npm versions published before dist.integrity existed carry only a SHA-1
dist.shasum, and Composer metadata lists only a SHA-1 dist.shasum, so
neither could be checked.
- Accept native integrity given as an algorithm-prefixed hex checksum,
verified with integrity's exact-digest check, so a recorded "sha1-<hex>"
is also checked on cache hits
- npm: fall back to dist.shasum when dist.integrity is missing or cannot
be parsed; a usable dist.integrity still takes precedence
- Composer: verify an archive against its dist.shasum, except another
commit of a branch fetched in place of the listed one, which the listed
shasum does not describe
- Fetch unverified as before when no shasum is listed, as Packagist does
for GitHub archives, or it is not a SHA-1 digest
The proxy cached the first tarball upstream sent for a version without
checking it against the packument, so a tampered tarball was served to
every client after it.
- Pass the packument's dist.integrity to the existing integrity checks, so
a fresh tarball is verified as it is stored or streamed; a mismatch is
discarded and returns 502, or aborts the streamed response
- Record it with the cached version, so cache hits are verified against it
through the same check as before
- Verify with integrity.Result.Verify, which accepts any digest of the
strongest algorithm listed
- Fetch unverified as before when dist.integrity is missing or cannot be
parsed, or the packument cannot be fetched
