[libvirt] [PATCH v5] Add helper program to create custom leases
Nehal J Wani
nehaljw.kkd1 at gmail.com
Fri Apr 25 23:59:16 UTC 2014
Introduce helper program to catch events from dnsmasq and maintain a custom
lease file per network. It supports dhcpv4 and dhcpv6. The file is saved as
"<interface-name>.status".
Each lease contains the following info:
<expiry-time (epoch time)> <mac> <iaid> <ip-address> <hostname> <clientid>
Example of custom leases file content:
[
{
"iaid": "1221229",
"ip-address": "2001:db8:ca2:2:1::95",
"mac-address": "52:54:00:12:a2:6d",
"hostname": "Fedora20",
"client-id": "00:04:1a:c1:d9:6b:5a:0a:e2:bc:f8:4b:1e:37:2e:38:22:55",
"expiry-time": 1393244216
},
{
"ip-address": "192.168.150.208",
"mac-address": "52:54:00:11:56:b3",
"hostname": "Wani-PC",
"client-id": "01:52:54:00:11:56:b3",
"expiry-time": 1393244248
}
]
src/Makefile.am:
* Add options to compile the helper program
src/network/bridge_driver.c:
* Introduce networkDnsmasqLeaseFileNameCustom()
* Invoke helper program along with dnsmasq
* Delete the .status file when corresponding n/w is destroyed.
src/network/leaseshelper.c
* Helper program to create the custom lease file
---
v5:
* More comments added, for better explanation
* Use of virFileFindResource() to identify proper path to helper binary
* Use of VIR_ENUM_IMPL for handling action events added
v4:
* Addition of pidfile and a corresponding lock for it
* Make correction for dnsmasq < 2.52 (Only IPv4)
* Move helper file from src/util to src/network
* Increase limit on max size of leases file
* Refer: https://www.redhat.com/archives/libvir-list/2014-March/msg01038.html
v3:
* Improved file handling, removed redundant copying, introduced --help and --version
* Refer: https://www.redhat.com/archives/libvir-list/2014-February/msg01431.html
v2:
* Changed format to JSON
* Refer: https://www.redhat.com/archives/libvir-list/2014-January/msg01234.html
v1:
* Refer: https://www.redhat.com/archives/libvir-list/2014-January/msg00626.html
src/Makefile.am | 22 +++
src/network/bridge_driver.c | 27 ++++
src/network/leaseshelper.c | 360 +++++++++++++++++++++++++++++++++++++++++++
3 files changed, 409 insertions(+), 0 deletions(-)
create mode 100644 src/network/leaseshelper.c
diff --git a/src/Makefile.am b/src/Makefile.am
index dd0abe7..fbe72c4 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -859,6 +859,9 @@ STORAGE_HELPER_DISK_SOURCES = \
UTIL_IO_HELPER_SOURCES = \
util/iohelper.c
+NETWORK_LEASES_HELPER_SOURCES = \
+ network/leaseshelper.c
+
# Network filters
NWFILTER_DRIVER_SOURCES = \
nwfilter/nwfilter_driver.h nwfilter/nwfilter_driver.c \
@@ -2466,6 +2469,25 @@ libvirt_iohelper_CFLAGS = \
$(AM_CFLAGS) \
$(PIE_CFLAGS) \
$(NULL)
+
+if WITH_NETWORK
+libexec_PROGRAMS += libvirt_leaseshelper
+libvirt_leaseshelper_SOURCES = $(NETWORK_LEASES_HELPER_SOURCES)
+libvirt_leaseshelper_LDADD = \
+ libvirt_util.la \
+ ../gnulib/lib/libgnu.la
+if WITH_DTRACE_PROBES
+libvirt_leaseshelper_LDADD += libvirt_probes.lo
+endif WITH_DTRACE_PROBES
+
+libvirt_leaseshelper_CFLAGS = \
+ $(AM_CFLAGS) \
