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Re: [PATCH v4 04/11] osdep: implement qemu_socketpair() for win32
From: |
Daniel P . Berrangé |
Subject: |
Re: [PATCH v4 04/11] osdep: implement qemu_socketpair() for win32 |
Date: |
Tue, 7 Mar 2023 14:50:06 +0000 |
User-agent: |
Mutt/2.2.9 (2022-11-12) |
On Mon, Mar 06, 2023 at 04:27:44PM +0400, marcandre.lureau@redhat.com wrote:
> From: Marc-André Lureau <marcandre.lureau@redhat.com>
>
> Manually implement a socketpair() function, using UNIX sockets and
> simple peer credential checking.
>
> QEMU doesn't make much use of socketpair, beside vhost-user which is not
> available for win32 at this point. However, I intend to use it for
> writing some new portable tests.
>
> Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
> ---
> include/qemu/sockets.h | 2 -
> util/oslib-win32.c | 110 +++++++++++++++++++++++++++++++++++++++++
> 2 files changed, 110 insertions(+), 2 deletions(-)
>
> diff --git a/include/qemu/sockets.h b/include/qemu/sockets.h
> index 2b0698a7c9..d935fd80da 100644
> --- a/include/qemu/sockets.h
> +++ b/include/qemu/sockets.h
> @@ -15,7 +15,6 @@ int inet_aton(const char *cp, struct in_addr *ia);
> bool fd_is_socket(int fd);
> int qemu_socket(int domain, int type, int protocol);
>
> -#ifndef WIN32
> /**
> * qemu_socketpair:
> * @domain: specifies a communication domain, such as PF_UNIX
> @@ -30,7 +29,6 @@ int qemu_socket(int domain, int type, int protocol);
> * Return 0 on success.
> */
> int qemu_socketpair(int domain, int type, int protocol, int sv[2]);
> -#endif
>
> int qemu_accept(int s, struct sockaddr *addr, socklen_t *addrlen);
> /*
> diff --git a/util/oslib-win32.c b/util/oslib-win32.c
> index 29a667ae3d..16f8a67f7e 100644
> --- a/util/oslib-win32.c
> +++ b/util/oslib-win32.c
> @@ -310,6 +310,116 @@ bool qemu_socket_unselect(int sockfd, Error **errp)
> return qemu_socket_select(sockfd, NULL, 0, errp);
> }
>
> +int qemu_socketpair(int domain, int type, int protocol, int sv[2])
> +{
> + struct sockaddr_un addr = {
> + 0,
> + };
> + socklen_t socklen;
> + int listener = -1;
> + int client = -1;
> + int server = -1;
> + g_autofree char *path = NULL;
> + int tmpfd;
> + u_long arg;
> + int ret = -1;
> +
> + g_return_val_if_fail(sv != NULL, -1);
> +
> + addr.sun_family = AF_UNIX;
> + socklen = sizeof(addr);
> +
> + tmpfd = g_file_open_tmp(NULL, &path, NULL);
> + if (tmpfd == -1 || !path) {
> + errno = EACCES;
> + goto out;
> + }
> +
> + close(tmpfd);
> +
> + if (strlen(path) >= sizeof(addr.sun_path)) {
> + errno = EINVAL;
> + goto out;
> + }
> +
> + strncpy(addr.sun_path, path, sizeof(addr.sun_path) - 1);
> +
> + listener = socket(domain, type, protocol);
> + if (listener == -1) {
> + goto out;
> + }
> +
> + if (DeleteFile(path) == 0 && GetLastError() != ERROR_FILE_NOT_FOUND) {
> + errno = EACCES;
> + goto out;
> + }
> + g_clear_pointer(&path, g_free);
> +
> + if (bind(listener, (struct sockaddr *)&addr, socklen) == -1) {
> + goto out;
> + }
> +
> + if (listen(listener, 1) == -1) {
> + goto out;
> + }
> +
> + client = socket(domain, type, protocol);
> + if (client == -1) {
> + goto out;
> + }
> +
> + arg = 1;
> + if (ioctlsocket(client, FIONBIO, &arg) != NO_ERROR) {
> + goto out;
> + }
> +
> + if (connect(client, (struct sockaddr *)&addr, socklen) == -1 &&
> + WSAGetLastError() != WSAEWOULDBLOCK) {
> + goto out;
> + }
> +
> + server = accept(listener, NULL, NULL);
> + if (server == -1) {
> + goto out;
> + }
In theory at this point 'client' if connect() returned WSAEWOULDBLOCK,
then at this point it should be fully connected. I wonder if that is
actually guaranteed though, or should we do something to validate
there's no race condition ?
> +
> + arg = 0;
> + if (ioctlsocket(client, FIONBIO, &arg) != NO_ERROR) {
> + goto out;
> + }
> +
> + arg = 0;
> + if (ioctlsocket(client, SIO_AF_UNIX_GETPEERPID, &arg) != NO_ERROR) {
> + goto out;
> + }
Maybe this will force a synchronization point ?
Alteratively select() + getsockopt(SO_ERROR) is what we used to
do to check for connect() completion (logic removed now but can
be seen in b2587932582333197c88bf663785b19f441989d7)
> +
> + if (arg != GetCurrentProcessId()) {
> + errno = EPERM;
> + goto out;
> + }
> +
> + sv[0] = server;
> + server = -1;
> + sv[1] = client;
> + client = -1;
> + ret = 0;
> +
> +out:
> + if (listener != -1) {
> + close(listener);
> + }
> + if (client != -1) {
> + close(client);
> + }
> + if (server != -1) {
> + close(server);
> + }
> + if (path) {
> + DeleteFile(path);
> + }
> + return ret;
> +}
> +
> #undef connect
> int qemu_connect_wrap(int sockfd, const struct sockaddr *addr,
> socklen_t addrlen)
> --
> 2.39.2
>
With regards,
Daniel
--
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- [PATCH v4 00/11] QMP command to import win32 sockets, marcandre . lureau, 2023/03/06
- [PATCH v4 01/11] tests: fix path separator, use g_build_filename(), marcandre . lureau, 2023/03/06
- [PATCH v4 02/11] char: do not double-close fd when failing to add client, marcandre . lureau, 2023/03/06
- [PATCH v4 03/11] tests/docker: fix a win32 error due to portability, marcandre . lureau, 2023/03/06
- [PATCH v4 04/11] osdep: implement qemu_socketpair() for win32, marcandre . lureau, 2023/03/06
- Re: [PATCH v4 04/11] osdep: implement qemu_socketpair() for win32,
Daniel P . Berrangé <=
- [PATCH v4 05/11] qmp: 'add_client' actually expects sockets, marcandre . lureau, 2023/03/06
- [PATCH v4 06/11] monitor: release the lock before calling close(), marcandre . lureau, 2023/03/06
- [PATCH v4 07/11] qapi/gen: run C code through clang-format, if possible, marcandre . lureau, 2023/03/06