[Libguestfs] [PATCH libnbd 3/4] api: Add nbd_connect_socket.
Richard W.M. Jones
rjones at redhat.com
Fri Oct 4 19:50:09 UTC 2019
This allows us to connect directly to a connected socket. How exactly
the socket is created and connected to the NBD server is left up to
the main program.
The only real complexity in this patch is allowing file descriptors to
be passed to libnbd APIs. Luckily in C and Python we can treat them
exactly as integers, and in OCaml they are also integers but with a
different type.
---
generator/generator | 72 ++++++++++++++++++++++++++++++++++++---------
lib/connect.c | 47 +++++++++++++++++++++++++++++
2 files changed, 105 insertions(+), 14 deletions(-)
diff --git a/generator/generator b/generator/generator
index c7464d5..54a8eb7 100755
--- a/generator/generator
+++ b/generator/generator
@@ -96,6 +96,7 @@ type external_event =
| CmdConnectTCP (* [nbd_aio_connect_tcp] *)
| CmdConnectCommand (* [nbd_aio_connect_command] *)
| CmdConnectSA (* [nbd_aio_connect_systemd_socket_activation]*)
+ | CmdConnectSocket (* [nbd_aio_connect_socket] *)
| CmdIssue (* issuing an NBD command *)
type location = string * int (* source location: file, line number *)
@@ -170,7 +171,8 @@ let rec state_machine = [
CmdConnectUnix, "CONNECT_UNIX.START";
CmdConnectTCP, "CONNECT_TCP.START";
CmdConnectCommand, "CONNECT_COMMAND.START";
- CmdConnectSA, "CONNECT_SA.START" ];
+ CmdConnectSA, "CONNECT_SA.START";
+ CmdConnectSocket, "MAGIC.START" ];
};
Group ("CONNECT", connect_state_machine);
@@ -883,6 +885,7 @@ and arg =
| BytesPersistOut of string * string
| Closure of closure (* function pointer + void *opaque *)
| Enum of string * enum (* enum/union type, int in C *)
+| Fd of string (* file descriptor *)
| Flags of string * flags (* flags, uint32_t in C *)
| Int of string (* small int *)
| Int64 of string (* 64 bit signed int *)
@@ -1501,6 +1504,21 @@ such as C<\"10809\">. This call returns when the connection
has been made.";
};
+ "connect_socket", {
+ default_call with
+ args = [ Fd "sock" ]; ret = RErr;
+ permitted_states = [ Created ];
+ shortdesc = "connect directly to a connected socket";
+ longdesc = "\
+Pass a connected socket (file descriptor) which libnbd will
+talk to. The program is responsible for connecting this
+somehow to an NBD server. Once the socket is passed to
+libnbd it is the responsibility of libnbd. Libnbd may
+read and write to it, set it to non-blocking, etc., and
+will finally close it when the handle is closed. The
+program must no longer use the socket.";
+ };
+
"connect_command", {
default_call with
args = [ StringList "argv" ]; ret = RErr;
@@ -2139,6 +2157,21 @@ on the connection.";
Begin connecting to the NBD server listening on C<hostname:port>.
Parameters behave as documented in L<nbd_connect_tcp(3)>.
+You can check if the connection is still connecting by calling
+L<nbd_aio_is_connecting(3)>, or if it has connected to the server
+and completed the NBD handshake by calling L<nbd_aio_is_ready(3)>,
+on the connection.";
+ };
+
+ "aio_connect_socket", {
+ default_call with
+ args = [ Fd "sock" ]; ret = RErr;
+ permitted_states = [ Created ];
+ shortdesc = "connect directly to a connected socket";
+ longdesc = "\
+Begin connecting to the connected socket C<fd>.
+Parameters behave as documented in L<nbd_connect_socket(3)>.
+
You can check if the connection is still connecting by calling
L<nbd_aio_is_connecting(3)>, or if it has connected to the server
and completed the NBD handshake by calling L<nbd_aio_is_ready(3)>,
@@ -2758,6 +2791,8 @@ let first_version = [
"get_handshake_flags", (1, 2);
"connect_systemd_socket_activation", (1, 2);
"aio_connect_systemd_socket_activation", (1, 2);
+ "connect_socket", (1, 2);
+ "aio_connect_socket", (1, 2);
(* These calls are proposed for a future version of libnbd, but
* have not been added to any released version so far.
