debuginfod: PR27277 - Describe retrieved files when verbose

Allow users, with enough verbosity, to print the HTTP response headers
upon retrieving a file. These files may include several custome http
response headers such as X-DEBUGINFOD-FILE, X-DEBUGINFOD-SIZE, and
X-DEBUGINFOD-ARCHIVE. These headers are added from the daemon, in
debuginfod.cxx.

E.g output:

HTTP/1.1 200 OK
Connection: Keep-Alive
Content-Length: 4095072
Cache-Control: public
Last-Modified: Thu, 09 Sep 2021 19:06:40 GMT
X-FILE: debuginfod
X-FILE-SIZE: 4095072
Content-Type: application/octet-stream
Date: Fri, 10 Sep 2021 16:38:06 GMT

https://sourceware.org/bugzilla/show_bug.cgi?id=27277

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

9 files changed, 208 insertions, 3 deletions

diff --git a/debuginfod/ChangeLog b/debuginfod/ChangeLog
index 4649acee..e2e6c5f8 100644
--- a/debuginfod/ChangeLog
+++ b/debuginfod/ChangeLog
@@ -43,6 +43,22 @@
 	* debuginfod.cxx (handler_cb): Fix after_you unique_set key
 	to the entire incoming URL.
 
+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, response_data_size.
+	(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-DEBUGINFOD-FILE
+	path. Add X-DEBUGINFOD-FILE and X-DEBUGINFOD-SIZE headers.
+	(handle_buildid_r_match): remove X-DEBUGINFOD-FILE path. Add
+	X-DEBUGINFOD-FILE, X-DEBUGINFOD-SIZE
+	headers, and X-ARCHIVE headers.
+
 2021-07-26  Noah Sanci  <nsanci@redhat.com>
 
 	PR27982
diff --git a/debuginfod/debuginfod-client.c b/debuginfod/debuginfod-client.c
index 8a1c68d5..4d5dbd95 100644
--- a/debuginfod/debuginfod-client.c
+++ b/debuginfod/debuginfod-client.c
@@ -127,6 +127,7 @@ struct debuginfod_client
      timeout or other info gotten from environment variables, the
      handle data, etc. So those don't have to be reparsed and
      recreated on each request.  */
+  char * winning_headers;
 };
 
 /* The cache_clean_interval_s file within the debuginfod cache specifies
@@ -183,6 +184,9 @@ struct handle_data
      to the cache. Used to ensure that a file is not downloaded from
      multiple servers unnecessarily.  */
   CURL **target_handle;
+  /* Response http headers for this client handle, sent from the server */
+  char *response_data;
+  size_t response_data_size;
 };
 
 static size_t
@@ -498,6 +502,37 @@ default_progressfn (debuginfod_client *c, long a, long b)
   return 0;
 }
 
+/* This is a callback function that receives http response headers in buffer for use
+ * in this program. https://curl.se/libcurl/c/CURLOPT_HEADERFUNCTION.html is the
+ * online documentation.
+ */
+static size_t
+header_callback (char * buffer, size_t size, size_t numitems, void * userdata)
+{
+  if (size != 1)
+    return 0;
+  /* Temporary buffer for realloc */
+  char *temp = NULL;
+  struct handle_data *data = (struct handle_data *) userdata;
+  if (data->response_data == NULL)
+    {
+      temp = malloc(numitems+1);
+      if (temp == NULL)
+        return 0;
+    }
+  else
+    {
+      temp = realloc(data->response_data, data->response_data_size + numitems + 1);
+      if (temp == NULL)
+        return 0;
+    }
+
+  memcpy(temp + data->response_data_size, buffer, numitems);
+  data->response_data = temp;
+  data->response_data_size += numitems;
+  data->response_data[data->response_data_size] = '\0';
+  return numitems;
+}
 
