[net] Add libcurl based support for files on HTTP remotes

[jblomer]

Add new TFile and RRawFile plugins that use libcurl for the HTTP transfers. This can eventually replace the Davix dependency and also the older TWebFile and TS3WebFile. The curl library gives access to a modern HTTP implementation (e.g., h2), and it works on Linux, macOS, and Windows with their respective native SSL stacks.

@bellenot: on Windows, we may need to build libcurl ourselves. As far as I understand, Windows ships the curl command line library but not the library.

The current implementation does HEAD and (multi-)range GET queries, which provides the basics for efficient use of HTTP in ROOT. It can be enabled with -Dcurl=on. If davix is available alongside the curl plugins, the curl plugins replace the davix plugins if Curl.ReplaceDavix: yes is set in the rootrc file.

Authentication can relatively easily be added, since S3 (AWSv4 signatures), bearer token authentication and X.509 client certificates are already supported by libcurl.

Metalink support can in principle be added if still needed. It requires XML parsing of the metalink snippet.

Write support (POST, PUT) requests can in principle be added if still needed, but require a closer look.

See also root-project/root-ci-images#73 and root-project/root-ci-images#75

Note that for the moment we disable curl on EL8 due to the old libcurl version on this platform.

[bellenot]

@jblomer I'll check

[github-actions]

Test Results

    22 files      22 suites   3d 20h 8m 20s ⏱️
 3 757 tests  3 757 ✅ 0 💤 0 ❌
75 642 runs  75 642 ✅ 0 💤 0 ❌

Results for commit 1b75b5d.

♻️ This comment has been updated with latest results.

[bellenot]

Note that after successful build on Windows, some of the tests fail like:

The following tests FAILED:
        157 - gtest-io-io-RRawFile (Failed)
        262 - gtest-net-curl-rawfile-curl (Failed)
        263 - gtest-net-curl-tfile-curl (Failed)
        488 - gtest-tree-dataframe-datasource-csv (Failed)
        493 - gtest-tree-dataframe-datasource-sqlite (Failed)
Errors while running CTest

[dpiparo]

Thanks for these changes. I approved them provided that the win tests are understood and something in the release notes is added about this new option.

[bellenot]

Thanks @jblomer . FYI, I'll have to install libcurl and modify the environment on the build nodes (one after the other, by hand). Will try to do that tonight or over the weekend, and then I'll restart the builds on Windows.

[bellenot]

Thanks Jakob!