When creating metalink_checksum from metalink_checksum_t, first
check hex digest is valid for the given hash function. We do
this check in the order of digest_aliases so that first good
match will be chosen (strongest hash function available). As a
result, the metalinkfile now only contains at most one
metalink_checksum because other entries are just redundant.
Additionally, make hash checking ability mandatory in order to allow metalink
support in curl.
A command line option could be introduced to skip hash checking at runtime,
but the ability to check hashes should always be built-in when providing
metalink support.
Metalink file contains several hash types of checksums, such as
md5, sha-1, sha-256, etc. To deal with these checksums, I created
abstraction layer based on lib/curl_md5.h and
lib/md5.c. Basically, they are almost the same but I changed the
code so that it is not hash type dependent. Currently,
GNUTLS(nettle or gcrypt) and OpenSSL functions are supported.
Checksum checking is done by reopening download file. If there
is an I/O error, the current implementation just prints error
message and does not try next resource.
In this patch, the supported hash types are: md5, sha-1 and sha-256.
This change adds experimental Metalink support to curl.
To enable Metalink support, run configure with --with-libmetalink.
To feed Metalink file to curl, use --metalink option like this:
$ curl -O --metalink foo.metalink
We use libmetalink to parse Metalink files.