+ $(PIE_CFLAGS) \
+ $(NULL)
+else ! WITH_NETWORK
+EXTRA_DIST += $(NETWORK_LEASES_HELPER_SOURCES)
+endif ! WITH_NETWORK
+
endif WITH_LIBVIRTD
if WITH_STORAGE_DISK
diff --git a/src/network/bridge_driver.c b/src/network/bridge_driver.c
index 201b22f..ade664d 100644
--- a/src/network/bridge_driver.c
+++ b/src/network/bridge_driver.c
@@ -210,6 +210,16 @@ networkDnsmasqLeaseFileNameFunc networkDnsmasqLeaseFileName =
networkDnsmasqLeaseFileNameDefault;
static char *
+networkDnsmasqLeaseFileNameCustom(const char *bridge)
+{
+ char *leasefile;
+
+ ignore_value(virAsprintf(&leasefile, "%s/%s.status",
+ driverState->dnsmasqStateDir, bridge));
+ return leasefile;
+}
+
+static char *
networkDnsmasqConfigFileName(const char *netname)
{
char *conffile;
@@ -245,6 +255,7 @@ networkRemoveInactive(virNetworkDriverStatePtr driver,
virNetworkObjPtr net)
{
char *leasefile = NULL;
+ char *customleasefile = NULL;
char *radvdconfigfile = NULL;
char *configfile = NULL;
char *radvdpidbase = NULL;
@@ -263,6 +274,9 @@ networkRemoveInactive(virNetworkDriverStatePtr driver,
if (!(leasefile = networkDnsmasqLeaseFileName(def->name)))
goto cleanup;
+ if (!(customleasefile = networkDnsmasqLeaseFileNameCustom(def->bridge)))
+ goto cleanup;
+
if (!(radvdconfigfile = networkRadvdConfigFileName(def->name)))
goto cleanup;
@@ -279,6 +293,7 @@ networkRemoveInactive(virNetworkDriverStatePtr driver,
/* dnsmasq */
dnsmasqDelete(dctx);
unlink(leasefile);
+ unlink(customleasefile);
unlink(configfile);
/* radvd */
@@ -296,6 +311,7 @@ networkRemoveInactive(virNetworkDriverStatePtr driver,
cleanup:
VIR_FREE(leasefile);
VIR_FREE(configfile);
+ VIR_FREE(customleasefile);
VIR_FREE(radvdconfigfile);
VIR_FREE(radvdpidbase);
VIR_FREE(statusfile);
@@ -1120,6 +1136,7 @@ networkBuildDhcpDaemonCommandLine(virNetworkObjPtr network,
int ret = -1;
char *configfile = NULL;
char *configstr = NULL;
+ char *leaseshelper_path;
network->dnsmasqPid = -1;
@@ -1142,11 +1159,21 @@ networkBuildDhcpDaemonCommandLine(virNetworkObjPtr network,
cmd = virCommandNew(dnsmasqCapsGetBinaryPath(caps));
virCommandAddArgFormat(cmd, "--conf-file=%s", configfile);
+
+ /* This helper is used to create custom leases file for libvirt */
+ if (!(leaseshelper_path = virFileFindResource("libvirt_leaseshelper",
+ "src",
+ LIBEXECDIR)))
+ goto cleanup;
+
+ virCommandAddArgFormat(cmd, "--dhcp-script=%s", leaseshelper_path);
+
*cmdout = cmd;
ret = 0;
cleanup:
VIR_FREE(configfile);
VIR_FREE(configstr);
+ VIR_FREE(leaseshelper_path);
return ret;
}
diff --git a/src/network/leaseshelper.c b/src/network/leaseshelper.c
new file mode 100644
index 0000000..d580369
--- /dev/null
+++ b/src/network/leaseshelper.c
@@ -0,0 +1,360 @@
+/*
+ * leasehelper.c: Helper program to create custom leases file
+ *
+ * Copyright (C) 2014 Red Hat, Inc.
+ * Copyright (C) 2014 Nehal J Wani
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library 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
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library. If not, see
+ * <http://www.gnu.org/licenses/>.
