[PATCH RFC] tests: check decoding of libudev netlink header
Dmitry V. Levin
ldv at altlinux.org
Mon Feb 26 01:58:48 UTC 2018
On Sun, Feb 18, 2018 at 10:09:07AM +0530, Harsha Sharma wrote:
> On Sun, Feb 18, 2018 at 9:08 AM, Chen Jingpiao <chenjingpiao at gmail.com> wrote:
> > On 02/16 02:19, Harsha Sharma wrote:
> >> * tests/netlink_kobject_uevent_libudev.c: New file.
> >> * tests/gen_tests.in (netlink_kobject_uevent_libudev): New entry.
> >> * tests/pure_executables.list: Add netlink_kobject_uevent_libudev.
> >> * tests/.gitignore: Likewise.
Sorry for delay with review, see my comments below.
> >>
> >> Signed-off-by: Harsha Sharma <harshasharmaiitr at gmail.com>
> >> ---
> >> tests/.gitignore | 1 +
> >> tests/gen_tests.in | 1 +
> >> tests/netlink_kobject_uevent_libudev.c | 88 ++++++++++++++++++++++++++++++++++
> >> tests/pure_executables.list | 1 +
> >> 4 files changed, 91 insertions(+)
> >> create mode 100644 tests/netlink_kobject_uevent_libudev.c
> >>
> >> diff --git a/tests/.gitignore b/tests/.gitignore
> >> index 2541ec24..623b98f8 100644
> >> --- a/tests/.gitignore
> >> +++ b/tests/.gitignore
> >> @@ -215,6 +215,7 @@ netlink_crypto
> >> netlink_generic
> >> netlink_inet_diag
> >> netlink_kobject_uevent
> >> +netlink_kobject_uevent_libudev
> >> netlink_netfilter
> >> netlink_netlink_diag
> >> netlink_protocol
> >> diff --git a/tests/gen_tests.in b/tests/gen_tests.in
> >> index 18f36408..263479a5 100644
> >> --- a/tests/gen_tests.in
> >> +++ b/tests/gen_tests.in
> >> @@ -199,6 +199,7 @@ netlink_audit +netlink_sock_diag.test
> >> netlink_crypto +netlink_sock_diag.test
> >> netlink_generic +netlink_sock_diag.test
> >> netlink_kobject_uevent +netlink_sock_diag.test
> >> +netlink_kobject_uevent_libudev +netlink_sock_diag.test
> >> netlink_netfilter +netlink_sock_diag.test
> >> netlink_protocol -e trace=sendto
> >> netlink_route +netlink_sock_diag.test
> >> diff --git a/tests/netlink_kobject_uevent_libudev.c b/tests/netlink_kobject_uevent_libudev.c
> >> new file mode 100644
> >> index 00000000..8f0b2bfa
> >> --- /dev/null
> >> +++ b/tests/netlink_kobject_uevent_libudev.c
> >> @@ -0,0 +1,88 @@
> >> +/*
> >> + * Copyright (c) 2017 JingPiao Chen <chenjingpiao at gmail.com>
> >> + * Copyright (c) 2017 The strace developers.
> >> + * All rights reserved.
> >> + *
> >> + * Redistribution and use in source and binary forms, with or without
> >> + * modification, are permitted provided that the following conditions
> >> + * are met:
> >> + * 1. Redistributions of source code must retain the above copyright
> >> + * notice, this list of conditions and the following disclaimer.
> >> + * 2. Redistributions in binary form must reproduce the above copyright
> >> + * notice, this list of conditions and the following disclaimer in the
> >> + * documentation and/or other materials provided with the distribution.
> >> + * 3. The name of the author may not be used to endorse or promote products
> >> + * derived from this software without specific prior written permission.
