Similar to nbd_supports_tls(), it is nice to know from a feature probe whether we are likely to have VSOCK support before even trying more expensive APIs like nbd_connect_uri("nbd+vsock://..."). --- https://bugzilla.redhat.com/show_bug.cgi?id=2069558 documents a case where AF_VSOCK is compiled, but vsock still doesn't work because vsock_loopback is not loaded. Should we make nbd_supports_vsock() return true only when ALL aspects of vsock are known to be working? --- generator/API.ml | 25 ++++++++++++++++++++++--- lib/handle.c | 17 +++++++++++++++++ 2 files changed, 39 insertions(+), 3 deletions(-) diff --git a/generator/API.ml b/generator/API.ml index b377b9f..7ec85ca 100644 --- a/generator/API.ml +++ b/generator/API.ml @@ -1393,7 +1393,8 @@ "connect_uri", { =item C<nbds+vsock:> Connect over the C<AF_VSOCK> transport, without or with -TLS respectively. +TLS respectively. You can use L<nbd_supports_vsock(3)> to +see if this build of libnbd supports C<AF_VSOCK>. =back @@ -1494,7 +1495,8 @@ "connect_uri", { see_also = [URLLink "https://github.com/NetworkBlockDevice/nbd/blob/master/doc/uri.md"; Link "aio_connect_uri"; Link "set_export_name"; Link "set_tls"; - Link "set_opt_mode"; Link "get_uri"]; + Link "set_opt_mode"; Link "get_uri"; + Link "supports_vsock"; Link "supports_uri"]; }; "connect_unix", { @@ -1522,8 +1524,12 @@ "connect_vsock", { C<cid> should be C<2> (to connect to the host), and C<port> might be C<10809> or another port number assigned to you by the host administrator. + +Not all systems support C<AF_VSOCK>; to determine if libnbd was +built on a system with vsock support, see L<nbd_supports_vsock(3)>. " ^ blocking_connect_call_description; - see_also = [Link "aio_connect_vsock"; Link "set_opt_mode"]; + see_also = [Link "aio_connect_vsock"; Link "set_opt_mode"; + Link "supports_vsock"]; }; "connect_tcp", { @@ -3061,6 +3067,16 @@ "supports_tls", { see_also = [Link "set_tls"]; }; + "supports_vsock", { + default_call with + args = []; ret = RBool; is_locked = false; may_set_error = false; + shortdesc = "true if libnbd was compiled with support for AF_VSOCK"; + longdesc = "\ +Returns true if libnbd was compiled with support for the AF_VSOCK family +of sockets, or false if not."; + see_also = [Link "connect_vsock"; Link "connect_uri"]; + }; + "supports_uri", { default_call with args = []; ret = RBool; is_locked = false; may_set_error = false; @@ -3233,6 +3249,9 @@ let first_version = "set_request_block_size", (1, 12); "get_request_block_size", (1, 12); + (* Added in 1.13.x development cycle, will be stable and supported in 1.14. *) + "supports_vsock", (1, 14); + (* These calls are proposed for a future version of libnbd, but * have not been added to any released version so far. "get_tls_certificates", (1, ??); diff --git a/lib/handle.c b/lib/handle.c index 8713e18..ac64fe9 100644 --- a/lib/handle.c +++ b/lib/handle.c @@ -28,6 +28,12 @@ #include <sys/types.h> #include <sys/wait.h> +#ifdef HAVE_LINUX_VM_SOCKETS_H +#include <linux/vm_sockets.h> +#elif HAVE_SYS_VSOCK_H +#include <sys/vsock.h> +#endif + #include "internal.h" static void @@ -483,6 +489,17 @@ nbd_unlocked_supports_tls (struct nbd_handle *h) #endif } +/* NB: is_locked = false, may_set_error = false. */ +int +nbd_unlocked_supports_vsock (struct nbd_handle *h) +{ +#ifdef AF_VSOCK + return 1; +#else + return 0; +#endif +} + /* NB: is_locked = false, may_set_error = false. */ int nbd_unlocked_supports_uri (struct nbd_handle *h) -- 2.37.2