+ *
+ * Author: Nehal J Wani <nehaljw.kkd1 at gmail.com>
+ *
+ * For IPv6 support, use dnsmasq >= 2.67
+ */
+
+#include <config.h>
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/stat.h>
+
+#include "virutil.h"
+#include "virthread.h"
+#include "virfile.h"
+#include "virpidfile.h"
+#include "virbuffer.h"
+#include "virstring.h"
+#include "virerror.h"
+#include "viralloc.h"
+#include "virjson.h"
+#include "configmake.h"
+
+#define VIR_FROM_THIS VIR_FROM_NETWORK
+
+/**
+ * VIR_NETWORK_DHCP_LEASE_FILE_SIZE_MAX:
+ *
+ * Macro providing the upper limit on the size of leases file
+ */
+#define VIR_NETWORK_DHCP_LEASE_FILE_SIZE_MAX (32 * 1024 * 1024)
+
+static const char *program_name;
+
+/* Display version information. */
+static void
+helperVersion(const char *argv0)
+{
+ printf("%s (%s) %s\n", argv0, PACKAGE_NAME, PACKAGE_VERSION);
+}
+
+ATTRIBUTE_NORETURN static void
+usage(int status)
+{
+ if (status) {
+ fprintf(stderr, _("%s: try --help for more details\n"), program_name);
+ } else {
+ printf(_("Usage: %s add|old|del mac|clientid ip [hostname]\n"
+ "Designed for use with 'dnsmasq --dhcp-script'\n"
+ "Refer to man page of dnsmasq for more details'\n"),
+ program_name);
+ }
+ exit(status);
+}
+
+static int
+customLeaseRewriteFile(int fd, void *opaque)
+{
+ char **data = opaque;
+
+ if (safewrite(fd, *data, strlen(*data)) < 0)
+ return -1;
+
+ return 0;
+}
+
+/* Flags denoting actions for a lease */
+enum virLeaseActionFlags {
+ VIR_LEASE_ACTION_ADD, /* Create new lease */
+ VIR_LEASE_ACTION_OLD, /* Lease already exists, renew it */
+ VIR_LEASE_ACTION_DEL, /* Delete the lease */
+
+ VIR_LEASE_ACTION_LAST
+};
+
+VIR_ENUM_DECL(virLeaseAction);
+
+VIR_ENUM_IMPL(virLeaseAction, VIR_LEASE_ACTION_LAST,
+ "add", "old", "del");
+
+int
+main(int argc, char **argv)
+{
+ char *exptime = NULL;
+ char *pid_file = NULL;
+ char *lease_entries = NULL;
+ char *custom_lease_file = NULL;
+ const char *ip = NULL;
+ const char *mac = NULL;
+ const char *iaid = virGetEnvAllowSUID("DNSMASQ_IAID");
+ const char *clientid = virGetEnvAllowSUID("DNSMASQ_CLIENT_ID");
+ const char *interface = virGetEnvAllowSUID("DNSMASQ_INTERFACE");
+ const char *exptime_tmp = virGetEnvAllowSUID("DNSMASQ_LEASE_EXPIRES");
+ const char *hostname = virGetEnvAllowSUID("DNSMASQ_SUPPLIED_HOSTNAME");
+ const char *leases_str = NULL;
+ long long currtime = 0;
+ long long expirytime = 0;
+ size_t i = 0;
+ int size = 0;
+ int action = -1;
+ int pid_file_fd = -1;
+ int rv = EXIT_FAILURE;
+ int custom_lease_file_len = 0;
+ bool add = false;
+ bool delete = false;
+ virJSONValuePtr lease_new = NULL;
+ virJSONValuePtr lease_tmp = NULL;
+ virJSONValuePtr leases_array = NULL;
+ virJSONValuePtr leases_array_new = NULL;
+
+ virSetErrorFunc(NULL, NULL);
+ virSetErrorLogPriorityFunc(NULL);
+
+ program_name = argv[0];
+
+ if (setlocale(LC_ALL, "") == NULL ||
+ bindtextdomain(PACKAGE, LOCALEDIR) == NULL ||
+ textdomain(PACKAGE) == NULL) {
+ fprintf(stderr, _("%s: initialization failed\n"), program_name);
+ exit(EXIT_FAILURE);
+ }
+
+ if (virThreadInitialize() < 0 ||
+ virErrorInitialize() < 0) {
+ fprintf(stderr, _("%s: initialization failed\n"), program_name);
+ exit(EXIT_FAILURE);
+ }
+
+ /* Doesn't hurt to check */
+ if (argc > 1) {
+ if(STREQ(argv[1], "--help"))
+ usage(EXIT_SUCCESS);
+
+ if (STREQ(argv[1], "--version")) {
+ helperVersion(argv[0]);
+ exit(EXIT_SUCCESS);
+ }
+ }
+
+ if (argc != 4 && argc != 5) {
+ /* Refer man page of dnsmasq --dhcp-script for more details */
+ usage(EXIT_FAILURE);
+ }
+
+ /* Make sure dnsmasq knows the interface. The interface name is not known
+ * when dnsmasq (re)starts and throws 'del' events for expired leases.
