tree 4dbafcfc7ac55661d0aee508eaa07328e27844b6
parent b2d3c10cdc8fb642a842db2c6061743b4604b0b5
author David Benjamin <davidben@google.com> 1658972511 -0700
committer Boringssl LUCI CQ <boringssl-scoped@luci-project-accounts.iam.gserviceaccount.com> 1661448950 +0000

Track SSL_ERROR_ZERO_RETURN explicitly.

Most SSL_ERROR_* values are tracked directly with rwstate. SSL_get_error
is just reading the extra return value out from the previous call.
However, SSL_ERROR_ZERO_RETURN infers close_notify from the SSL's
shutdown state and a zero return value (EOF).

This works, but if we implement SSL_read_ex and SSL_write_ex, a zero
return value is no longer as carefully correlated with EOF. Moreover,
it's already possible to get a non-EOF zero return post-close_notify if
BIO_write returns an (arguably incorrect) return value. Instead, track
SSL_ERROR_ZERO_RETURN in rwstate explicitly.

Since rwstate is exposed as SSL_want and SSL_ERROR_ZERO_RETURN was
previously never returned there, I've made it map SSL_ERROR_ZERO_RETURN
back to SSL_ERROR_NONE. I've also added a test for BIO_write returning
zero, though the real purpose is for a subsequent SSL_write_ex
implementation to retain all the other tests we've added in here.

Update-Note: This is intended to be safe, but if anything breaks around
EOFs, this change is a likely culprit.

Bug: 507
Change-Id: Ide0807665f2e02ee695c4976dc5e99fb10502cf0
Reviewed-on: https://boringssl-review.googlesource.com/c/boringssl/+/53946
Auto-Submit: David Benjamin <davidben@google.com>
Reviewed-by: Adam Langley <agl@google.com>
Commit-Queue: David Benjamin <davidben@google.com>