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[libvirt] [libvirt PATCHv5 2/2] add leasefile support



	This patch adds support for saving DHCP snooping leases to an on-disk
file and restoring saved leases that are still active on restart.

Signed-off-by: David L Stevens <dlstevens us ibm com>
---
 src/nwfilter/nwfilter_dhcpsnoop.c |  270 +++++++++++++++++++++++++++++++++----
 1 files changed, 243 insertions(+), 27 deletions(-)

diff --git a/src/nwfilter/nwfilter_dhcpsnoop.c b/src/nwfilter/nwfilter_dhcpsnoop.c
index 8a37a6f..918ad7b 100644
--- a/src/nwfilter/nwfilter_dhcpsnoop.c
+++ b/src/nwfilter/nwfilter_dhcpsnoop.c
@@ -55,10 +55,18 @@
 #include "nwfilter_gentech_driver.h"
 #include "nwfilter_ebiptables_driver.h"
 #include "nwfilter_dhcpsnoop.h"
+#include "virfile.h"
+#include "configmake.h"
 
 #define VIR_FROM_THIS VIR_FROM_NWFILTER
 
 #ifdef HAVE_LIBPCAP
+ 
+#define LEASEFILE LOCALSTATEDIR "/run/libvirt/network/nwfilter.leases"
+#define TMPLEASEFILE LOCALSTATEDIR "/run/libvirt/network/nwfilter.ltmp"
+static int lease_fd = -1;
+static int nleases = 0; /* number of active leases */
+static int wleases = 0; /* number of written leases */
 
 static virHashTablePtr SnoopReqs;
 static pthread_mutex_t SnoopLock;
@@ -76,6 +84,7 @@ struct virNWFilterSnoopReq {
     const char               *filtername;
     virNWFilterHashTablePtr   vars;
     virNWFilterDriverStatePtr driver;
+    bool                      running;
     /* start and end of lease list, ordered by lease time */
     struct iplease           *start;
     struct iplease           *end;
@@ -96,7 +105,15 @@ struct iplease {
 
 static struct iplease *ipl_getbyip(struct iplease *start, uint32_t ipaddr);
 static void ipl_update(struct iplease *pl, uint32_t timeout);
+ 
+static struct virNWFilterSnoopReq *newreq(const char *ifname);
 
+static void lease_open(void);
+static void lease_close(void);
+static void lease_load(void);
+static void lease_save(struct iplease *ipl);
+static void lease_restore(struct virNWFilterSnoopReq *req);
+static void lease_refresh(void);
 
 /*
  * ipl_ladd - add an IP lease to a list
@@ -187,7 +204,7 @@ ipl_install(struct iplease *ipl)
  * ipl_add - create or update an IP lease
  */
 static void
-ipl_add(struct iplease *plnew)
+ipl_add(struct iplease *plnew, bool update_leasefile)
 {
     struct iplease *pl;
     struct virNWFilterSnoopReq *req = plnew->ipl_req;
@@ -195,6 +212,8 @@ ipl_add(struct iplease *plnew)
     pl = ipl_getbyip(req->start, plnew->ipl_ipaddr);
     if (pl) {
         ipl_update(pl, plnew->ipl_timeout);
+        if (update_leasefile)
+            lease_save(pl);
         return;
     }
     /* support for multiple addresses requires the ability to add filters
@@ -212,11 +231,14 @@ ipl_add(struct iplease *plnew)
     }
     *pl = *plnew;
 
-    if (ipl_install(pl) < 0) {
+    if (req->running && ipl_install(pl) < 0) {
         VIR_FREE(pl);
         return;
     }
     ipl_tadd(pl);
+    nleases++;
+    if (update_leasefile)
+        lease_save(pl);
 }
 
