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[Libvir] Proposed remote protocol (XDR source file qemud/remote_protocol.x)



Attached are the args (*_args) and return structures (*_ret) for all the calls covered by the remote protocol, that is to say everything except Save, Restore and CoreDump (see previous email).

The only problem area are the upper limits imposed on the lengths of various strings and arrays. The upper limits seem to be required for safely decoding messages from untrusted sources. Some of them however would impose limits on such things as the number of CPUs supported, and perhaps those limits are too low (or too high)? I don't really have any experience of the sort of huge machines that people might be running libvirt on.

Rich.

--
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/* -*- c -*-
 * remote_protocol.x: private protocol for communicating between
 *   remote_internal driver and libvirtd.  This protocol is
 *   internal and may change at any time.
 *
 * Copyright (C) 2006-2007 Red Hat, Inc.
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307  USA
 *
 * Author: Richard Jones <rjones redhat com>
 */

/* Notes:
 *
 * (1) The protocol is internal and may change at any time, without
 * notice.  Do not use it.  Instead link to libvirt and use the remote
 * driver.
 *
 * (2) See bottom of this file for a description of the home-brew RPC.
 *
 * (3) Authentication/encryption is done outside this protocol.
 *
 * (4) For namespace reasons, all exported names begin 'remote_' or
 * 'REMOTE_'.  This makes names quite long.
 */

%#include "libvirt/libvirt.h"

/*----- Data types. -----*/

/* Maximum total message size (serialised). */
const REMOTE_MESSAGE_MAX = 262144;

/* Length of long, but not unbounded, strings.
 * This is an arbitrary limit designed to stop the decoder from trying
 * to allocate unbounded amounts of memory when fed with a bad message.
 */
const REMOTE_STRING_MAX = 65536;

/* A long string, which may NOT be NULL. */
typedef string remote_nonnull_string<REMOTE_STRING_MAX>;

/* A long string, which may be NULL. */
typedef remote_nonnull_string *remote_string;

/* This just places an upper limit on the length of lists of
 * domain IDs which may be sent via the protocol.
 */
const REMOTE_DOMAIN_ID_LIST_MAX = 4096;

/* Upper limit on lists of domain names. */
const REMOTE_DOMAIN_NAME_LIST_MAX = 256;

/* Upper limit on cpumap (bytes) passed to virDomainPinVcpu. */
const REMOTE_CPUMAP_MAX = 256;

/* Upper limit on number of info fields returned by virDomainGetVcpus. */
const REMOTE_VCPUINFO_MAX = 2048;

/* Upper limit on cpumaps (bytes) passed to virDomainGetVcpus. */
const REMOTE_CPUMAPS_MAX = 16384;

/* Upper limit on lists of network names. */
const REMOTE_NETWORK_NAME_LIST_MAX = 256;

/* Domains and networks are represented on the wire by (name, UUID). */
typedef opaque remote_uuid[VIR_UUID_BUFLEN];

struct remote_name {
    remote_nonnull_string name;
    remote_uuid uuid;
};

/* A domain or network which may not be NULL. */
typedef struct remote_name remote_nonnull_domain;
typedef struct remote_name remote_nonnull_network;

/* A domain or network which may be NULL. */
typedef remote_nonnull_domain *remote_domain;
typedef remote_nonnull_network *remote_network;

/* Error message. See <virterror.h> for explanation of fields. */

/* NB. Fields "code", "domain" and "level" are really enums.  The
 * numeric value should remain compatible between libvirt and
 * libvirtd.  This means, no changing or reordering the enums as
 * defined in <virterror.h> (but we don't do that anyway, for separate
 * ABI reasons).
 */
struct remote_error {
    int code;
    int domain;
    remote_string message;
    int level;
    remote_domain dom;
    remote_string str1;
    remote_string str2;
    remote_string str3;
    int int1;
    int int2;
    remote_network net;
};

/* Wire encoding of virVcpuInfo. */
struct remote_vcpu_info {
    unsigned int number;
    int state;
    unsigned hyper cpu_time;
    int cpu;
};

