diff options
| author | Eric Blake <eblake@redhat.com> | 2018-12-15 07:53:10 -0600 |
|---|---|---|
| committer | Eric Blake <eblake@redhat.com> | 2019-01-05 07:53:22 -0600 |
| commit | ef2e35fcc8e14bcc9366df5fdf53f65d679f8dca (patch) | |
| tree | 9566fc73deb06530ce8ef5207748ea2ba3c40f82 /nbd | |
| parent | 3c1fa35d74aabe9c3ab642d2591b087e53d7a616 (diff) | |
nbd/client: Drop pointless buf variable
There's no need to read into a temporary buffer (oversized
since commit 7d3123e1) followed by a byteswap into a uint64_t
to check for a magic number via memcmp(), when the code
immediately below demonstrates reading into the uint64_t then
byteswapping in place and checking for a magic number via
integer math. What's more, having a different error message
when the server's first reply byte is 0 is unusual - it's no
different from any other wrong magic number, and we already
detected short reads. That whole strlen() issue has been
present and useless since commit 1d45f8b5 in 2010; perhaps it
was leftover debugging (since the correct magic number happens
to be ASCII)? Make the error messages more consistent and
detailed while touching things.
Signed-off-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Richard W.M. Jones <rjones@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Message-Id: <20181215135324.152629-9-eblake@redhat.com>
Diffstat (limited to 'nbd')
| -rw-r--r-- | nbd/client.c | 22 | ||||
| -rw-r--r-- | nbd/nbd-internal.h | 3 |
2 files changed, 9 insertions, 16 deletions
diff --git a/nbd/client.c b/nbd/client.c index 5a03a84418..f625c207c5 100644 --- a/nbd/client.c +++ b/nbd/client.c @@ -733,7 +733,6 @@ int nbd_receive_negotiate(QIOChannel *ioc, const char *name, QIOChannel **outioc, NBDExportInfo *info, Error **errp) { - char buf[256]; uint64_t magic; int rc; bool zeroes = true; @@ -754,27 +753,20 @@ int nbd_receive_negotiate(QIOChannel *ioc, const char *name, goto fail; } - if (nbd_read(ioc, buf, 8, errp) < 0) { - error_prepend(errp, "Failed to read data: "); - goto fail; - } - - buf[8] = '\0'; - if (strlen(buf) == 0) { - error_setg(errp, "Server connection closed unexpectedly"); + if (nbd_read(ioc, &magic, sizeof(magic), errp) < 0) { + error_prepend(errp, "Failed to read initial magic: "); goto fail; } - - magic = ldq_be_p(buf); + magic = be64_to_cpu(magic); trace_nbd_receive_negotiate_magic(magic); - if (memcmp(buf, "NBDMAGIC", 8) != 0) { - error_setg(errp, "Invalid magic received"); + if (magic != NBD_INIT_MAGIC) { + error_setg(errp, "Bad initial magic received: 0x%" PRIx64, magic); goto fail; } if (nbd_read(ioc, &magic, sizeof(magic), errp) < 0) { - error_prepend(errp, "Failed to read magic: "); + error_prepend(errp, "Failed to read server magic: "); goto fail; } magic = be64_to_cpu(magic); @@ -913,7 +905,7 @@ int nbd_receive_negotiate(QIOChannel *ioc, const char *name, } info->flags = oldflags; } else { - error_setg(errp, "Bad magic received"); + error_setg(errp, "Bad server magic received: 0x%" PRIx64, magic); goto fail; } diff --git a/nbd/nbd-internal.h b/nbd/nbd-internal.h index f38be9ebaa..82aa221227 100644 --- a/nbd/nbd-internal.h +++ b/nbd/nbd-internal.h @@ -46,8 +46,9 @@ /* Size of oldstyle negotiation */ #define NBD_OLDSTYLE_NEGOTIATE_SIZE (8 + 8 + 8 + 4 + 124) +#define NBD_INIT_MAGIC 0x4e42444d41474943LL /* ASCII "NBDMAGIC" */ #define NBD_REQUEST_MAGIC 0x25609513 -#define NBD_OPTS_MAGIC 0x49484156454F5054LL +#define NBD_OPTS_MAGIC 0x49484156454F5054LL /* ASCII "IHAVEOPT" */ #define NBD_CLIENT_MAGIC 0x0000420281861253LL #define NBD_REP_MAGIC 0x0003e889045565a9LL |