 /*
@@ -252,7 +274,7 @@ ipl_tdel(struct iplease *ipl)
  * ipl_del - delete an IP lease
  */
 static void
-ipl_del(struct virNWFilterSnoopReq *req, uint32_t ipaddr)
+ipl_del(struct virNWFilterSnoopReq *req, uint32_t ipaddr, bool update_leasefile)
 {
     struct iplease *ipl;
 
@@ -262,13 +284,18 @@ ipl_del(struct virNWFilterSnoopReq *req, uint32_t ipaddr)
 
     ipl_tdel(ipl);
 
-    /* for multiple address support, this needs to remove those rules
-     * referencing "IP" with ipl's ip value.
-     */
-    if (req->techdriver->applyDHCPOnlyRules(req->ifname, req->macaddr, NULL)) {
-        virNWFilterReportError(VIR_ERR_INTERNAL_ERROR, "ipl_ldel failed");
+    if (update_leasefile) {
+        lease_save(ipl);
+
+        /*
+         * for multiple address support, this needs to remove those rules
+         * referencing "IP" with ipl's ip value.
+         */
+        if (req->techdriver->applyDHCPOnlyRules(req->ifname,req->macaddr,NULL))
+            virNWFilterReportError(VIR_ERR_INTERNAL_ERROR, "ipl_ldel failed");
     }
     VIR_FREE(ipl);
+    nleases--;
 }
 
 /*
@@ -308,7 +335,7 @@ ipl_trun(struct virNWFilterSnoopReq *req)
 
     now = time(0);
     while (req->start && req->start->ipl_timeout <= now)
-        ipl_del(req, req->start->ipl_ipaddr);
+        ipl_del(req, req->start->ipl_ipaddr, 1);
     return 0;
 }
 
@@ -467,11 +494,11 @@ dhcpdecode(struct virNWFilterSnoopReq *req, struct eth *pep, int len)
 
     switch (mtype) {
         case DHCPACK:
-            ipl_add(&ipl);
+            ipl_add(&ipl, 1);
             break;
         case DHCPDECLINE:
         case DHCPRELEASE:
-            ipl_del(req, ipl.ipl_ipaddr);
+            ipl_del(req, ipl.ipl_ipaddr, 1);
             break;
         default:
             break;
@@ -521,7 +548,7 @@ snoopReqFree(struct virNWFilterSnoopReq *req)
     /* free all leases */
     snoop_lock();
     for (ipl = req->start; ipl; ipl = req->start)
-        ipl_del(req, ipl->ipl_ipaddr);
+        ipl_del(req, ipl->ipl_ipaddr, 0);
     snoop_unlock();
 
     /* free all req data */
@@ -547,6 +574,8 @@ virNWFilterDHCPSnoop(void *req0)
 
     ifindex = if_nametoindex(req->ifname);
 
+    lease_restore(req);
+
     while (1) {
         if (req->die)
             break;
@@ -583,23 +612,22 @@ virNWFilterDHCPSnoopReq(virNWFilterTechDriverPtr techdriver,
 {
     struct virNWFilterSnoopReq *req;
     pthread_t                   thread;
+    bool                        isnewreq;
 
     snoop_lock();
     req = virHashLookup(SnoopReqs, ifname);
-    snoop_unlock();
-    if (req)
-        return 0;
-
-    if (VIR_ALLOC(req) < 0) {
-        virReportOOMError();
-        return 1;
-    }
-
-    req->ifname = strdup(ifname);
-    if (req->ifname == NULL) {
-        snoopReqFree(req);
-        virReportOOMError();
-        return 1;
+    isnewreq = req == NULL;
+    if (!isnewreq) {
+        if (req->running) {
+            snoop_unlock();
+            return 0;
+        }
+        snoop_unlock();
+    } else {
+        snoop_unlock();
+        req = newreq(ifname);
+        if (!req)
+            return 1;
     }
 
     req->techdriver = techdriver;
@@ -634,8 +662,10 @@ virNWFilterDHCPSnoopReq(virNWFilterTechDriverPtr techdriver,
     }
     req->driver = driver;
 
