include/block/nbd.h

   1 /*
   2  *  Copyright (C) 2016 Red Hat, Inc.
   3  *  Copyright (C) 2005  Anthony Liguori <anthony@codemonkey.ws>
   4  *
   5  *  Network Block Device
   6  *
   7  *  This program is free software; you can redistribute it and/or modify
   8  *  it under the terms of the GNU General Public License as published by
   9  *  the Free Software Foundation; under version 2 of the License.
  10  *
  11  *  This program is distributed in the hope that it will be useful,
  12  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  *  GNU General Public License for more details.
  15  *
  16  *  You should have received a copy of the GNU General Public License
  17  *  along with this program; if not, see <http://www.gnu.org/licenses/>.
  18  */
  19
  20 #ifndef NBD_H
  21 #define NBD_H
  22
  23
  24 #include "qemu-common.h"
  25 #include "qemu/option.h"
  26 #include "io/channel-socket.h"
  27 #include "crypto/tlscreds.h"
  28
  29 /* Handshake phase structs - this struct is passed on the wire */
  30
  31 struct nbd_option {
  32     uint64_t magic; /* NBD_OPTS_MAGIC */
  33     uint32_t option; /* NBD_OPT_* */
  34     uint32_t length;
  35 } QEMU_PACKED;
  36 typedef struct nbd_option nbd_option;
  37
  38 struct nbd_opt_reply {
  39     uint64_t magic; /* NBD_REP_MAGIC */
  40     uint32_t option; /* NBD_OPT_* */
  41     uint32_t type; /* NBD_REP_* */
  42     uint32_t length;
  43 } QEMU_PACKED;
  44 typedef struct nbd_opt_reply nbd_opt_reply;
  45
  46 /* Transmission phase structs
  47  *
  48  * Note: these are _NOT_ the same as the network representation of an NBD
  49  * request and reply!
  50  */
  51 struct NBDRequest {
  52     uint64_t handle;
  53     uint64_t from;
  54     uint32_t len;
  55     uint16_t flags; /* NBD_CMD_FLAG_* */
  56     uint16_t type; /* NBD_CMD_* */
  57 };
  58 typedef struct NBDRequest NBDRequest;
  59
  60 struct NBDReply {
  61     uint64_t handle;
  62     uint32_t error;
  63 };
  64 typedef struct NBDReply NBDReply;
  65
  66 /* Transmission (export) flags: sent from server to client during handshake,
  67    but describe what will happen during transmission */
  68 #define NBD_FLAG_HAS_FLAGS      (1 << 0)        /* Flags are there */
  69 #define NBD_FLAG_READ_ONLY      (1 << 1)        /* Device is read-only */
  70 #define NBD_FLAG_SEND_FLUSH     (1 << 2)        /* Send FLUSH */
  71 #define NBD_FLAG_SEND_FUA       (1 << 3)        /* Send FUA (Force Unit Access) */
  72 #define NBD_FLAG_ROTATIONAL     (1 << 4)        /* Use elevator algorithm - rotational media */
  73 #define NBD_FLAG_SEND_TRIM      (1 << 5)        /* Send TRIM (discard) */
  74 #define NBD_FLAG_SEND_WRITE_ZEROES (1 << 6)     /* Send WRITE_ZEROES */
  75
  76 /* New-style handshake (global) flags, sent from server to client, and
  77    control what will happen during handshake phase. */
  78 #define NBD_FLAG_FIXED_NEWSTYLE   (1 << 0) /* Fixed newstyle protocol. */
  79 #define NBD_FLAG_NO_ZEROES        (1 << 1) /* End handshake without zeroes. */
  80
  81 /* New-style client flags, sent from client to server to control what happens
  82    during handshake phase. */
  83 #define NBD_FLAG_C_FIXED_NEWSTYLE (1 << 0) /* Fixed newstyle protocol. */
  84 #define NBD_FLAG_C_NO_ZEROES      (1 << 1) /* End handshake without zeroes. */
  85
  86 /* Reply types. */
  87 #define NBD_REP_ERR(value) ((UINT32_C(1) << 31) | (value))
  88
  89 #define NBD_REP_ACK             (1)             /* Data sending finished. */
