Add API gpgme_op_random_bytes.

* src/genrandom.c: New.
* src/Makefile.am: Add new file.
* src/engine-backend.h (struct engine_ops): Add func ptr getdirect.
Adjust all engine_ops.
* src/engine-gpg.c (gpg_getdirect): New.
(_gpgme_engine_ops_gpg): Connect new handler.
* src/gpgme.h.in (gpgme_random_mode_t): New.
(GPGME_RANDOM_MODE_NORMAL): New.
(GPGME_RANDOM_MODE_ZBASE32): New.
(gpgme_op_random_bytes): New public function
* src/libgpgme.vers: Add function.
* src/gpgme.def: Add function.

* tests/run-genrandom.c: New.
* tests/Makefile.am: Add new file.
--

This is a first take on this the mode parameter allows to extend the
function if ever needed.  Due to the gpg calling and fd setup overhead
this function is not yet very fast but its purpose is to get
"approved" random bytes.  We might eventually extend it to keep a
small internal cache of random numbers and get for example 128 random
bytes directly from gpg and deliver only the few required.

GnuPG-bug-id: 6694

2 files changed, 126 insertions, 1 deletions

diff --git a/tests/Makefile.am b/tests/Makefile.am
index 0147b4b7..d2e01dc0 100644
--- a/tests/Makefile.am
+++ b/tests/Makefile.am
@@ -42,7 +42,7 @@ noinst_HEADERS = run-support.h
 noinst_PROGRAMS = $(TESTS) run-keylist run-export run-import run-sign \
 		  run-verify run-encrypt run-identify run-decrypt run-genkey \
 		  run-keysign run-tofu run-swdb run-threaded \
-		  run-receive-keys run-setownertrust
+		  run-receive-keys run-setownertrust run-genrandom
 
 run_threaded_CPPFLAGS = -I$(top_builddir)/src @GPG_ERROR_MT_CFLAGS@
 run_threaded_LDADD = ../src/libgpgme.la \
diff --git a/tests/run-genrandom.c b/tests/run-genrandom.c
new file mode 100644
index 00000000..18b8c7ab
--- /dev/null
+++ b/tests/run-genrandom.c
@@ -0,0 +1,125 @@
+/* run-genrandom.c  - Test tool for the genrandom function
+ * Copyright (C) 2025 g10 Code GmbH
+ *
+ * This file is part of GPGME.
+ *
+ * GPGME is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU Lesser General Public License as
+ * published by the Free Software Foundation; either version 2.1 of
+ * the License, or (at your option) any later version.
+ *
+ * GPGME 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
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this program; if not, see <https://gnu.org/licenses/>.
+ * SPDX-License-Identifier: LGPL-2.1-or-later
+ */
+
+/* We need to include config.h so that we know whether we are building
+   with large file system (LFS) support. */
+#ifdef HAVE_CONFIG_H
+#include <config.h>
+#endif
+
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+#include <assert.h>
+
+#include <gpgme.h>
+
+#define PGM "run-genrandom"
+
+#include "run-support.h"
+
+
+static int verbose;
+
+
+static int
+show_usage (int ex)
+{
+  fputs ("usage: " PGM " [options]\n\n"
+         "Options:\n"
+         "  --verbose        run in verbose mode\n"
+         "  --zbase32        generate 30 zbase32 characters\n"
+         , stderr);
+  exit (ex);
+}
+
+
+int
+main (int argc, char **argv)
+{
+  int last_argc = -1;
+  gpgme_error_t err;
+  gpgme_ctx_t ctx;
+  gpgme_protocol_t protocol = GPGME_PROTOCOL_OPENPGP;
+  gpgme_random_mode_t mode = 0;
+  char buffer[128];
+
+
+  if (argc)
+    { argc--; argv++; }
+
+  while (argc && last_argc != argc )
+    {
+      last_argc = argc;
+      if (!strcmp (*argv, "--"))
+        {
+          argc--; argv++;
+          break;
+        }
+      else if (!strcmp (*argv, "--help"))
+        show_usage (0);
+      else if (!strcmp (*argv, "--verbose"))
+        {
+          verbose = 1;
+          argc--; argv++;
+        }
+      else if (!strcmp (*argv, "--zbase32"))
+        {
+          mode = GPGME_RANDOM_MODE_ZBASE32;
+          argc--; argv++;
+        }
+      else if (!strncmp (*argv, "--", 2))
+        show_usage (1);
+    }
+
+  if (argc)
+    show_usage (1);
+
+  init_gpgme (protocol);
+
+  err = gpgme_new (&ctx);
+  fail_if_err (err);
+  gpgme_set_protocol (ctx, protocol);
+
+  err = gpgme_op_random_bytes (ctx, mode, buffer, sizeof buffer);
+  if (err)
+    {
+      fprintf (stderr, PGM ": error getting random: %s\n", gpg_strerror (err));
+      exit (1);
+    }
+
+  if (mode == GPGME_RANDOM_MODE_ZBASE32)
+    puts (buffer);
+  else
+    {
+      int i;
+
+      for (i=0; i < sizeof buffer; i++)
+        {
+          if (i && !(i%32))
+            putchar ('\n');
+          printf ("%02x", ((unsigned char *)buffer)[i]);
+        }
+      putchar ('\n');
+    }
+
+  gpgme_release (ctx);
+  return 0;
+}