@@ -3117,7 +3152,7 @@ let all_external_events =
[NotifyRead; NotifyWrite;
CmdCreate;
CmdConnectSockAddr; CmdConnectUnix; CmdConnectTCP;
- CmdConnectCommand; CmdConnectSA;
+ CmdConnectCommand; CmdConnectSA; CmdConnectSocket;
CmdIssue]
let string_of_external_event = function
@@ -3129,6 +3164,7 @@ let string_of_external_event = function
| CmdConnectTCP -> "CmdConnectTCP"
| CmdConnectCommand -> "CmdConnectCommand"
| CmdConnectSA -> "CmdConnectSA"
+ | CmdConnectSocket -> "CmdConnectSocket"
| CmdIssue -> "CmdIssue"
let c_string_of_external_event = function
@@ -3140,6 +3176,7 @@ let c_string_of_external_event = function
| CmdConnectTCP -> "cmd_connect_tcp"
| CmdConnectCommand -> "cmd_connect_command"
| CmdConnectSA -> "cmd_connect_sa"
+ | CmdConnectSocket -> "cmd_connect_socket"
| CmdIssue -> "cmd_issue"
(* Find a state in the state machine hierarchy by path. The [path]
@@ -3588,7 +3625,7 @@ let generate_lib_states_run_c () =
| CmdCreate
| CmdConnectSockAddr
| CmdConnectUnix | CmdConnectTCP
- | CmdConnectCommand | CmdConnectSA
+ | CmdConnectCommand | CmdConnectSA | CmdConnectSocket
| CmdIssue -> ()
) events;
pr " break;\n";
@@ -3870,6 +3907,7 @@ let rec name_of_arg = function
| Closure { cbname } ->
[ sprintf "%s_callback" cbname; sprintf "%s_user_data" cbname ]
| Enum (n, _) -> [n]
+| Fd n -> [n]
| Flags (n, _) -> [n]
| Int n -> [n]
| Int64 n -> [n]
@@ -3926,7 +3964,7 @@ and print_arg_list_no_parens ?(handle = false) ?(types = true) args optargs =
| Flags (n, _) ->
if types then pr "uint32_t ";
pr "%s" n
- | Int n ->
+ | Fd n | Int n ->
if types then pr "int ";
pr "%s" n
| Int64 n ->
@@ -4350,7 +4388,7 @@ let generate_lib_api_c () =
| Closure { cbname } -> pr " %s=<fun>" cbname
| Enum (n, _) -> pr " %s=%%d" n
| Flags (n, _) -> pr " %s=0x%%x" n
- | Int n -> pr " %s=%%d" n
+ | Fd n | Int n -> pr " %s=%%d" n
| Int64 n -> pr " %s=%%\" PRIi64 \"" n
| SockAddrAndLen (n, len) -> pr " %s=<sockaddr> %s=%%d" n len
| Path n
@@ -4376,7 +4414,7 @@ let generate_lib_api_c () =
| Closure { cbname } -> ()
| Enum (n, _) -> pr ", %s" n
| Flags (n, _) -> pr ", %s" n
- | Int n -> pr ", %s" n
+ | Fd n | Int n -> pr ", %s" n
| Int64 n -> pr ", %s" n
| SockAddrAndLen (_, len) -> pr ", (int) %s" len
| Path n | String n -> pr ", %s ? %s : \"NULL\"" n n
@@ -4889,7 +4927,7 @@ let print_python_binding name { args; optargs; ret; may_set_error } =
| Flags (n, _) ->
pr " uint32_t %s_u32;\n" n;
pr " unsigned int %s; /* really uint32_t */\n" n
- | Int n -> pr " int %s;\n" n
+ | Fd n | Int n -> pr " int %s;\n" n
| Int64 n ->
pr " int64_t %s_i64;\n" n;
pr " long long %s; /* really int64_t */\n" n
@@ -4940,7 +4978,7 @@ let print_python_binding name { args; optargs; ret; may_set_error } =
| Closure _ -> pr " \"O\""
| Enum _ -> pr " \"i\""
| Flags _ -> pr " \"I\""
- | Int n -> pr " \"i\""
+ | Fd n | Int n -> pr " \"i\""
| Int64 n -> pr " \"L\""
| Path n -> pr " \"O&\""
| SockAddrAndLen (n, _) -> pr " \"O\""
@@ -4967,7 +5005,7 @@ let print_python_binding name { args; optargs; ret; may_set_error } =
| Closure { cbname } -> pr ", &%s_user_data->fn" cbname
| Enum (n, _) -> pr ", &%s" n
| Flags (n, _) -> pr ", &%s" n
- | Int n -> pr ", &%s" n
+ | Fd n | Int n -> pr ", &%s" n
| Int64 n -> pr ", &%s" n
| Path n -> pr ", PyUnicode_FSConverter, &py_%s" n
| SockAddrAndLen (n, _) -> pr ", &%s" n
@@ -5004,7 +5042,7 @@ let print_python_binding name { args; optargs; ret; may_set_error } =
pr " }\n"
| Enum _ -> ()
| Flags (n, _) -> pr " %s_u32 = %s;\n" n n
- | Int _ -> ()
+ | Fd _ | Int _ -> ()
| Int64 n -> pr " %s_i64 = %s;\n" n n
| Path n ->
pr " %s = PyBytes_AS_STRING (py_%s);\n" n n;
@@ -5062,7 +5100,7 @@ let print_python_binding name { args; optargs; ret; may_set_error } =
| Closure { cbname } -> pr ", %s" cbname
| Enum (n, _) -> pr ", %s" n
| Flags (n, _) -> pr ", %s_u32" n
- | Int n -> pr ", %s" n
