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[libvirt] [PATCH v2] Add helper program to create custom leases



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:
[
    {
        "expiry-time": "1390775837",
        "mac-address": "52:54:00:93:8c:63",
        "iaid": "*",
        "ip-address": "192.168.150.209",
        "hostname": "iit-ad885e4aa1",
        "client-id": "01:52:54:00:44:7c:d7"
    },
    {
        "expiry-time": "1390775950",
        "mac-address": "52:54:00:7b:6f:ba",
        "iaid": "8089530",
        "ip-address": "2001:db8:ca2:2:1::6d",
        "hostname": "*",
        "client-id": "00:04:76:00:cf:ae:b3:0b:fc:cd:0e:22:2e:97:76:65:74:ec"
    }
]

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/util/leaseshelper.c
   * Helper program to create the custom lease file

---
 v2:
 * Changed format to JSON

 v1:
 * Refer: https://www.redhat.com/archives/libvir-list/2014-January/msg00626.html

 src/Makefile.am             |  20 ++++
 src/network/bridge_driver.c |  19 ++++
 src/util/leaseshelper.c     | 271 ++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 310 insertions(+)
 create mode 100644 src/util/leaseshelper.c

diff --git a/src/Makefile.am b/src/Makefile.am
index 7844efa..1fa6263 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -840,6 +840,9 @@ STORAGE_HELPER_DISK_SOURCES =					\
 UTIL_IO_HELPER_SOURCES =					\
 		util/iohelper.c
 
+UTIL_LEASES_HELPER_SOURCES =					\
+		util/leaseshelper.c
+
 # Network filters
 NWFILTER_DRIVER_SOURCES =						\
 		nwfilter/nwfilter_driver.h nwfilter/nwfilter_driver.c	\
@@ -2410,6 +2413,23 @@ libvirt_iohelper_CFLAGS = \
 		$(NULL)
 endif WITH_LIBVIRTD
 
+if WITH_LIBVIRTD
+libexec_PROGRAMS += libvirt_leaseshelper
+libvirt_leaseshelper_SOURCES = $(UTIL_LEASES_HELPER_SOURCES)
+libvirt_leaseshelper_LDFLAGS = \
+               $(NULL)
+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 = \
+               $(PIE_CFLAGS) \
+               $(NULL)
+endif WITH_LIBVIRTD
+
 if WITH_STORAGE_DISK
 if WITH_LIBVIRTD
 libexec_PROGRAMS += libvirt_parthelper
diff --git a/src/network/bridge_driver.c b/src/network/bridge_driver.c
index 0b43a67..5440aef 100644
--- a/src/network/bridge_driver.c
+++ b/src/network/bridge_driver.c
@@ -148,6 +148,16 @@ 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;
@@ -183,6 +193,7 @@ networkRemoveInactive(virNetworkDriverStatePtr driver,
                       virNetworkObjPtr net)
 {
     char *leasefile = NULL;
+    char *customleasefile = NULL;
     char *radvdconfigfile = NULL;
     char *configfile = NULL;
     char *radvdpidbase = NULL;
@@ -201,6 +212,9 @@ networkRemoveInactive(virNetworkDriverStatePtr driver,
     if (!(leasefile = networkDnsmasqLeaseFileName(def->name)))
         goto cleanup;
 
+    if (!(customleasefile = networkDnsmasqLeaseFileNameCustom(def->bridge)))
+        goto cleanup;
+
     if (!(radvdconfigfile = networkRadvdConfigFileName(def->name)))
         goto cleanup;
 
@@ -217,6 +231,7 @@ networkRemoveInactive(virNetworkDriverStatePtr driver,
     /* dnsmasq */
     dnsmasqDelete(dctx);
     unlink(leasefile);
+    unlink(customleasefile);
     unlink(configfile);
 