/*----- Calls. -----*/

/* For each call we may have a 'remote_CALL_args' and 'remote_CALL_ret'
 * type.  These are omitted when they are NULL.  The virConnectPtr
 * is not passed at all (it is inferred on the remote server from the
 * connection).  Errors are returned implicitly in the RPC protocol.
 */

struct remote_open_args {
    /* NB. "name" might be NULL although in practice you can't
     * yet do that using the remote_internal driver.
     */
    remote_string name;
    int flags;
};

struct remote_get_type_ret {
    remote_nonnull_string type;
};

struct remote_get_version_ret {
    hyper hv_ver;
};

struct remote_get_max_vcpus_args {
    /* The only backend which supports this call is Xen HV, and
     * there the type is ignored so it could be NULL.
     */
    remote_string type;
};

struct remote_get_max_vcpus_ret {
    int max_vcpus;
};

struct remote_node_get_info_ret {
    string model<32>;
    hyper memory;
    int cpus;
    int mhz;
    int nodes;
    int sockets;
    int cores;
    int threads;
};

struct remote_get_capabilities_ret {
    remote_nonnull_string capabilities;
};

struct remote_list_domains_args {
    int maxids;
};

struct remote_list_domains_ret {
    int ids<REMOTE_DOMAIN_ID_LIST_MAX>;
};

struct remote_num_of_domains_ret {
    int num;
};

struct remote_domain_create_linux_args {
    remote_nonnull_string xml_desc;
    int flags;
};

struct remote_domain_create_linux_ret {
    remote_nonnull_domain dom;
};

struct remote_domain_lookup_by_id_args {
    int id;
};

struct remote_domain_lookup_by_id_ret {
    /* XXX "Not found" semantic is ill-defined. */
    remote_nonnull_domain dom;
};

struct remote_domain_lookup_by_uuid_args {
    remote_uuid uuid;
};

struct remote_domain_lookup_by_uuid_ret {
    /* XXX "Not found" semantic is ill-defined. */
    remote_nonnull_domain dom;
};

struct remote_domain_lookup_by_name_args {
    remote_nonnull_string name;
};

struct remote_domain_lookup_by_name_ret {
    /* XXX "Not found" semantic is ill-defined. */
    remote_nonnull_domain dom;
};

struct remote_domain_suspend_args {
    remote_nonnull_domain dom;
};

struct remote_domain_resume_args {
    remote_nonnull_domain dom;
};

struct remote_domain_shutdown_args {
    remote_nonnull_domain dom;
};

struct remote_domain_reboot_args {
    remote_nonnull_domain dom;
    int flags;
};

struct remote_domain_destroy_args {
    remote_nonnull_domain dom;
};

struct remote_domain_get_os_type_args {
    remote_nonnull_domain dom;
};

struct remote_domain_get_os_type_ret {
    remote_nonnull_string type;
};

struct remote_domain_get_max_memory_args {
    remote_nonnull_domain dom;
};

struct remote_domain_get_max_memory_ret {
    unsigned hyper memory;
};

struct remote_domain_set_max_memory_args {
    remote_nonnull_domain dom;
    unsigned hyper memory;
};

struct remote_domain_set_memory_args {
    remote_nonnull_domain dom;
    unsigned hyper memory;
};

struct remote_domain_get_info_args {
    remote_nonnull_domain dom;
};

struct remote_domain_get_info_ret {
    unsigned char state;
    unsigned hyper max_mem;
    unsigned hyper memory;
    unsigned short nr_virt_cpu;
    /* XXX cpu_time is declared as unsigned long long */
    unsigned hyper cpu_time;
};

/* XXX Save, Restore, CoreDump not yet implemented because we
 * don't know where we will write the images.
 */

struct remote_domain_dump_xml_args {
    remote_nonnull_domain dom;
    int flags;
};

struct remote_domain_dump_xml_ret {
    remote_nonnull_string xml;
};

struct remote_domain_list_defined_domains_args {
    int maxnames;
};

struct remote_domain_list_defined_domains_ret {
    remote_nonnull_string names<REMOTE_DOMAIN_NAME_LIST_MAX>;
};

struct remote_domain_num_of_defined_domains_ret {
    int num;
};

struct remote_domain_create_args {
    remote_nonnull_domain dom;
};

struct remote_domain_define_xml_args {
    remote_nonnull_string xml;
};

struct remote_domain_define_xml_ret {
    remote_nonnull_domain dom;
};

struct remote_domain_undefine_args {
    remote_nonnull_domain dom;
};

struct remote_domain_set_vcpus_args {
    int nvcpus;
};

struct remote_domain_pin_vcpu_args {
    int vcpu;
    opaque cpumap<REMOTE_CPUMAP_MAX>;
};

struct remote_domain_get_vcpus_args {
    remote_nonnull_domain dom;
    int maxinfo;
    int maplen;
};

struct remote_domain_get_vcpus_ret {
    remote_vcpu_info info<REMOTE_VCPUINFO_MAX>;
    opaque cpumaps<REMOTE_CPUMAPS_MAX>;
};

struct remote_domain_get_max_vcpus_args {
    remote_nonnull_domain dom;
};

struct remote_domain_get_max_vcpus_ret {
    int num;
};

struct remote_domain_attach_device_args {
    remote_nonnull_domain dom;
    remote_nonnull_string xml;
};

struct remote_domain_detach_device_args {
    remote_nonnull_domain dom;
    remote_nonnull_string xml;
};

struct remote_domain_get_autostart_args {
    remote_nonnull_domain dom;
};

struct remote_domain_get_autostart_ret {
    int autostart;
};

struct remote_domain_set_autostart_args {
    remote_nonnull_domain dom;
    int autostart;
};

