Use scripting for cleaning and renaming of chains

Use scripts for the renaming and cleaning up of chains. This allows us to get
rid of some of the code that is only capable of renaming and removing chains
whose names are hardcoded.

A shell function 'collect_chains' is introduced that is given the name
of an ebtables chain and then recursively determines the names of all
chains that are accessed from this chain and its sub-chains using 'jumps'.

The resulting list of chain names is then used to delete all the found
chains by first flushing and then deleting them.

The same function is also used for renaming temporary filters to their final
names.

I tested this with the bash and dash as script interpreters.
Signed-off-by: NStefan Berger <stefanb@linux.vnet.ibm.com>

src/nwfilter/nwfilter_ebiptables_driver.c

@@ -92,6 +92,59 @@ static char *gawk_cmd_path;
 #define PRINT_CHAIN(buf, prefix, ifname, suffix) \
     snprintf(buf, sizeof(buf), "%c-%s-%s", prefix, ifname, suffix)
 
+/* The collect_chains() script recursively determines all names
+ * of ebtables (nat) chains that are 'children' of a given 'root' chain.
+ * The typical output of an ebtables call is as follows:
+ *
+ * #> ebtables -t nat -L libvirt-I-tck-test205002
+ * Bridge table: nat
+ *
+ * Bridge chain: libvirt-I-tck-test205002, entries: 5, policy: ACCEPT
+ * -p IPv4 -j I-tck-test205002-ipv4
+ * -p ARP -j I-tck-test205002-arp
+ * -p 0x8035 -j I-tck-test205002-rarp
+ * -p 0x835 -j ACCEPT
+ * -j DROP
+ */
+static const char ebtables_script_func_collect_chains[] =
+    "collect_chains()\n"
+    "{\n"
+    "  for tmp2 in $*; do\n"
+    "    for tmp in $(%s -t %s -L $tmp2 | \\\n"
+    "      sed -n \"/Bridge chain/,\\$ s/.*-j \\\\([%s]-.*\\\\)/\\\\1/p\");\n"
+    "    do\n"
+    "      echo $tmp\n"
+    "      collect_chains $tmp\n"
+    "    done\n"
+    "  done\n"
+    "}\n";
+
+static const char ebiptables_script_func_rm_chains[] =
+    "rm_chains()\n"
+    "{\n"
+    "  for tmp in $*; do %s -t %s -F $tmp; done\n"
+    "  for tmp in $*; do %s -t %s -X $tmp; done\n"
+    "}\n";
+
+static const char ebiptables_script_func_rename_chains[] =
+    "rename_chains()\n"
+    "{\n"
+    "  for tmp in $*; do\n"
+    "    case $tmp in\n"
+    "      %c*) %s -t %s -E $tmp %c${tmp#?} ;;\n"
+    "      %c*) %s -t %s -E $tmp %c${tmp#?} ;;\n"
+    "    esac\n"
+    "  done\n"
+    "}\n";
+
+static const char ebiptables_script_set_ifs[] =
+    "tmp='\n'\n"
+    "IFS=' ''\t'$tmp\n";
+
+#define NWFILTER_FUNC_COLLECT_CHAINS ebtables_script_func_collect_chains
+#define NWFILTER_FUNC_RM_CHAINS ebiptables_script_func_rm_chains
+#define NWFILTER_FUNC_RENAME_CHAINS ebiptables_script_func_rename_chains
+#define NWFILTER_FUNC_SET_IFS ebiptables_script_set_ifs
 
 #define VIRT_IN_CHAIN      "libvirt-in"
 #define VIRT_OUT_CHAIN     "libvirt-out"
@@ -2698,95 +2751,66 @@ ebtablesCreateTmpSubChain(virBufferPtr buf,
     return 0;
 }
 
-
 static int
-_ebtablesRemoveSubChain(virBufferPtr buf,
-                        int incoming,
-                        const char *ifname,
-                        enum l3_proto_idx protoidx,
-                        int isTempChain)
+_ebtablesRemoveSubChains(virBufferPtr buf,
+                         const char *ifname,
+                         const char *chains)
 {
-    char rootchain[MAX_CHAINNAME_LENGTH], chain[MAX_CHAINNAME_LENGTH];
-    char chainPrefix;
+    char rootchain[MAX_CHAINNAME_LENGTH];
+    unsigned i;
 
-    if (isTempChain) {
-        chainPrefix =(incoming) ? CHAINPREFIX_HOST_IN_TEMP
-                                : CHAINPREFIX_HOST_OUT_TEMP;
-    } else {
-        chainPrefix =(incoming) ? CHAINPREFIX_HOST_IN
-                                : CHAINPREFIX_HOST_OUT;
-    }
-
-    PRINT_ROOT_CHAIN(rootchain, chainPrefix, ifname);
-    PRINT_CHAIN(chain, chainPrefix, ifname, l3_protocols[protoidx].val);
-
-    virBufferAsprintf(buf,
-                      "%s -t %s -D %s -p 0x%x -j %s" CMD_SEPARATOR
-                      "%s -t %s -F %s" CMD_SEPARATOR
-                      "%s -t %s -X %s" CMD_SEPARATOR,
+    virBufferAsprintf(buf, NWFILTER_FUNC_COLLECT_CHAINS,
+                      ebtables_cmd_path, EBTABLES_DEFAULT_TABLE, chains);
+    virBufferAsprintf(buf, NWFILTER_FUNC_RM_CHAINS,
                       ebtables_cmd_path, EBTABLES_DEFAULT_TABLE,
-                      rootchain, l3_protocols[protoidx].attr, chain,
+                      ebtables_cmd_path, EBTABLES_DEFAULT_TABLE);
 