+    req->running = 1;
+
     snoop_lock();
-    if (virHashAddEntry(SnoopReqs, ifname, req)) {
+    if (isnewreq && virHashAddEntry(SnoopReqs, ifname, req)) {
         snoop_unlock();
         virNWFilterReportError(VIR_ERR_INTERNAL_ERROR,
                                _("virNWFilterDHCPSnoopReq req add failed on "
@@ -669,6 +699,20 @@ freeReq(void *req0, const void *name ATTRIBUTE_UNUSED)
     req->die = 1;
 }
 
+static void
+lease_close(void)
+{
+    VIR_FORCE_CLOSE(lease_fd);
+}
+
+static void
+lease_open(void)
+{
+    lease_close();
+
+    lease_fd = open(LEASEFILE, O_CREAT|O_RDWR|O_APPEND, 0644);
+}
+
 int
 virNWFilterDHCPSnoopInit(void)
 {
@@ -687,6 +731,8 @@ virNWFilterDHCPSnoopInit(void)
         virReportOOMError();
         return -1;
     }
+    lease_load();
+    lease_open();
     snoop_unlock();
     return 0;
 }
@@ -709,10 +755,180 @@ virNWFilterDHCPSnoopEnd(const char *ifname)
             virReportOOMError();
             return;
         }
+        lease_load();
     }
+    lease_close();
     snoop_unlock();
 }
 