+ * So, if any old lease has expired, it will be automatically removed the
+ * next time this program is invoked */
+ if (!interface)
+ goto cleanup;
+
+ ip = argv[3];
+ mac = argv[2];
+ action = virLeaseActionTypeFromString(argv[1]);
+
+ /* In case hostname is known, it is the 5th argument */
+ if (argc == 5)
+ hostname = argv[4];
+
+ if (VIR_STRDUP(exptime, exptime_tmp) < 0)
+ goto cleanup;
+
+ /* Removed extraneous trailing space in DNSMASQ_LEASE_EXPIRES (dnsmasq < 2.52) */
+ if (exptime[strlen(exptime) - 1] == ' ')
+ exptime[strlen(exptime) - 1] = '\0';
+
+ /* Check if it is an IPv6 lease */
+ if (virGetEnvAllowSUID("DNSMASQ_IAID")) {
+ mac = virGetEnvAllowSUID("DNSMASQ_MAC");
+ clientid = argv[2];
+ }
+
+ if (virAsprintf(&custom_lease_file,
+ LOCALSTATEDIR "/lib/libvirt/dnsmasq/%s.status",
+ interface) < 0)
+ goto cleanup;
+
+ if (VIR_STRDUP(pid_file, LOCALSTATEDIR "/run/leaseshelper.pid") < 0)
+ goto cleanup;
+
+ /* Try to claim the pidfile, exiting if we can't */
+ if ((pid_file_fd = virPidFileAcquirePath(pid_file, true, getpid())) < 0)
+ goto cleanup;
+
+ /* Since interfaces can be hot plugged, we need to make sure that the
+ * corresponding custom lease file exists. If not, 'touch' it */
+ if (virFileTouch(custom_lease_file, 0644) < 0)
+ goto cleanup;
+
+ /* Read entire contents */
+ if ((custom_lease_file_len = virFileReadAll(custom_lease_file,
+ VIR_NETWORK_DHCP_LEASE_FILE_SIZE_MAX,
+ &lease_entries)) < 0) {
+ goto cleanup;
+ }
+
+ if (action == VIR_LEASE_ACTION_ADD ||
+ action == VIR_LEASE_ACTION_OLD ||
+ action == VIR_LEASE_ACTION_DEL) {
+ /* Custom ipv6 leases *will not* be created if the env-var DNSMASQ_MAC
+ * is not set. In the special case, when the $(interface).status file
+ * is not already present and dnsmasq is (re)started, the corresponding
+ * ipv6 custom lease will be created only when the guest sends the
+ * 'old' action for its existing ipv6 interfaces.
+ *
+ * According to rfc3315, the combination of DUID and IAID can be used
+ * to uniquely identify each ipv6 guest interface. So, in future, if
+ * we introduce virNetworkGetDHCPLeaseBy(IAID|DUID|IAID+DUID) for ipv6
+ * interfaces, then, the following if condition won't be required, as
+ * the new lease will be created irrespective of whether the MACID is
+ * known or not.
