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qemu/include/block/nbd.h

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/*
* Copyright (C) 2016-2017 Red Hat, Inc.
* Copyright (C) 2005 Anthony Liguori <anthony@codemonkey.ws>
*
* Network Block Device
*
* 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; under version 2 of the License.
*
* 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/>.
*/
#ifndef NBD_H
#define NBD_H
#include "qemu-common.h"
#include "qemu/option.h"
#include "io/channel-socket.h"
#include "crypto/tlscreds.h"
/* Handshake phase structs - this struct is passed on the wire */
struct nbd_option {
uint64_t magic; /* NBD_OPTS_MAGIC */
uint32_t option; /* NBD_OPT_* */
uint32_t length;
} QEMU_PACKED;
typedef struct nbd_option nbd_option;
struct nbd_opt_reply {
uint64_t magic; /* NBD_REP_MAGIC */
uint32_t option; /* NBD_OPT_* */
uint32_t type; /* NBD_REP_* */
uint32_t length;
} QEMU_PACKED;
typedef struct nbd_opt_reply nbd_opt_reply;
/* Transmission phase structs
*
* Note: these are _NOT_ the same as the network representation of an NBD
* request and reply!
*/
struct NBDRequest {
uint64_t handle;
uint64_t from;
uint32_t len;
uint16_t flags; /* NBD_CMD_FLAG_* */
uint16_t type; /* NBD_CMD_* */
};
typedef struct NBDRequest NBDRequest;
typedef struct NBDSimpleReply {
uint32_t magic; /* NBD_SIMPLE_REPLY_MAGIC */
uint32_t error;
uint64_t handle;
} QEMU_PACKED NBDSimpleReply;
/* Header of all structured replies */
typedef struct NBDStructuredReplyChunk {
uint32_t magic; /* NBD_STRUCTURED_REPLY_MAGIC */
uint16_t flags; /* combination of NBD_REPLY_FLAG_* */
uint16_t type; /* NBD_REPLY_TYPE_* */
uint64_t handle; /* request handle */
uint32_t length; /* length of payload */
} QEMU_PACKED NBDStructuredReplyChunk;
typedef union NBDReply {
NBDSimpleReply simple;
NBDStructuredReplyChunk structured;
struct {
/* @magic and @handle fields have the same offset and size both in
* simple reply and structured reply chunk, so let them be accessible
* without ".simple." or ".structured." specification
*/
uint32_t magic;
uint32_t _skip;
uint64_t handle;
} QEMU_PACKED;
} NBDReply;
/* Header of chunk for NBD_REPLY_TYPE_OFFSET_DATA */
typedef struct NBDStructuredReadData {
NBDStructuredReplyChunk h; /* h.length >= 9 */
uint64_t offset;
/* At least one byte of data payload follows, calculated from h.length */
} QEMU_PACKED NBDStructuredReadData;
/* Complete chunk for NBD_REPLY_TYPE_OFFSET_HOLE */
typedef struct NBDStructuredReadHole {
NBDStructuredReplyChunk h; /* h.length == 12 */
uint64_t offset;
uint32_t length;
} QEMU_PACKED NBDStructuredReadHole;
/* Header of all NBD_REPLY_TYPE_ERROR* errors */
typedef struct NBDStructuredError {
NBDStructuredReplyChunk h; /* h.length >= 6 */
uint32_t error;
uint16_t message_length;
} QEMU_PACKED NBDStructuredError;
/* Transmission (export) flags: sent from server to client during handshake,
but describe what will happen during transmission */
#define NBD_FLAG_HAS_FLAGS (1 << 0) /* Flags are there */
#define NBD_FLAG_READ_ONLY (1 << 1) /* Device is read-only */
#define NBD_FLAG_SEND_FLUSH (1 << 2) /* Send FLUSH */
#define NBD_FLAG_SEND_FUA (1 << 3) /* Send FUA (Force Unit Access) */
#define NBD_FLAG_ROTATIONAL (1 << 4) /* Use elevator algorithm -
rotational media */
#define NBD_FLAG_SEND_TRIM (1 << 5) /* Send TRIM (discard) */
#define NBD_FLAG_SEND_WRITE_ZEROES (1 << 6) /* Send WRITE_ZEROES */
#define NBD_FLAG_SEND_DF (1 << 7) /* Send DF (Do not Fragment) */
