SBUS: Generate introspection from the interface meta structure

https://fedorahosted.org/sssd/ticket/2234

This patch generates the introspection data from the sbus interface meta
structure. The generated XML conforms to
http://dbus.freedesktop.org/doc/dbus-specification.html#introspection-format

The XML description of the interface also always includes the
org.freedesktop.DBus.Introspectable interface, which this patch also allows
in the policy settings.

3 files changed, 368 insertions, 3 deletions

diff --git a/src/sbus/sssd_dbus_connection.c b/src/sbus/sssd_dbus_connection.c
index 150b5469e..64777fbe8 100644
--- a/src/sbus/sssd_dbus_connection.c
+++ b/src/sbus/sssd_dbus_connection.c
@@ -378,6 +378,8 @@ DBusHandlerResult sbus_message_handler(DBusConnection *dbus_conn,
     const struct sbus_interface_meta *interface;
     struct sbus_request *dbus_req = NULL;
     sbus_msg_handler_fn handler_fn = NULL;
+    void *handler_data = NULL; /* Must be a talloc pointer! */
+    struct sbus_introspect_ctx *ictx = NULL;
     DBusHandlerResult result;
     int ret;
 
@@ -425,19 +427,46 @@ DBusHandlerResult sbus_message_handler(DBusConnection *dbus_conn,
             dbus_message_unref(reply);
             result = DBUS_HANDLER_RESULT_HANDLED;
         }
+    } else {
+        /* Special case: check for Introspection request
+         * This is usually only useful for system bus connections
+         */
+        if (strcmp(msg_interface, DBUS_INTROSPECT_INTERFACE) == 0 &&
+                strcmp(msg_method, DBUS_INTROSPECT_METHOD) == 0) {
+            DEBUG(SSSDBG_TRACE_LIBS, "Got introspection request\n");
+            ictx = talloc(intf_p->conn, struct sbus_introspect_ctx);
+            if (ictx == NULL) {
+                result = sbus_reply_internal_error(message, intf_p->conn);
+            } else {
+                handler_fn = sbus_introspect;
+                ictx->iface = interface;
+                handler_data = ictx;
+            }
+        }
     }
 
