src/protocol.h

   1 /* nbdkit
   2  * Copyright (C) 2013 Red Hat Inc.
   3  * All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions are
   7  * met:
   8  *
   9  * * Redistributions of source code must retain the above copyright
  10  * notice, this list of conditions and the following disclaimer.
  11  *
  12  * * Redistributions in binary form must reproduce the above copyright
  13  * notice, this list of conditions and the following disclaimer in the
  14  * documentation and/or other materials provided with the distribution.
  15  *
  16  * * Neither the name of Red Hat nor the names of its contributors may be
  17  * used to endorse or promote products derived from this software without
  18  * specific prior written permission.
  19  *
  20  * THIS SOFTWARE IS PROVIDED BY RED HAT AND CONTRIBUTORS ''AS IS'' AND
  21  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
  22  * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
  23  * PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL RED HAT OR
  24  * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  25  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  26  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
  27  * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
  28  * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
  29  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
  30  * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  31  * SUCH DAMAGE.
  32  */
  33
  34 #ifndef NBDKIT_PROTOCOL_H
  35 #define NBDKIT_PROTOCOL_H
  36
  37 #include <stdint.h>
  38
  39 /* Old-style handshake */
  40 struct old_handshake {
  41   char nbdmagic[8];           /* "NBDMAGIC" */
  42   uint64_t version;           /* OLD_VERSION, in network byte order */
  43   uint64_t exportsize;        /* in network byte order */
  44   uint16_t gflags;            /* global flags, in network byte order */
  45   uint16_t eflags;            /* per-export flags, in network byte order */
  46   char zeroes[124];           /* must be sent as zero bytes */
  47 } __attribute__((packed));
  48
  49 #define OLD_VERSION UINT64_C(0x420281861253)
  50
  51 /* Global flags. */
  52 #define NBD_FLAG_FIXED_NEWSTYLE 1
  53
  54 /* Per-export flags. */
  55 #define NBD_FLAG_HAS_FLAGS   1
  56 #define NBD_FLAG_READ_ONLY   2
  57 #define NBD_FLAG_SEND_FLUSH  4
  58 #define NBD_FLAG_SEND_FUA    8
  59 #define NBD_FLAG_ROTATIONAL 16
  60 #define NBD_FLAG_SEND_TRIM  32
  61
  62 /* Request (client -> server). */
  63 struct request {
  64   uint32_t magic;               /* NBD_REQUEST_MAGIC. */
  65   uint32_t type;                /* Request type. */
  66   uint64_t handle;              /* Opaque handle. */
  67   uint64_t offset;              /* Request offset. */
  68   uint32_t count;               /* Request length. */
  69 } __attribute__((packed));
  70
  71 /* Reply (server -> client). */
  72 struct reply {
  73   uint32_t magic;               /* NBD_REPLY_MAGIC. */
  74   uint32_t error;               /* 0 = ok, error code */
  75   uint64_t handle;              /* Opaque handle. */
  76 } __attribute__((packed));
  77
  78 #define NBD_REQUEST_MAGIC 0x25609513
  79 #define NBD_REPLY_MAGIC 0x67446698
  80
  81 #define NBD_CMD_READ              0
  82 #define NBD_CMD_WRITE             1
  83 #define NBD_CMD_DISC              2 /* Disconnect. */
  84 #define NBD_CMD_FLUSH             3
  85 #define NBD_CMD_TRIM              4
  86 #define NBD_CMD_MASK_COMMAND 0xffff
  87 #define NBD_CMD_FLAG_FUA    (1<<16)
  88
  89 #endif /* NBDKIT_PROTOCOL_H */