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From 0095b003b56894baad8e6789d523cf3c51905c05 Mon Sep 17 00:00:00 2001
From: "Richard W.M. Jones" <rjones@redhat.com>
Date: Tue, 17 May 2016 19:43:16 +0100
Subject: [PATCH 10/10] Implement newstyle export names.
This is now required by qemu >= 2.6. See this lengthy qemu-devel
thread for details:
https://lists.nongnu.org/archive/html/qemu-devel/2016-05/threads.html#02752
---
TODO | 13 -------------
docs/nbdkit.pod | 52 ++++++++++++++++++++++++++++++++-------------------
src/connections.c | 49 ++++++++++++++++++++++++++++++++++++++++--------
src/internal.h | 1 +
src/main.c | 32 +++++++++++++++++++++++--------
src/protocol.h | 3 +--
tests/test-newstyle.c | 7 +++++--
7 files changed, 105 insertions(+), 52 deletions(-)
diff --git a/TODO b/TODO
index 177a07c..30bf72e 100644
--- a/TODO
+++ b/TODO
@@ -11,19 +11,6 @@
* Performance - measure and improve it.
-* Implement export names. With export names it should be possible to
- have multiple plugins on the command line (each responding to a
- different export of course):
-
- nbdkit --export /foo plugin.so --export /bar another-plugin.so
-
- Note it should also be possible to either elect one plugin as the
- default that accepts all exportnames, or to divide the export name
- "space" up using regexps or wildcards.
-
- Export names are not actually paths (although that is how they are
- often used), but arbitrary UTF-8 text strings.
-
* Implement true parallel request handling. Currently
NBDKIT_THREAD_MODEL_SERIALIZE_REQUESTS and
NBDKIT_THREAD_MODEL_PARALLEL are the same, because we handle
diff --git a/docs/nbdkit.pod b/docs/nbdkit.pod
index 7204a38..728aad3 100644
--- a/docs/nbdkit.pod
+++ b/docs/nbdkit.pod
@@ -6,7 +6,7 @@ nbdkit - A toolkit for creating NBD servers
=head1 SYNOPSIS
- nbdkit [--dump-config] [-f] [-g GROUP] [-i IPADDR]
+ nbdkit [--dump-config] [-e EXPORTNAME] [-f] [-g GROUP] [-i IPADDR]
[--newstyle] [--oldstyle] [-P PIDFILE] [-p PORT] [-r]
[--run CMD] [-s] [-U SOCKET] [-u USER] [-v] [-V]
PLUGIN [key=value [key=value [...]]]
@@ -74,6 +74,19 @@ Display brief command line usage information and exit.
Dump out the compile-time configuration values and exit.
+=item B<-e> EXPORTNAME
+
+=item B<--export> EXPORTNAME
+
+=item B<--export-name> EXPORTNAME
+
+=item B<--exportname> EXPORTNAME
+
+Set the exportname and use the newstyle protocol (implies I<-n>).
+
+If not set, exportname C<""> (empty string) is used. Exportnames are
+not allowed with the oldstyle protocol.
+
=item B<-f>
=item B<--foreground>
@@ -118,9 +131,10 @@ protocol. See L</NEW STYLE VS OLD STYLE PROTOCOL> below.
=item B<--oldstyle>
-Use the oldstyle NBD protocol. This is currently the default, so this
-flag does nothing, but it is possible we might change the default
-protocol in future. See L</NEW STYLE VS OLD STYLE PROTOCOL> below.
+Use the oldstyle NBD protocol. This is currently the default (unless
+you use I<-n> or I<-e>), so this flag does nothing, but it is possible
+we might change the default protocol in future. See L</NEW STYLE VS
+OLD STYLE PROTOCOL> below.
=item B<-P> PIDFILE
@@ -307,27 +321,29 @@ use depends on the client and cannot be known in advance, nor can it
be negotiated from the server side.
nbdkit currently defaults to the oldstyle protocol for compatibility
-with qemu and libguestfs. This is also the same behaviour as
-qemu-nbd. Use the I<-n> or I<--newstyle> flag on the command line to
-use the newstyle protocol. Use the I<-o> or I<--oldstyle> flag to
-force the oldstyle protocol.
+with qemu and libguestfs. This is also the same behaviour as qemu-nbd
+E<le> 2.5. Use the I<-n> or I<--newstyle> flag on the command line to
+use the newstyle protocol. Use the I<-e> or I<--exportname> flag to
+set the exportname for the newstyle protocol. Use the I<-o> or
+I<--oldstyle> flag to force the oldstyle protocol.