  90 #define NBD_REP_SERVER          (2)             /* Export description. */
  91
  92 #define NBD_REP_ERR_UNSUP       NBD_REP_ERR(1)  /* Unknown option */
  93 #define NBD_REP_ERR_POLICY      NBD_REP_ERR(2)  /* Server denied */
  94 #define NBD_REP_ERR_INVALID     NBD_REP_ERR(3)  /* Invalid length */
  95 #define NBD_REP_ERR_PLATFORM    NBD_REP_ERR(4)  /* Not compiled in */
  96 #define NBD_REP_ERR_TLS_REQD    NBD_REP_ERR(5)  /* TLS required */
  97 #define NBD_REP_ERR_SHUTDOWN    NBD_REP_ERR(7)  /* Server shutting down */
  98
  99 /* Request flags, sent from client to server during transmission phase */
 100 #define NBD_CMD_FLAG_FUA        (1 << 0) /* 'force unit access' during write */
 101 #define NBD_CMD_FLAG_NO_HOLE    (1 << 1) /* don't punch hole on zero run */
 102
 103 /* Supported request types */
 104 enum {
 105     NBD_CMD_READ = 0,
 106     NBD_CMD_WRITE = 1,
 107     NBD_CMD_DISC = 2,
 108     NBD_CMD_FLUSH = 3,
 109     NBD_CMD_TRIM = 4,
 110     /* 5 reserved for failed experiment NBD_CMD_CACHE */
 111     NBD_CMD_WRITE_ZEROES = 6,
 112 };
 113
 114 #define NBD_DEFAULT_PORT        10809
 115
 116 /* Maximum size of a single READ/WRITE data buffer */
 117 #define NBD_MAX_BUFFER_SIZE (32 * 1024 * 1024)
 118
 119 /* Maximum size of an export name. The NBD spec requires 256 and
 120  * suggests that servers support up to 4096, but we stick to only the
 121  * required size so that we can stack-allocate the names, and because
 122  * going larger would require an audit of more code to make sure we
 123  * aren't overflowing some other buffer. */
 124 #define NBD_MAX_NAME_SIZE 256
 125
 126 ssize_t nbd_wr_syncv(QIOChannel *ioc,
 127                      struct iovec *iov,
 128                      size_t niov,
 129                      size_t length,
 130                      bool do_read);
 131 int nbd_receive_negotiate(QIOChannel *ioc, const char *name, uint16_t *flags,
 132                           QCryptoTLSCreds *tlscreds, const char *hostname,
 133                           QIOChannel **outioc,
 134                           off_t *size, Error **errp);
 135 int nbd_init(int fd, QIOChannelSocket *sioc, uint16_t flags, off_t size);
 136 ssize_t nbd_send_request(QIOChannel *ioc, NBDRequest *request);
 137 ssize_t nbd_receive_reply(QIOChannel *ioc, NBDReply *reply);
 138 int nbd_client(int fd);
 139 int nbd_disconnect(int fd);
 140
 141 typedef struct NBDExport NBDExport;
 142 typedef struct NBDClient NBDClient;
 143
 144 NBDExport *nbd_export_new(BlockDriverState *bs, off_t dev_offset, off_t size,
 145                           uint16_t nbdflags, void (*close)(NBDExport *),
 146                           bool writethrough, BlockBackend *on_eject_blk,
 147                           Error **errp);
 148 void nbd_export_close(NBDExport *exp);
 149 void nbd_export_get(NBDExport *exp);
 150 void nbd_export_put(NBDExport *exp);
 151
 152 BlockBackend *nbd_export_get_blockdev(NBDExport *exp);
 153
 154 NBDExport *nbd_export_find(const char *name);
 155 void nbd_export_set_name(NBDExport *exp, const char *name);
 156 void nbd_export_set_description(NBDExport *exp, const char *description);
 157 void nbd_export_close_all(void);
 158
 159 void nbd_client_new(NBDExport *exp,
 160                     QIOChannelSocket *sioc,
 161                     QCryptoTLSCreds *tlscreds,
 162                     const char *tlsaclname,
 163                     void (*close)(NBDClient *));
 164 void nbd_client_get(NBDClient *client);
 165 void nbd_client_put(NBDClient *client);
 166
 167 #endif