New agent option pinentry-mode.

This provides the framework and implements the ask, cancel and error.
loopback will be implemented later.

agent/ChangeLog

@@ -1,3 +1,16 @@
+2011-03-03  Werner Koch  <wk@g10code.com>
+
+	* gpg-agent.c: Add option --allow-loopback-pinentry.
+	* command.c (option_handler): Add option pinentry-mode.
+	* agent.h (pinentry_mode_t): New enum.
+	(struct server_local_s): Add PINENTRY_MODE.
+	(struct opt): Add ALLOW_LOOPBACK_PINENTRY.
+	* call-pinentry.c (agent_askpin): Implement ask, cancel and error
+	pinentry modes.
+	(agent_get_passphrase, agent_get_confirmation): Ditto.
+	(agent_show_message): Return cancel if pinentry mode is not "ask".
+	(agent_popup_message_start): Ditto.
+
 2011-03-02  Werner Koch  <wk@g10code.com>
 
 	* call-scd.c (hash_algo_option): New.

agent/agent.h

@@ -45,6 +45,18 @@
 /* Maximum length of a digest.  */
 #define MAX_DIGEST_LEN 64
 
+
+/* Values for the pinentry mode.  */
+typedef enum
+  {
+    PINENTRY_MODE_ASK = 0, /* Ask via pinentry (default).  */
+    PINENTRY_MODE_CANCEL,  /* Always return a cancel error.  */
+    PINENTRY_MODE_ERROR,   /* Return error code for no pinentry.  */
+    PINENTRY_MODE_LOOPBACK,/* Use an inquiry to get the value.    */
+  }
+pinentry_mode_t;
+
+
 /* A large struct name "opt" to keep global flags */
 struct
 {
@@ -67,7 +79,6 @@ struct
   char *startup_lc_ctype;
   char *startup_lc_messages;
 
-
   const char *pinentry_program; /* Filename of the program to start as
                                    pinentry.  */
   const char *scdaemon_program; /* Filename of the program to handle
@@ -105,6 +116,7 @@ struct
   int ignore_cache_for_signing;
   int allow_mark_trusted;
   int allow_preset_passphrase;
+  int allow_loopback_pinentry;
   int keep_tty;      /* Don't switch the TTY (for pinentry) on request */
   int keep_display;  /* Don't switch the DISPLAY (for pinentry) on request */
   int ssh_support;   /* Enable ssh-agent emulation.  */
@@ -149,6 +161,9 @@ struct server_control_s
   char *lc_ctype;
   char *lc_messages;
 
+  /* The current pinentry mode.  */
+  pinentry_mode_t pinentry_mode;
+
   struct {
     int algo;
     unsigned char value[MAX_DIGEST_LEN];

agent/call-pinentry.c

@@ -742,6 +742,14 @@ agent_askpin (ctrl_t ctrl,
   if (opt.batch)
     return 0; /* fixme: we should return BAD PIN */
 
+  if (ctrl->pinentry_mode != PINENTRY_MODE_ASK)
+    {
+      if (ctrl->pinentry_mode == PINENTRY_MODE_CANCEL)
+        return gpg_error (GPG_ERR_CANCELED);
+      /*FIXME:  Implement loopback mode.  */
+      return gpg_error (GPG_ERR_NO_PIN_ENTRY);
+    }
+
   if (!pininfo || pininfo->max_length < 1)
     return gpg_error (GPG_ERR_INV_VALUE);
   if (!desc_text && pininfo->min_digits)
@@ -895,6 +903,14 @@ agent_get_passphrase (ctrl_t ctrl,
   if (opt.batch)
     return gpg_error (GPG_ERR_BAD_PASSPHRASE);
 