/* New-style handshake (global) flags, sent from server to client, and
control what will happen during handshake phase. */
#define NBD_FLAG_FIXED_NEWSTYLE (1 << 0) /* Fixed newstyle protocol. */
#define NBD_FLAG_NO_ZEROES (1 << 1) /* End handshake without zeroes. */
/* New-style client flags, sent from client to server to control what happens
during handshake phase. */
#define NBD_FLAG_C_FIXED_NEWSTYLE (1 << 0) /* Fixed newstyle protocol. */
#define NBD_FLAG_C_NO_ZEROES (1 << 1) /* End handshake without zeroes. */
/* Option requests. */
#define NBD_OPT_EXPORT_NAME (1)
#define NBD_OPT_ABORT (2)
#define NBD_OPT_LIST (3)
/* #define NBD_OPT_PEEK_EXPORT (4) not in use */
#define NBD_OPT_STARTTLS (5)
#define NBD_OPT_INFO (6)
#define NBD_OPT_GO (7)
#define NBD_OPT_STRUCTURED_REPLY (8)
/* Option reply types. */
#define NBD_REP_ERR(value) ((UINT32_C(1) << 31) | (value))
#define NBD_REP_ACK (1) /* Data sending finished. */
#define NBD_REP_SERVER (2) /* Export description. */
#define NBD_REP_INFO (3) /* NBD_OPT_INFO/GO. */
#define NBD_REP_ERR_UNSUP NBD_REP_ERR(1) /* Unknown option */
#define NBD_REP_ERR_POLICY NBD_REP_ERR(2) /* Server denied */
#define NBD_REP_ERR_INVALID NBD_REP_ERR(3) /* Invalid length */
#define NBD_REP_ERR_PLATFORM NBD_REP_ERR(4) /* Not compiled in */
#define NBD_REP_ERR_TLS_REQD NBD_REP_ERR(5) /* TLS required */
#define NBD_REP_ERR_UNKNOWN NBD_REP_ERR(6) /* Export unknown */
#define NBD_REP_ERR_SHUTDOWN NBD_REP_ERR(7) /* Server shutting down */
#define NBD_REP_ERR_BLOCK_SIZE_REQD NBD_REP_ERR(8) /* Need INFO_BLOCK_SIZE */
/* Info types, used during NBD_REP_INFO */
#define NBD_INFO_EXPORT 0
#define NBD_INFO_NAME 1
#define NBD_INFO_DESCRIPTION 2
#define NBD_INFO_BLOCK_SIZE 3
/* Request flags, sent from client to server during transmission phase */
#define NBD_CMD_FLAG_FUA (1 << 0) /* 'force unit access' during write */
#define NBD_CMD_FLAG_NO_HOLE (1 << 1) /* don't punch hole on zero run */
#define NBD_CMD_FLAG_DF (1 << 2) /* don't fragment structured read */
/* Supported request types */
enum {
NBD_CMD_READ = 0,
NBD_CMD_WRITE = 1,
NBD_CMD_DISC = 2,
NBD_CMD_FLUSH = 3,
NBD_CMD_TRIM = 4,
/* 5 reserved for failed experiment NBD_CMD_CACHE */
NBD_CMD_WRITE_ZEROES = 6,
};
#define NBD_DEFAULT_PORT 10809
/* Maximum size of a single READ/WRITE data buffer */
#define NBD_MAX_BUFFER_SIZE (32 * 1024 * 1024)
/* Maximum size of an export name. The NBD spec requires 256 and
* suggests that servers support up to 4096, but we stick to only the
* required size so that we can stack-allocate the names, and because
* going larger would require an audit of more code to make sure we
* aren't overflowing some other buffer. */
#define NBD_MAX_NAME_SIZE 256
/* Two types of reply structures */
#define NBD_SIMPLE_REPLY_MAGIC 0x67446698
#define NBD_STRUCTURED_REPLY_MAGIC 0x668e33ef
/* Structured reply flags */
#define NBD_REPLY_FLAG_DONE (1 << 0) /* This reply-chunk is last */
/* Structured reply types */
#define NBD_REPLY_ERR(value) ((1 << 15) | (value))
#define NBD_REPLY_TYPE_NONE 0
#define NBD_REPLY_TYPE_OFFSET_DATA 1
#define NBD_REPLY_TYPE_OFFSET_HOLE 2
#define NBD_REPLY_TYPE_ERROR NBD_REPLY_ERR(1)
#define NBD_REPLY_TYPE_ERROR_OFFSET NBD_REPLY_ERR(2)
static inline bool nbd_reply_type_is_error(int type)
{
return type & (1 << 15);
}
/* NBD errors are based on errno numbers, so there is a 1:1 mapping,
* but only a limited set of errno values is specified in the protocol.