 /* Query each of the server URLs found in $DEBUGINFOD_URLS for the file
    with the specified build-id, type (debuginfo, executable or source)
@@ -954,10 +989,14 @@ debuginfod_query_server (debuginfod_client *c,
 	  curl_easy_setopt (data[i].handle, CURLOPT_LOW_SPEED_LIMIT,
 			    100 * 1024L);
 	}
+      data[i].response_data = NULL;
+      data[i].response_data_size = 0;
       curl_easy_setopt(data[i].handle, CURLOPT_FILETIME, (long) 1);
       curl_easy_setopt(data[i].handle, CURLOPT_FOLLOWLOCATION, (long) 1);
       curl_easy_setopt(data[i].handle, CURLOPT_FAILONERROR, (long) 1);
       curl_easy_setopt(data[i].handle, CURLOPT_NOSIGNAL, (long) 1);
+      curl_easy_setopt(data[i].handle, CURLOPT_HEADERFUNCTION, header_callback);
+      curl_easy_setopt(data[i].handle, CURLOPT_HEADERDATA, (void *) &(data[i]));
 #if LIBCURL_VERSION_NUM >= 0x072a00 /* 7.42.0 */
       curl_easy_setopt(data[i].handle, CURLOPT_PATH_AS_IS, (long) 1);
 #else
@@ -980,6 +1019,7 @@ debuginfod_query_server (debuginfod_client *c,
   int committed_to = -1;
   bool verbose_reported = false;
   struct timespec start_time, cur_time;
+  c->winning_headers = NULL;
   if ( maxtime > 0 && clock_gettime(CLOCK_MONOTONIC_RAW, &start_time) == -1)
     {
       rc = errno;
@@ -1014,7 +1054,17 @@ debuginfod_query_server (debuginfod_client *c,
 	    if (data[i].handle != target_handle)
 	      curl_multi_remove_handle(curlm, data[i].handle);
 	    else
-	      committed_to = i;
+              {
+	        committed_to = i;
+                if (c->winning_headers == NULL)
+                  {
+                    c->winning_headers = data[committed_to].response_data;
+                    if (vfd >= 0 && c->winning_headers != NULL)
+                      dprintf(vfd, "\n%s", c->winning_headers);
+                    data[committed_to].response_data = NULL;
+                  }
+
+              }
 	}
 
       if (vfd >= 0 && !verbose_reported && committed_to >= 0)
@@ -1257,7 +1307,10 @@ debuginfod_query_server (debuginfod_client *c,
             {
               curl_multi_remove_handle(curlm, data[i].handle); /* ok to repeat */
               curl_easy_cleanup (data[i].handle);
+              free(data[i].response_data);
             }
+            free(c->winning_headers);
+            c->winning_headers = NULL;
 	    goto query_in_parallel;
 	}
       else
@@ -1300,6 +1353,7 @@ debuginfod_query_server (debuginfod_client *c,
     {
       curl_multi_remove_handle(curlm, data[i].handle); /* ok to repeat */
       curl_easy_cleanup (data[i].handle);
+      free (data[i].response_data);
     }
 
   for (int i = 0; i < num_urls; ++i)
@@ -1323,6 +1377,7 @@ debuginfod_query_server (debuginfod_client *c,
     {
       curl_multi_remove_handle(curlm, data[i].handle); /* ok to repeat */
       curl_easy_cleanup (data[i].handle);
+      free (data[i].response_data);
     }
 
   unlink (target_cache_tmppath);
@@ -1434,6 +1489,7 @@ debuginfod_end (debuginfod_client *client)
 
   curl_multi_cleanup (client->server_mhandle);
   curl_slist_free_all (client->headers);
+  free (client->winning_headers);
   free (client->url);
   free (client);
 }
diff --git a/debuginfod/debuginfod.cxx b/debuginfod/debuginfod.cxx
index 1267efbe..2b9a1c41 100644
--- a/debuginfod/debuginfod.cxx
+++ b/debuginfod/debuginfod.cxx
@@ -1087,6 +1087,9 @@ 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-DEBUGINFOD-SIZE", to_string(s.st_size).c_str() );
+      MHD_add_response_header (r, "X-DEBUGINFOD-FILE", file.c_str() );
       add_mhd_last_modified (r, s.st_mtime);
       if (verbose > 1)
         obatched(clog) << "serving file " << b_source0 << endl;
@@ -1556,6 +1559,9 @@ 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-DEBUGINFOD-SIZE", to_string(fs.st_size).c_str());
+      MHD_add_response_header (r, "X-DEBUGINFOD-ARCHIVE", b_source0.c_str());
+      MHD_add_response_header (r, "X-DEBUGINFOD-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;
@@ -1697,6 +1703,11 @@ 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-DEBUGINFOD-SIZE", to_string(fs.st_size).c_str());
+          MHD_add_response_header (r, "X-DEBUGINFOD-ARCHIVE", b_source0.c_str());
+          MHD_add_response_header (r, "X-DEBUGINFOD-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;
diff --git a/doc/ChangeLog b/doc/ChangeLog
index ada48383..db3a3584 100644
--- a/doc/ChangeLog
+++ b/doc/ChangeLog
@@ -18,6 +18,14 @@
 	* Makefile.am: Updated to include debuginfod-client-config.7
 	* man3, man7: Symlinks for source tree man page testing.
 