Some common clients and the protocol they require:
- Client Protocol
+ Client Protocol
------------------------------------------------------------
- qemu without exportname oldstyle
- qemu with exportname newstyle
- nbd-client < 3.10 client can talk either protocol
- nbd-client >= 3.10 newstyle
+ qemu <= 2.5 without exportname oldstyle
+ qemu <= 2.5 with exportname newstyle
+ qemu >= 2.6 client can talk either protocol
+ nbd-client < 3.10 client can talk either protocol
+ nbd-client >= 3.10 newstyle
-If you use qemu without the exportname field against a newstyle
-server, it will give the error:
+If you use qemu E<le> 2.5 without the exportname field against a
+newstyle server, it will give the error:
Server requires an export name
-If you use qemu with the exportname field against an oldstyle server,
-it will give the error:
+If you use qemu E<le> 2.5 with the exportname field against an
+oldstyle server, it will give the error:
Server does not support export names
@@ -341,8 +357,6 @@ document says should be the case (which isn't based in reality), then
you should always use newstyle when using port 10809, and use oldstyle
on all other ports.
-nbdkit ignores export names at present (see also the C<TODO> file).
-
=head1 SIGNALS
C<nbdkit> responds to the following signals:
diff --git a/src/connections.c b/src/connections.c
index 34566b3..0c93f35 100644
--- a/src/connections.c
+++ b/src/connections.c
@@ -222,13 +222,8 @@ _negotiate_handshake_oldstyle (struct connection *conn)
return 0;
}
-/* Receive newstyle options.
- *
- * Currently we ignore NBD_OPT_EXPORT_NAME (see TODO), we close the
- * connection if sent NBD_OPT_ABORT, we send a canned list of
- * options for NBD_OPT_LIST, and we send NBD_REP_ERR_UNSUP for
- * everything else.
- */
+/* Receive newstyle options. */
+
static int
send_newstyle_option_reply (struct connection *conn,
uint32_t option, uint32_t reply)
@@ -250,6 +245,39 @@ send_newstyle_option_reply (struct connection *conn,
}
static int
+send_newstyle_option_reply_exportname (struct connection *conn,
+ uint32_t option, uint32_t reply,
+ const char *exportname)
+{
+ struct fixed_new_option_reply fixed_new_option_reply;
+ size_t name_len = strlen (exportname);
+ uint32_t len;
+
+ fixed_new_option_reply.magic = htobe64 (NBD_REP_MAGIC);
+ fixed_new_option_reply.option = htobe32 (option);
+ fixed_new_option_reply.reply = htobe32 (reply);
+ fixed_new_option_reply.replylen = htobe32 (name_len + sizeof (len));
+
+ if (xwrite (conn->sockout,
+ &fixed_new_option_reply, sizeof fixed_new_option_reply) == -1) {
+ nbdkit_error ("write: %m");
+ return -1;
+ }
+
+ len = htobe32 (name_len);
+ if (xwrite (conn->sockout, &len, sizeof len) == -1) {
+ nbdkit_error ("write: %m");
+ return -1;
+ }
+ if (xwrite (conn->sockout, exportname, name_len) == -1) {
+ nbdkit_error ("write: %m");
+ return -1;
+ }
+
+ return 0;
+}
+
+static int
_negotiate_handshake_newstyle_options (struct connection *conn)
{
struct new_option new_option;
@@ -309,7 +337,12 @@ _negotiate_handshake_newstyle_options (struct connection *conn)
continue;
}
- /* Since we don't support export names, there is nothing to list. */
+ /* Send back the exportname. */
+ debug ("newstyle negotiation: advertising export '%s'", exportname);
+ if (send_newstyle_option_reply_exportname (conn, option, NBD_REP_SERVER,
+ exportname) == -1)
+ return -1;
+
if (send_newstyle_option_reply (conn, option, NBD_REP_ACK) == -1)
return -1;
break;
diff --git a/src/internal.h b/src/internal.h
index 0603779..f58086a 100644
--- a/src/internal.h
+++ b/src/internal.h
@@ -48,6 +48,7 @@
#endif
/* main.c */
+extern const char *exportname;
extern const char *ipaddr;
extern int newstyle;
extern const char *port;
diff --git a/src/main.c b/src/main.c
index db4361e..9529f19 100644
--- a/src/main.c
+++ b/src/main.c
