Handle pinentry-mode=loopback.

When this mode is set an inquire will be sent to the client to retrieve
the passphrase. This adds a new inquire keyword "NEW_PASSPHRASE" that the
GENKEY and PASSWD commands use when generating a new key.

agent/ChangeLog

@@ -1,3 +1,12 @@
+2011-09-10  Ben Kibbey <bjk@luxsci.net>
+
+	* agent.h (pinentry_loopback): New prototype.
+	* command.c (pinentry_loopback): New function to inquire a passphrase
+	from the client. For use with pinentry-mode=loopback.
+	* call-pinentry.c (agent_askpin): Handle PINENTRY_MODE_LOOPBACK.
+	* call-pinentry.c (agent_get_passphrase): Ditto.
+	* genkey.c (agent_ask_new_passphrase): Ditto.
+
 2011-08-10  Werner Koch  <wk@g10code.com>
 
 	* genkey.c (check_passphrase_pattern): Use gpg_strerror instead of

agent/agent.h

@@ -252,6 +252,9 @@ gpg_error_t agent_write_status (ctrl_t ctrl, const char *keyword, ...)
 void bump_key_eventcounter (void);
 void bump_card_eventcounter (void);
 void start_command_handler (ctrl_t, gnupg_fd_t, gnupg_fd_t);
+gpg_error_t pinentry_loopback(ctrl_t, const char *keyword,
+	                      unsigned char **buffer, size_t *size,
+			      size_t max_length);
 
 /*-- command-ssh.c --*/
 void start_command_handler_ssh (ctrl_t, gnupg_fd_t);

agent/call-pinentry.c

@@ -746,8 +746,29 @@ agent_askpin (ctrl_t ctrl,
     {
       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 (ctrl->pinentry_mode == PINENTRY_MODE_LOOPBACK)
+        {
+	  unsigned char *passphrase;
+	  size_t size;
+
+	  *pininfo->pin = 0; /* Reset the PIN. */
+	  rc = pinentry_loopback(ctrl, "PASSPHRASE", &passphrase, &size,
+		  pininfo->max_length);
+	  if (rc)
+	    return rc;
+
+	  memcpy(&pininfo->pin, passphrase, size);
+	  xfree(passphrase);
+	  pininfo->pin[size] = 0;
+	  if (pininfo->check_cb)
+	    {
+	      /* More checks by utilizing the optional callback. */
+	      pininfo->cb_errtext = NULL;
+	      rc = pininfo->check_cb (pininfo);
+	    }
+	  return rc;
+	}
+      return gpg_error(GPG_ERR_NO_PIN_ENTRY);
     }
 
   if (!pininfo || pininfo->max_length < 1)
@@ -908,6 +929,22 @@ agent_get_passphrase (ctrl_t ctrl,
       if (ctrl->pinentry_mode == PINENTRY_MODE_CANCEL)
         return gpg_error (GPG_ERR_CANCELED);
 
+      if (ctrl->pinentry_mode == PINENTRY_MODE_LOOPBACK)
+        {
+	  size_t size;
+	  size_t len = ASSUAN_LINELENGTH/2;
+	  unsigned char *buffer = gcry_malloc_secure (len);
+
+	  rc = pinentry_loopback(ctrl, "PASSPHRASE", &buffer, &size, len);
+	  if (rc)
+	    xfree(buffer);
+	  else
+	    {
+	      buffer[size] = 0;
+	      *retpass = buffer;
+	    }
+	  return rc;
+        }
       return gpg_error (GPG_ERR_NO_PIN_ENTRY);
     }
 

agent/command.c

@@ -2731,3 +2731,18 @@ start_command_handler (ctrl_t ctrl, gnupg_fd_t listen_fd, gnupg_fd_t fd)
   xfree (ctrl->server_local);
   ctrl->server_local = NULL;
 }
+
+
+gpg_error_t
+pinentry_loopback(ctrl_t ctrl, const char *keyword,
+                  unsigned char **buffer, size_t *size,
+                  size_t max_length)
+{
+  gpg_error_t rc;
+  assuan_context_t ctx = ctrl->server_local->assuan_ctx;
+
+  assuan_begin_confidential (ctx);
+  rc = assuan_inquire (ctx, keyword, buffer, size, max_length);
+  assuan_end_confidential (ctx);
+  return rc;
+}

agent/genkey.c

@@ -304,6 +304,23 @@ agent_ask_new_passphrase (ctrl_t ctrl, const char *prompt,
 
   *r_passphrase = NULL;
 
+  if (ctrl->pinentry_mode == PINENTRY_MODE_LOOPBACK)
+    {
+	size_t size;
+	size_t len = 100;
+	unsigned char *buffer;
+
+	err = pinentry_loopback(ctrl, "NEW_PASSPHRASE", &buffer, &size, len);
+	if (err)
+	  xfree(buffer);
+	else
+	  {
+	    buffer[size] = 0;
+	    *r_passphrase = buffer;
+	  }
+	return err;
+    }
+
   pi = gcry_calloc_secure (2, sizeof (*pi) + 100);
   pi2 = pi + (sizeof *pi + 100);
   pi->max_length = 100;