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[Qemu-devel] [PATCH 10/14] nbd/client: Split handshake into two function
From: |
Eric Blake |
Subject: |
[Qemu-devel] [PATCH 10/14] nbd/client: Split handshake into two functions |
Date: |
Fri, 30 Nov 2018 16:03:39 -0600 |
An upcoming patch will add the ability for qemu-nbd to list
the services provided by an NBD server. Share the common
code of the TLS handshake by splitting the initial exchange
into a separate function, leaving only the export handling
in the original function. Functionally, there should be no
change in behavior in this patch, although some of the code
motion may be difficult to follow due to indentation changes
(view with 'git diff -w' for a smaller changeset).
Signed-off-by: Eric Blake <address@hidden>
---
nbd/client.c | 142 ++++++++++++++++++++++++++++++-----------------
nbd/trace-events | 2 +-
2 files changed, 92 insertions(+), 52 deletions(-)
diff --git a/nbd/client.c b/nbd/client.c
index 1ed5009642e..a282712724d 100644
--- a/nbd/client.c
+++ b/nbd/client.c
@@ -768,21 +768,22 @@ static int nbd_negotiate_simple_meta_context(QIOChannel
*ioc,
return received || opt == NBD_OPT_LIST_META_CONTEXT;
}
-int nbd_receive_negotiate(QIOChannel *ioc, QCryptoTLSCreds *tlscreds,
- const char *hostname, QIOChannel **outioc,
- NBDExportInfo *info, Error **errp)
+/* Start the handshake to the server. After a positive return, the server
+ * is ready to accept additional NBD_OPT requests.
+ * Returns: negative errno: failure talking to server
+ * 0: server is oldstyle, client must still parse export size
+ * 1: server is newstyle, but can only accept EXPORT_NAME
+ * 2: server is newstyle, but lacks structured replies
+ * 3: server is newstyle and set up for structured replies
+ */
+static int nbd_start_negotiate(QIOChannel *ioc, QCryptoTLSCreds *tlscreds,
+ const char *hostname, QIOChannel **outioc,
+ bool structured_reply, bool *zeroes,
+ Error **errp)
{
uint64_t magic;
- bool zeroes = true;
- bool structured_reply = info->structured_reply;
- bool base_allocation = info->base_allocation;
- trace_nbd_receive_negotiate(tlscreds, hostname ? hostname : "<null>");
-
- assert(info->name);
- trace_nbd_receive_negotiate_name(info->name);
- info->structured_reply = false;
- info->base_allocation = false;
+ trace_nbd_start_negotiate(tlscreds, hostname ? hostname : "<null>");
if (outioc) {
*outioc = NULL;
@@ -827,7 +828,7 @@ int nbd_receive_negotiate(QIOChannel *ioc, QCryptoTLSCreds
*tlscreds,
clientflags |= NBD_FLAG_C_FIXED_NEWSTYLE;
}
if (globalflags & NBD_FLAG_NO_ZEROES) {
- zeroes = false;
+ *zeroes = false;
clientflags |= NBD_FLAG_C_NO_ZEROES;
}
/* client requested flags */
@@ -849,7 +850,7 @@ int nbd_receive_negotiate(QIOChannel *ioc, QCryptoTLSCreds
*tlscreds,
}
}
if (fixedNewStyle) {
- int result;
+ int result = 0;
if (structured_reply) {
result = nbd_request_simple_option(ioc,
@@ -858,42 +859,86 @@ int nbd_receive_negotiate(QIOChannel *ioc,
QCryptoTLSCreds *tlscreds,
if (result < 0) {
return -EINVAL;
}
- info->structured_reply = result == 1;
}
+ return 2 + result;
+ } else {
+ return 1;
+ }
+ } else if (magic == NBD_CLIENT_MAGIC) {
+ if (tlscreds) {
+ error_setg(errp, "Server does not support STARTTLS");
+ return -EINVAL;
+ }
+ return 0;
+ } else {
+ error_setg(errp, "Bad magic received");
+ return -EINVAL;
+ }
+}
- if (info->structured_reply && base_allocation) {
- result = nbd_negotiate_simple_meta_context(
+/* Connect to server, complete negotiation, and move into transmission phase.