     /* radvd */
@@ -1063,6 +1078,10 @@ networkBuildDhcpDaemonCommandLine(virNetworkObjPtr network,
 
     cmd = virCommandNew(dnsmasqCapsGetBinaryPath(caps));
     virCommandAddArgFormat(cmd, "--conf-file=%s", configfile);
+
+    /* This helper is used to create cutom leases file for libvirt */
+    virCommandAddArgFormat(cmd, "--dhcp-script=%s", LIBEXECDIR "/libvirt_leaseshelper");
+
     *cmdout = cmd;
     ret = 0;
 cleanup:
diff --git a/src/util/leaseshelper.c b/src/util/leaseshelper.c
new file mode 100644
index 0000000..a9aaf3f
--- /dev/null
+++ b/src/util/leaseshelper.c
@@ -0,0 +1,271 @@
+/*
+ * leasehelper.c: Helper program to create custom leases file
+ *
+ * Copyright (C) 2013 Red Hat, Inc.
+ *
+ * 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 gmail com>
+ *
+ */
+
+#include <config.h>
+
+#include <stdio.h>
+#include <stdlib.h>
+
+#include "virutil.h"
+#include "virthread.h"
+#include "virfile.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 2097152
+
+/*
+ * Use this when passing possibly-NULL strings to printf-a-likes.
+ */
+# define EMPTY_STR(s) ((s) ? (s) : "*")
+
+int
+main(int argc, char **argv) {
+
+    /* Doesn't hurt to check */
+    if (argc < 4) {
+        /* Refer man page of dnsmasq --dhcp-script for more details */
+        fprintf(stderr, "Usage: $program $action ${mac|clientid} $ip\n");
+        return -1;
+    }
+
+    char *lease_file = NULL;
+    char *lease_entries = NULL;
+    const char *ip = argv[3];
+    const char *mac = argv[2];
+    const char *action = argv[1];
+    const char *program_name = argv[0];
+    const char *iaid = EMPTY_STR(virGetEnvAllowSUID("DNSMASQ_IAID"));
+    const char *clientid = EMPTY_STR(virGetEnvAllowSUID("DNSMASQ_CLIENT_ID"));
+    const char *interface = EMPTY_STR(virGetEnvAllowSUID("DNSMASQ_INTERFACE"));
+    const char *exptime = EMPTY_STR(virGetEnvAllowSUID("DNSMASQ_LEASE_EXPIRES"));
+    const char *hostname = EMPTY_STR(virGetEnvAllowSUID("DNSMASQ_SUPPLIED_HOSTNAME"));
+    const char *leases_str = NULL;
+    size_t i = 0;
+    int rv = -1;
+    int size = 0;
+    int lease_file_len = 0;
+    FILE *fp = NULL;
+    bool add = false;
+    bool delete = false;
+    virJSONValuePtr lease_new;
+    virJSONValuePtr lease_tmp;
+    virJSONValuePtr leases_array;
+    virJSONValuePtr lease_new_tmp;
+    virJSONValuePtr leases_array_new;
+
+    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);
+    }
+
+    if (virAsprintf(&lease_file, "%s/%s.status", LOCALSTATEDIR
+                    "/lib/libvirt/dnsmasq/", interface) < 0)
+        goto cleanup;
+
+    if (virGetEnvAllowSUID("DNSMASQ_IAID")) {
+        mac = EMPTY_STR(virGetEnvAllowSUID("DNSMASQ_MAC"));
+        clientid = argv[2];
+    }
+
+    /* Make sure dnsmasq knows the interface, otherwise something is wrong */
+    if (STREQ(interface, "*"))
+        goto cleanup;
+
+    /* Make sure the file exists. If not, 'touch' it */
+    if (virFileTouch(lease_file, 0644) < 0)
+        goto cleanup;
+
+    /* Read entire contents */
+    if ((lease_file_len = virFileReadAll(lease_file,
+                                         VIR_NETWORK_DHCP_LEASE_FILE_SIZE_MAX,
+                                         &lease_entries)) < 0) {
+        goto cleanup;
+    }
+
+    if (STREQ(action, "add") || STREQ(action, "old") || STREQ(action, "del")) {
+        if (mac || STREQ(action, "del")) {
+            /* Delete the corresponding lease */
+            delete = true;
+            if (STREQ(action, "add") || STREQ(action, "old")) {
+                add = true;
+                /* Enter new lease */
+                if (!(lease_new = virJSONValueNewObject())) {
+                    virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
+                                   _("failed to create json"));
+                    goto cleanup;
+                }
+                if (virJSONValueObjectAppendString(lease_new, "expiry-time",
+                                                   exptime) < 0 ||
+                    virJSONValueObjectAppendString(lease_new, "mac-address",
+                                                   mac) < 0 ||
+                    virJSONValueObjectAppendString(lease_new, "iaid",
+                                                   iaid) < 0 ||
+                    virJSONValueObjectAppendString(lease_new, "ip-address",
+                                                   ip) < 0 ||
+                    virJSONValueObjectAppendString(lease_new, "hostname",
