Expand SQLite3 data validation

[PimSanders]

This PR close #16 by expanding the data validation capabilities in SQLite3.

The SQLite3 WAL file can store multiple versions of the same frame, when reading only valid frames should be returned. The docs define a valid frame as follows:

A frame is considered valid if and only if the following conditions are true:

1. The salt-1 and salt-2 values in the frame-header match salt values in the wal-header
2. The checksum values in the final 8 bytes of the frame-header exactly match the checksum computed consecutively on the first 24 bytes of the WAL header and the first 8 bytes and the content of all frames up to and including the current frame.

The first check was already implemented, I have interpreted the second check as:

The checksum values in the final 8 bytes of the frame-header (checksum-1 and checksum-2) exactly match the computed checksum over:

1. the first 24 bytes of the WAL header
2. the first 8 bytes of each frame header (up to and including this frame)
3. the page data of each frame (up to and including this frame)

When initializing a database the option validate_checksum can be passed to use the new validation. I have chosen to only calculate the salts by default (just like before) as this will probably be good enough, and a lot faster. See the example below for the time impact:

In [1]: %timeit -n10 list(list(sqlite3.SQLite3(Path("./big.sqlite"), Path("./big.sqlite-wal"), validate_checksum=False).tables())[0].rows())
33 ms ± 1.06 ms per loop (mean ± std. dev. of 7 runs, 10 loops each)

In [2]: %timeit -n10 list(list(sqlite3.SQLite3(Path("./big.sqlite"), Path("./big.sqlite-wal"), validate_checksum=True).tables())[0].rows())
1.05 s ± 4.88 ms per loop (mean ± std. dev. of 7 runs, 10 loops each)

[codecov]

Codecov Report

❌ Patch coverage is 0% with 38 lines in your changes missing coverage. Please review.
✅ Project coverage is 0.00%. Comparing base (64ae6d8) to head (0e3eeb6).

Files with missing lines	Patch %	Lines
dissect/database/sqlite3/wal.py	0.00%	36 Missing ⚠️
dissect/database/sqlite3/sqlite3.py	0.00%	2 Missing ⚠️

Additional details and impacted files

@@          Coverage Diff          @@
##            main     #23   +/-   ##
=====================================
  Coverage   0.00%   0.00%           
=====================================
  Files        146     146           
  Lines       3881    3914   +33     
=====================================
- Misses      3881    3914   +33     

Flag	Coverage Δ
unittests	0.00% <0.00%> (ø)

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[codspeed-hq]

Merging this PR will not alter performance

✅ 6 untouched benchmarks

---

_{Comparing PimSanders:improvement/expand-wal-validation (0e3eeb6) with main (64ae6d8)}

[Schamper]

Maybe add a benchmark test too? I'll look at the actual checksum checking part later when I have a bit more time.

[Schamper]

Suggested change

	validate_checksum: bool = False,
	*,
	validate_checksums: bool = False,

Can you also add it to the docstring?

[Schamper]

Maybe change this to a verb-style name now that it's a method. is_valid?

[Schamper]

Suggested change

	def validate_salt(self) -> bool:
	"""Check if the frame's salt values match those in the WAL header.
	def is_valid_salt(self) -> bool:
	"""Return whether the frame's salt values match those in the WAL header.

[Schamper]

Suggested change

	def validate_checksum(self) -> bool:
	"""Check if the frame's checksum matches the calculated checksum.
	def is_valid_checksum(self) -> bool:
	"""Return whether the frame's checksum matches the calculated checksum.