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From:   Chuck Lever III <chuck.lever@oracle.com>
To:     Benjamin Coddington <bcodding@redhat.com>
CC:     Steve Dickson <steved@redhat.com>,
        Linux NFS Mailing List <linux-nfs@vger.kernel.org>
Subject: Re: [PATCH v2 1/2] nfsuuid: a tool to create and persist nfs4 client
 uniquifiers
Thread-Topic: [PATCH v2 1/2] nfsuuid: a tool to create and persist nfs4 client
 uniquifiers
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Date:   Thu, 10 Feb 2022 18:15:43 +0000
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> On Feb 10, 2022, at 1:01 PM, Benjamin Coddington <bcodding@redhat.com> wr=
ote:
>=20
> The nfsuuid program will either create a new UUID from a random source or
> derive it from /etc/machine-id, else it returns a UUID that has already
> been written to /etc/nfsuuid or the file specified.  This small,
> lightweight tool is suitable for execution by systemd-udev in rules to
> populate the nfs4 client uniquifier.

I like everything but the name. Without context, even if
I read NFS protocol specifications, I have no idea what
"nfsuuid" does.

Possible alternatives:

nfshostuniquifier
nfsuniquehost
nfshostuuid


> Signed-off-by: Benjamin Coddington <bcodding@redhat.com>
> ---
> .gitignore                |   1 +
> aclocal/libuuid.m4        |  17 ++++
> configure.ac              |   4 +
> tools/Makefile.am         |   1 +
> tools/nfsuuid/Makefile.am |   8 ++
> tools/nfsuuid/nfsuuid.c   | 203 ++++++++++++++++++++++++++++++++++++++
> tools/nfsuuid/nfsuuid.man |  33 +++++++
> 7 files changed, 267 insertions(+)
> create mode 100644 aclocal/libuuid.m4
> create mode 100644 tools/nfsuuid/Makefile.am
> create mode 100644 tools/nfsuuid/nfsuuid.c
> create mode 100644 tools/nfsuuid/nfsuuid.man
>=20
> diff --git a/.gitignore b/.gitignore
> index c89d1cd2583d..4d63ee93b2dc 100644
> --- a/.gitignore
> +++ b/.gitignore
> @@ -61,6 +61,7 @@ utils/statd/statd
> tools/locktest/testlk
> tools/getiversion/getiversion
> tools/nfsconf/nfsconf
> +tools/nfsuuid/nfsuuid
> support/export/mount.h
> support/export/mount_clnt.c
> support/export/mount_xdr.c
> diff --git a/aclocal/libuuid.m4 b/aclocal/libuuid.m4
> new file mode 100644
> index 000000000000..f64085010d1d
> --- /dev/null
> +++ b/aclocal/libuuid.m4
> @@ -0,0 +1,17 @@
> +AC_DEFUN([AC_LIBUUID], [
> +        LIBUUID=3D
> +
> +        AC_CHECK_LIB([uuid], [uuid_generate_random], [], [AC_MSG_FAILURE=
(
> +                [Missing libuuid uuid_generate_random, needed to build n=
fs4id])])
> +
> +        AC_CHECK_LIB([uuid], [uuid_generate_sha1], [], [AC_MSG_FAILURE(
> +                [Missing libuuid uuid_generate_sha1, needed to build nfs=
4id])])
> +
> +        AC_CHECK_LIB([uuid], [uuid_unparse], [], [AC_MSG_FAILURE(
> +                [Missing libuuid uuid_unparse, needed to build nfs4id])]=
)
> +
> +        AC_CHECK_HEADER([uuid/uuid.h], [], [AC_MSG_FAILURE(
> +                [Missing uuid/uuid.h, needed to build nfs4id])])
> +
> +        AC_SUBST([LIBUUID], ["-luuid"])
> +])
> diff --git a/configure.ac b/configure.ac
> index 50e9b321dcf3..1342c471f142 100644
> --- a/configure.ac
> +++ b/configure.ac
> @@ -355,6 +355,9 @@ if test "$enable_nfsv4" =3D yes; then
>   dnl check for the keyutils libraries and headers
>   AC_KEYUTILS
>=20
> +  dnl check for the libuuid library and headers
> +  AC_LIBUUID
> +
>   dnl Check for sqlite3
>   AC_SQLITE3_VERS
>=20
> @@ -740,6 +743,7 @@ AC_CONFIG_FILES([
> 	tools/nfsdclnts/Makefile
> 	tools/nfsconf/Makefile
> 	tools/nfsdclddb/Makefile
> +	tools/nfsuuid/Makefile
> 	utils/Makefile
> 	utils/blkmapd/Makefile