+                                                   hostname) < 0 ||
+                    virJSONValueObjectAppendString(lease_new, "client-id",
+                                                   clientid) < 0) {
+                    virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
+                                   _("failed to create json"));
+                    goto cleanup;
+                }
+            }
+        }
+    }
+
+    /* Check for previous leases */
+    if (lease_file_len) {
+        if (!(leases_array = virJSONValueFromString(lease_entries))) {
+            virReportError(VIR_ERR_INTERNAL_ERROR,
+                           _("invalid json in file: %s"), 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;
+    }
+
+    for (i = 0; i < size; i++) {
+        const char *ip_tmp = NULL;
+        const char *mac_tmp = NULL;
+        const char *iaid_tmp = NULL;
+        const char *exptime_tmp = NULL;
+        const char *clientid_tmp = NULL;
+        const char *hostname_tmp = NULL;
+        long long expirytime_tmp = 0;
+
+        if (!(lease_tmp = virJSONValueArrayGet(leases_array, i))) {
+            virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
+                           _("failed to parse json"));
+            goto cleanup;
+        }
+
+        if (!(iaid_tmp = virJSONValueObjectGetString(lease_tmp, "iaid")) ||
+            !(ip_tmp = virJSONValueObjectGetString(lease_tmp, "ip-address")) ||
+            !(mac_tmp = virJSONValueObjectGetString(lease_tmp, "mac-address")) ||
+            !(hostname_tmp = virJSONValueObjectGetString(lease_tmp, "hostname")) ||
+            !(clientid_tmp = virJSONValueObjectGetString(lease_tmp, "client-id")) ||
+            !(exptime_tmp = virJSONValueObjectGetString(lease_tmp, "expiry-time"))) {
+            virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
+                           _("failed to parse json"));
+            goto cleanup;
+        }
+
+        if (virStrToLong_ll(exptime_tmp, NULL, 10, &expirytime_tmp) < 0) {
+            virReportError(VIR_ERR_INTERNAL_ERROR,
+                           _("Unable to convert lease expiry time to integer: %s"),
+                           exptime_tmp);
+            goto cleanup;
+        }
+
+        /* Check whether lease has expired or not */
+        if (expirytime_tmp < (long long) time(NULL))
+            continue;
+        else if (delete && STREQ(ip_tmp, ip))
+            continue;
+        else {
+            if (!(lease_new_tmp = virJSONValueNewObject())) {
+                virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
+                               _("failed to create json"));
+                goto cleanup;
+            }
+            if (virJSONValueObjectAppendString(lease_new_tmp, "expiry-time",
+                                               exptime_tmp) < 0 ||
+                virJSONValueObjectAppendString(lease_new_tmp, "mac-address",
+                                               mac_tmp) < 0 ||
+                virJSONValueObjectAppendString(lease_new_tmp, "iaid",
+                                               iaid_tmp) < 0 ||
+                virJSONValueObjectAppendString(lease_new_tmp, "ip-address",
+                                               ip_tmp) < 0 ||
+                virJSONValueObjectAppendString(lease_new_tmp, "hostname",
+                                               hostname_tmp) < 0 ||
+                virJSONValueObjectAppendString(lease_new_tmp, "client-id",
+                                               clientid_tmp) < 0) {
+                virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
+                               _("failed to create json"));
+                goto cleanup;
+            }
+            if (virJSONValueArrayAppend(leases_array_new, lease_new_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;
+        }
+    }
+
+    rv = 0;
+
+    /* Write to file */
+    leases_str = virJSONValueToString(leases_array_new, true);
+    if (!leases_str)
+        leases_str = "";
+
+    if (virFileWriteStr(lease_file, leases_str, 0) < 0)
+        rv = -1;
+
+cleanup:
+    VIR_FREE(lease_file);
+    virJSONValueFree(lease_new);
+    virJSONValueFree(leases_array);
+    virJSONValueFree(lease_new_tmp);
+    virJSONValueFree(leases_array_new);
+    return rv;
+}
-- 
1.8.1.4


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