+2021-08-04  Noah Sanci  <nsanci@redhat.com>
+
+	PR27277
+	* debuginfod-find.1: Increasing verbosity describes the downloaded
+	file.
+	* debuginfod.8: Describe X-DEBUGINFOD-FILE, X-DEBUGINFOD-SIZE, and
+	X-DEBUGINFOD-ARCHIVE.
+
 2021-07-26  Noah Sanci <nsanci@redhat.com>
 
 	PR27982
diff --git a/doc/debuginfod-find.1 b/doc/debuginfod-find.1
index a61673f5..957ec7e7 100644
--- a/doc/debuginfod-find.1
+++ b/doc/debuginfod-find.1
@@ -110,7 +110,8 @@ l l.
 
 .TP
 .B "\-v"
-Increase verbosity, including printing frequent download-progress messages.
+Increase verbosity, including printing frequent download-progress messages
+and printing the http response headers from the server.
 
 
 .SH "SECURITY"
diff --git a/doc/debuginfod.8 b/doc/debuginfod.8
index f9a418d1..fde06bb8 100644
--- a/doc/debuginfod.8
+++ b/doc/debuginfod.8
@@ -258,6 +258,15 @@ 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-DEBUGINFOD-FILE and X-DEBUGINFOD-SIZE are added.
+X-DEBUGINFOD-FILE is simply the unescaped filename and
+X-DEBUGINFOD-SIZE is the size of the file. For files found in archives,
+in addition to X-DEBUGINFOD-FILE and X-DEBUGINFOD-SIZE,
+X-DEBUGINFOD-ARCHIVE is added.  X-DEBUGINFOD-ARCHIVE is the name of the
+archive the file was found in.
+
 There are three requests.  In each case, the buildid is encoded as a
 lowercase hexadecimal string.  For example, for a program \fI/bin/ls\fP,
 look at the ELF note GNU_BUILD_ID:
diff --git a/tests/ChangeLog b/tests/ChangeLog
index 3f219320..c73f2534 100644
--- a/tests/ChangeLog
+++ b/tests/ChangeLog
@@ -111,6 +111,12 @@
 
 	* debuginfod-subr.sh (EXTRA_DIST): Add debuginfod-subr.sh.
 
+2021-08-20  Noah Sanci  <nsanci@redhat.com>
+
+	* run-debuginfod-response-headers.sh: Ensures custom http response
+	headers are used and functional
+	* Makefile.am: Added the above new file to TESTS and EXTRA_DIST
+
 2021-08-28  Mark Wielaard  <mark@klomp.org>
 
 	* run-debuginfod-find.sh: Use ":memory:" for the
diff --git a/tests/Makefile.am b/tests/Makefile.am
index 43c34ce6..54b38954 100644
--- a/tests/Makefile.am
+++ b/tests/Makefile.am
@@ -232,7 +232,8 @@ TESTS += run-debuginfod-dlopen.sh \
 	 run-debuginfod-federation-link.sh \
 	 run-debuginfod-federation-metrics.sh \
          run-debuginfod-percent-escape.sh \
-	 run-debuginfod-x-forwarded-for.sh
+         run-debuginfod-x-forwarded-for.sh \
+         run-debuginfod-response-headers.sh
 endif
 endif
 
