Libguestfs - Aug 2023 - [libnbd PATCH v4 16/25] info: Expose extended-headers support through nbdinfo

Add another bit of overall server information, as well as a '--has
extended-headers' silent query.  For now, the testsuite is written
assuming that when nbdkit finally adds extended headers support, it
will also add a --no-eh kill switch comparable to its existing --no-sr
switch.

Signed-off-by: Eric Blake <eblake at redhat.com>
---

v4: s/can/has/ [Rich]
---
 info/nbdinfo.pod     |  9 +++++++++
 info/can.c           |  9 +++++++++
 info/info-can.sh     | 27 +++++++++++++++++++++++++++
 info/info-packets.sh | 17 ++++++++++++++++-
 info/main.c          |  7 ++++++-
 5 files changed, 67 insertions(+), 2 deletions(-)

diff --git a/info/nbdinfo.pod b/info/nbdinfo.pod
index 72193c24..2bdd573f 100644
--- a/info/nbdinfo.pod
+++ b/info/nbdinfo.pod
@@ -86,6 +86,7 @@ the I<--json> parameter:
    "protocol": "newstyle-fixed",
    "TLS": false,
    "structured": true,
+   "extended": false,
    "exports": [
      {
        "export-name": "",
@@ -165,6 +166,11 @@ Test if the NBD URI connection is using TLS.
 Test if server has support for structured replies (a prerequisite
 for supporting block status commands).

+=item nbdinfo --has extended-headers URI
+
+Test if server supports extended headers (a prerequisite for
+supporting 64-bit commands; implies structured replies as well).
+
 =item nbdinfo --is rotational URI

 Test if the server export is backed by something which behaves like a
@@ -367,6 +373,8 @@ When using I<--list>, the default is
I<--no-content> (since
 downloading from each export is expensive).  To enable content probing
 use I<--list --content>.

+=item B<--has extended-headers>
+
 =item B<--has structured-reply>

 Test properties of the NBD server connection.  The command does not
@@ -377,6 +385,7 @@ indicate an error querying the flag).
 For further information see the L<NBD
 protocol|https://github.com/NetworkBlockDevice/nbd/blob/master/doc/proto.md>
 and the following libnbd functions:
+L<nbd_get_extended_headers_negotiated(3)>,
 L<nbd_get_structured_replies_negotiated(3)>.

 =item B<--is read-only>
diff --git a/info/can.c b/info/can.c
index 8514fd5a..8547ef04 100644
--- a/info/can.c
+++ b/info/can.c
@@ -50,6 +50,15 @@ do_can (void)
            strcasecmp (can, "structured_replies") == 0)
     feature = nbd_get_structured_replies_negotiated (nbd);

+  else if (strcasecmp (can, "eh") == 0 ||
+           strcasecmp (can, "extended header") == 0 ||
+           strcasecmp (can, "extended-header") == 0 ||
+           strcasecmp (can, "extended_header") == 0 ||
+           strcasecmp (can, "extended headers") == 0 ||
+           strcasecmp (can, "extended-headers") == 0 ||
+           strcasecmp (can, "extended_headers") == 0)
+    feature = nbd_get_extended_headers_negotiated (nbd);
+
   else if (strcasecmp (can, "readonly") == 0 ||
            strcasecmp (can, "read-only") == 0 ||
            strcasecmp (can, "read_only") == 0)
diff --git a/info/info-can.sh b/info/info-can.sh
index 13ef1032..5d9f2e89 100755
--- a/info/info-can.sh
+++ b/info/info-can.sh
@@ -61,6 +61,33 @@ esac
 EOF
 test $st = 2

