
bip32_derivation-coverage	0.00% <ø> (ø)
buffer_sv2-coverage	25.02% <ø> (ø)
codec_sv2-coverage	0.01% <0.00%> (ø)
common_messages_sv2-coverage	0.13% <0.00%> (-0.01%)	⬇️
const_sv2-coverage	0.00% <0.00%> (ø)
error_handling-coverage	0.00% <ø> (ø)
framing_sv2-coverage	0.28% <0.00%> (-0.01%)	⬇️
jd_client-coverage	0.00% <ø> (ø)
jd_server-coverage	7.79% <ø> (ø)
job_declaration_sv2-coverage	0.00% <0.00%> (ø)
key-utils-coverage	2.39% <ø> (ø)
mining-coverage	2.44% <0.00%> (-0.01%)	⬇️
mining_device-coverage	0.00% <ø> (ø)
mining_proxy_sv2-coverage	0.70% <ø> (ø)
noise_sv2-coverage	4.44% <0.00%> (-0.01%)	⬇️
pool_sv2-coverage	2.04% <ø> (ø)
protocols	24.57% <0.00%> (-0.01%)	⬇️
roles	6.54% <ø> (ø)
roles_logic_sv2-coverage	7.93% <0.00%> (-0.01%)	⬇️
sv2_ffi-coverage	0.00% <0.00%> (ø)
template_distribution_sv2-coverage	0.00% <0.00%> (ø)
translator_sv2-coverage	9.60% <ø> (ø)
utils	25.13% <ø> (ø)
v1-coverage	2.41% <0.00%> (-0.01%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[plebhash]

thanks for this @Georges760

on the PR description you mention:

getrandom which is not compatible with no_std

I was looking at the Rust Docs for the getrandom crate, and I noticed a few things:

• description of Error type mentions no_std support
• list of feature flags has a std feature
• the crate supports WASM targets
• the link you provided (https://docs.rs/getrandom/latest/getrandom/#unsupported-targets) doesn't seem to resolve to anything (more specifically, the #unsupported-targets suffix)

while I don't really oppose this PR (as the changes are mostly harmless) I wonder if the initial assumptions are correct?

[Georges760]

thanks for this @Georges760

on the PR description you mention:

getrandom which is not compatible with no_std

I was looking at the Rust Docs for the getrandom crate, and I noticed a few things:

• description of Error type mentions no_std support
• list of feature flags has a std feature
• the crate supports WASM targets
• the link you provided (https://docs.rs/getrandom/latest/getrandom/#unsupported-targets) doesn't seem to resolve to anything (more specifically, the #unsupported-targets suffix)

while I don't really oppose this PR (as the changes are mostly harmless) I wonder if the initial assumptions are correct?

To be accurate getrandom crate can be no_std for WASM for example, but is not compatible with embedded system (often amalgamed to no_std).

In embedded system the HW RNG can be (and should be) used to get random number. That's why in noise_sv and codec_sv2 (and key-utils too) I had to add an intermediary API for embedded system to provide their specific HW RNG by argument of xxx_with_rng() function.
getrandom is a (convenient) crate that get random number from any std or some no_std system but not all. It can't know about the specific HW RNG that some MCU have.

Trying to build the stm32_sv2 demo (in the context of embedded stm32 embassy project), the build fail on getrandom because we are not in a supported target.
But the getrandom dependancy is itself unused and result in a lazy dep feature selection, so just adding some features to some deps, remove the getrandom crate from the depenancy graph (without the need to provide any other RNG so it proves it was not used at all).

TLDR: you are right the inital assumption was incorrect, was just a shortcut of all above explanations.

[Sjors]

Code review ACK 1694832

Caveat: I'm not a Rust dev :-)

[jbesraa]

LGTM

[plebhash]

hey @Georges760 we're ready to merge this

unfortunately our magic ready-to-be-merged label doesn't work to keep this up-to-date, so we have to coordinate so you rebase it and we merge this before some other PR

[Shourya742]

I want to re-review this, can we defer merging till tomorrow?

[plebhash]

ping @Georges760 again, I guess now we're good to go