+ * Returns: negative errno: failure talking to server
+ * 0: server is connected
+ */
+int nbd_receive_negotiate(QIOChannel *ioc, QCryptoTLSCreds *tlscreds,
+ const char *hostname, QIOChannel **outioc,
+ NBDExportInfo *info, Error **errp)
+{
+ int result;
+ bool zeroes = true;
+ bool base_allocation = info->base_allocation;
+ uint32_t oldflags;
+
+ assert(info->name);
+ trace_nbd_receive_negotiate_name(info->name);
+
+ result = nbd_start_negotiate(ioc, tlscreds, hostname, outioc,
+ info->structured_reply, &zeroes, errp);
+
+ info->structured_reply = false;
+ info->base_allocation = false;
+ if (tlscreds && *outioc) {
+ ioc = *outioc;
+ }
+
+ switch (result) {
+ case 3: /* newstyle, with structured replies */
+ info->structured_reply = true;
+ if (base_allocation) {
+ result = nbd_negotiate_simple_meta_context(
ioc, NBD_OPT_SET_META_CONTEXT,
info->x_dirty_bitmap ?: "base:allocation",
info, errp);
- if (result < 0) {
- return -EINVAL;
- }
- info->base_allocation = result == 1;
- }
-
- /* Try NBD_OPT_GO first - if it works, we are done (it
- * also gives us a good message if the server requires
- * TLS). If it is not available, fall back to
- * NBD_OPT_LIST for nicer error messages about a missing
- * export, then use NBD_OPT_EXPORT_NAME. */
- result = nbd_opt_go(ioc, info, errp);
if (result < 0) {
return -EINVAL;
}
- if (result > 0) {
- return 0;
- }
- /* Check our desired export is present in the
- * server export list. Since NBD_OPT_EXPORT_NAME
- * cannot return an error message, running this
- * query gives us better error reporting if the
- * export name is not available.
- */
- if (nbd_receive_query_exports(ioc, info->name, errp) < 0) {
- return -EINVAL;
- }
+ info->base_allocation = result == 1;
}
+ /* fall through */
+ case 2: /* newstyle, try OPT_GO */
+ /* Try NBD_OPT_GO first - if it works, we are done (it
+ * also gives us a good message if the server requires
+ * TLS). If it is not available, fall back to
+ * NBD_OPT_LIST for nicer error messages about a missing
+ * export, then use NBD_OPT_EXPORT_NAME. */
+ result = nbd_opt_go(ioc, info, errp);
+ if (result < 0) {
+ return -EINVAL;
+ }
+ if (result > 0) {
+ return 0;
+ }
+ /* Check our desired export is present in the
+ * server export list. Since NBD_OPT_EXPORT_NAME
+ * cannot return an error message, running this
+ * query gives us better error reporting if the
+ * export name is not available.