     if (handler_fn) {
         dbus_req = sbus_new_request(intf_p->conn, intf_p->intf, message);
         if (!dbus_req) {
+            talloc_zfree(handler_data);
             ret = ENOMEM;
         } else {
             dbus_req->method = method;
-            ret = handler_fn(dbus_req, intf_p->intf->instance_data);
+            if (handler_data) {
+                /* If the handler uses private instance data, make
+                 * sure they go away when the request does
+                 */
+                talloc_steal(dbus_req, handler_data);
+            } else {
+                /* If no custom handler data is set, pass on the
+                 * interface data
+                 */
+                handler_data = intf_p->intf->instance_data;
+            }
+            ret = handler_fn(dbus_req, handler_data);
         }
         if (ret != EOK) {
-            if (dbus_req)
-                talloc_free(dbus_req);
+            talloc_free(dbus_req);
             result = sbus_reply_internal_error(message, intf_p->conn);
         } else {
             result = DBUS_HANDLER_RESULT_HANDLED;
diff --git a/src/sbus/sssd_dbus_introspect.c b/src/sbus/sssd_dbus_introspect.c
new file mode 100644
index 000000000..ffc1f4d38
--- /dev/null
+++ b/src/sbus/sssd_dbus_introspect.c
@@ -0,0 +1,330 @@
+/*
+    Authors:
+        Jakub Hrozek <jhrozek@redhat.com>
+
+    Copyright (C) 2014 Red Hat
+
+    SBUS: Interface introspection
+
+    This program is free software; you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation; either version 3 of the License, or
+    (at your option) any later version.
+
+    This program 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 General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#include <sys/time.h>
+#include <dbus/dbus.h>
+
+#include "util/util.h"
+#include "sbus/sssd_dbus.h"
+#include "sbus/sssd_dbus_private.h"
+#include "sbus/sssd_dbus_meta.h"
+
+#define SSS_INTROSPECT_DOCTYPE  \
+    "<!DOCTYPE node PUBLIC \"-//freedesktop//DTD D-BUS Object Introspection 1.0//EN\"\n" \
+    "\"http://www.freedesktop.org/standards/dbus/1.0/introspect.dtd\">\n"
+
+#define SSS_INTROSPECT_INTERFACE_INTROSPECTABLE                      \
+     " <interface name=\"org.freedesktop.DBus.Introspectable\">\n"   \
+     "   <method name=\"Introspect\">\n"                             \
+     "     <arg name=\"data\" type=\"s\" direction=\"out\"/>\n"      \
+     "   </method>\n"                                                \
+     " </interface>\n"
+
+
+struct introspect_ctx {
+    FILE *f;
+    char *buf;
+    size_t size;
+
+    const struct sbus_interface_meta *iface;
+};
+
+static int introspect_ctx_destructor(struct introspect_ctx *ictx)
+{
+    free(ictx->buf);
+    ictx->buf = NULL;
+    return 0;
+}
+
+static errno_t introspect_begin(struct introspect_ctx *ictx)
+{
+    errno_t ret;
+
+    ictx->f = open_memstream(&ictx->buf, &ictx->size);
+    if (ictx->f == NULL) {
+        return ENOMEM;
+    }
+
+    ret = fputs(SSS_INTROSPECT_DOCTYPE, ictx->f);
+    if (ret < 0) return EIO;
+    ret = fputs("<node>\n", ictx->f);
+    if (ret < 0) return EIO;
+
+    ret = fprintf(ictx->f, "  <interface name=\"%s\">\n", ictx->iface->name);
+    if (ret <= 0) return EIO;
+
+    return EOK;
+}
+
+static errno_t introspect_add_arg(struct introspect_ctx *ictx,
+                                  const struct sbus_arg_meta *a,
+                                  const char *direction)
+{
+    errno_t ret;
+
+    ret = fprintf(ictx->f,
+                  "      <arg type=\"%s\" name=\"%s\"",
+                  a->type, a->name);
+    if (ret <= 0) return EIO;
+
+    if (direction) {
+        ret = fprintf(ictx->f, " direction=\"%s\"", direction);
+        if (ret <= 0) return EIO;
+    }
+
+    ret = fprintf(ictx->f, "/>\n");
+    if (ret <= 0) return EIO;
+
+    return EOK;
+}
+
+#define introspect_add_in_arg(i, a) introspect_add_arg(i, a, "in");
+#define introspect_add_out_arg(i, a) introspect_add_arg(i, a, "out");
+#define introspect_add_sig_arg(i, a) introspect_add_arg(i, a, NULL);
+
+static errno_t introspect_add_meth(struct introspect_ctx *ictx,
+                                   const struct sbus_method_meta *m)
+{
+    errno_t ret;
+    int i;
+
+    ret = fprintf(ictx->f, "    <method name=\"%s\">\n", m->name);
+    if (ret <= 0) return EIO;
+
+    if (m->in_args != NULL) {
+        for (i = 0; m->in_args[i].name != NULL; i++) {
+            ret = introspect_add_in_arg(ictx, &m->in_args[i]);
+            if (ret != EOK) {
+                continue;
+            }
+        }
+    }
+
+    if (m->out_args != NULL) {
+        for (i = 0; m->out_args[i].name != NULL; i++) {
+            ret = introspect_add_out_arg(ictx, &m->out_args[i]);
+            if (ret != EOK) {
+                continue;
+            }
+        }
+    }
+
+    ret = fputs("    </method>\n", ictx->f);
+    if (ret < 0) return EIO;
+
+    return EOK;
+}
+
+static errno_t introspect_add_methods(struct introspect_ctx *ictx)
+{
+    errno_t ret;
+    int i;
+
+    if (ictx->iface->methods == NULL) {
+        /* An interface with no methods */
+        return EOK;
+    }
+
+    for (i = 0; ictx->iface->methods[i].name != NULL; i++) {
+        ret = introspect_add_meth(ictx, &ictx->iface->methods[i]);
+        if (ret != EOK) {
+            continue;
