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[PATCH v4 14/24] nbd/server: Prepare to receive extended header requests
From: |
Eric Blake |
Subject: |
[PATCH v4 14/24] nbd/server: Prepare to receive extended header requests |
Date: |
Thu, 8 Jun 2023 08:56:43 -0500 |
Although extended mode is not yet enabled, once we do turn it on, we
need to accept extended requests for all messages. Previous patches
have already taken care of supporting 64-bit lengths, now we just need
to read it off the wire.
Note that this implementation will block indefinitely on a buggy
client that sends a non-extended payload (that is, we try to read a
full packet before we ever check the magic number, but a client that
mistakenly sends a simple request after negotiating extended headers
doesn't send us enough bytes), but it's no different from any other
client that stops talking to us partway through a packet and thus not
worth coding around.
Signed-off-by: Eric Blake <eblake@redhat.com>
---
v4: new patch, split out from v3 9/14
---
nbd/nbd-internal.h | 5 ++++-
nbd/server.c | 43 ++++++++++++++++++++++++++++++-------------
2 files changed, 34 insertions(+), 14 deletions(-)
diff --git a/nbd/nbd-internal.h b/nbd/nbd-internal.h
index 133b1d94b50..dfa02f77ee4 100644
--- a/nbd/nbd-internal.h
+++ b/nbd/nbd-internal.h
@@ -34,8 +34,11 @@
* https://github.com/yoe/nbd/blob/master/doc/proto.md
*/
-/* Size of all NBD_OPT_*, without payload */
+/* Size of all compact NBD_CMD_*, without payload */
#define NBD_REQUEST_SIZE (4 + 2 + 2 + 8 + 8 + 4)
+/* Size of all extended NBD_CMD_*, without payload */
+#define NBD_EXTENDED_REQUEST_SIZE (4 + 2 + 2 + 8 + 8 + 8)
+
/* Size of all NBD_REP_* sent in answer to most NBD_OPT_*, without payload */
#define NBD_REPLY_SIZE (4 + 4 + 8)
/* Size of reply to NBD_OPT_EXPORT_NAME */
diff --git a/nbd/server.c b/nbd/server.c
index d7dc29f0445..119ac765f09 100644
--- a/nbd/server.c
+++ b/nbd/server.c
@@ -1413,11 +1413,13 @@ nbd_read_eof(NBDClient *client, void *buffer, size_t
size, Error **errp)
static int coroutine_fn nbd_receive_request(NBDClient *client, NBDRequest
*request,
Error **errp)
{
- uint8_t buf[NBD_REQUEST_SIZE];
- uint32_t magic;
+ uint8_t buf[NBD_EXTENDED_REQUEST_SIZE];
+ uint32_t magic, expect;
int ret;
+ size_t size = client->mode >= NBD_MODE_EXTENDED ?
+ NBD_EXTENDED_REQUEST_SIZE : NBD_REQUEST_SIZE;
- ret = nbd_read_eof(client, buf, sizeof(buf), errp);
+ ret = nbd_read_eof(client, buf, size, errp);
if (ret < 0) {
return ret;
}
@@ -1425,13 +1427,21 @@ static int coroutine_fn nbd_receive_request(NBDClient
*client, NBDRequest *reque
return -EIO;
}
- /* Request
- [ 0 .. 3] magic (NBD_REQUEST_MAGIC)
- [ 4 .. 5] flags (NBD_CMD_FLAG_FUA, ...)
- [ 6 .. 7] type (NBD_CMD_READ, ...)
- [ 8 .. 15] cookie
- [16 .. 23] from
- [24 .. 27] len
+ /*
+ * Compact request
+ * [ 0 .. 3] magic (NBD_REQUEST_MAGIC)
+ * [ 4 .. 5] flags (NBD_CMD_FLAG_FUA, ...)
+ * [ 6 .. 7] type (NBD_CMD_READ, ...)
+ * [ 8 .. 15] cookie
+ * [16 .. 23] from
+ * [24 .. 27] len
+ * Extended request
+ * [ 0 .. 3] magic (NBD_EXTENDED_REQUEST_MAGIC)
+ * [ 4 .. 5] flags (NBD_CMD_FLAG_FUA, NBD_CMD_FLAG_PAYLOAD_LEN, ...)
+ * [ 6 .. 7] type (NBD_CMD_READ, ...)
+ * [ 8 .. 15] cookie
+ * [16 .. 23] from
+ * [24 .. 31] len
*/
magic = ldl_be_p(buf);
@@ -1439,13 +1449,20 @@ static int coroutine_fn nbd_receive_request(NBDClient
*client, NBDRequest *reque
request->type = lduw_be_p(buf + 6);
request->cookie = ldq_be_p(buf + 8);
request->from = ldq_be_p(buf + 16);
- request->len = ldl_be_p(buf + 24); /* widen 32 to 64 bits */
+ if (client->mode >= NBD_MODE_EXTENDED) {
+ request->len = ldq_be_p(buf + 24);
+ expect = NBD_EXTENDED_REQUEST_MAGIC;
+ } else {
+ request->len = ldl_be_p(buf + 24); /* widen 32 to 64 bits */
+ expect = NBD_REQUEST_MAGIC;
+ }
trace_nbd_receive_request(magic, request->flags, request->type,
request->from, request->len);
- if (magic != NBD_REQUEST_MAGIC) {
- error_setg(errp, "invalid magic (got 0x%" PRIx32 ")", magic);
+ if (magic != expect) {
+ error_setg(errp, "invalid magic (got 0x%" PRIx32 ", expected 0x%"
+ PRIx32 ")", magic, expect);
return -EINVAL;
}
return 0;
--
2.40.1
- Re: [PATCH v4 03/24] nbd/server: Prepare for alternate-size headers, (continued)
- [PATCH v4 04/24] nbd/server: Refactor to pass full request around, Eric Blake, 2023/06/08
- [PATCH v4 05/24] nbd: s/handle/cookie/ to match NBD spec, Eric Blake, 2023/06/08
- [PATCH v4 08/24] nbd: Use enum for various negotiation modes, Eric Blake, 2023/06/08
- [PATCH v4 06/24] nbd/client: Simplify cookie vs. index computation, Eric Blake, 2023/06/08
- [PATCH v4 14/24] nbd/server: Prepare to receive extended header requests,
Eric Blake <=
- [PATCH v4 17/24] nbd/server: Enable initial support for extended headers, Eric Blake, 2023/06/08
- [PATCH v4 07/24] nbd/client: Add safety check on chunk payload length, Eric Blake, 2023/06/08
- [PATCH v4 10/24] nbd/client: Pass mode through to nbd_send_request, Eric Blake, 2023/06/08
- [PATCH v4 12/24] nbd: Prepare for 64-bit request effect lengths, Eric Blake, 2023/06/08
- [PATCH v4 11/24] nbd: Add types for extended headers, Eric Blake, 2023/06/08