+  if (ctrl->pinentry_mode != PINENTRY_MODE_ASK)
+    {
+      if (ctrl->pinentry_mode == PINENTRY_MODE_CANCEL)
+        return gpg_error (GPG_ERR_CANCELED);
+
+      return gpg_error (GPG_ERR_NO_PIN_ENTRY);
+    }
+
   rc = start_pinentry (ctrl);
   if (rc)
     return rc;
@@ -981,6 +997,14 @@ agent_get_confirmation (ctrl_t ctrl,
   int rc;
   char line[ASSUAN_LINELENGTH];
 
+  if (ctrl->pinentry_mode != PINENTRY_MODE_ASK)
+    {
+      if (ctrl->pinentry_mode == PINENTRY_MODE_CANCEL)
+        return gpg_error (GPG_ERR_CANCELED);
+
+      return gpg_error (GPG_ERR_NO_PIN_ENTRY);
+    }
+
   rc = start_pinentry (ctrl);
   if (rc)
     return rc;
@@ -1046,7 +1070,7 @@ agent_get_confirmation (ctrl_t ctrl,
 
 
 /* Pop up the PINentry, display the text DESC and a button with the
-   text OK_BTN (which may be NULL to use the default of "OK") and waut
+   text OK_BTN (which may be NULL to use the default of "OK") and wait
    for the user to hit this button.  The return value is not
    relevant.  */
 int
@@ -1055,6 +1079,9 @@ agent_show_message (ctrl_t ctrl, const char *desc, const char *ok_btn)
   int rc;
   char line[ASSUAN_LINELENGTH];
 
+  if (ctrl->pinentry_mode != PINENTRY_MODE_ASK)
+    return gpg_error (GPG_ERR_CANCELED);
+
   rc = start_pinentry (ctrl);
   if (rc)
     return rc;
@@ -1123,6 +1150,9 @@ agent_popup_message_start (ctrl_t ctrl, const char *desc, const char *ok_btn)
   char line[ASSUAN_LINELENGTH];
   pth_attr_t tattr;
 
+  if (ctrl->pinentry_mode != PINENTRY_MODE_ASK)
+    return gpg_error (GPG_ERR_CANCELED);
+
   rc = start_pinentry (ctrl);
   if (rc)
     return rc;

agent/command.c

@@ -2402,6 +2402,24 @@ option_handler (assuan_context_t ctx, const char *key, const char *value)
     ctrl->server_local->use_cache_for_signing = *value? atoi (value) : 0;
   else if (!strcmp (key, "allow-pinentry-notify"))
     ctrl->server_local->allow_pinentry_notify = 1;
+  else if (!strcmp (key, "pinentry-mode"))
+    {
+      if (!strcmp (value, "ask") || !strcmp (value, "default"))
+        ctrl->pinentry_mode = PINENTRY_MODE_ASK;
+      else if (!strcmp (value, "cancel"))
+        ctrl->pinentry_mode = PINENTRY_MODE_CANCEL;
+      else if (!strcmp (value, "error"))
+        ctrl->pinentry_mode = PINENTRY_MODE_ERROR;
+      else if (!strcmp (value, "loopback"))
+        {
+          if (opt.allow_loopback_pinentry)
+            ctrl->pinentry_mode = PINENTRY_MODE_LOOPBACK;
+          else
+            err = gpg_error (GPG_ERR_NOT_SUPPORTED);
+        }
+      else
+        err = gpg_error (GPG_ERR_INV_VALUE);
+    }
   else
     err = gpg_error (GPG_ERR_UNKNOWN_OPTION);
 