* Everything else is squashed to EINVAL.
*/
#define NBD_SUCCESS 0
#define NBD_EPERM 1
#define NBD_EIO 5
#define NBD_ENOMEM 12
#define NBD_EINVAL 22
#define NBD_ENOSPC 28
#define NBD_EOVERFLOW 75
#define NBD_ESHUTDOWN 108
/* Details collected by NBD_OPT_EXPORT_NAME and NBD_OPT_GO */
struct NBDExportInfo {
/* Set by client before nbd_receive_negotiate() */
bool request_sizes;
/* In-out fields, set by client before nbd_receive_negotiate() and
* updated by server results during nbd_receive_negotiate() */
bool structured_reply;
/* Set by server results during nbd_receive_negotiate() */
uint64_t size;
uint16_t flags;
uint32_t min_block;
uint32_t opt_block;
uint32_t max_block;
};
typedef struct NBDExportInfo NBDExportInfo;
int nbd_receive_negotiate(QIOChannel *ioc, const char *name,
QCryptoTLSCreds *tlscreds, const char *hostname,
QIOChannel **outioc, NBDExportInfo *info,
Error **errp);
int nbd_init(int fd, QIOChannelSocket *sioc, NBDExportInfo *info,
Error **errp);
int nbd_send_request(QIOChannel *ioc, NBDRequest *request);
int nbd_receive_reply(QIOChannel *ioc, NBDReply *reply, Error **errp);
int nbd_client(int fd);
int nbd_disconnect(int fd);
int nbd_errno_to_system_errno(int err);
typedef struct NBDExport NBDExport;
typedef struct NBDClient NBDClient;
NBDExport *nbd_export_new(BlockDriverState *bs, off_t dev_offset, off_t size,
uint16_t nbdflags, void (*close)(NBDExport *),
bool writethrough, BlockBackend *on_eject_blk,
Error **errp);
void nbd_export_close(NBDExport *exp);
void nbd_export_get(NBDExport *exp);
void nbd_export_put(NBDExport *exp);
BlockBackend *nbd_export_get_blockdev(NBDExport *exp);
NBDExport *nbd_export_find(const char *name);
void nbd_export_set_name(NBDExport *exp, const char *name);
void nbd_export_set_description(NBDExport *exp, const char *description);
void nbd_export_close_all(void);
void nbd_client_new(NBDExport *exp,
QIOChannelSocket *sioc,
QCryptoTLSCreds *tlscreds,
const char *tlsaclname,
void (*close_fn)(NBDClient *, bool));
void nbd_client_get(NBDClient *client);
void nbd_client_put(NBDClient *client);
void nbd_server_start(SocketAddress *addr, const char *tls_creds,
Error **errp);
/* nbd_read
* Reads @size bytes from @ioc. Returns 0 on success.
*/
static inline int nbd_read(QIOChannel *ioc, void *buffer, size_t size,
Error **errp)
{
return qio_channel_read_all(ioc, buffer, size, errp) < 0 ? -EIO : 0;
}
static inline bool nbd_reply_is_simple(NBDReply *reply)
{
return reply->magic == NBD_SIMPLE_REPLY_MAGIC;
}
static inline bool nbd_reply_is_structured(NBDReply *reply)
{
return reply->magic == NBD_STRUCTURED_REPLY_MAGIC;
}
const char *nbd_reply_type_lookup(uint16_t type);
#endif
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