+ */
+ if (nbd_receive_query_exports(ioc, info->name, errp) < 0) {
+ return -EINVAL;
+ }
+ /* fall through */
+ case 1: /* newstyle, but limited to EXPORT_NAME */
/* write the export name request */
if (nbd_send_option_request(ioc, NBD_OPT_EXPORT_NAME, -1, info->name,
errp) < 0) {
@@ -912,17 +957,12 @@ int nbd_receive_negotiate(QIOChannel *ioc,
QCryptoTLSCreds *tlscreds,
return -EINVAL;
}
info->flags = be16_to_cpu(info->flags);
- } else if (magic == NBD_CLIENT_MAGIC) {
- uint32_t oldflags;
-
+ break;
+ case 0: /* oldstyle, parse length and flags */
if (*info->name) {
error_setg(errp, "Server does not support non-empty export names");
return -EINVAL;
}
- if (tlscreds) {
- error_setg(errp, "Server does not support STARTTLS");
- return -EINVAL;
- }
if (nbd_read(ioc, &info->size, sizeof(info->size), errp) < 0) {
error_prepend(errp, "Failed to read export length: ");
@@ -940,9 +980,9 @@ int nbd_receive_negotiate(QIOChannel *ioc, QCryptoTLSCreds
*tlscreds,
return -EINVAL;
}
info->flags = oldflags;
- } else {
- error_setg(errp, "Bad magic received");
- return -EINVAL;
+ break;
+ default:
+ return result;
}
trace_nbd_receive_negotiate_size_flags(info->size, info->flags);
diff --git a/nbd/trace-events b/nbd/trace-events
index 5d0d202fad2..570b04997ff 100644
--- a/nbd/trace-events
+++ b/nbd/trace-events
@@ -12,7 +12,7 @@ nbd_receive_starttls_new_client(void) "Setting up TLS"
nbd_receive_starttls_tls_handshake(void) "Starting TLS handshake"
nbd_opt_meta_request(const char *opt, const char *context, const char *export)
"Requesting to %s %s for export %s"
nbd_opt_meta_reply(const char *context, uint32_t id) "Received mapping of
context %s to id %" PRIu32
-nbd_receive_negotiate(void *tlscreds, const char *hostname) "Receiving
negotiation tlscreds=%p hostname=%s"
+nbd_start_negotiate(void *tlscreds, const char *hostname) "Receiving
negotiation tlscreds=%p hostname=%s"
nbd_receive_negotiate_magic(uint64_t magic) "Magic is 0x%" PRIx64
nbd_receive_negotiate_server_flags(uint32_t globalflags) "Global flags are
0x%" PRIx32
nbd_receive_negotiate_name(const char *name) "Requesting NBD export name
\"%s\""
--
2.17.2
- [Qemu-devel] [PATCH 05/14] nbd/client: Drop pointless buf variable, (continued)
- [Qemu-devel] [PATCH 05/14] nbd/client: Drop pointless buf variable, Eric Blake, 2018/11/30
- [Qemu-devel] [PATCH 01/14] qemu-nbd: Use program name in error messages, Eric Blake, 2018/11/30
- [Qemu-devel] [PATCH 06/14] nbd/client: Move export name into NBDExportInfo, Eric Blake, 2018/11/30
- [Qemu-devel] [PATCH 02/14] nbd/client: More consistent error messages, Eric Blake, 2018/11/30
- [Qemu-devel] [PATCH 03/14] qemu-nbd: Fail earlier for -c/-d on non-linux, Eric Blake, 2018/11/30
- [Qemu-devel] [PATCH 10/14] nbd/client: Split handshake into two functions,
Eric Blake <=
- [Qemu-devel] [PATCH 08/14] nbd/client: Refactor nbd_receive_list(), Eric Blake, 2018/11/30
- [Qemu-devel] [PATCH 07/14] nbd/client: Refactor nbd_negotiate_simple_meta_context(), Eric Blake, 2018/11/30
- [Qemu-devel] [PATCH 09/14] nbd/client: Refactor return of nbd_receive_negotiate(), Eric Blake, 2018/11/30
- [Qemu-devel] [PATCH 14/14] iotests: Enhance 223, 233 to cover 'qemu-nbd --list', Eric Blake, 2018/11/30
- [Qemu-devel] [PATCH 11/14] nbd/client: Add nbd_receive_export_list(), Eric Blake, 2018/11/30
- [Qemu-devel] [PATCH 12/14] nbd/client: Work around 3.0 bug for listing meta contexts, Eric Blake, 2018/11/30
- [Qemu-devel] [PATCH 13/14] qemu-nbd: Add --list option, Eric Blake, 2018/11/30