@@ -526,6 +527,7 @@ EXTRA_DIST = run-arextract.sh run-arsymtest.sh run-ar.sh \
 	     run-debuginfod-archive-rename.sh \
              run-debuginfod-archive-test.sh \
              run-debuginfod-percent-escape.sh \
+	     run-debuginfod-response-headers.sh \
 	     debuginfod-rpms/fedora30/hello2-1.0-2.src.rpm \
 	     debuginfod-rpms/fedora30/hello2-1.0-2.x86_64.rpm \
 	     debuginfod-rpms/fedora30/hello2-debuginfo-1.0-2.x86_64.rpm \
diff --git a/tests/run-debuginfod-response-headers.sh b/tests/run-debuginfod-response-headers.sh
new file mode 100755
index 00000000..bdb39b4d
--- /dev/null
+++ b/tests/run-debuginfod-response-headers.sh
@@ -0,0 +1,96 @@
+#!/usr/bin/env bash
+#
+# Copyright (C) 2019-2021 Red Hat, Inc.
+# This file is part of elfutils.
+#
+# This file is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+#
+# elfutils is distributed in the hope that it will be useful, but
+# WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+. $srcdir/debuginfod-subr.sh  # includes set -e
+
+# for test case debugging, uncomment:
+set -x
+
+DB=${PWD}/.debuginfod_tmp.sqlite
+tempfiles $DB
+export DEBUGINFOD_CACHE_PATH=${PWD}/.client_cache
+
+# This variable is essential and ensures no time-race for claiming ports occurs
+# set base to a unique multiple of 100 not used in any other 'run-debuginfod-*' test
+base=9500
+get_ports
+mkdir F R
+env LD_LIBRARY_PATH=$ldpath DEBUGINFOD_URLS= ${abs_builddir}/../debuginfod/debuginfod $VERBOSE -F -R -d $DB -p $PORT1 -t0 -g0 -v R F > vlog$PORT1 2>&1 &
+PID1=$!
+tempfiles vlog$PORT1
+errfiles vlog$PORT1
+# Server must become ready
+wait_ready $PORT1 'ready' 1
+export DEBUGINFOD_URLS=http://127.0.0.1:$PORT1/   # or without trailing /
+########################################################################
+
+# Compile a simple program, strip its debuginfo and save the build-id.
+# Also move the debuginfo into another directory so that elfutils
+# cannot find it without debuginfod.
+echo "int main() { return 0; }" > ${PWD}/prog.c
+tempfiles prog.c
+# Create a subdirectory to confound source path names
+mkdir foobar
+gcc -Wl,--build-id -g -o prog ${PWD}/foobar///./../prog.c
+
+mv prog F
+
+cp -rvp ${abs_srcdir}/debuginfod-rpms R
+if [ "$zstd" = "false" ]; then  # nuke the zstd fedora 31 ones
+    rm -vrf R/debuginfod-rpms/fedora31
+fi
+
+kill -USR1 $PID1
+# Wait till both files are in the index and scan/index fully finished
+wait_ready $PORT1 'thread_work_total{role="traverse"}' 1
+# All rpms need to be in the index, except the dummy permission-000 one
+rpms=$(find R -name \*rpm | grep -v nothing | wc -l)
+wait_ready $PORT1 'scanned_files_total{source=".rpm archive"}' $rpms
+kill -USR1 $PID1  # two hits of SIGUSR1 may be needed to resolve .debug->dwz->srefs
+# Wait till both files are in the index and scan/index fully finished
+wait_ready $PORT1 'thread_work_total{role="traverse"}' 2
+
+########################################################################
+## PR27277
+# Make a simple request to the debuginfod server and check debuginfod-find's vlog to see if
+# the custom HTTP headers are received.
+rm -rf $DEBUGINFOD_CACHE_PATH
+env DEBUGINFOD_URLS="http://127.0.0.1:"$PORT1 LD_LIBRARY_PATH=$ldpath ${abs_top_builddir}/debuginfod/debuginfod-find\
+    -vvv executable F/prog > vlog-find$PORT1.1 2>&1
+tempfiles vlog-find$PORT1.1
+grep 'Content-Length: ' vlog-find$PORT1.1
+grep 'Connection: ' vlog-find$PORT1.1
+grep 'Cache-Control: ' vlog-find$PORT1.1
+grep 'X-DEBUGINFOD-FILE: ' vlog-find$PORT1.1
+grep 'X-DEBUGINFOD-SIZE: ' vlog-find$PORT1.1
+
+# Check to see if an executable file located in an archive prints the file's description and archive
+env DEBUGINFOD_URLS="http://127.0.0.1:"$PORT1 LD_LIBRARY_PATH=$ldpath ${abs_top_builddir}/debuginfod/debuginfod-find\
+    -vvv executable c36708a78618d597dee15d0dc989f093ca5f9120 > vlog-find$PORT1.2 2>&1
+tempfiles vlog-find$PORT1.2
+grep 'Content-Length: ' vlog-find$PORT1.2
+grep 'Connection: ' vlog-find$PORT1.2
+grep 'Cache-Control: ' vlog-find$PORT1.2
+grep 'X-DEBUGINFOD-FILE: ' vlog-find$PORT1.2
+grep 'X-DEBUGINFOD-SIZE: ' vlog-find$PORT1.2
+grep 'X-DEBUGINFOD-ARCHIVE: ' vlog-find$PORT1.2
+
+kill $PID1
+wait $PID1
+PID1=0
+exit 0