+        }
+    }
+
+    return EOK;
+}
+
+static errno_t introspect_add_sig(struct introspect_ctx *ictx,
+                                  const struct sbus_signal_meta *s)
+{
+    errno_t ret;
+    int i;
+
+    ret = fprintf(ictx->f, "    <signal name=\"%s\">\n", s->name);
+    if (ret <= 0) return EIO;
+
+    if (s->args != NULL) {
+        for (i = 0; s->args[i].name != NULL; i++) {
+            ret = introspect_add_sig_arg(ictx, &s->args[i]);
+            if (ret != EOK) {
+                continue;
+            }
+        }
+    }
+
+    ret = fputs("    </signal>\n", ictx->f);
+    if (ret < 0) return EIO;
+
+    return EOK;
+}
+
+static errno_t introspect_add_signals(struct introspect_ctx *ictx)
+{
+    errno_t ret;
+    int i;
+
+    if (ictx->iface->signals == NULL) {
+        /* An interface with no signals */
+        return EOK;
+    }
+
+    for (i = 0; ictx->iface->signals[i].name != NULL; i++) {
+        ret = introspect_add_sig(ictx, &ictx->iface->signals[i]);
+        if (ret != EOK) {
+            continue;
+        }
+    }
+
+    return EOK;
+}
+
+static errno_t introspect_add_prop(struct introspect_ctx *ictx,
+                                   const struct sbus_property_meta *p)
+{
+    errno_t ret;
+
+    ret = fprintf(ictx->f, "    <property name=\"%s\" type=\"%s\" access=\"%s\"/>\n",
+                           p->name, p->type,
+                           p->flags & SBUS_PROPERTY_WRITABLE ? "readwrite" : "read");
+    if (ret <= 0) return EIO;
+
+    return EOK;
+}
+
+static errno_t introspect_add_properties(struct introspect_ctx *ictx)
+{
+    errno_t ret;
+    int i;
+
+    if (ictx->iface->properties == NULL) {
+        /* An interface with no properties */
+        return EOK;
+    }
+
+    for (i = 0; ictx->iface->properties[i].name != NULL; i++) {
+        ret = introspect_add_prop(ictx, &ictx->iface->properties[i]);
+        if (ret != EOK) {
+            continue;
+        }
+    }
+
+    return EOK;
+}
+
+static errno_t introspect_finish(struct introspect_ctx *ictx)
+{
+    errno_t ret;
+
+    ret = fputs("  </interface>\n", ictx->f);
+    if (ret < 0) return EIO;
+
+    ret = fputs(SSS_INTROSPECT_INTERFACE_INTROSPECTABLE, ictx->f);
+    if (ret < 0) return EIO;
+
+    ret = fputs("</node>\n", ictx->f);
+    if (ret < 0) return EIO;
+
+    fflush(ictx->f);
+    return EOK;
+}
+
+static char *sbus_introspect_xml(TALLOC_CTX *mem_ctx,
+                                 const struct sbus_interface_meta *iface)
+{
+    struct introspect_ctx *ictx;
+    char *buf_out = NULL;
+    errno_t ret;
+
+    ictx = talloc_zero(mem_ctx, struct introspect_ctx);
+    if (ictx == NULL) {
+        return NULL;
+    }
+    ictx->iface = iface;
+    talloc_set_destructor(ictx, introspect_ctx_destructor);
+
+    ret = introspect_begin(ictx);
+    if (ret != EOK) {
+        DEBUG(SSSDBG_OP_FAILURE, "introspect_begin failed: %d\n", ret);
+        goto done;
+    }
+
+    ret = introspect_add_methods(ictx);
+    if (ret != EOK) {
+        DEBUG(SSSDBG_OP_FAILURE, "introspect_add_methods failed: %d\n", ret);
+        goto done;
+    }
+
+    ret = introspect_add_signals(ictx);
+    if (ret != EOK) {
+        DEBUG(SSSDBG_OP_FAILURE, "introspect_add_signals failed: %d\n", ret);
+        goto done;
+    }
+
+    ret = introspect_add_properties(ictx);
+    if (ret != EOK) {
+        DEBUG(SSSDBG_OP_FAILURE,
+              "introspect_add_properties failed: %d\n", ret);
+        goto done;
+    }
+
+    ret = introspect_finish(ictx);
+    if (ret != EOK) {
+        DEBUG(SSSDBG_OP_FAILURE, "introspect_finish failed: %d\n", ret);
+        goto done;
+    }
+
+    buf_out = talloc_memdup(mem_ctx, ictx->buf, ictx->size + 1);
+    DEBUG(SSSDBG_TRACE_LIBS, "Introspection: \n%s\n", buf_out);
+done:
+    talloc_free(ictx);
+    return buf_out;
+}
+
+int sbus_introspect(struct sbus_request *dbus_req, void *pvt)
+{
+    char *xml;
+    DBusError dberr;
+    const struct sbus_interface_meta *iface;
+    struct sbus_introspect_ctx *ictx;
+
+    ictx = talloc_get_type(pvt, struct sbus_introspect_ctx);
+    if (ictx == NULL) {
+        DEBUG(SSSDBG_CRIT_FAILURE, "Invalid pointer!\n");
+        return sbus_request_return_and_finish(dbus_req, DBUS_TYPE_INVALID);
+    }
+    iface = ictx->iface;
+
+    xml = sbus_introspect_xml(dbus_req, iface);
+    if (xml == NULL) {
+        dbus_error_init(&dberr);
+        dbus_set_error_const(&dberr,
+                             DBUS_ERROR_NO_MEMORY,
+                             "Failed to generate introspection data\n");
+        return sbus_request_fail_and_finish(dbus_req, &dberr);
+    }
+
+    return sbus_request_return_and_finish(dbus_req,
+                                          DBUS_TYPE_STRING, &xml,
+                                          DBUS_TYPE_INVALID);
+
+}
diff --git a/src/sbus/sssd_dbus_private.h b/src/sbus/sssd_dbus_private.h
index 88230cfca..929caeccb 100644
--- a/src/sbus/sssd_dbus_private.h
+++ b/src/sbus/sssd_dbus_private.h
@@ -98,4 +98,10 @@ struct sbus_request *
 sbus_new_request(struct sbus_connection *conn, struct sbus_interface *intf,
                  DBusMessage *message);
 
+struct sbus_introspect_ctx {
+    const struct sbus_interface_meta *iface;
+};
+
+int sbus_introspect(struct sbus_request *dbus_req, void *pvt);
+
 #endif /* _SSSD_DBUS_PRIVATE_H_ */