> 	utils/nfsdcld/Makefile
> diff --git a/tools/Makefile.am b/tools/Makefile.am
> index 9b4b0803db39..a12b0f34f4e7 100644
> --- a/tools/Makefile.am
> +++ b/tools/Makefile.am
> @@ -7,6 +7,7 @@ OPTDIRS +=3D rpcgen
> endif
>=20
> OPTDIRS +=3D nfsconf
> +OPTDIRS +=3D nfsuuid
>=20
> if CONFIG_NFSDCLD
> OPTDIRS +=3D nfsdclddb
> diff --git a/tools/nfsuuid/Makefile.am b/tools/nfsuuid/Makefile.am
> new file mode 100644
> index 000000000000..7b3a54c30d50
> --- /dev/null
> +++ b/tools/nfsuuid/Makefile.am
> @@ -0,0 +1,8 @@
> +## Process this file with automake to produce Makefile.in
> +
> +man8_MANS	=3D nfsuuid.man
> +
> +bin_PROGRAMS =3D nfsuuid
> +
> +nfsuuid_SOURCES =3D nfsuuid.c
> +nfsuuid_LDADD =3D $(LIBUUID)
> diff --git a/tools/nfsuuid/nfsuuid.c b/tools/nfsuuid/nfsuuid.c
> new file mode 100644
> index 000000000000..bbdec59f1afe
> --- /dev/null
> +++ b/tools/nfsuuid/nfsuuid.c
> @@ -0,0 +1,203 @@
> +/*
> + * nfsuuid.c -- create and persist uniquifiers for nfs4 clients
> + *
> + * Copyright (C) 2022  Red Hat, Benjamin Coddington <bcodding@redhat.com=
>
> + *
> + * This program is free software; you can redistribute it and/or
> + * modify it under the terms of the GNU General Public License
> + * as published by the Free Software Foundation; either version 2
> + * of the License, or (at your option) any later version.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> + * GNU General Public License for more details.
> + *
> + * You should have received a copy of the GNU General Public License
> + * along with this program; if not, write to the Free Software
> + * Foundation, Inc., 51 Franklin Street, Fifth Floor,
> + * Boston, MA 02110-1301, USA.
> + */
> +
> +#include <stdio.h>
> +#include <stdarg.h>
> +#include <getopt.h>
> +#include <string.h>
> +#include <errno.h>
> +#include <stdlib.h>
> +#include <fcntl.h>
> +#include <unistd.h>
> +#include <uuid/uuid.h>
> +
> +#define DEFAULT_ID_FILE "/etc/nfsuuid"
> +
> +UUID_DEFINE(nfs4_clientid_uuid_template,
> +	0xa2, 0x25, 0x68, 0xb2, 0x7a, 0x5f, 0x49, 0x90,
> +	0x8f, 0x98, 0xc5, 0xf0, 0x67, 0x78, 0xcc, 0xf1);
> +
> +static char *prog;
> +static char *source =3D NULL;
> +static char *id_file =3D DEFAULT_ID_FILE;
> +static char nfs_unique_id[64];
> +static int replace =3D 0;
> +
> +static void usage(void)
> +{
> +	fprintf(stderr, "usage: %s [-r|--replace] [-f <file> |--file <file> ] [=
machine]\n", prog);
> +}
> +
> +static void fatal(const char *fmt, ...)
> +{
> +	int err =3D errno;
> +	va_list args;
> +	char fatal_msg[256] =3D "fatal: ";
> +
> +	va_start(args, fmt);
> +	vsnprintf(&fatal_msg[7], 255, fmt, args);
> +	if (err)
> +		fprintf(stderr, "%s: %s\n", fatal_msg, strerror(err));
> +	else
> +		fprintf(stderr, "%s\n", fatal_msg);
> +	exit(-1);
> +}
> +
> +static int read_nfs_unique_id(void)
> +{
> +	int fd;
> +	ssize_t len;
> +
> +	if (replace) {
> +		errno =3D ENOENT;
> +		return -1;
> +	}
> +
> +	fd =3D open(id_file, O_RDONLY);
> +	if (fd < 0)
> +		return fd;
> +	len =3D read(fd, nfs_unique_id, 64);
> +	close(fd);
> +	return len;
> +}
> +
> +static void write_nfs_unique_id(void)
> +{
> +	int fd;
> +
> +	fd =3D open(id_file, O_RDWR|O_TRUNC|O_CREAT, S_IRUSR|S_IWUSR|S_IRGRP|S_=
IROTH);
> +	if (fd < 0)
> +		fatal("could not write id to %s", id_file);
> +	write(fd, nfs_unique_id, 37);
> +}
> +
> +static void print_nfs_unique_id(void)
> +{
> +	fprintf(stdout, "%s", nfs_unique_id);
> +}
> +
> +static void check_or_make_id(void)
> +{
> +	int ret;
> +	uuid_t uuid;
> +
> +	ret =3D read_nfs_unique_id();
> +	if (ret < 1) {
> +		if (errno !=3D ENOENT )
> +			fatal("reading file %s", id_file);
> +		uuid_generate_random(uuid);
