[PATCH 11/14] nbd/client: Accept 64-bit hole chunks

[Eric Blake]

Although our read requests are sized such that servers need not send
an extended hole chunk, we still have to be prepared for it to be
fully compliant if we request extended headers.  We can also tolerate
a non-compliant server sending the new chunk even when it should not.

Signed-off-by: Eric Blake <eblake@redhat.com>
---
 block/nbd.c        | 26 ++++++++++++++++++++------
 block/trace-events |  1 +
 2 files changed, 21 insertions(+), 6 deletions(-)

diff --git a/block/nbd.c b/block/nbd.c
index da5e6ac2d9a5..c5dea864ebb6 100644
--- a/block/nbd.c
+++ b/block/nbd.c
@@ -518,20 +518,26 @@ static inline uint64_t payload_advance64(uint8_t 
**payload)

 static int nbd_parse_offset_hole_payload(BDRVNBDState *s,
                                          NBDStructuredReplyChunk *chunk,
-                                         uint8_t *payload, uint64_t 
orig_offset,
+                                         uint8_t *payload, bool wide,
+                                         uint64_t orig_offset,
                                          QEMUIOVector *qiov, Error **errp)
 {
     uint64_t offset;
-    uint32_t hole_size;
+    uint64_t hole_size;
+    size_t len = wide ? sizeof(hole_size) : sizeof(uint32_t);

-    if (chunk->length != sizeof(offset) + sizeof(hole_size)) {
+    if (chunk->length != sizeof(offset) + len) {
         error_setg(errp, "Protocol error: invalid payload for "
                          "NBD_REPLY_TYPE_OFFSET_HOLE");
         return -EINVAL;
     }

     offset = payload_advance64(&payload);
-    hole_size = payload_advance32(&payload);
+    if (wide) {
+        hole_size = payload_advance64(&payload);
+    } else {
+        hole_size = payload_advance32(&payload);
+    }

     if (!hole_size || offset < orig_offset || hole_size > qiov->size ||
         offset > orig_offset + qiov->size - hole_size) {
@@ -544,6 +550,7 @@ static int nbd_parse_offset_hole_payload(BDRVNBDState *s,
         trace_nbd_structured_read_compliance("hole");
     }

+    assert(hole_size <= SIZE_MAX);
     qemu_iovec_memset(qiov, offset - orig_offset, 0, hole_size);

     return 0;
@@ -1037,9 +1044,16 @@ static int nbd_co_receive_cmdread_reply(BDRVNBDState *s, 
uint64_t handle,
              * in qiov
              */
             break;
+        case NBD_REPLY_TYPE_OFFSET_HOLE_EXT:
+            if (!s->info.extended_headers) {
+                trace_nbd_extended_headers_compliance("hole_ext");
+            }
+            /* fallthrough */
         case NBD_REPLY_TYPE_OFFSET_HOLE:
-            ret = nbd_parse_offset_hole_payload(s, &reply.structured, payload,
-                                                offset, qiov, &local_err);
+            ret = nbd_parse_offset_hole_payload(
+                s, &reply.structured, payload,
+                chunk->type == NBD_REPLY_TYPE_OFFSET_HOLE_EXT,
+                offset, qiov, &local_err);
             if (ret < 0) {
                 nbd_channel_error(s, ret);
                 nbd_iter_channel_error(&iter, ret, &local_err);
diff --git a/block/trace-events b/block/trace-events
index 549090d453e7..ee65da204dde 100644
--- a/block/trace-events
+++ b/block/trace-events
@@ -168,6 +168,7 @@ iscsi_xcopy(void *src_lun, uint64_t src_off, void *dst_lun, 
uint64_t dst_off, ui
 # nbd.c
 nbd_parse_blockstatus_compliance(const char *err) "ignoring extra data from 
non-compliant server: %s"
 nbd_structured_read_compliance(const char *type) "server sent non-compliant 
unaligned read %s chunk"
+nbd_extended_headers_compliance(const char *type) "server sent non-compliant 
%s chunk without extended headers"
 nbd_read_reply_entry_fail(int ret, const char *err) "ret = %d, err: %s"
 nbd_co_request_fail(uint64_t from, uint32_t len, uint64_t handle, uint16_t 
flags, uint16_t type, const char *name, int ret, const char *err) "Request 
failed { .from = %" PRIu64", .len = %" PRIu32 ", .handle = %" PRIu64 ", .flags 
= 0x%" PRIx16 ", .type = %" PRIu16 " (%s) } ret = %d, err: %s"
 nbd_client_handshake(const char *export_name) "export '%s'"
-- 
2.33.1