+# --has extended-headers cannot be positively tested until nbdkit gains
+# --no-eh support.  Otherwise, it is similar to --has structured-reply.
+
+no_eh+if nbdkit --no-eh --help >/dev/null 2>/dev/null; then
+    no_eh=--no-eh
+    nbdkit -v -U - sh - \
+           --run '$VG nbdinfo --has extended-headers
"nbd+unix:///?socket=$unixsocket"' <<'EOF'
+case "$1" in
+  get_size) echo 1024 ;;
+  pread) ;;
+  *) exit 2 ;;
+esac
+EOF
+fi
+
+st=0
+nbdkit -v -U - $no_eh sh - \
+       --run '$VG nbdinfo --has extended-headers
"nbd+unix:///?socket=$unixsocket"' <<'EOF' || st=$?
+case "$1" in
+  get_size) echo 1024 ;;
+  pread) ;;
+  *) exit 2 ;;
+esac
+EOF
+test $st = 2
+
 # --can cache and --can fua require special handling because in
 # nbdkit-sh-plugin we must print "native" or "none".  Also
the can_fua
 # flag is only sent if the export is writable (hence can_write below).
diff --git a/info/info-packets.sh b/info/info-packets.sh
index 2460052e..410faef8 100755
--- a/info/info-packets.sh
+++ b/info/info-packets.sh
@@ -27,12 +27,27 @@ requires nbdkit --no-sr memory --version
 out=info-packets.out
 cleanup_fn rm -f $out

+# Older nbdkit does not support extended headers; --no-eh is a reliable
+# witness of whether nbdkit is new enough.
+
+no_eh+if nbdkit --no-eh --help >/dev/null 2>/dev/null; then
+    no_eh=--no-eh
+fi
+
 nbdkit --no-sr -U - memory size=1M \
        --run '$VG nbdinfo "nbd+unix:///?socket=$unixsocket"'
> $out
 cat $out
 grep "protocol: .*using simple packets" $out

-nbdkit -U - memory size=1M \
+nbdkit $no_eh -U - memory size=1M \
        --run '$VG nbdinfo "nbd+unix:///?socket=$unixsocket"'
> $out
 cat $out
 grep "protocol: .*using structured packets" $out
+
+if test x != "x$no_eh"; then
+    nbdkit -U - memory size=1M \
+           --run '$VG nbdinfo
"nbd+unix:///?socket=$unixsocket"' > $out
+    cat $out
+    grep "protocol: .*using extended packets" $out
+fi
diff --git a/info/main.c b/info/main.c
index dbcc5a14..572dd536 100644
--- a/info/main.c
+++ b/info/main.c
@@ -306,11 +306,13 @@ main (int argc, char *argv[])
     const char *protocol;
     int tls_negotiated;
     int sr_negotiated;
+    int eh_negotiated;

     /* Print per-connection fields. */
     protocol = nbd_get_protocol (nbd);
     tls_negotiated = nbd_get_tls_negotiated (nbd);
     sr_negotiated = nbd_get_structured_replies_negotiated (nbd);
+    eh_negotiated = nbd_get_extended_headers_negotiated (nbd);

     if (!json_output) {
       if (protocol) {
@@ -318,8 +320,9 @@ main (int argc, char *argv[])
         fprintf (fp, "protocol: %s", protocol);
         if (tls_negotiated >= 0)
           fprintf (fp, " %s TLS", tls_negotiated ? "with" :
"without");
-        if (sr_negotiated >= 0)
+        if (eh_negotiated >= 0 && sr_negotiated >= 0)
           fprintf (fp, ", using %s packets",
+                   eh_negotiated ? "extended" :
                    sr_negotiated ? "structured" :
"simple");
         fprintf (fp, "\n");
         ansi_restore (fp);
@@ -337,6 +340,8 @@ main (int argc, char *argv[])
         fprintf (fp, "\"TLS\": %s,\n", tls_negotiated ?
"true" : "false");
       if (sr_negotiated >= 0)
         fprintf (fp, "\"structured\": %s,\n", sr_negotiated
? "true" : "false");
+      if (eh_negotiated >= 0)
+        fprintf (fp, "\"extended\": %s,\n", eh_negotiated ?
"true" : "false");
     }

