[Bug debuginfod/27277] Describe retrieved files when verbose

[Mark Wielaard]

Hi Noah,

Looks like I reviewed a slightly older version earlier.  Could you
merge the reviewes/changes for both version in a new version of this
patch?

On Fri, Aug 27, 2021 at 02:38:27PM -0400, Noah Sanci via Elfutils-devel wrote:
> From ed7638571f188e346dd466c195b9ebda028d1c65 Mon Sep 17 00:00:00 2001
> From: Noah Sanci <nsanci@redhat.com>
> Date: Wed, 28 Jul 2021 14:46:05 -0400
> Subject: [PATCH] debuginfod: PR27277 - Describe retrieved files when verbose
> 
> There appear to exist use cases that intend to simply check for the
> existence of content in a debuginfod server, without actually
> downloading it.  In HTTP land, the HEAD operation is the natural
> expression of this.
> Instead of implementing a HEAD/describe option, allow users, with enough
> verbosity, to print the HTTP response headers upon retrieving a file.

Same comment as earlier, but now please also state the debuginfod
changes itself (the extra headers added).

> E.g output:
> 
> HTTP/1.1 200 OK
> Connection: Keep-Alive
> Content-Length: 2428240
> Cache-Control: public
> Last-Modified: Sat, 15 May 2021 20:49:51 GMT
> X-FILE: "file name"
> X-FILE-SIZE: "byte length of file"

I think an actual output example is better than including "place
holder text".

> +2021-08-02  Noah Sanci  <nsanci@redhat.com>
> +
> +	PR27277
> +	* debuginfod-client.c (struct debuginfod_client): New field
> +	winning_headers.
> +	(struct handle_data): New field response_data.
> +	(header_callback): Store received headers in response_data.
> +	(debuginfod_query_server): Activate CURLOPT_HEADERFUNCTION.
> +	Save winning response_data.
> +	(debuginfod_end): free client winning headers.
> +	* debuginfod.cxx (handle_buildid_f_match): remove X-FILE path. Add
> +	X-FILE and X-FILE-SIZE headers.
> +	(handle_buildid_r_match): remove X-FILE path. Add X-FILE, X-FILE-SIZE
> +	headers, and X-ARCHIVE headers.

So the changes compared to the other one are just in the
debuginfod.cxx file.

> diff --git a/debuginfod/debuginfod.cxx b/debuginfod/debuginfod.cxx
> index 6e182a84..e9b7e76c 100644
> --- a/debuginfod/debuginfod.cxx
> +++ b/debuginfod/debuginfod.cxx
> @@ -1068,6 +1068,9 @@ handle_buildid_f_match (bool internal_req_t,
>    else
>      {
>        MHD_add_response_header (r, "Content-Type", "application/octet-stream");
> +      std::string file = b_source0.substr(b_source0.find_last_of("/")+1, b_source0.length());
> +      MHD_add_response_header (r, "X-FILE-SIZE", to_string(s.st_size).c_str() );
> +      MHD_add_response_header (r, "X-FILE", file.c_str() );
>        add_mhd_last_modified (r, s.st_mtime);
>        if (verbose > 1)
>          obatched(clog) << "serving file " << b_source0 << endl;
> @@ -1537,6 +1540,9 @@ handle_buildid_r_match (bool internal_req_p,
>        inc_metric ("http_responses_total","result","archive fdcache");
>  
>        MHD_add_response_header (r, "Content-Type", "application/octet-stream");
> +      MHD_add_response_header (r, "X-FILE-SIZE", to_string(fs.st_size).c_str());
> +      MHD_add_response_header (r, "X-ARCHIVE", b_source0.c_str());
> +      MHD_add_response_header (r, "X-FILE", b_source1.c_str());
>        add_mhd_last_modified (r, fs.st_mtime);
>        if (verbose > 1)
>          obatched(clog) << "serving fdcache archive " << b_source0 << " file " << b_source1 << endl;
> @@ -1678,6 +1684,11 @@ handle_buildid_r_match (bool internal_req_p,
>        else
>          {
>            MHD_add_response_header (r, "Content-Type", "application/octet-stream");
> +          std::string file = b_source1.substr(b_source1.find_last_of("/")+1, b_source1.length());
> +          MHD_add_response_header (r, "X-FILE-SIZE", to_string(fs.st_size).c_str());
> +          MHD_add_response_header (r, "X-ARCHIVE", b_source0.c_str());
> +          MHD_add_response_header (r, "X-FILE", file.c_str());
> +
>            add_mhd_last_modified (r, archive_entry_mtime(e));
>            if (verbose > 1)
>              obatched(clog) << "serving archive " << b_source0 << " file " << b_source1 << endl;

This looks good. But I wonder if, since these are headers specific to
debuginfod, they shouldn't be named X-DEBUGINFOD-... Just to make sure
they don't clash with any others a proxy might insert.

> +2021-08-04  Noah Sanci  <nsanci@redhat.com>
> +
> +	PR27277
> +	* debuginfod-find.1: Increasing verbosity describes the downloaded
> +	file.
> +	* debuginfod.8: Describe X-FILE, X-FILE-SIZE, and X-ARCHIVE.
> +

> diff --git a/doc/debuginfod.8 b/doc/debuginfod.8
> index 5b0d793c..e9c58fbb 100644
> --- a/doc/debuginfod.8
> +++ b/doc/debuginfod.8
> @@ -256,6 +256,13 @@ Unknown buildid / request combinations result in HTTP error codes.
>  This file service resemblance is intentional, so that an installation
>  can take advantage of standard HTTP management infrastructure.
>  
> +Upon finding a file in an archive or simply in the database, some
> +custom http headers are added to the response. For files in the
> +database X-FILE and X-FILE-SIZE are added. X-FILE is simply the
> +filename and X-FILE-SIZE is the size of the file. For files found
> +in archives, in addition to X-FILE and X-FILE-SIZE, X-ARCHIVE is added.
> +X-ARCHIVE is the name of the the file was found in.

Probably should mention that the file name is unescaped (not url
encoded). The last sentence has too many "the". I think a word is
missing between the last two.

I have again not reviewed the testcase yet.

Cheers,

Mark