Add offline mode support for CMS keylisting

* doc/gpgme.texi: Document offline mode.
* src/context.h (gpgme_context): Add offline.
* src/engine-backend.h (keylist, keylist_ext): Add engine_flags.
* src/engine.c, src/engine.h (_gpgme_engine_op_keylist): Ditto.
  (_gpgme_engine_op_keylist_ext): Ditto.
* src/engine.h (GPGME_ENGINE_FLAG_OFFLINE): New.
* src/engine-gpg.c (gpg_keylist, gpg_keylist_ext): Ditto.
* src/engine-gpgsm.c (gpgsm_keylist): Handle engine_flags.
  (gpgsm_keylist_ext): Ditto.
* src/gpgme.c (gpgme_set_offline, gpgme_get_offline): New.
* src/gpgme.def (gpgme_set_offline, gpgme_get_offline): New.
* src/gpgme.h.in (gpgme_set_offline, gpgme_get_offline): New.
* src/libgpgme.vers (gpgme_set_offline, gpgme_get_offline): New.
* src/keylist.c (gpgme_op_keylist_start): Set offline flag.
  (gpgme_op_keylist_ext_start): Ditto.
* tests/run-keylist.c (show_usage, main): Add offline argument.

--
The offline engine option was introduced with gpgsm 2.1.6
it is mainly useful for a full keylisting that includes
the certificate validation but does not depend on external
information that could take an indefinite amount of time to
collect.

Signed-off-by: Andre Heinecke <aheinecke@intevation.de>

doc/gpgme.texi

@@ -189,6 +189,7 @@ Context Attributes
 * Crypto Engine::                 Configuring the crypto engine.
 * ASCII Armor::                   Requesting @acronym{ASCII} armored output.
 * Text Mode::                     Choosing canonical text mode.
+* Offline Mode::                  Choosing offline mode.
 * Included Certificates::         Including a number of certificates.
 * Key Listing Mode::              Selecting key listing mode.
 * Passphrase Callback::           Getting the passphrase from the user.
@@ -2285,6 +2286,7 @@ started.  In fact, these references are accessed through the
 * Crypto Engine::                 Configuring the crypto engine.
 * ASCII Armor::                   Requesting @acronym{ASCII} armored output.
 * Text Mode::                     Choosing canonical text mode.
+* Offline Mode::                  Choosing offline mode.
 * Included Certificates::         Including a number of certificates.
 * Key Listing Mode::              Selecting key listing mode.
 * Passphrase Callback::           Getting the passphrase from the user.
@@ -2413,6 +2415,37 @@ valid pointer.
 @end deftypefun
 
 
+@node Offline Mode
+@subsection Offline Mode
+@cindex context, offline mode
+@cindex offline mode
+
+@deftypefun void gpgme_set_offline (@w{gpgme_ctx_t @var{ctx}}, @w{int @var{yes}})
+The function @code{gpgme_set_offline} specifies if offline mode
+should be used.  By default, offline mode is not used.
+
+The offline mode specifies if dirmngr should be used to do additional
+validation that might require connections to external services.
+(e.g. CRL / OCSP checks).
+
+Offline mode only affects the keylist mode @code{GPGME_KEYLIST_MODE_VALIDATE}
+and is only relevant to the CMS crypto engine. Offline mode
+is ignored otherwise.
+
+This option may be extended in the future to completely disable
+the use of dirmngr for any engine.
+
+Offline mode is disabled if @var{yes} is zero, and enabled
+otherwise.
+@end deftypefun
+
+@deftypefun int gpgme_get_offline (@w{gpgme_ctx_t @var{ctx}})
+The function @code{gpgme_get_offline} returns 1 if offline
+mode is enabled, and @code{0} if it is not, or if @var{ctx} is not a
+valid pointer.
+@end deftypefun
+
+
 @node Included Certificates
 @subsection Included Certificates
 @cindex certificates, included

src/context.h

@@ -98,6 +98,9 @@ struct gpgme_context
   /* True if text mode should be used.  */
   unsigned int use_textmode : 1;
 