agent/gpg-agent.c

@@ -105,6 +105,7 @@ enum cmd_and_opt_values
   oIgnoreCacheForSigning,
   oAllowMarkTrusted,
   oAllowPresetPassphrase,
+  oAllowLoopbackPinentry,
   oKeepTTY,
   oKeepDISPLAY,
   oSSHSupport,
@@ -179,6 +180,8 @@ static ARGPARSE_OPTS opts[] = {
                              N_("allow clients to mark keys as \"trusted\"")},
   { oAllowPresetPassphrase, "allow-preset-passphrase", 0,
                              N_("allow presetting passphrase")},
+  { oAllowLoopbackPinentry, "allow-loopback-pinentry", 0,
+                             N_("allow presetting passphrase")},
   { oSSHSupport, "enable-ssh-support", 0, N_("enable ssh-agent emulation") },
   { oWriteEnvFile, "write-env-file", 2|8,
             N_("|FILE|write environment settings also to FILE")},
@@ -549,6 +552,8 @@ parse_rereadable_options (ARGPARSE_ARGS *pargs, int reread)
 
     case oAllowPresetPassphrase: opt.allow_preset_passphrase = 1; break;
 
+    case oAllowLoopbackPinentry: opt.allow_loopback_pinentry = 1; break;
+
     default:
       return 0; /* not handled */
     }

doc/gpg-agent.texi

@@ -348,6 +348,12 @@ Allow clients to mark keys as trusted, i.e. put them into the
 @file{trustlist.txt} file.  This is by default not allowed to make it
 harder for users to inadvertently accept Root-CA keys.
 
+@anchor{option --allow-loopback-pinentry}
+@item --allow-loopback-pinentry
+@opindex allow-loopback-pinentry
+Allow clients to use the loopback pinentry features; see the option
+@option{pinentry-mode} for details.
+
 @item --ignore-cache-for-signing
 @opindex ignore-cache-for-signing
 This option will let @command{gpg-agent} bypass the passphrase cache for all
@@ -800,6 +806,7 @@ secret keys.
 * Agent UPDATESTARTUPTTY:: Change the Standard Display
 * Agent GETEVENTCOUNTER:: Get the Event Counters
 * Agent GETINFO::         Return information about the process
+* Agent OPTION::          Set options for the session
 @end menu
 
 @node Agent PKDECRYPT
@@ -1279,6 +1286,70 @@ Return the name of the socket used for SSH connections.  If SSH support
 has not been enabled the error @code{GPG_ERR_NO_DATA} will be returned.
 @end table
 
+@node Agent OPTION
+@subsection Set options for the session
+
+Here is a list of session options which are not yet described with
+other commands.  The general syntax for an Assuan option is:
+
+@smallexample
+OPTION  @var{key}=@var{value}
+@end smallexample
+
+@noindent
+Supported @var{key}s are:
+
+@table @code
+@item agent-awareness
+This may be used to tell gpg-agent of which gpg-agent version the
+client is aware of.  gpg-agent uses this information to enable
+features which might break older clients.
+
+@item putenv
+Change the session's environment to be used for the
+Pinentry.  Valid values are:
+
+  @table @code
+  @item @var{name}
+  Delete envvar @var{name}
+  @item @var{name}=
+  Set envvar @var{name} to the empty string
+  @item @var{name}=@var{value}
+  Set envvar @var{name} to the string @var{value}.
+  @end table
+
+@item use-cache-for-signing
+See Assuan command @code{PKSIGN}.
+
+@item allow-pinentry-notify
+This does not need any value.  It is used to enable the
+PINENTRY_LAUNCHED inquiry.
+
+@item pinentry-mode
+This option is used to change the operation mode of the pinentry.  The
+following values are defined:
+
+  @table @code
+  @item ask
+  This is the default mode which pops up a pinentry as needed.
+
+  @item cancel
+  Instead of popping up a pinentry, return the error code
+  @code{GPG_ERR_CANCELED}.
+
+  @item error
+  Instead of popping up a pinentry, return the error code
+  @code{GPG_ERR_NO_PIN_ENTRY}.
+
+  @item loopback
+  Use a loopback pinentry.  This fakes a pinentry by using inquiries
+  back to the caller to ask for a passphrase.  This option may only be
+  set if the agent has been configured for that.
+  Use the @xref{option --allow-loopback-pinentry}.
+
+  @end table
+@end table
+
 
 @mansect see also
 @ifset isman