     if (!list_all)
-- 
2.41.0

On Wed, Aug 02, 2023 at 08:50:36PM -0500, Eric Blake
wrote:
> Add another bit of overall server information, as well as a '--has
> extended-headers' silent query.  For now, the testsuite is written
> assuming that when nbdkit finally adds extended headers support, it
> will also add a --no-eh kill switch comparable to its existing --no-sr
> switch.
> 
> Signed-off-by: Eric Blake <eblake at redhat.com>
> ---
> 
> v4: s/can/has/ [Rich]
> ---
>  info/nbdinfo.pod     |  9 +++++++++
>  info/can.c           |  9 +++++++++
>  info/info-can.sh     | 27 +++++++++++++++++++++++++++
>  info/info-packets.sh | 17 ++++++++++++++++-
>  info/main.c          |  7 ++++++-
>  5 files changed, 67 insertions(+), 2 deletions(-)
> 
> diff --git a/info/nbdinfo.pod b/info/nbdinfo.pod
> index 72193c24..2bdd573f 100644
> --- a/info/nbdinfo.pod
> +++ b/info/nbdinfo.pod
> @@ -86,6 +86,7 @@ the I<--json> parameter:
>     "protocol": "newstyle-fixed",
>     "TLS": false,
>     "structured": true,
> +   "extended": false,
>     "exports": [
>       {
>         "export-name": "",
> @@ -165,6 +166,11 @@ Test if the NBD URI connection is using TLS.
>  Test if server has support for structured replies (a prerequisite
>  for supporting block status commands).
> 
> +=item nbdinfo --has extended-headers URI
> +
> +Test if server supports extended headers (a prerequisite for
> +supporting 64-bit commands; implies structured replies as well).
> +
>  =item nbdinfo --is rotational URI
> 
>  Test if the server export is backed by something which behaves like a
> @@ -367,6 +373,8 @@ When using I<--list>, the default is
I<--no-content> (since
>  downloading from each export is expensive).  To enable content probing
>  use I<--list --content>.
> 
> +=item B<--has extended-headers>
> +
>  =item B<--has structured-reply>
> 
>  Test properties of the NBD server connection.  The command does not
> @@ -377,6 +385,7 @@ indicate an error querying the flag).
>  For further information see the L<NBD
> 
protocol|https://github.com/NetworkBlockDevice/nbd/blob/master/doc/proto.md>
>  and the following libnbd functions:
> +L<nbd_get_extended_headers_negotiated(3)>,
>  L<nbd_get_structured_replies_negotiated(3)>.
> 
>  =item B<--is read-only>
> diff --git a/info/can.c b/info/can.c
> index 8514fd5a..8547ef04 100644
> --- a/info/can.c
> +++ b/info/can.c
> @@ -50,6 +50,15 @@ do_can (void)
>             strcasecmp (can, "structured_replies") == 0)
>      feature = nbd_get_structured_replies_negotiated (nbd);
> 
> +  else if (strcasecmp (can, "eh") == 0 ||
> +           strcasecmp (can, "extended header") == 0 ||
> +           strcasecmp (can, "extended-header") == 0 ||
> +           strcasecmp (can, "extended_header") == 0 ||
> +           strcasecmp (can, "extended headers") == 0 ||
> +           strcasecmp (can, "extended-headers") == 0 ||
> +           strcasecmp (can, "extended_headers") == 0)
> +    feature = nbd_get_extended_headers_negotiated (nbd);
> +
>    else if (strcasecmp (can, "readonly") == 0 ||
>             strcasecmp (can, "read-only") == 0 ||
>             strcasecmp (can, "read_only") == 0)
> diff --git a/info/info-can.sh b/info/info-can.sh
> index 13ef1032..5d9f2e89 100755
> --- a/info/info-can.sh
> +++ b/info/info-can.sh
> @@ -61,6 +61,33 @@ esac
>  EOF
>  test $st = 2
> 
> +# --has extended-headers cannot be positively tested until nbdkit gains
> +# --no-eh support.  Otherwise, it is similar to --has structured-reply.
> +
> +no_eh> +if nbdkit --no-eh --help >/dev/null 2>/dev/null; then
> +    no_eh=--no-eh
> +    nbdkit -v -U - sh - \
