core: New function gpgme_op_revsig.

* src/gpgme.h.in (gpgme_op_revsig_start, gpgme_op_revsig): New.
(GPGME_REVSIG_LFSEP): New.
* src/context.h (ctx_op_data_id_t): Add OPDATA_REVSIG.
* src/revsig.c: New.
* src/Makefile.am (main_sources): Add revsig.
* src/libgpgme.vers, src/gpgme.def: Add gpgme_op_revsig and
gpgme_op_revsig_start.
* src/engine.h, src/engine.c: (_gpgme_engine_op_revsig): New.
* src/engine-backend.h (engine_ops): Add 'revsig' and adjust all
engine initializers.
* src/engine-gpg.c (gpg_revsig): New.
(_gpgme_engine_ops_gpg): Set revsig to gpg_revsig.
* doc/gpgme.texi: Document new functions.
* tests/run-keysign.c: Add option --revoke.
--

This extends GPGME to support the --quick-revoke-sig command
added by GnuPG 2.2.24. This allows revoking key signatures.

GnuPG-bug-id: 5094

1 files changed, 203 insertions, 0 deletions

diff --git a/src/revsig.c b/src/revsig.c
new file mode 100644
index 00000000..8c61f730
--- /dev/null
+++ b/src/revsig.c
@@ -0,0 +1,203 @@
+/* revsig.c - Revoke signature helpers.
+ * Copyright (C) 2020 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
+ */
+
+#if HAVE_CONFIG_H
+#include <config.h>
+#endif
+#include <stdlib.h>
+
+#include "gpgme.h"
+#include "debug.h"
+#include "context.h"
+#include "ops.h"
+
+
+typedef struct
+{
+  /* The error code from a FAILURE status line or 0.  */
+  gpg_error_t failure_code;
+
+  /* The error code from certain ERROR status lines or 0.  */
+  gpg_error_t error_code;
+
+} *op_data_t;
+
+
+/* Parse an error status line.  Return the error location and the
+   error code.  The function may modify ARGS. */
+static char *
+parse_error (char *args, gpg_error_t *r_err)
+{
+  char *where = strchr (args, ' ');
+  char *which;
+
+  if (where)
+    {
+      *where = '\0';
+      which = where + 1;
+
+      where = strchr (which, ' ');
+      if (where)
+	*where = '\0';
+
+      where = args;
+    }
+  else
+    {
+      *r_err = trace_gpg_error (GPG_ERR_INV_ENGINE);
+      return NULL;
+    }
+
+  *r_err = atoi (which);
+
+  return where;
+}
+
+
+static gpgme_error_t
+revsig_status_handler (void *priv, gpgme_status_code_t code, char *args)
+{
+  gpgme_ctx_t ctx = (gpgme_ctx_t) priv;
+  gpgme_error_t err;
+  void *hook;
+  op_data_t opd;
+  char *loc;
+
+  /* Pipe the status code through the progress status handler.  */
+  err = _gpgme_progress_status_handler (ctx, code, args);
+  if (err)
+    return err;
+
+  err = _gpgme_op_data_lookup (ctx, OPDATA_REVSIG, &hook, -1, NULL);
+  opd = hook;
+  if (err)
+    return err;
+
+  switch (code)
+    {
+    case GPGME_STATUS_ERROR:
+      loc = parse_error (args, &err);
+      if (!loc)
+        return err;
+      if (!opd->error_code)
+        opd->error_code = err;
+      break;
+
+    case GPGME_STATUS_FAILURE:
+      opd->failure_code = _gpgme_parse_failure (args);
+      break;
+
+    case GPGME_STATUS_EOF:
+      if (opd->error_code)
+        return opd->error_code;
+      else if (opd->failure_code)
+        return opd->failure_code;
+      break;
+
+    case GPGME_STATUS_INQUIRE_MAXLEN:
+      if (ctx->status_cb && !ctx->full_status)
+        {
+          err = ctx->status_cb (ctx->status_cb_value, "INQUIRE_MAXLEN", args);
+          if (err)
+            return err;
+        }
+      break;
+
+    default:
+      break;
+    }
+  return 0;
+}
+
+
+/* Revoke the signature(s) on USERID of KEY made with SIGNING_KEY.
+ * If USERID is NULL, revoke signatures on all user ids.  To put several
+ * user ids into USERID, separate them by LF and set the flag
+ * GPGME_REVSIG_LFSEP.  */
+static gpgme_error_t
+revsig_start (gpgme_ctx_t ctx, int synchronous,
+              gpgme_key_t key, gpgme_key_t signing_key,
+              const char *userid, unsigned int flags)
+{
+  gpgme_error_t err;
+  void *hook;
+  op_data_t opd;
+
+  if (!ctx)
+    return gpg_error (GPG_ERR_INV_ARG);
+
+  if (ctx->protocol != GPGME_PROTOCOL_OPENPGP)
+    return gpgme_error (GPG_ERR_UNSUPPORTED_PROTOCOL);
+
+  if (!key)
+    return gpg_error (GPG_ERR_INV_ARG);
+
+  err = _gpgme_op_reset (ctx, synchronous);
+  if (err)
+    return err;
+
+  err = _gpgme_op_data_lookup (ctx, OPDATA_REVSIG, &hook, sizeof (*opd),
+                               NULL);
+  opd = hook;
+  if (err)
+    return err;
+
+  _gpgme_engine_set_status_handler (ctx->engine, revsig_status_handler, ctx);
+
+  if (ctx->passphrase_cb)
+    {
+      err = _gpgme_engine_set_command_handler
+        (ctx->engine, _gpgme_passphrase_command_handler, ctx);
+      if (err)
+        return err;
+    }
+
+  return _gpgme_engine_op_revsig (ctx->engine, key, signing_key, userid, flags);
+}
+
+
+gpgme_error_t
+gpgme_op_revsig_start (gpgme_ctx_t ctx, gpgme_key_t key, gpgme_key_t signing_key,
+                       const char *userid, unsigned int flags)
+{
+  gpgme_error_t err;
+
+  TRACE_BEG  (DEBUG_CTX, "gpgme_op_revsig_start", ctx,
+	      "key=%p, uid='%s' flags=0x%x", key, userid, flags);
+
+  err = revsig_start (ctx, 0, key, signing_key, userid, flags);
+  return TRACE_ERR (err);
+}
+
+
+gpgme_error_t
+gpgme_op_revsig (gpgme_ctx_t ctx, gpgme_key_t key, gpgme_key_t signing_key,
+                 const char *userid, unsigned int flags)
+{
+  gpgme_error_t err;
+
+  TRACE_BEG  (DEBUG_CTX, "gpgme_op_revsig", ctx,
+	      "key=%p, uid='%s' flags=0x%x", key, userid, flags);
+
+  err = revsig_start (ctx, 1, key, signing_key, userid, flags);
+  if (!err)
+    err = _gpgme_wait_one (ctx);
+  return TRACE_ERR (err);
+}