server/protocol-handshake.c

   1 /* nbdkit
   2  * Copyright (C) 2013-2019 Red Hat Inc.
   3  *
   4  * Redistribution and use in source and binary forms, with or without
   5  * modification, are permitted provided that the following conditions are
   6  * met:
   7  *
   8  * * Redistributions of source code must retain the above copyright
   9  * notice, this list of conditions and the following disclaimer.
  10  *
  11  * * Redistributions in binary form must reproduce the above copyright
  12  * notice, this list of conditions and the following disclaimer in the
  13  * documentation and/or other materials provided with the distribution.
  14  *
  15  * * Neither the name of Red Hat nor the names of its contributors may be
  16  * used to endorse or promote products derived from this software without
  17  * specific prior written permission.
  18  *
  19  * THIS SOFTWARE IS PROVIDED BY RED HAT AND CONTRIBUTORS ''AS IS'' AND
  20  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
  21  * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
  22  * PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL RED HAT OR
  23  * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  24  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  25  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
  26  * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
  27  * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
  28  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
  29  * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  30  * SUCH DAMAGE.
  31  */
  32
  33 #include <config.h>
  34
  35 #include <stdio.h>
  36 #include <stdlib.h>
  37 #include <stdint.h>
  38 #include <inttypes.h>
  39 #include <string.h>
  40 #include <unistd.h>
  41
  42 #include "internal.h"
  43 #include "byte-swapping.h"
  44 #include "protocol.h"
  45
  46 /* eflags calculation is the same between oldstyle and newstyle
  47  * protocols.
  48  */
  49 int
  50 protocol_compute_eflags (struct connection *conn, uint16_t *flags)
  51 {
  52   uint16_t eflags = NBD_FLAG_HAS_FLAGS;
  53   int fl;
  54
  55   fl = backend_can_write (backend, conn);
  56   if (fl == -1)
  57     return -1;
  58   if (readonly || !fl) {
  59     eflags |= NBD_FLAG_READ_ONLY;
  60     conn->readonly = true;
  61   }
  62   if (!conn->readonly) {
  63     fl = backend_can_zero (backend, conn);
  64     if (fl == -1)
  65       return -1;
  66     if (fl) {
  67       eflags |= NBD_FLAG_SEND_WRITE_ZEROES;
  68       conn->can_zero = true;
  69     }
  70
  71     fl = backend_can_trim (backend, conn);
  72     if (fl == -1)
  73       return -1;
  74     if (fl) {
  75       eflags |= NBD_FLAG_SEND_TRIM;
  76       conn->can_trim = true;
  77     }
  78
  79     fl = backend_can_fua (backend, conn);
  80     if (fl == -1)
  81       return -1;
  82     if (fl) {
  83       eflags |= NBD_FLAG_SEND_FUA;
  84       conn->can_fua = true;
  85     }
  86   }
  87
  88   fl = backend_can_flush (backend, conn);
  89   if (fl == -1)
  90     return -1;
  91   if (fl) {
  92     eflags |= NBD_FLAG_SEND_FLUSH;
  93     conn->can_flush = true;
  94   }
  95
  96   fl = backend_is_rotational (backend, conn);
  97   if (fl == -1)
  98     return -1;
  99   if (fl) {
 100     eflags |= NBD_FLAG_ROTATIONAL;
 101     conn->is_rotational = true;
 102   }
 103
 104   /* multi-conn is useless if parallel connections are not allowed */
 105   if (backend->thread_model (backend) >
 106       NBDKIT_THREAD_MODEL_SERIALIZE_CONNECTIONS) {
 107     fl = backend_can_multi_conn (backend, conn);
 108     if (fl == -1)
 109       return -1;
 110     if (fl) {
 111       eflags |= NBD_FLAG_CAN_MULTI_CONN;
 112       conn->can_multi_conn = true;
 113     }
 114   }
 115
 116   fl = backend_can_cache (backend, conn);
 117   if (fl == -1)
 118     return -1;
 119   if (fl) {
 120     eflags |= NBD_FLAG_SEND_CACHE;
 121     conn->can_cache = true;
 122     conn->emulate_cache = fl == NBDKIT_CACHE_EMULATE;
 123   }
 124
 125   /* The result of this is not returned to callers here (or at any
 126    * time during the handshake).  However it makes sense to do it once
 127    * per connection and store the result in the handle anyway.  This
 128    * protocol_compute_eflags function is a bit misnamed XXX.
 129    */
 130   fl = backend_can_extents (backend, conn);
 131   if (fl == -1)
 132     return -1;
 133   if (fl)
 134     conn->can_extents = true;
 135
 136   if (conn->structured_replies)
 137     eflags |= NBD_FLAG_SEND_DF;
 138
 139   *flags = eflags;
 140   return 0;
 141 }
 142
 143 int
 144 protocol_handshake (struct connection *conn)
 145 {
 146   int r;
 147
 148   lock_request (conn);
 149   if (!newstyle)
 150     r = protocol_handshake_oldstyle (conn);
 151   else
 152     r = protocol_handshake_newstyle (conn);
 153   unlock_request (conn);
 154
 155   return r;
 156 }