> >> + *
> >> + * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
> >> + * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
> >> + * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
> >> + * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
> >> + * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
> >> + * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
> >> + * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
> >> + * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
> >> + * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
> >> + * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
> >> + */
> >> +
> >> +#include "tests.h"
> >> +#include <stdio.h>
> >> +#include <string.h>
> >> +#include <sys/socket.h>
> >> +#include "netlink.h"
> >> +#include "netlink_kobject_uevent.h"
> >> +#include <sys/types.h>
> >> +#include <unistd.h>
> >> +#include <arpa/inet.h>
> >> +#include <fcntl.h>
> >> +
> >> +int
> >> +main(void)
> >> +{
> >> + skip_if_unavailable("/proc/self/fd/");
> >> +
> >> + int fd, ret;
> >> + struct sockaddr_nl nls;
> >> + struct udev_monitor_netlink_header uh;
> >> +
> >> + memset(&nls, 0, sizeof(nls));
> >> + nls.nl_family = AF_NETLINK;
> >> + nls.nl_pid = getpid();
> >> + nls.nl_groups = -1;
> >> +
> >> + fd = socket(AF_NETLINK, (SOCK_DGRAM | SOCK_CLOEXEC),
> >> + NETLINK_KOBJECT_UEVENT);
> >> + if (fd < 0)
> >> + perror_msg_and_skip("socket AF_NETLINK");
> >> +
> >> + ret = bind(fd, (struct sockaddr *) &nls, sizeof(nls));
> >> + if (ret)
> >> + perror_msg_and_skip("bind AF_NETLINK");
> >
> > Replace with create_nl_socket().
>
> I need to set nls.nl_pid = getpid();
> and nls.nl_groups = -1; to recieve from kernel broadcast so using
> create_nl_socket in place of this doesn't work.
>
> >> +
> >> + printf("Waiting for events now...\n");
> >
> > Why print this message?
>
> This is a RFC patch so to clear what's happening I left this.
>
> >> + while (1) {
> >> + int r = recv(fd, &uh, sizeof(uh), MSG_ERRQUEUE);
> >> + if (r <= 0)
> >> + perror_msg_and_skip("recv");
> >> + if (!strcmp(uh.prefix, "libudev"))
> >> + printf("recvfrom(%i, {{prefix=\"%s\""
> >> + ", magic=htonl(%#x), header_size=%u"
> >> + ", properties_off=%u, properties_len=%u"
> >> + ", filter_subsystem_hash=htonl(%#x)"
> >> + ", filter_devtype_hash=htonl(%#x)"
> >> + ", filter_tag_bloom_hi=htonl(%#x)"
> >> + ", filter_tag_bloom_lo=htonl(%#x)}}, %li"
> >> + ", MSG_ERRQUEUE, NULL, NULL)\n",
> >> + fd, uh.prefix, ntohl(uh.magic), uh.header_size,
> >> + uh.properties_off, uh.properties_len,
> >> + ntohl(uh.filter_subsystem_hash),
> >> + ntohl(uh.filter_devtype_hash),
> >> + ntohl(uh.filter_tag_bloom_hi),
> >> + ntohl(uh.filter_tag_bloom_lo), sizeof(uh));
> >> + }
> >
> > I do not understand how this work. travis-ci is fail.
>
> This actually waits for kernel uevents and prints decoding of
> udev_monitor_netlink_header.
> On strace -e trace=network ./tests/netlink_kobject_uvent_libudev, it
> shows decoding of libudev header along with printf output which is
> exactly same.
>
> > netlink_kobject_uevent_libudev.gen.test source netlink_sock_diag.test,
> > which only trace sendto syscall.
>
> strace -e trace=sendto udevadm monitor > /dev/null shows no output.
> NETLINK_KOBJECT_UEVENT protocol is used to receive kernel messages to
> userspace so sendto syscall is never used in this process. So make
> check for this test is supposed to fail.
Sorry but "make check" is an instrument of regression testing,
it is supposed to succeed.
As you could have noticed, all other tests of netlink protocol decoders
do not wait for kernel messages, unlike normal netlink users.
Instead, they generate these messages themselves to let strace decode
them.
I think it's quite logical if this test used the same method.
--
ldv
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