[Bug debuginfod/28284] New: support description functionality through HEAD

[Bug debuginfod/28284] New: support description functionality through HEAD

[nsanci at redhat dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=28284

            Bug ID: 28284
           Summary: support description functionality through HEAD
           Product: elfutils
           Version: unspecified
            Status: NEW
          Severity: normal
          Priority: P2
         Component: debuginfod
          Assignee: unassigned at sourceware dot org
          Reporter: nsanci at redhat dot com
                CC: elfutils-devel at sourceware dot org
  Target Milestone: ---

Currently, checking the existence of a file and gathering its information
requires a user to download the file. This can be inconvenient for some users
who, for example, are curious to know information on a file before its
downloaded. Queries should be supported which allow a user to analyze some
information relating to a file without downloading it.

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[Bug debuginfod/28284] support description functionality through HEAD

[nsanci at redhat dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=28284

Noah Sanci <nsanci at redhat dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Assignee|unassigned at sourceware dot org   |nsanci at redhat dot com

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[Bug debuginfod/28284] support description functionality through HEAD

[fche at redhat dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=28284

Frank Ch. Eigler <fche at redhat dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |fche at redhat dot com

--- Comment #1 from Frank Ch. Eigler <fche at redhat dot com> ---
The tricky aspect of this is not so much the webapi, but the C api and the
debuginfod-find cli.

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[Bug debuginfod/28284] support description functionality through HEAD

[mark at klomp dot org]

https://sourceware.org/bugzilla/show_bug.cgi?id=28284

Mark Wielaard <mark at klomp dot org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |mark at klomp dot org

--- Comment #2 from Mark Wielaard <mark at klomp dot org> ---
A suggested C api was discussed here:
https://sourceware.org/pipermail/elfutils-devel/2021q4/004239.html
(see also the whole thread in the previous quarter)

/* Get info about an debuginfod artifact. Used to know whether
   the target is already in local cache or whether it can be retrieved
   from one if the urls contained in $DEBUGINFOD_URLS.

   If build_id_len == 0, the build_id is supplied as a lowercase
   hexadecimal string; otherwise it is a binary blob of given length.

   If the requested resource is in cache, return a file descriptor
   which an be used as is. If the requested resource can be found
   through one of the DEBUGINFOD_URLS then -1 is returned and
   file_size and transfer_size are set to the number of bytes of
   the target file and the number if bytes that need to be transferred
   from the server (file_size is the uncompressed size, transfer_size
   might be the compressed size). Otherwise return -2 to indicate the
   requested artifact cannot be found.

   If the file wasn't in cache, but can be retrieved from a remote
   server, then debuginfod_get_url () will return where the target
   can be found. A successive debuginfod_find_* call will retieve
   the resource (unless a network error occurs).  */

int debuginfod_info_debuginfo (debuginfod_client *client,
                               const unsigned char *build_id,
                               int build_id_len,
                               size_t *size, size_t *transfer_size);

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[Bug debuginfod/28284] support description functionality through HEAD

[fche at redhat dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=28284

--- Comment #3 from Frank Ch. Eigler <fche at redhat dot com> ---
The problem of federation reminded me that we haven't solved this problem yet.

> int debuginfod_info_debuginfo (debuginfod_client *client,
>                                const unsigned char *build_id,
>                                int build_id_len,
>                                size_t *size, size_t *transfer_size);

It'd also need the other current X-DEBUGINFOD-* response headers, -FILE: and
-ARCHIVE:.  And we'd need two other functions for source and executable.  And
if any fields get added at the server by our software (or someone else's
proxy!), the API would have to expand to match.

For federation purposes, we'd need to forward all these headers from upstream
to downstream.  And we'd like to get this data for an active transfer, not
really a historical one (don't want to have to save/cache), and not make an
extra query to a debuginfod server just to fetch this.

These considerations lead me back to suggesting an API oriented toward fetching
the headers of the current/last fetch made with a debuginfod_client, just like
the debuginfod_get_url(), returning some subset of what's currently stored by
the client code as ->winning_headers.  Specifically, I'd say save & return
those response headers with prefix "x-debuginfod-".

These ones would be the same ones that a hypothetical "debuginfod-find -d"
(describe?) option would want to print to stderr: a more concentrated output
than the -v (verbose) firehose we were talking about earlier.

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[Bug debuginfod/28284] support description functionality through HEAD

[nsanci at redhat dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=28284

Noah Sanci <nsanci at redhat dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Assignee|nsanci at redhat dot com           |unassigned at sourceware dot org

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[Bug debuginfod/28284] support description functionality through HEAD

[fche at redhat dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=28284

Frank Ch. Eigler <fche at redhat dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |mliska at suse dot cz

--- Comment #4 from Frank Ch. Eigler <fche at redhat dot com> ---
*** Bug 29469 has been marked as a duplicate of this bug. ***

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[Bug debuginfod/28284] support description functionality through HEAD

[mliska at suse dot cz]

https://sourceware.org/bugzilla/show_bug.cgi?id=28284

Martin Liska <mliska at suse dot cz> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           See Also|                            |https://sourceware.org/bugz
                   |                            |illa/show_bug.cgi?id=29472

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[Bug debuginfod/28284] support description functionality through HEAD

[fche at redhat dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=28284

Frank Ch. Eigler <fche at redhat dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|---                         |FIXED

--- Comment #5 from Frank Ch. Eigler <fche at redhat dot com> ---
commit 8760e931abf33ed2b215809d5ebf653ced934152
Author: Frank Ch. Eigler <fche@redhat.com>
Date:   Fri Sep 2 12:41:38 2022 -0400

    PR28284: add tweaks on previous debuginfod x-debuginfod* header forwarding
work

    Embrace case-independent headers, more fully document, handle HTTP \r.
    In addition to test case, hand-tested against fedora debuginfod
    instances, running federated servers under valgrind.

    Signed-off-by: Frank Ch. Eigler <fche@redhat.com>

commit bbc2ca6d553f0ce3e670303ac9a3c764cf10d779
Author: Noah Sanci <nsanci@redhat.com>
Date:   Wed Jun 15 10:07:29 2022 -0400

    PR28284 - Debuginfod header functionality implemented

    Debuginfod and debuginfod clients are now equipped to send
    and receive http headers prefixed with X-DEBUGINFOD and
    print them in verbose mode for more context

    Signed-off-by: Noah Sanci <nsanci@redhat.com>

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