/* Network calls: */

struct remote_num_of_networks_ret {
    int num;
};

struct remote_list_networks_args {
    int maxnames;
};

struct remote_list_networks_ret {
    remote_nonnull_string names<REMOTE_NETWORK_NAME_LIST_MAX>;
};

struct remote_num_of_defined_networks_ret {
    int num;
};

struct remote_list_defined_networks_args {
    int maxnames;
};

struct remote_list_defined_networks_ret {
    remote_nonnull_string names<REMOTE_NETWORK_NAME_LIST_MAX>;
};

struct remote_network_lookup_by_uuid_args {
    remote_uuid uuid;
};

struct remote_network_lookup_by_uuid_ret {
    /* XXX "Not found" semantic is ill-defined. */
    remote_nonnull_network net;
};

struct remote_network_lookup_by_name_args {
    remote_nonnull_string name;
};

struct remote_network_lookup_by_name_ret {
    /* XXX "Not found" semantic is ill-defined. */
    remote_nonnull_network net;
};

struct remote_network_create_xml_args {
    remote_nonnull_string xml;
};

struct remote_network_create_xml_ret {
    remote_nonnull_network net;
};

struct remote_network_define_xml_args {
    remote_nonnull_string xml;
};

struct remote_network_define_xml_ret {
    remote_nonnull_network net;
};

struct remote_network_undefine_args {
    remote_nonnull_network net;
};

struct remote_network_create_args {
    remote_nonnull_network net;
};

struct remote_network_destroy_args {
    remote_nonnull_network net;
};

struct remote_network_dump_xml_args {
    remote_nonnull_network net;
    int flags;
};

struct remote_network_dump_xml_ret {
    remote_nonnull_string xml;
};

struct remote_network_get_bridge_name_args {
    remote_nonnull_network net;
};

struct remote_network_get_bridge_name_ret {
    remote_nonnull_string name;
};

struct remote_network_get_autostart_args {
    remote_nonnull_network net;
};

struct remote_network_get_autostart_ret {
    int autostart;
};

struct remote_network_set_autostart_args {
    remote_nonnull_network net;
    int autostart;
};

/*----- Protocol. -----*/

/* Define the program number, protocol version and procedure numbers here. */
const REMOTE_PROGRAM = 0x20008086;
const REMOTE_PROTOCOL_VERSION = 1;

enum remote_procedure {
    REMOTE_PROC_OPEN = 1,
    REMOTE_PROC_CLOSE = 2,
    REMOTE_PROC_GET_CAPABILITIES = 3
};

/* Custom RPC structure. */
/* Each message consists of:
 *    int length               Number of bytes in message _including_ length.
 *    remote_message_header    Header.
 * then either: args           Arguments (for REMOTE_CALL).
 *          or: ret            Return (for REMOTE_REPLY, status = REMOTE_OK)
 *          or: remote_error   Error (for REMOTE_REPLY, status = REMOTE_ERROR)
 *
 * The first two words (length, program number) are meant to be compatible
 * with the qemud protocol (qemud/protocol.x), although the rest of the
 * messages are completely different.
 */

enum remote_message_direction {
    REMOTE_CALL = 0,            /* client -> server */
    REMOTE_REPLY = 1,           /* server -> client */
    REMOTE_MESSAGE = 2          /* server -> client, asynchronous [NYI] */
};

enum remote_message_status {
    /* Status is always REMOTE_OK for calls.
     * For replies, indicates no error.
     */
    REMOTE_OK = 0,

    /* For replies, indicates that an error happened, and a struct
     * remote_error follows.
     */
    REMOTE_ERROR = 1
};

struct remote_message_header {
    unsigned prog;              /* REMOTE_PROGRAM */
    unsigned vers;              /* REMOTE_PROTOCOL_VERSION */
    remote_procedure proc;      /* REMOTE_PROC_x */
    remote_message_direction direction;
    unsigned serial;            /* Serial number of message. */
    remote_message_status status;
};


/*
 * vim: set tabstop=4:
 * vim: set shiftwidth=4:
 * vim: set expandtab:
 */
/*
 * Local variables:
 *  indent-tabs-mode: nil
 *  c-indent-level: 4
 *  c-basic-offset: 4
 *  tab-width: 4
 * End:
 */

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