+  /* True if offline mode should be used.  */
+  unsigned int offline : 1;
+
   /* Flags for keylist mode.  */
   gpgme_keylist_mode_t keylist_mode;
 

src/engine-backend.h

@@ -85,10 +85,12 @@ struct engine_ops
   gpgme_error_t (*import) (void *engine, gpgme_data_t keydata,
                            gpgme_key_t *keyarray);
   gpgme_error_t (*keylist) (void *engine, const char *pattern,
-			    int secret_only, gpgme_keylist_mode_t mode);
+			    int secret_only, gpgme_keylist_mode_t mode,
+			    int engine_flags);
   gpgme_error_t (*keylist_ext) (void *engine, const char *pattern[],
 				int secret_only, int reserved,
-				gpgme_keylist_mode_t mode);
+				gpgme_keylist_mode_t mode,
+				int engine_flags);
   gpgme_error_t (*sign) (void *engine, gpgme_data_t in, gpgme_data_t out,
 			 gpgme_sig_mode_t mode, int use_armor,
 			 int use_textmode, int include_certs,

src/engine-gpg.c

@@ -2279,7 +2279,7 @@ gpg_keylist_build_options (engine_gpg_t gpg, int secret_only,
 
 static gpgme_error_t
 gpg_keylist (void *engine, const char *pattern, int secret_only,
-	     gpgme_keylist_mode_t mode)
+	     gpgme_keylist_mode_t mode, int engine_flags)
 {
   engine_gpg_t gpg = engine;
   gpgme_error_t err;
@@ -2298,7 +2298,7 @@ gpg_keylist (void *engine, const char *pattern, int secret_only,
 
 static gpgme_error_t
 gpg_keylist_ext (void *engine, const char *pattern[], int secret_only,
-		 int reserved, gpgme_keylist_mode_t mode)
+		 int reserved, gpgme_keylist_mode_t mode, int engine_flags)
 {
   engine_gpg_t gpg = engine;
   gpgme_error_t err;

src/engine-gpgsm.c

@@ -1542,7 +1542,7 @@ gpgsm_import (void *engine, gpgme_data_t keydata, gpgme_key_t *keyarray)
 
 static gpgme_error_t
 gpgsm_keylist (void *engine, const char *pattern, int secret_only,
-	       gpgme_keylist_mode_t mode)
+	       gpgme_keylist_mode_t mode, int engine_flags)
 {
   engine_gpgsm_t gpgsm = engine;
   char *line;
@@ -1599,6 +1599,11 @@ gpgsm_keylist (void *engine, const char *pattern, int secret_only,
                                "OPTION with-secret=1":
                                "OPTION with-secret=0" ,
                                NULL, NULL);
+  gpgsm_assuan_simple_command (gpgsm->assuan_ctx,
+                               (engine_flags & GPGME_ENGINE_FLAG_OFFLINE)?
+                               "OPTION offline=1":
+                               "OPTION offline=0" ,
+                               NULL, NULL);
 
 
   /* Length is "LISTSECRETKEYS " + p + '\0'.  */
@@ -1629,7 +1634,7 @@ gpgsm_keylist (void *engine, const char *pattern, int secret_only,
 
 static gpgme_error_t
 gpgsm_keylist_ext (void *engine, const char *pattern[], int secret_only,
-		   int reserved, gpgme_keylist_mode_t mode)
+		   int reserved, gpgme_keylist_mode_t mode, int engine_flags)
 {
   engine_gpgsm_t gpgsm = engine;
   char *line;
@@ -1669,7 +1674,11 @@ gpgsm_keylist_ext (void *engine, const char *pattern[], int secret_only,
                                "OPTION with-secret=1":
                                "OPTION with-secret=0" ,
                                NULL, NULL);
-
+  gpgsm_assuan_simple_command (gpgsm->assuan_ctx,
+                               (engine_flags & GPGME_ENGINE_FLAG_OFFLINE)?
+                               "OPTION offline=1":
+                               "OPTION offline=0" ,
+                               NULL, NULL);
 
   if (pattern && *pattern)
     {

src/engine.c

@@ -726,7 +726,8 @@ _gpgme_engine_op_import (engine_t engine, gpgme_data_t keydata,
 
 gpgme_error_t
 _gpgme_engine_op_keylist (engine_t engine, const char *pattern,
-			  int secret_only, gpgme_keylist_mode_t mode)
+			  int secret_only, gpgme_keylist_mode_t mode,
+			  int engine_flags)
 {
   if (!engine)
     return gpg_error (GPG_ERR_INV_VALUE);
@@ -734,14 +735,15 @@ _gpgme_engine_op_keylist (engine_t engine, const char *pattern,
   if (!engine->ops->keylist)
     return gpg_error (GPG_ERR_NOT_IMPLEMENTED);
 
