cleanup: Use memzero(x, s) instead of memset(x, 0, s).

[iphydf]

It's clearer and doesn't risk having a non-zero filler value.

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This change is 

[codecov]

Codecov Report

Attention: 5 lines in your changes are missing coverage. Please review.

Comparison is base (a7258e4) 73.60% compared to head (7dba23d) 73.60%.

❗ Current head 7dba23d differs from pull request most recent head 8f07755. Consider uploading reports for the commit 8f07755 to get more accurate results

Files	Patch %	Lines
toxcore/group_chats.c	66.66%	2 Missing ⚠️
toxcore/crypto_core.c	88.88%	1 Missing ⚠️
toxcore/friend_connection.c	0.00%	1 Missing ⚠️
toxcore/network.c	75.00%	1 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #2594   +/-   ##
=======================================
  Coverage   73.60%   73.60%           
=======================================
  Files         148      148           
  Lines       30342    30339    -3     
=======================================
- Hits        22333    22332    -1     
+ Misses       8009     8007    -2     

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[JFreegman]

Reviewed 16 of 17 files at r1, 2 of 2 files at r2, all commit messages.
Reviewable status: 1 change requests, 0 of 1 approvals obtained (waiting on @iphydf)

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toxcore/net_crypto.c line 1142 at r2 (raw file):

    memcpy(packet, &buffer_start, sizeof(uint32_t));
    memcpy(packet + sizeof(uint32_t), &num, sizeof(uint32_t));
    memzero(packet + (sizeof(uint32_t) * 2), padding_length);

I'm not sure about this one. The packet padding bytes needs to match PACKET_ID_PADDING, which we're now just assuming is 0. We should either remove the define or adhere to it.

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toxcore/util.h line 52 at r2 (raw file):

/**
 * @brief Set all bytes in `data` to 0.

Maybe mention that this doesn't do a secure wipe, and a different function should be used for sensitive data.

[iphydf]

Reviewable status: 1 change requests, 0 of 1 approvals obtained (waiting on @JFreegman)

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toxcore/net_crypto.c line 1142 at r2 (raw file):

Previously, JFreegman wrote…

I'm not sure about this one. The packet padding bytes needs to match PACKET_ID_PADDING, which we're now just assuming is 0. We should either remove the define or adhere to it.

I agree. #2593 should be done first. I factored that out of this PR into a separate PR.

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toxcore/util.h line 52 at r2 (raw file):

Previously, JFreegman wrote…

Maybe mention that this doesn't do a secure wipe, and a different function should be used for sensitive data.

Good point. Added.

[JFreegman]

Reviewed 1 of 1 files at r3, 1 of 1 files at r4, all commit messages.
Reviewable status: complete! 1 of 1 approvals obtained