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[Qemu-devel] [PATCH v5 06/14] nbd: Send message along with server NBD_RE
From: |
Eric Blake |
Subject: |
[Qemu-devel] [PATCH v5 06/14] nbd: Send message along with server NBD_REP_ERR errors |
Date: |
Mon, 18 Jul 2016 22:07:53 -0600 |
The NBD Protocol allows us to send human-readable messages
along with any NBD_REP_ERR error during option negotiation;
make use of this fact for clients that know what to do with
our message.
Signed-off-by: Eric Blake <address@hidden>
---
v5: don't leak 'msg'
v4: new patch
---
nbd/server.c | 78 +++++++++++++++++++++++++++++++++++++++++++++---------------
1 file changed, 59 insertions(+), 19 deletions(-)
diff --git a/nbd/server.c b/nbd/server.c
index c8716f1..ad31c4a 100644
--- a/nbd/server.c
+++ b/nbd/server.c
@@ -235,6 +235,38 @@ static int nbd_negotiate_send_rep(QIOChannel *ioc,
uint32_t type, uint32_t opt)
return nbd_negotiate_send_rep_len(ioc, type, opt, 0);
}
+/* Send an error reply.
+ * Return -errno to kill connection, 0 to continue negotiation. */
+static int GCC_FMT_ATTR(4, 5)
+ nbd_negotiate_send_rep_err(QIOChannel *ioc, uint32_t type,
+ uint32_t opt, const char *fmt, ...)
+{
+ va_list va;
+ char *msg;
+ int ret;
+ size_t len;
+
+ va_start(va, fmt);
+ msg = g_strdup_vprintf(fmt, va);
+ va_end(va);
+ len = strlen(msg);
+ assert(len < 4096);
+ TRACE("sending error message \"%s\"", msg);
+ ret = nbd_negotiate_send_rep_len(ioc, type, opt, len);
+ if (ret < 0) {
+ goto out;
+ }
+ if (nbd_negotiate_write(ioc, msg, len) != len) {
+ LOG("write failed (error message)");
+ ret = -EIO;
+ } else {
+ ret = 0;
+ }
+out:
+ g_free(msg);
+ return ret;
+}
+
/* Send an NBD_REP_SERVER reply to NBD_OPT_LIST, including payload.
* Return -errno to kill connection, 0 to continue negotiation. */
static int nbd_negotiate_send_rep_list(QIOChannel *ioc, NBDExport *exp)
@@ -278,8 +310,9 @@ static int nbd_negotiate_handle_list(NBDClient *client,
uint32_t length)
if (nbd_negotiate_drop_sync(client->ioc, length) != length) {
return -EIO;
}
- return nbd_negotiate_send_rep(client->ioc,
- NBD_REP_ERR_INVALID, NBD_OPT_LIST);
+ return nbd_negotiate_send_rep_err(client->ioc,
+ NBD_REP_ERR_INVALID, NBD_OPT_LIST,
+ "OPT_LIST should not have length");
}
/* For each export, send a NBD_REP_SERVER reply. */
@@ -326,7 +359,8 @@ fail:
return rc;
}
-
+/* Handle NBD_OPT_STARTTLS. Return NULL to drop connection, or else the
+ * new channel for all further (now-encrypted) communication. */
static QIOChannel *nbd_negotiate_handle_starttls(NBDClient *client,
uint32_t length)
{
@@ -340,7 +374,8 @@ static QIOChannel *nbd_negotiate_handle_starttls(NBDClient
*client,
if (nbd_negotiate_drop_sync(ioc, length) != length) {
return NULL;
}
- nbd_negotiate_send_rep(ioc, NBD_REP_ERR_INVALID, NBD_OPT_STARTTLS);
+ nbd_negotiate_send_rep_err(ioc, NBD_REP_ERR_INVALID, NBD_OPT_STARTTLS,
+ "OPT_STARTTLS should not have length");
return NULL;
}
@@ -468,13 +503,15 @@ static int nbd_negotiate_options(NBDClient *client)
return -EINVAL;
default:
- TRACE("Option 0x%" PRIx32 " not permitted before TLS",
- clientflags);
if (nbd_negotiate_drop_sync(client->ioc, length) != length) {
return -EIO;
}
- ret = nbd_negotiate_send_rep(client->ioc, NBD_REP_ERR_TLS_REQD,
- clientflags);
+ ret = nbd_negotiate_send_rep_err(client->ioc,
+ NBD_REP_ERR_TLS_REQD,
+ clientflags,
+ "Option 0x%" PRIx32
+ "not permitted before TLS",
+ clientflags);
if (ret < 0) {
return ret;
}
@@ -500,27 +537,30 @@ static int nbd_negotiate_options(NBDClient *client)
return -EIO;
}
if (client->tlscreds) {
- TRACE("TLS already enabled");
- ret = nbd_negotiate_send_rep(client->ioc,
- NBD_REP_ERR_INVALID,
- clientflags);
+ ret = nbd_negotiate_send_rep_err(client->ioc,
+ NBD_REP_ERR_INVALID,
+ clientflags,
+ "TLS already enabled");
} else {
- TRACE("TLS not configured");
- ret = nbd_negotiate_send_rep(client->ioc,
- NBD_REP_ERR_POLICY,
- clientflags);
+ ret = nbd_negotiate_send_rep_err(client->ioc,
+ NBD_REP_ERR_POLICY,
+ clientflags,
+ "TLS not configured");
}
if (ret < 0) {
return ret;
}
break;
default:
- TRACE("Unsupported option 0x%" PRIx32, clientflags);
if (nbd_negotiate_drop_sync(client->ioc, length) != length) {
return -EIO;
}
- ret = nbd_negotiate_send_rep(client->ioc, NBD_REP_ERR_UNSUP,
- clientflags);
+ ret = nbd_negotiate_send_rep_err(client->ioc,
+ NBD_REP_ERR_UNSUP,
+ clientflags,
+ "Unsupported option 0x%"
+ PRIx32,
+ clientflags);
if (ret < 0) {
return ret;
}
--
2.5.5
- Re: [Qemu-devel] [PATCH v5 13/14] nbd: Implement NBD_CMD_WRITE_ZEROES on server, (continued)
[Qemu-devel] [PATCH v5 11/14] nbd: Support shorter handshake, Eric Blake, 2016/07/19
[Qemu-devel] [PATCH v5 14/14] nbd: Implement NBD_CMD_WRITE_ZEROES on client, Eric Blake, 2016/07/19
[Qemu-devel] [PATCH v5 07/14] nbd: Share common option-sending code in client, Eric Blake, 2016/07/19
[Qemu-devel] [PATCH v5 06/14] nbd: Send message along with server NBD_REP_ERR errors,
Eric Blake <=
[Qemu-devel] [PATCH v5 05/14] nbd: Share common reply-sending code in server, Eric Blake, 2016/07/19
[Qemu-devel] [PATCH v5 02/14] nbd: Add qemu-nbd -D for human-readable description, Eric Blake, 2016/07/19
[Qemu-devel] [PATCH v5 04/14] nbd: Treat flags vs. command type as separate fields, Eric Blake, 2016/07/19
[Qemu-devel] [PATCH v5 12/14] nbd: Improve server handling of shutdown requests, Eric Blake, 2016/07/19
[Qemu-devel] [PATCH v5 10/14] nbd: Less allocation during NBD_OPT_LIST, Eric Blake, 2016/07/19
Re: [Qemu-devel] [PATCH for-2.7 v5 00/14] nbd: efficient write zeroes, Fam Zheng, 2016/07/19