> +		uuid_unparse(uuid, nfs_unique_id);
> +		nfs_unique_id[36] =3D '\n';
> +		nfs_unique_id[37] =3D '\0';
> +		write_nfs_unique_id();
> +	}
> +	print_nfs_unique_id();
> +}
> +
> +static void check_or_make_id_from_machine(void)
> +{
> +	int fd, ret;
> +	char machineid[32];
> +	uuid_t uuid;
> +
> +	ret =3D read_nfs_unique_id();
> +	if (ret < 1) {
> +		if (errno !=3D ENOENT )
> +			fatal("reading file %s", id_file);
> +
> +		fd =3D open("/etc/machine-id", O_RDONLY);
> +		if (fd < 0)
> +			fatal("unable to read /etc/machine-id");
> +
> +		read(fd, machineid, 32);
> +		close(fd);
> +
> +		uuid_generate_sha1(uuid, nfs4_clientid_uuid_template, machineid, 32);
> +		uuid_unparse(uuid, nfs_unique_id);
> +		nfs_unique_id[36] =3D '\n';
> +		nfs_unique_id[37] =3D '\0';
> +		write_nfs_unique_id();
> +	}
> +	print_nfs_unique_id();
> +}
> +
> +int main(int argc, char **argv)
> +{
> +	prog =3D argv[0];
> +
> +	while (1) {
> +		int opt, prev_ind;
> +		int option_index =3D 0;
> +		static struct option long_options[] =3D {
> +			{"replace",	no_argument,		0, 'r' },
> +			{"file",	required_argument,	0, 'f' },
> +			{ 0, 0, 0, 0 }
> +		};
> +
> +		errno =3D 0;
> +		prev_ind =3D optind;
> +		opt =3D getopt_long(argc, argv, ":rf:", long_options, &option_index);
> +		if (opt =3D=3D -1)
> +			break;
> +
> +		/* Let's detect missing options in the middle of an option list */
> +		if (optind =3D=3D prev_ind + 2 && *optarg =3D=3D '-') {
> +			opt =3D ':';
> +			--optind;
> +		}
> +
> +		switch (opt) {
> +		case 'r':
> +			replace =3D 1;
> +			break;
> +		case 'f':
> +			id_file =3D optarg;
> +			break;
> +		case ':':
> +			usage();
> +			fatal("option \"%s\" requires an argument", argv[prev_ind]);
> +			break;
> +		case '?':
> +			usage();
> +			fatal("unexpected arg \"%s\"", argv[optind - 1]);
> +			break;
> +		}
> +	}
> +
> +	argc -=3D optind;
> +
> +	if (argc > 1) {
> +		usage();
> +		fatal("Too many arguments");
> +	}
> +
> +	if (argc)
> +		source =3D argv[optind++];
> +
> +	if (!source)
> +		check_or_make_id();
> +	else if (strcmp(source, "machine") =3D=3D 0)
> +		check_or_make_id_from_machine();
> +	else {
> +		usage();
> +		fatal("unrecognized source %s\n", source);
> +	}
> +}
> diff --git a/tools/nfsuuid/nfsuuid.man b/tools/nfsuuid/nfsuuid.man
> new file mode 100644
> index 000000000000..856d2f383e0f
> --- /dev/null
> +++ b/tools/nfsuuid/nfsuuid.man
> @@ -0,0 +1,33 @@
> +.\"
> +.\" nfsuuid(8)
> +.\"
> +.TH nfsuuid 8 "10 Feb 2022"
> +.SH NAME
> +nfsuuid \- Generate or return nfs client id uniquifiers
> +.SH SYNOPSIS
> +.B nfsuuid [ -r | --replace ] [ -f | --file <file> ] [<source>]
> +
> +.SH DESCRIPTION
> +The
> +.B nfsuuid
> +command provides a simple utility to help NFS Version 4 clients use uniq=
ue
> +and persistent client id values.  The command checks for the existence o=
f a
> +file /etc/nfsuuid and returns the first 64 chars read from that file.  I=
f
> +the file is not found, a UUID is generated from the specified source and
> +written to the file and returned.
> +.SH OPTIONS
> +.TP
> +.BR \-r,\ \-\-replace
> +Overwrite the <file> with a UUID generated from <source>.
> +.TP
> +.BR \-f,\ \-\-file
> +Use the specified file to lookup or store any generated UUID.  If <file>=
 is
> +not specified, the default file used is /etc/nfsuuid.
> +.SH Sources
> +If <source> is not specified, nfsuuid will generate a new random UUID.
> +
> +If <source> is "machine", nfsuuid will generate a deterministic UUID val=
ue
> +derived from a sha1 hash of the contents of /etc/machine-id and a static
> +key.
> +.SH SEE ALSO
> +.BR machine-id (5)
> --=20
> 2.31.1
>=20

--
Chuck Lever