@@ -65,6 +65,7 @@ static void fork_into_background (void);
static uid_t parseuser (const char *);
static gid_t parsegroup (const char *);
+const char *exportname; /* -e */
int foreground; /* -f */
const char *ipaddr; /* -i */
int newstyle; /* -n */
@@ -84,10 +85,13 @@ static char *random_fifo = NULL;
enum { HELP_OPTION = CHAR_MAX + 1 };
-static const char *short_options = "fg:i:nop:P:rsu:U:vV";
+static const char *short_options = "e:fg:i:nop:P:rsu:U:vV";
static const struct option long_options[] = {
{ "help", 0, NULL, HELP_OPTION },
{ "dump-config",0, NULL, 0 },
+ { "export", 1, NULL, 'e' },
+ { "export-name",1, NULL, 'e' },
+ { "exportname", 1, NULL, 'e' },
{ "foreground", 0, NULL, 'f' },
{ "no-fork", 0, NULL, 'f' },
{ "group", 1, NULL, 'g' },
@@ -115,7 +119,7 @@ static const struct option long_options[] = {
static void
usage (void)
{
- printf ("nbdkit [--dump-config] [-f] [-g GROUP] [-i IPADDR]\n"
+ printf ("nbdkit [--dump-config] [-e EXPORTNAME] [-f] [-g GROUP] [-i IPADDR]\n"
" [--newstyle] [--oldstyle] [-P PIDFILE] [-p PORT] [-r]\n"
" [--run CMD] [-s] [-U SOCKET] [-u USER] [-v] [-V]\n"
" PLUGIN [key=value [key=value [...]]]\n"
@@ -173,6 +177,11 @@ main (int argc, char *argv[])
}
break;
+ case 'e':
+ exportname = optarg;
+ newstyle = 1;
+ break;
+
case 'f':
foreground = 1;
break;
@@ -190,9 +199,6 @@ main (int argc, char *argv[])
break;
case 'o':
- /* XXX When we add support for exportnames, we will need to
- * ensure that the user does not use -o + --export.
- */
newstyle = 0;
break;
@@ -263,12 +269,22 @@ main (int argc, char *argv[])
exit (EXIT_FAILURE);
}
+ /* Oldstyle protocol + exportname not allowed. */
+ if (newstyle == 0 && exportname != NULL) {
+ fprintf (stderr,
+ "%s: cannot use oldstyle protocol (-o) and exportname (-e)\n",
+ program_name);
+ exit (EXIT_FAILURE);
+ }
+
+ /* If exportname was not set on the command line, use "". */
+ if (exportname == NULL)
+ exportname = "";
+
/* Remaining command line arguments define the plugins and plugin
* configuration. If --help or --version was specified, we still
* partially parse these in order that we can display the per-plugin
- * help/version information. In future (when the new protocol and
- * export names are permitted) we will allow multiple plugins to be
- * given, but at the moment only one plugin is allowed.
+ * help/version information.
*/
while (optind < argc) {
const char *filename = argv[optind];
diff --git a/src/protocol.h b/src/protocol.h
index 71a8098..c885d9e 100644
--- a/src/protocol.h
+++ b/src/protocol.h
@@ -70,8 +70,7 @@ struct fixed_new_option_reply {
uint64_t magic; /* NBD_REP_MAGIC, network byte order */
uint32_t option; /* option we are replying to */
uint32_t reply; /* NBD_REP_* */
- uint32_t replylen; /* we always send zero at the moment */
- /* reply data follows, but we currently never send any */
+ uint32_t replylen;
} __attribute__((packed));
#define NBD_REP_MAGIC UINT64_C(0x3e889045565a9)
diff --git a/tests/test-newstyle.c b/tests/test-newstyle.c
index b1d8ce7..adcc568 100644
--- a/tests/test-newstyle.c
+++ b/tests/test-newstyle.c
@@ -44,6 +44,8 @@
#include "test.h"
+#define EXPORTNAME "/"
+
int
main (int argc, char *argv[])
{
@@ -52,7 +54,8 @@ main (int argc, char *argv[])
char *data;
size_t i, size;
- if (test_start_nbdkit ("-n", NBDKIT_PLUGIN ("file"), "file=file-data",
+ if (test_start_nbdkit ("-e", EXPORTNAME,
+ "-n", NBDKIT_PLUGIN ("file"), "file=file-data",
NULL) == -1)
exit (EXIT_FAILURE);
@@ -63,7 +66,7 @@ main (int argc, char *argv[])
}
/* Using any exportname causes qemu to use the newstyle protocol. */
- r = guestfs_add_drive_opts (g, "/" /* exportname */,
+ r = guestfs_add_drive_opts (g, EXPORTNAME,
GUESTFS_ADD_DRIVE_OPTS_FORMAT, "raw",
GUESTFS_ADD_DRIVE_OPTS_PROTOCOL, "nbd",
GUESTFS_ADD_DRIVE_OPTS_SERVER, server,
--
2.7.4
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