+ | Fd n | Int n -> pr ", %s" n
| Int64 n -> pr ", %s_i64" n
| Path n -> pr ", %s" n
| SockAddrAndLen (n, _) -> pr ", /* XXX */ (void *) %s, 0" n
@@ -5100,7 +5138,7 @@ let print_python_binding name { args; optargs; ret; may_set_error } =
| Closure _
| Enum _
| Flags _
- | Int _
+ | Fd _ | Int _
| Int64 _
| Path _
| SockAddrAndLen _
@@ -5142,7 +5180,7 @@ let print_python_binding name { args; optargs; ret; may_set_error } =
| Closure _ -> ()
| Enum _ -> ()
| Flags _ -> ()
- | Int _ -> ()
+ | Fd _ | Int _ -> ()
| Int64 _ -> ()
| Path n ->
pr " Py_XDECREF (py_%s);\n" n
@@ -5351,7 +5389,7 @@ class NBD (object):
| Closure { cbname } -> cbname, None, None
| Enum (n, _) -> n, None, None
| Flags (n, _) -> n, None, None
- | Int n -> n, None, None
+ | Fd n | Int n -> n, None, None
| Int64 n -> n, None, None
| Path n -> n, None, None
| SockAddrAndLen (n, _) -> n, None, None
@@ -5431,6 +5469,7 @@ and ocaml_arg_to_string = function
| Closure { cbargs } ->
sprintf "(%s)" (ocaml_closuredecl_to_string cbargs)
| Enum (_, { enum_prefix }) -> sprintf "%s.t" enum_prefix
+ | Fd _ -> "Unix.file_descr"
| Flags (_, { flag_prefix }) -> sprintf "%s.t" flag_prefix
| Int _ -> "int"
| Int64 _ -> "int64"
@@ -5482,6 +5521,7 @@ let ocaml_name_of_arg = function
| BytesPersistOut (n, len) -> n
| Closure { cbname } -> cbname
| Enum (n, _) -> n
+ | Fd n -> n
| Flags (n, _) -> n
| Int n -> n
| Int64 n -> n
@@ -5945,6 +5985,9 @@ let print_ocaml_binding (name, { args; optargs; ret }) =
pr " %s_callback.free = free_user_data;\n" cbname
| Enum (n, { enum_prefix }) ->
pr " int %s = %s_val (%sv);\n" n enum_prefix n
+ | Fd n ->
+ pr " /* OCaml Unix.file_descr is just an int, at least on Unix. */\n";
+ pr " int %s = Int_val (%sv);\n" n n
| Flags (n, { flag_prefix }) ->
pr " uint32_t %s = %s_val (%sv);\n" n flag_prefix n
| Int n ->
@@ -6018,6 +6061,7 @@ let print_ocaml_binding (name, { args; optargs; ret }) =
| BytesPersistOut _
| Closure _
| Enum _
+ | Fd _
| Flags _
| Int _
| Int64 _
diff --git a/lib/connect.c b/lib/connect.c
index d648dd3..a0ef5f1 100644
--- a/lib/connect.c
+++ b/lib/connect.c
@@ -23,6 +23,7 @@
#include <stdbool.h>
#include <errno.h>
#include <unistd.h>
+#include <fcntl.h>
#include <netdb.h>
#include <netinet/in.h>
#include <netinet/tcp.h>
@@ -102,6 +103,16 @@ nbd_unlocked_connect_tcp (struct nbd_handle *h,
return wait_until_connected (h);
}
+/* Connect to a connected socket. */
+int
+nbd_unlocked_connect_socket (struct nbd_handle *h, int sock)
+{
+ if (nbd_unlocked_aio_connect_socket (h, sock) == -1)
+ return -1;
+
+ return wait_until_connected (h);
+}
+
/* Connect to a local command. */
int
nbd_unlocked_connect_command (struct nbd_handle *h, char **argv)
@@ -399,6 +410,42 @@ nbd_unlocked_aio_connect_tcp (struct nbd_handle *h,
return nbd_internal_run (h, cmd_connect_tcp);
}
+int
+nbd_unlocked_aio_connect_socket (struct nbd_handle *h, int sock)
+{
+ int flags;
+
+ /* Set O_NONBLOCK on the file and FD_CLOEXEC on the file descriptor.
+ * We can't trust that the calling process did either of these.
+ */
+ flags = fcntl (sock, F_GETFL, 0);
+ if (flags == -1 ||
+ fcntl (sock, F_SETFL, flags|O_NONBLOCK) == -1) {
+ set_error (errno, "fcntl: set O_NONBLOCK");
+ close (sock);
+ return -1;
+ }
+
+ flags = fcntl (sock, F_GETFD, 0);
+ if (flags == -1 ||
+ fcntl (sock, F_SETFD, flags|FD_CLOEXEC) == -1) {
+ set_error (errno, "fcntl: set FD_CLOEXEC");
+ close (sock);
+ return -1;
+ }
+
+ h->sock = nbd_internal_socket_create (sock);
+ if (!h->sock) {
+ close (sock);
+ return -1;
+ }
+
+ /* This jumps straight to %MAGIC.START (to start the handshake)
+ * because the socket is already connected.
+ */
+ return nbd_internal_run (h, cmd_connect_socket);
+}
+
int
nbd_unlocked_aio_connect_command (struct nbd_handle *h, char **argv)
{
--
2.23.0
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