-  return (*engine->ops->keylist) (engine->engine, pattern, secret_only, mode);
+  return (*engine->ops->keylist) (engine->engine, pattern, secret_only, mode,
+                                  engine_flags);
 }
 
 
 gpgme_error_t
 _gpgme_engine_op_keylist_ext (engine_t engine, const char *pattern[],
 			      int secret_only, int reserved,
-			      gpgme_keylist_mode_t mode)
+			      gpgme_keylist_mode_t mode, int engine_flags)
 {
   if (!engine)
     return gpg_error (GPG_ERR_INV_VALUE);
@@ -750,7 +752,7 @@ _gpgme_engine_op_keylist_ext (engine_t engine, const char *pattern[],
     return gpg_error (GPG_ERR_NOT_IMPLEMENTED);
 
   return (*engine->ops->keylist_ext) (engine->engine, pattern, secret_only,
-				      reserved, mode);
+				      reserved, mode, engine_flags);
 }
 
 

src/engine.h

@@ -113,12 +113,14 @@ gpgme_error_t _gpgme_engine_op_import (engine_t engine,
 gpgme_error_t _gpgme_engine_op_keylist (engine_t engine,
 					const char *pattern,
 					int secret_only,
-					gpgme_keylist_mode_t mode);
+					gpgme_keylist_mode_t mode,
+					int engine_flags);
 gpgme_error_t _gpgme_engine_op_keylist_ext (engine_t engine,
 					    const char *pattern[],
 					    int secret_only,
 					    int reserved,
-					    gpgme_keylist_mode_t mode);
+					    gpgme_keylist_mode_t mode,
+					    int engine_flags);
 gpgme_error_t _gpgme_engine_op_sign (engine_t engine, gpgme_data_t in,
 				     gpgme_data_t out, gpgme_sig_mode_t mode,
 				     int use_armor, int use_textmode,
@@ -170,5 +172,8 @@ gpgme_error_t _gpgme_engine_op_spawn (engine_t engine,
                                       gpgme_data_t dataerr,
                                       unsigned int flags);
 
+/* The available engine option flags.  */
+#define GPGME_ENGINE_FLAG_OFFLINE        1
+
 
 #endif /* ENGINE_H */

src/gpgme.c

@@ -472,6 +472,30 @@ gpgme_get_textmode (gpgme_ctx_t ctx)
 }
 
 
+/* Enable offline mode for this context. In offline mode dirmngr
+  will be disabled. */
+void
+gpgme_set_offline (gpgme_ctx_t ctx, int offline)
+{
+  TRACE2 (DEBUG_CTX, "gpgme_set_offline", ctx, "offline=%i (%s)",
+          offline, offline ? "yes" : "no");
+
+  if (!ctx)
+    return;
+
+  ctx->offline = offline;
+}
+
+/* Return the state of the offline flag.  */
+int
+gpgme_get_offline (gpgme_ctx_t ctx)
+{
+  TRACE2 (DEBUG_CTX, "gpgme_get_offline", ctx, "ctx->offline=%i (%s)",
+          ctx->offline, ctx->offline ? "yes" : "no");
+  return ctx->offline;
+}
+
+
 /* Set the number of certifications to include in an S/MIME message.
    The default is GPGME_INCLUDE_CERTS_DEFAULT.  -1 means all certs,
    and -2 means all certs except the root cert.  */

src/gpgme.def

@@ -217,5 +217,8 @@ EXPORTS
 
     gpgme_op_spawn_start                  @163
     gpgme_op_spawn                        @164
+
+    gpgme_set_offline                     @165
+    gpgme_get_offline                     @166
 ; END
 

src/gpgme.h.in

@@ -887,6 +887,12 @@ void gpgme_set_textmode (gpgme_ctx_t ctx, int yes);
 /* Return non-zero if text mode is set in CTX.  */
 int gpgme_get_textmode (gpgme_ctx_t ctx);
 
