From 02130314d8c71743e6d1fefc2b08a608516bccc7 Mon Sep 17 00:00:00 2001 From: Peter Xu Date: Fri, 9 Mar 2018 16:59:53 +0800 Subject: [PATCH] qmp: introduce QMPCapability There were no QMP capabilities defined. Define the first capability, "oob", to allow out-of-band messages. After this patch, we will allow QMP clients to enable QMP capabilities when sending the first "qmp_capabilities" command. Originally we are starting QMP session with no arguments like: { "execute": "qmp_capabilities" } Now we can enable some QMP capabilities using (take OOB as example, which is the only capability that we support): { "execute": "qmp_capabilities", "arguments": { "enable": [ "oob" ] } } When the "arguments" key is not provided, no capability is enabled. For capability "oob", the monitor needs to be run on a dedicated IO thread, otherwise the command will fail. For example, trying to enable OOB on a MUXed typed QMP monitor will fail. One thing to mention is that QMP capabilities are per-monitor, and also when the connection is closed due to some reason, the capabilities will be reset. Also, touch up qmp-test.c to test the new bits. Signed-off-by: Peter Xu Message-Id: <20180309090006.10018-11-peterx@redhat.com> Reviewed-by: Eric Blake [eblake: touch up commit message] Signed-off-by: Eric Blake --- monitor.c | 77 ++++++++++++++++++++++++++++++++++++++++++++---- qapi/misc.json | 32 ++++++++++++++++++-- tests/qmp-test.c | 10 ++++++- 3 files changed, 110 insertions(+), 9 deletions(-) diff --git a/monitor.c b/monitor.c index 44b2fa2f4a..d31ec703e3 100644 --- a/monitor.c +++ b/monitor.c @@ -59,6 +59,7 @@ #include "qapi/qmp/qjson.h" #include "qapi/qmp/json-streamer.h" #include "qapi/qmp/json-parser.h" +#include "qapi/qmp/qlist.h" #include "qom/object_interfaces.h" #include "trace-root.h" #include "trace/control.h" @@ -170,6 +171,7 @@ typedef struct { * mode. */ QmpCommandList *commands; + bool qmp_caps[QMP_CAPABILITY__MAX]; } MonitorQMP; /* @@ -1042,8 +1044,42 @@ static void monitor_init_qmp_commands(void) qmp_marshal_qmp_capabilities, QCO_NO_OPTIONS); } -void qmp_qmp_capabilities(Error **errp) +static void qmp_caps_check(Monitor *mon, QMPCapabilityList *list, + Error **errp) { + for (; list; list = list->next) { + assert(list->value < QMP_CAPABILITY__MAX); + switch (list->value) { + case QMP_CAPABILITY_OOB: + if (!mon->use_io_thr) { + /* + * Out-Of-Band only works with monitors that are + * running on dedicated IOThread. + */ + error_setg(errp, "This monitor does not support " + "Out-Of-Band (OOB)"); + return; + } + break; + default: + break; + } + } +} + +/* This function should only be called after capabilities are checked. */ +static void qmp_caps_apply(Monitor *mon, QMPCapabilityList *list) +{ + for (; list; list = list->next) { + mon->qmp.qmp_caps[list->value] = true; + } +} + +void qmp_qmp_capabilities(bool has_enable, QMPCapabilityList *enable, + Error **errp) +{ + Error *local_err = NULL; + if (cur_mon->qmp.commands == &qmp_commands) { error_set(errp, ERROR_CLASS_COMMAND_NOT_FOUND, "Capabilities negotiation is already complete, command " @@ -1051,6 +1087,21 @@ void qmp_qmp_capabilities(Error **errp) return; } + /* Enable QMP capabilities provided by the client if applicable. */ + if (has_enable) { + qmp_caps_check(cur_mon, enable, &local_err); + if (local_err) { + /* + * Failed check on any of the capabilities will fail the + * entire command (and thus not apply any of the other + * capabilities that were also requested). + */ + error_propagate(errp, local_err); + return; + } + qmp_caps_apply(cur_mon, enable); + } + cur_mon->qmp.commands = &qmp_commands; } @@ -3896,14 +3947,29 @@ void monitor_resume(Monitor *mon) readline_show_prompt(mon->rs); } -static QObject *get_qmp_greeting(void) +static QObject *get_qmp_greeting(Monitor *mon) { + QList *cap_list = qlist_new(); QObject *ver = NULL; + QMPCapability cap; qmp_marshal_query_version(NULL, &ver, NULL); - return qobject_from_jsonf("{'QMP': {'version': %p, 'capabilities': []}}", - ver); + for (cap = 0; cap < QMP_CAPABILITY__MAX; cap++) { + if (!mon->use_io_thr && cap == QMP_CAPABILITY_OOB) { + /* Monitors that are not using IOThread won't support OOB */ + continue; + } + qlist_append(cap_list, qstring_from_str(QMPCapability_str(cap))); + } + + return qobject_from_jsonf("{'QMP': {'version': %p, 'capabilities': %p}}", + ver, cap_list); +} + +static void monitor_qmp_caps_reset(Monitor *mon) +{ + memset(mon->qmp.qmp_caps, 0, sizeof(mon->qmp.qmp_caps)); } static void monitor_qmp_event(void *opaque, int event) @@ -3914,7 +3980,8 @@ static void monitor_qmp_event(void *opaque, int event) switch (event) { case CHR_EVENT_OPENED: mon->qmp.commands = &qmp_cap_negotiation_commands; - data = get_qmp_greeting(); + monitor_qmp_caps_reset(mon); + data = get_qmp_greeting(mon); monitor_json_emitter(mon, data); qobject_decref(data); mon_refcount++; diff --git a/qapi/misc.json b/qapi/misc.json index 6150b9a003..564216ae97 100644 --- a/qapi/misc.json +++ b/qapi/misc.json @@ -10,21 +10,47 @@ # # Enable QMP capabilities. # -# Arguments: None. +# Arguments: +# +# @enable: An optional list of QMPCapability values to enable. The +# client must not enable any capability that is not +# mentioned in the QMP greeting message. If the field is not +# provided, it means no QMP capabilities will be enabled. +# (since 2.12) # # Example: # -# -> { "execute": "qmp_capabilities" } +# -> { "execute": "qmp_capabilities", +# "arguments": { "enable": [ "oob" ] } } # <- { "return": {} } # # Notes: This command is valid exactly when first connecting: it must be # issued before any other command will be accepted, and will fail once the # monitor is accepting other commands. (see qemu docs/interop/qmp-spec.txt) # +# The QMP client needs to explicitly enable QMP capabilities, otherwise +# all the QMP capabilities will be turned off by default. +# # Since: 0.13 # ## -{ 'command': 'qmp_capabilities' } +{ 'command': 'qmp_capabilities', + 'data': { '*enable': [ 'QMPCapability' ] } } + +## +# @QMPCapability: +# +# Enumeration of capabilities to be advertised during initial client +# connection, used for agreeing on particular QMP extension behaviors. +# +# @oob: QMP ability to support Out-Of-Band requests. +# (Please refer to qmp-spec.txt for more information on OOB) +# +# Since: 2.12 +# +## +{ 'enum': 'QMPCapability', + 'data': [ 'oob' ] } ## # @VersionTriple: diff --git a/tests/qmp-test.c b/tests/qmp-test.c index 7470c6b754..d1fa1cb217 100644 --- a/tests/qmp-test.c +++ b/tests/qmp-test.c @@ -20,6 +20,7 @@ #include "qapi/qobject-input-visitor.h" #include "qapi/util.h" #include "qapi/visitor.h" +#include "qapi/qmp/qstring.h" const char common_args[] = "-nodefaults -machine none"; @@ -79,6 +80,8 @@ static void test_qmp_protocol(void) QDict *resp, *q, *ret; QList *capabilities; QTestState *qts; + const QListEntry *entry; + QString *qstr; qts = qtest_init_without_qmp_handshake(common_args); @@ -88,7 +91,12 @@ static void test_qmp_protocol(void) g_assert(q); test_version(qdict_get(q, "version")); capabilities = qdict_get_qlist(q, "capabilities"); - g_assert(capabilities && qlist_empty(capabilities)); + g_assert(capabilities); + entry = qlist_first(capabilities); + g_assert(entry); + qstr = qobject_to(QString, entry->value); + g_assert(qstr); + g_assert_cmpstr(qstring_get_str(qstr), ==, "oob"); QDECREF(resp); /* Test valid command before handshake */