[libvirt] [PATCH v2 1/2] firewall: add dump function

[Nikolay Shirokovskiy]

We are going to save this dump on applying rules so that on
next applying we can compare dump of current rules with dump of
previous rules. Which in turn will help us to decide wether to
reinstantiate rules or not.

Signed-off-by: Nikolay Shirokovskiy <nshirokovskiy at virtuozzo.com>
---
 src/libvirt_private.syms |   1 +
 src/util/virfirewall.c   | 111 +++++++++++++++++++++++++++++++++++++++++++++++
 src/util/virfirewall.h   |   3 ++
 3 files changed, 115 insertions(+)

diff --git a/src/libvirt_private.syms b/src/libvirt_private.syms
index 335210c..612ad41 100644
--- a/src/libvirt_private.syms
+++ b/src/libvirt_private.syms
@@ -1892,6 +1892,7 @@ virFileCacheSetPriv;
 # util/virfirewall.h
 virFirewallAddRuleFull;
 virFirewallApply;
+virFirewallDumpRules;
 virFirewallFree;
 virFirewallNew;
 virFirewallRemoveRule;
diff --git a/src/util/virfirewall.c b/src/util/virfirewall.c
index c786d76..ed7f9e6 100644
--- a/src/util/virfirewall.c
+++ b/src/util/virfirewall.c
@@ -949,3 +949,114 @@ virFirewallApply(virFirewallPtr firewall)
     virMutexUnlock(&ruleLock);
     return ret;
 }
+
+
+static void
+virFirewallDumpRule(virBufferPtr buf,
+                    const char *ifname,
+                    virFirewallRulePtr rule)
+{
+    size_t i = 0;
+    size_t j, idx;
+    const char *concurrent = NULL;
+
+    switch (rule->layer) {
+    case VIR_FIREWALL_LAYER_ETHERNET:
+        concurrent = "--concurrent";
+        break;
+
+    case VIR_FIREWALL_LAYER_IPV4:
+    case VIR_FIREWALL_LAYER_IPV6:
+        concurrent = "-w";
+        break;
+
+    case VIR_FIREWALL_LAYER_LAST:
+        break;
+    }
+
+    /* don't dump concurrent option */
+    if (concurrent && rule->argsLen > 0 && STREQ(rule->args[0], concurrent))
+        i++;
+
+    /* calculate index of 'command' argument like -N or -A etc */
+    idx = i;
+    if (i < rule->argsLen && STREQ(rule->args[i], "-t"))
+        idx += 2;
+
+    /* Whitelist commands that can go to dump. These are -N and -A.
+     * Commands D, L, X, F are used only for cleanup purpuses and do
+     * not present result rules list. -I is only used by
+     * iptablesCreateBaseChainsFW to [re]insert common non binding specific
+     * rules.
+     */
+    if (idx >= rule->argsLen ||
+        (STRNEQ(rule->args[idx], "-N") && STRNEQ(rule->args[idx], "-A")))
+         return;
+
+    for (j = i; j < rule->argsLen; j++)
+        if (strstr(rule->args[j], ifname))
+            break;
+
+    /* We also need to filter common non binding specific rules originated
+     * from iptablesCreateBaseChainsFW - these are -N for libvirt-in etc. */
+    if (j == rule->argsLen)
+        return;
+
+    switch (rule->layer) {
+    case VIR_FIREWALL_LAYER_ETHERNET:
+        virBufferAddLit(buf, "ebtables ");
+        break;
+
+    case VIR_FIREWALL_LAYER_IPV4:
+        virBufferAddLit(buf, "iptables ");
+        break;
+
+    case VIR_FIREWALL_LAYER_IPV6:
+        virBufferAddLit(buf, "ip6tables ");
+        break;
+
+    case VIR_FIREWALL_LAYER_LAST:
+        break;
+    }
+
+    /* dump default table explicitly */
+    if (i < rule->argsLen && STRNEQ(rule->args[i], "-t"))
+        virBufferAddLit(buf, "-t filter ");
+
+    for (; i < rule->argsLen; i++) {
+        virBufferAddStr(buf, rule->args[i]);
+
+        if (i < rule->argsLen - 1)
+            virBufferAddLit(buf, " ");
+    }
+
+    virBufferAddLit(buf, "\n");
+}
+
+
+/*
+ * Dump rules for all transactions. Transaction rollbacks are not dumped.
+ * The order of rules in dump follows from order of transactions and
+ * order of rules in transactions. Only creation rules (-N, -A) are dumped.
+ * Example:
+ *
+ * ebtables -t nat -N libvirt-P-vme001c42fd388c
+ * ebtables -t nat -A libvirt-P-vme001c42fd388c -d 00:1c:42:fd:38:9d -j RETURN
+ * ..
+ */
+char*
+virFirewallDumpRules(virFirewallPtr firewall,
+                     const char *ifname)
+{
+    size_t i, j;
+    virBuffer buf = VIR_BUFFER_INITIALIZER;
+
+    if (!firewall || firewall->err)
+        return NULL;
+
+    for (i = 0; i < firewall->ngroups; i++)
+        for (j = 0; j < firewall->groups[i]->naction; j++)
+            virFirewallDumpRule(&buf, ifname, firewall->groups[i]->action[j]);
+
+    return virBufferContentAndReset(&buf);
+}
diff --git a/src/util/virfirewall.h b/src/util/virfirewall.h
index e024e88..bbbc561 100644
--- a/src/util/virfirewall.h
+++ b/src/util/virfirewall.h
@@ -115,6 +115,9 @@ void virFirewallStartRollback(virFirewallPtr firewall,
 
 int virFirewallApply(virFirewallPtr firewall);
 
+char* virFirewallDumpRules(virFirewallPtr firewall,
+                           const char *ifname);
+
 void virFirewallSetLockOverride(bool avoid);
 
 VIR_DEFINE_AUTOPTR_FUNC(virFirewall, virFirewallFree)
-- 
1.8.3.1