+ */
+ if (mac || action == VIR_LEASE_ACTION_DEL) {
+ /* Delete the corresponding lease, if it already exists */
+ delete = true;
+ if (action == VIR_LEASE_ACTION_ADD ||
+ action == VIR_LEASE_ACTION_OLD) {
+ add = true;
+ /* Create new lease */
+ if (!(lease_new = virJSONValueNewObject())) {
+ virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
+ _("failed to create json"));
+ goto cleanup;
+ }
+
+ if (virStrToLong_ll(exptime, NULL, 10, &expirytime) < 0) {
+ virReportError(VIR_ERR_INTERNAL_ERROR,
+ _("Unable to convert lease expiry time to long long: %s"),
+ exptime);
+ goto cleanup;
+ }
+
+ if (iaid && virJSONValueObjectAppendString(lease_new, "iaid", iaid) < 0)
+ goto cleanup;
+ if (ip && virJSONValueObjectAppendString(lease_new, "ip-address", ip) < 0)
+ goto cleanup;
+ if (mac && virJSONValueObjectAppendString(lease_new, "mac-address", mac) < 0)
+ goto cleanup;
+ if (hostname && virJSONValueObjectAppendString(lease_new, "hostname", hostname) < 0)
+ goto cleanup;
+ if (clientid && virJSONValueObjectAppendString(lease_new, "client-id", clientid) < 0)
+ goto cleanup;
+ if (expirytime && virJSONValueObjectAppendNumberLong(lease_new, "expiry-time", expirytime) < 0)
+ goto cleanup;
+ }
+ }
+ } else {
+ fprintf(stderr, _("Unsupported action: %s\n"),
+ virLeaseActionTypeToString(action));
+ exit(EXIT_FAILURE);
+ }
+ /* Check for previous leases */
+ if (custom_lease_file_len) {
+ if (!(leases_array = virJSONValueFromString(lease_entries))) {
+ virReportError(VIR_ERR_INTERNAL_ERROR,
+ _("invalid json in file: %s"), custom_lease_file);
+ goto cleanup;
+ }
+
+ if ((size = virJSONValueArraySize(leases_array)) < 0) {
+ virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
+ _("couldn't fetch array of leases"));
+ goto cleanup;
+ }
+ }
+
+ if (!(leases_array_new = virJSONValueNewArray())) {
+ virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
+ _("failed to create json"));
+ goto cleanup;
+ }
+
+ currtime = (long long) time(NULL);
+
+ for (i = 0; i < size; i++) {
+ const char *ip_tmp = NULL;
+ long long expirytime_tmp = -1;
+
+ if (!(lease_tmp = virJSONValueArrayGet(leases_array, i))) {
+ virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
+ _("failed to parse json"));
+ goto cleanup;
+ }
+
+ if (!(ip_tmp = virJSONValueObjectGetString(lease_tmp, "ip-address")) ||
+ (virJSONValueObjectGetNumberLong(lease_tmp, "expiry-time", &expirytime_tmp) < 0)) {
+ virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
+ _("failed to parse json"));
+ goto cleanup;
+ }
+
+ /* Check whether lease has expired or not */
+ if (expirytime_tmp < currtime)
+ continue;
+
+ /* Check whether lease has to be included or not */
+ if (delete && STREQ(ip_tmp, ip))
+ continue;
+
+ /* Add old lease to new array */
+ if (virJSONValueArrayAppend(leases_array_new, lease_tmp) < 0) {
+ virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
+ _("failed to create json"));
+ goto cleanup;
+ }
+ }
+
+ if (add) {
+ if (virJSONValueArrayAppend(leases_array_new, lease_new) < 0) {
+ virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
+ _("failed to create json"));
+ goto cleanup;
+ }
+ }
+
+ if (!(leases_str = virJSONValueToString(leases_array_new, true))) {
+ virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
+ _("empty json array"));
+ goto cleanup;
+ }
+
+ /* Write to file */
+ if (virFileRewrite(custom_lease_file, 0644,
+ customLeaseRewriteFile, &leases_str) < 0)
+ goto cleanup;
+
+ rv = EXIT_SUCCESS;
+
+cleanup:
+ if (pid_file_fd != -1)
+ virPidFileReleasePath(pid_file, pid_file_fd);
+
+ VIR_FREE(pid_file);
+ VIR_FREE(exptime_tmp);
+ VIR_FREE(custom_lease_file);
+ virJSONValueFree(lease_new);
+ virJSONValueFree(leases_array);
+ virJSONValueFree(leases_array_new);
+
+ return rv;
+}
--
1.7.1
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