+/* If YES is non-zero, enable offline mode in CTX, disable it otherwise.  */
+void gpgme_set_offline (gpgme_ctx_t ctx, int yes);
+
+/* Return non-zero if offline mode is set in CTX.  */
+int gpgme_get_offline (gpgme_ctx_t ctx);
+
 /* Use whatever the default of the backend crypto engine is.  */
 #define GPGME_INCLUDE_CERTS_DEFAULT	-256
 

src/keylist.c

@@ -889,6 +889,7 @@ gpgme_op_keylist_start (gpgme_ctx_t ctx, const char *pattern, int secret_only)
   gpgme_error_t err;
   void *hook;
   op_data_t opd;
+  int flags = 0;
 
   TRACE_BEG2 (DEBUG_CTX, "gpgme_op_keylist_start", ctx,
 	      "pattern=%s, secret_only=%i", pattern, secret_only);
@@ -913,8 +914,11 @@ gpgme_op_keylist_start (gpgme_ctx_t ctx, const char *pattern, int secret_only)
   if (err)
     return TRACE_ERR (err);
 
+  if (ctx->offline)
+    flags |= GPGME_ENGINE_FLAG_OFFLINE;
+
   err = _gpgme_engine_op_keylist (ctx->engine, pattern, secret_only,
-				  ctx->keylist_mode);
+				  ctx->keylist_mode, flags);
   return TRACE_ERR (err);
 }
 
@@ -929,6 +933,7 @@ gpgme_op_keylist_ext_start (gpgme_ctx_t ctx, const char *pattern[],
   gpgme_error_t err;
   void *hook;
   op_data_t opd;
+  int flags = 0;
 
   TRACE_BEG2 (DEBUG_CTX, "gpgme_op_keylist_ext_start", ctx,
 	      "secret_only=%i, reserved=0x%x", secret_only, reserved);
@@ -952,8 +957,12 @@ gpgme_op_keylist_ext_start (gpgme_ctx_t ctx, const char *pattern[],
   if (err)
     return TRACE_ERR (err);
 
+  if (ctx->offline)
+    flags |= GPGME_ENGINE_FLAG_OFFLINE;
+
   err = _gpgme_engine_op_keylist_ext (ctx->engine, pattern, secret_only,
-				      reserved, ctx->keylist_mode);
+				      reserved, ctx->keylist_mode,
+				      flags);
   return TRACE_ERR (err);
 }
 

src/libgpgme.vers

@@ -92,6 +92,9 @@ GPGME_1.1 {
 
     gpgme_op_spawn_start;
     gpgme_op_spawn;
+
+    gpgme_set_offline;
+    gpgme_get_offline;
 };
 
 

tests/run-keylist.c

@@ -53,6 +53,7 @@ show_usage (int ex)
          "  --ephemeral      use GPGME_KEYLIST_MODE_EPHEMERAL\n"
          "  --validate       use GPGME_KEYLIST_MODE_VALIDATE\n"
          "  --import         import all keys\n"
+         "  --offline        use offline mode\n"
          , stderr);
   exit (ex);
 }
@@ -72,6 +73,7 @@ main (int argc, char **argv)
   int keyidx = 0;
   gpgme_protocol_t protocol = GPGME_PROTOCOL_OpenPGP;
   int only_secret = 0;
+  int offline = 0;
 
   if (argc)
     { argc--; argv++; }
@@ -141,6 +143,11 @@ main (int argc, char **argv)
           import = 1;
           argc--; argv++;
         }
+      else if (!strcmp (*argv, "--offline"))
+        {
+          offline = 1;
+          argc--; argv++;
+        }
       else if (!strncmp (*argv, "--", 2))
         show_usage (1);
 
@@ -157,6 +164,8 @@ main (int argc, char **argv)
 
   gpgme_set_keylist_mode (ctx, mode);
 
+  gpgme_set_offline (ctx, offline);
+
   err = gpgme_op_keylist_start (ctx, argc? argv[0]:NULL, only_secret);
   fail_if_err (err);