qapi/qmp-dispatch.c

   1 /*
   2  * Core Definitions for QAPI/QMP Dispatch
   3  *
   4  * Copyright IBM, Corp. 2011
   5  *
   6  * Authors:
   7  *  Anthony Liguori   <aliguori@us.ibm.com>
   8  *
   9  * This work is licensed under the terms of the GNU LGPL, version 2.1 or later.
  10  * See the COPYING.LIB file in the top-level directory.
  11  *
  12  */
  13
  14 #include "qemu/osdep.h"
  15 #include "qapi/error.h"
  16 #include "qapi/qmp/dispatch.h"
  17 #include "qapi/qmp/qdict.h"
  18 #include "qapi/qmp/qjson.h"
  19 #include "sysemu/runstate.h"
  20 #include "qapi/qmp/qbool.h"
  21
  22 static QDict *qmp_dispatch_check_obj(QDict *dict, bool allow_oob,
  23                                      Error **errp)
  24 {
  25     const char *exec_key = NULL;
  26     const QDictEntry *ent;
  27     const char *arg_name;
  28     const QObject *arg_obj;
  29
  30     for (ent = qdict_first(dict); ent;
  31          ent = qdict_next(dict, ent)) {
  32         arg_name = qdict_entry_key(ent);
  33         arg_obj = qdict_entry_value(ent);
  34
  35         if (!strcmp(arg_name, "execute")
  36             || (!strcmp(arg_name, "exec-oob") && allow_oob)) {
  37             if (qobject_type(arg_obj) != QTYPE_QSTRING) {
  38                 error_setg(errp, "QMP input member '%s' must be a string",
  39                            arg_name);
  40                 return NULL;
  41             }
  42             if (exec_key) {
  43                 error_setg(errp, "QMP input member '%s' clashes with '%s'",
  44                            arg_name, exec_key);
  45                 return NULL;
  46             }
  47             exec_key = arg_name;
  48         } else if (!strcmp(arg_name, "arguments")) {
  49             if (qobject_type(arg_obj) != QTYPE_QDICT) {
  50                 error_setg(errp,
  51                            "QMP input member 'arguments' must be an object");
  52                 return NULL;
  53             }
  54         } else if (!strcmp(arg_name, "id")) {
  55             continue;
  56         } else {
  57             error_setg(errp, "QMP input member '%s' is unexpected",
  58                        arg_name);
  59             return NULL;
  60         }
  61     }
  62
  63     if (!exec_key) {
  64         error_setg(errp, "QMP input lacks member 'execute'");
  65         return NULL;
  66     }
  67
  68     return dict;
  69 }
  70
  71 QDict *qmp_error_response(Error *err)
  72 {
  73     QDict *rsp;
  74
  75     rsp = qdict_from_jsonf_nofail("{ 'error': { 'class': %s, 'desc': %s } }",
  76                                   QapiErrorClass_str(error_get_class(err)),
  77                                   error_get_pretty(err));
  78     error_free(err);
  79     return rsp;
  80 }
  81
  82 /*
  83  * Does @qdict look like a command to be run out-of-band?
  84  */
  85 bool qmp_is_oob(const QDict *dict)
  86 {
  87     return qdict_haskey(dict, "exec-oob")
  88         && !qdict_haskey(dict, "execute");
  89 }
  90
  91 QDict *qmp_dispatch(const QmpCommandList *cmds, QObject *request,
  92                     bool allow_oob)
  93 {
  94     Error *err = NULL;
  95     bool oob;
  96     const char *command;
  97     QDict *args;
  98     const QmpCommand *cmd;
  99     QDict *dict;
 100     QObject *id;
 101     QObject *ret = NULL;
 102     QDict *rsp = NULL;
 103
 104     dict = qobject_to(QDict, request);
 105     if (!dict) {
 106         id = NULL;
 107         error_setg(&err, "QMP input must be a JSON object");
 108         goto out;
 109     }
 110
 111     id = qdict_get(dict, "id");
 112
 113     if (!qmp_dispatch_check_obj(dict, allow_oob, &err)) {
 114         goto out;
 115     }
 116
 117     command = qdict_get_try_str(dict, "execute");
 118     oob = false;
 119     if (!command) {
 120         assert(allow_oob);
 121         command = qdict_get_str(dict, "exec-oob");
 122         oob = true;
 123     }
 124     cmd = qmp_find_command(cmds, command);
 125     if (cmd == NULL) {
 126         error_set(&err, ERROR_CLASS_COMMAND_NOT_FOUND,
 127                   "The command %s has not been found", command);
 128         goto out;
 129     }
 130     if (!cmd->enabled) {
 131         error_set(&err, ERROR_CLASS_COMMAND_NOT_FOUND,
 132                   "The command %s has been disabled for this instance",
 133                   command);
 134         goto out;
 135     }
 136     if (oob && !(cmd->options & QCO_ALLOW_OOB)) {
 137         error_setg(&err, "The command %s does not support OOB",
 138                    command);
 139         goto out;
 140     }
 141
 142     if (runstate_check(RUN_STATE_PRECONFIG) &&
 143         !(cmd->options & QCO_ALLOW_PRECONFIG)) {
 144         error_setg(&err, "The command '%s' isn't permitted in '%s' state",
 145                    cmd->name, RunState_str(RUN_STATE_PRECONFIG));
 146         goto out;
 147     }
 148
 149     if (!qdict_haskey(dict, "arguments")) {
 150         args = qdict_new();
 151     } else {
 152         args = qdict_get_qdict(dict, "arguments");
 153         qobject_ref(args);
 154     }
 155     cmd->fn(args, &ret, &err);
 156     qobject_unref(args);
 157     if (err) {
 158         /* or assert(!ret) after reviewing all handlers: */
 159         qobject_unref(ret);
 160         goto out;
 161     }
 162
 163     if (cmd->options & QCO_NO_SUCCESS_RESP) {
 164         g_assert(!ret);
 165         return NULL;
 166     } else if (!ret) {
 167         /*
 168          * When the command's schema has no 'returns', cmd->fn()
 169          * leaves @ret null.  The QMP spec calls for an empty object
 170          * then; supply it.
 171          */
 172         ret = QOBJECT(qdict_new());
 173     }
 174
 175     rsp = qdict_new();
 176     qdict_put_obj(rsp, "return", ret);
 177
 178 out:
 179     if (err) {
 180         assert(!rsp);
 181         rsp = qmp_error_response(err);
 182     }
 183
 184     assert(rsp);
 185
 186     if (id) {
 187         qdict_put_obj(rsp, "id", qobject_ref(id));
 188     }
 189
 190     return rsp;
 191 }