> +           --run '$VG nbdinfo --has extended-headers
"nbd+unix:///?socket=$unixsocket"' <<'EOF'
> +case "$1" in
> +  get_size) echo 1024 ;;
> +  pread) ;;
> +  *) exit 2 ;;
> +esac
> +EOF
> +fi
> +
> +st=0
> +nbdkit -v -U - $no_eh sh - \
> +       --run '$VG nbdinfo --has extended-headers
"nbd+unix:///?socket=$unixsocket"' <<'EOF' || st=$?
> +case "$1" in
> +  get_size) echo 1024 ;;
> +  pread) ;;
> +  *) exit 2 ;;
> +esac
> +EOF
> +test $st = 2
> +
>  # --can cache and --can fua require special handling because in
>  # nbdkit-sh-plugin we must print "native" or "none". 
Also the can_fua
>  # flag is only sent if the export is writable (hence can_write below).
> diff --git a/info/info-packets.sh b/info/info-packets.sh
> index 2460052e..410faef8 100755
> --- a/info/info-packets.sh
> +++ b/info/info-packets.sh
> @@ -27,12 +27,27 @@ requires nbdkit --no-sr memory --version
>  out=info-packets.out
>  cleanup_fn rm -f $out
> 
> +# Older nbdkit does not support extended headers; --no-eh is a reliable
> +# witness of whether nbdkit is new enough.
> +
> +no_eh> +if nbdkit --no-eh --help >/dev/null 2>/dev/null; then
> +    no_eh=--no-eh
> +fi
> +
>  nbdkit --no-sr -U - memory size=1M \
>         --run '$VG nbdinfo
"nbd+unix:///?socket=$unixsocket"' > $out
>  cat $out
>  grep "protocol: .*using simple packets" $out
> 
> -nbdkit -U - memory size=1M \
> +nbdkit $no_eh -U - memory size=1M \
>         --run '$VG nbdinfo
"nbd+unix:///?socket=$unixsocket"' > $out
>  cat $out
>  grep "protocol: .*using structured packets" $out
> +
> +if test x != "x$no_eh"; then
> +    nbdkit -U - memory size=1M \
> +           --run '$VG nbdinfo
"nbd+unix:///?socket=$unixsocket"' > $out
> +    cat $out
> +    grep "protocol: .*using extended packets" $out
> +fi
> diff --git a/info/main.c b/info/main.c
> index dbcc5a14..572dd536 100644
> --- a/info/main.c
> +++ b/info/main.c
> @@ -306,11 +306,13 @@ main (int argc, char *argv[])
>      const char *protocol;
>      int tls_negotiated;
>      int sr_negotiated;
> +    int eh_negotiated;
> 
>      /* Print per-connection fields. */
>      protocol = nbd_get_protocol (nbd);
>      tls_negotiated = nbd_get_tls_negotiated (nbd);
>      sr_negotiated = nbd_get_structured_replies_negotiated (nbd);
> +    eh_negotiated = nbd_get_extended_headers_negotiated (nbd);
> 
>      if (!json_output) {
>        if (protocol) {
> @@ -318,8 +320,9 @@ main (int argc, char *argv[])
>          fprintf (fp, "protocol: %s", protocol);
>          if (tls_negotiated >= 0)
>            fprintf (fp, " %s TLS", tls_negotiated ?
"with" : "without");
> -        if (sr_negotiated >= 0)
> +        if (eh_negotiated >= 0 && sr_negotiated >= 0)
>            fprintf (fp, ", using %s packets",
> +                   eh_negotiated ? "extended" :
>                     sr_negotiated ? "structured" :
"simple");
Interesting - there's never a case where we could have extended
headers && ! structured replies?
>          fprintf (fp, "\n");
>          ansi_restore (fp);
> @@ -337,6 +340,8 @@ main (int argc, char *argv[])
>          fprintf (fp, "\"TLS\": %s,\n", tls_negotiated
? "true" : "false");
>        if (sr_negotiated >= 0)
>          fprintf (fp, "\"structured\": %s,\n",
sr_negotiated ? "true" : "false");
> +      if (eh_negotiated >= 0)
> +        fprintf (fp, "\"extended\": %s,\n",
eh_negotiated ? "true" : "false");
>      }
> 
>      if (!list_all)
> -- 
Reviewed-by: Richard W.M. Jones <rjones at redhat.com>

Rich.

-- 
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
Read my programming and virtualization blog: http://rwmj.wordpress.com
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