+static int
+lease_write(int lfd, const char *ifname, struct iplease *ipl)
+{
+    char lbuf[256],ipstr[16],dhcpstr[16];
+
+    if (inet_ntop(AF_INET, &ipl->ipl_ipaddr, ipstr, sizeof ipstr) == 0) {
+        virNWFilterReportError(VIR_ERR_INTERNAL_ERROR,
+                               _("inet_ntop(0x%08X) failed"), ipl->ipl_ipaddr);
+        return -1;
+    }
+    if (inet_ntop(AF_INET, &ipl->ipl_server, dhcpstr, sizeof dhcpstr) == 0) {
+        virNWFilterReportError(VIR_ERR_INTERNAL_ERROR,
+                               _("inet_ntop(0x%08X) failed"), ipl->ipl_server);
+        return -1;
+    }
+    /* time intf ip dhcpserver */
+    snprintf(lbuf, sizeof(lbuf), "%u %s %s %s\n", ipl->ipl_timeout,
+             ifname, ipstr, dhcpstr);
+    if (write(lfd, lbuf, strlen(lbuf)) < 0) {
+        virNWFilterReportError(VIR_ERR_INTERNAL_ERROR,
+                               _("lease file write failed: %s"),
+                               strerror(errno));
+        return -1;
+    }
+    (void) fsync(lfd);
+    return 0;
+}
+
+static void
+lease_save(struct iplease *ipl)
+{
+    struct virNWFilterSnoopReq *req = ipl->ipl_req;
+
+    if (lease_fd < 0)
+       lease_open();
+    if (lease_write(lease_fd, req->ifname, ipl) < 0)
+       return;
+    /* keep dead leases at < ~95% of file size */
+    if (++wleases >= nleases*20)
+        lease_load();   /* load & refresh lease file */
+}
+
+static struct virNWFilterSnoopReq *
+newreq(const char *ifname)
+{
+    struct virNWFilterSnoopReq *req;
+
+    if (VIR_ALLOC(req) < 0) {
+        virReportOOMError();
+        return NULL;
+    }
+    req->ifname = strdup(ifname);
+
+    return req;
+}
+
+static void
+SaveSnoopReqIter(void *payload,
+                 const void *name ATTRIBUTE_UNUSED,
+                 void *data)
+{
+    struct virNWFilterSnoopReq *req = payload;
+    int tfd = (int)data;
+    struct iplease *ipl;
+
+    for (ipl = req->start; ipl; ipl = ipl->ipl_next)
+        (void) lease_write(tfd, req->ifname, ipl);
+}
+
+static void
+lease_refresh(void)
+{
+    int tfd;
+
+    (void) unlink(TMPLEASEFILE);
+    /* lease file loaded, delete old one */
+    tfd = open(TMPLEASEFILE, O_CREAT|O_RDWR|O_TRUNC|O_EXCL, 0644);
+    if (tfd < 0) {
+        virNWFilterReportError(VIR_ERR_INTERNAL_ERROR,
+                               _("open(\"%s\"): %s"),
+                               TMPLEASEFILE, strerror(errno));
+        return;
+    }
+    if (SnoopReqs)
+        virHashForEach(SnoopReqs, SaveSnoopReqIter, (void *)tfd);
+    (void) close(tfd);
+    if (rename(TMPLEASEFILE, LEASEFILE) < 0) {
+        virNWFilterReportError(VIR_ERR_INTERNAL_ERROR,
+                               _("rename(\"%s\", \"%s\"): %s"),
+                               TMPLEASEFILE, LEASEFILE, strerror(errno));
+        (void) unlink(TMPLEASEFILE);
+    }
+    wleases = 0;
+    lease_open();
+}
+
+
+static void
+lease_load(void)
+{
+    char line[256], ifname[16], ipstr[16], srvstr[16];
+    struct iplease ipl;
+    struct virNWFilterSnoopReq *req;
+    time_t now;
+    FILE *fp;
+    int ln = 0;
+
+    fp = fopen(LEASEFILE, "r");
+    time(&now);
+    while (fp && fgets(line, sizeof(line), fp)) {
+        if (line[strlen(line)-1] != '\n') {
+            virNWFilterReportError(VIR_ERR_INTERNAL_ERROR,
+                                   _("lease_load lease file line %d corrupt"),
+                                   ln);
+            break;
+        }
+        ln++;
+        if (sscanf(line, "%u %16s %16s %16s", &ipl.ipl_timeout,
+                   ifname, ipstr, srvstr) < 4) {
+            virNWFilterReportError(VIR_ERR_INTERNAL_ERROR,
+                                   _("lease_load lease file line %d corrupt"),
+                                   ln);
+            break;;
+        }
+        if (ipl.ipl_timeout && ipl.ipl_timeout < now)
+            continue;
+        req = virHashLookup(SnoopReqs, ifname);
+        if (!req) {
+            req = newreq(ifname);
+            if (!req)
+               break;
+            if (virHashAddEntry(SnoopReqs, ifname, req)) {
+                snoopReqFree(req);
+                virNWFilterReportError(VIR_ERR_INTERNAL_ERROR,
+                                       _("lease_load req add failed on "
+                                       "interface \"%s\""), ifname);
+                continue;
+            }
+        }
+
+        if (inet_pton(AF_INET, ipstr, &ipl.ipl_ipaddr) <= 0) {
+            virNWFilterReportError(VIR_ERR_INTERNAL_ERROR,
+                                  _("line %d corrupt ipaddr \"%s\""),
+                                  ln, ipstr);
+            continue;
+        }
+        (void) inet_pton(AF_INET, srvstr, &ipl.ipl_server);
+        ipl.ipl_req = req;
+
+        if (ipl.ipl_timeout)
+            ipl_add(&ipl, 0);
+        else
+            ipl_del(req, ipl.ipl_ipaddr, 0);
+    }
+    if (fp != NULL)
+        (void) fclose(fp);
+    lease_refresh();
+}
+
+static void
+lease_restore(struct virNWFilterSnoopReq *req)
+{
+    struct iplease *ipl;
+
+    for (ipl=req->start; ipl; ipl=ipl->ipl_next)
+        (void) ipl_install(ipl);
+}
+
 #else /* HAVE_LIBPCAP */
 int
 virNWFilterDHCPSnoopInit(void)
-- 
1.7.6.4


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