Convert ng_deflate to use new zlib.

[delphij]

Summary

Convert ng_deflate to use new zlib.

Test Plan

Test against mpd5 PPTP server with deflate enabled, watch the numbers reported.

[ota_j.email.ne.jp]

I haven't looked into FreeBSD extension of zlib yet to see if this change is safe.

sys/netgraph/ng_deflate.c

489 ↗

(On Diff #60573)

Z_PACKET_FLUSH is the FreeBSD only and specific implementation.

[delphij]

Revamp.

[delphij]

(Hopefully have fixed all issues I have found so far).

[delphij]

Remove bogus inflateInit().

[emaste]

(I've looked over the change other than the just update dictionary section so far)

sys/netgraph/ng_deflate.c

377–379 ↗

(On Diff #60711)

unrelated whitespace change?

485 ↗

(On Diff #60711)

maybe a kassert that outlen > 4 && the last 4 bytes are the expected 00 00 ff ff?

[delphij]

Undo unrelated space change.

[delphij]

Assert that the empty block actually exists.

[ota_j.email.ne.jp]

I will take a closer look.
I've never used nor looked into details of this API.
Please allow me a bit extra time for review.

[ota_j.email.ne.jp]

sys/netgraph/ng_deflate.c

667 ↗

(On Diff #60875)

Does this fnflate() really do a work?
Its output buffer begins with priv->outbuf just like before although it passes the fake header to zlib.
Is this to pass the size of uncompressed stream to zip?

[delphij]

sys/netgraph/ng_deflate.c

667 ↗

(On Diff #60875)

Yes, this would pass the uncompressed data through inflate engine and update the dictionary, which will be used for later decompression (the first few packets are not compressible normally).

[ota_j.email.ne.jp]

The change looks reasonable based on PPP protocol and comparison to existing zlib code.

I didn't know ng_deflate was for ppp.
I was curious how others implemented and found that NetBSD, OpenBSD, and Linux uses Z_PACKET_FLUSH as well, interestingly.
I never looked at ppp implementation and didn't know all others have same base code along with modified zlib.
I am no longer sure if Z_PACKET_FLUSH was FreeBSD original implementation.

It will be nice if we can get another person familiar with netgraph/ppp.

[delphij]

In D21186#463637, @ota_j.email.ne.jp wrote:

The change looks reasonable based on PPP protocol and comparison to existing zlib code.

I didn't know ng_deflate was for ppp.
I was curious how others implemented and found that NetBSD, OpenBSD, and Linux uses Z_PACKET_FLUSH as well, interestingly.
I never looked at ppp implementation and didn't know all others have same base code along with modified zlib.
I am no longer sure if Z_PACKET_FLUSH was FreeBSD original implementation.

No, it was not. Z_PACKET_FLUSH was from Paul Mackerras's PPP package, where the original PPP specific version of zlib was bundled. You can find additional history at Paul's git repository at https://github.com/paulusmack/ppp .

It will be nice if we can get another person familiar with netgraph/ppp.

Unfortunately, all reviewers didn't respond my private requests except Alexander who have gave me some hints on how to test the code.

I have so far only gently tested it against another FreeBSD -STABLE system with deflate enabled to make sure that two way communication with it still works.

[ota_j.email.ne.jp]

Thank you for explanations.
I found and had looked at that git repo while reviewing this change.
However, I didn't have enough guts to look into each of repo history to figure out which one came from where.
That explains why all of ppp use Z_PACKET_FLUSH while really NONE uses Z_SYNC_FLUSH.