-                      ebtables_cmd_path, EBTABLES_DEFAULT_TABLE, chain,
+    virBufferAsprintf(buf, NWFILTER_FUNC_SET_IFS);
+    virBufferAddLit(buf, "chains=\"$(collect_chains");
+    for (i = 0; chains[i] != 0; i++) {
+        PRINT_ROOT_CHAIN(rootchain, chains[i], ifname);
+        virBufferAsprintf(buf, " %s", rootchain);
+    }
+    virBufferAddLit(buf, ")\"\n");
 
-                      ebtables_cmd_path, EBTABLES_DEFAULT_TABLE, chain);
+    for (i = 0; chains[i] != 0; i++) {
+        PRINT_ROOT_CHAIN(rootchain, chains[i], ifname);
+        virBufferAsprintf(buf,
+                          "%s -t %s -F %s\n",
+                          ebtables_cmd_path, EBTABLES_DEFAULT_TABLE,
+                          rootchain);
+    }
+    virBufferAddLit(buf, "rm_chains $chains\n");
 
     return 0;
 }
 
-
-static int
-ebtablesRemoveSubChain(virBufferPtr buf,
-                       int incoming,
-                       const char *ifname,
-                       enum l3_proto_idx protoidx)
-{
-    return _ebtablesRemoveSubChain(buf,
-                                   incoming, ifname, protoidx, 0);
-}
-
-
 static int
 ebtablesRemoveSubChains(virBufferPtr buf,
                         const char *ifname)
 {
-    enum l3_proto_idx i;
-
-    for (i = 0; i < L3_PROTO_LAST_IDX; i++) {
-        ebtablesRemoveSubChain(buf, 1, ifname, i);
-        ebtablesRemoveSubChain(buf, 0, ifname, i);
-    }
+    char chains[3] = {
+        CHAINPREFIX_HOST_IN,
+        CHAINPREFIX_HOST_OUT,
+        0
+    };
 
-    return 0;
+    return _ebtablesRemoveSubChains(buf, ifname, chains);
 }
 
-
-static int
-ebtablesRemoveTmpSubChain(virBufferPtr buf,
-                          int incoming,
-                          const char *ifname,
-                          enum l3_proto_idx protoidx)
-{
-    return _ebtablesRemoveSubChain(buf,
-                                   incoming, ifname, protoidx, 1);
-}
-
-
 static int
 ebtablesRemoveTmpSubChains(virBufferPtr buf,
                            const char *ifname)
 {
-    enum l3_proto_idx i;
-
-    for (i = 0; i < L3_PROTO_LAST_IDX; i++) {
-        ebtablesRemoveTmpSubChain(buf, 1, ifname, i);
-        ebtablesRemoveTmpSubChain(buf, 0, ifname, i);
-    }
+    char chains[3] = {
+        CHAINPREFIX_HOST_IN_TEMP,
+        CHAINPREFIX_HOST_OUT_TEMP,
+        0
+    };
 
-    return 0;
+    return _ebtablesRemoveSubChains(buf, ifname, chains);
 }
 
-
 static int
 ebtablesRenameTmpSubChain(virBufferPtr buf,
                           int incoming,
@@ -2813,31 +2837,51 @@ ebtablesRenameTmpSubChain(virBufferPtr buf,
     return 0;
 }
 
-
 static int
-ebtablesRenameTmpSubChains(virBufferPtr buf,
+ebtablesRenameTmpRootChain(virBufferPtr buf,
+                           int incoming,
                            const char *ifname)
 {
-    enum l3_proto_idx i;
+    return ebtablesRenameTmpSubChain(buf, incoming, ifname, NULL);
+}
+
+static int
+ebtablesRenameTmpSubAndRootChains(virBufferPtr buf,
+                                  const char *ifname)
+{
+    char rootchain[MAX_CHAINNAME_LENGTH];
+    unsigned i;
+    char chains[3] = {
+        CHAINPREFIX_HOST_IN_TEMP,
+        CHAINPREFIX_HOST_OUT_TEMP,
+        0};
 
-    for (i = 0; i < L3_PROTO_LAST_IDX; i++) {
-        ebtablesRenameTmpSubChain (buf, 1, ifname, l3_protocols[i].val);
-        ebtablesRenameTmpSubChain (buf, 0, ifname, l3_protocols[i].val);
+    virBufferAsprintf(buf, NWFILTER_FUNC_COLLECT_CHAINS,
+                      ebtables_cmd_path, EBTABLES_DEFAULT_TABLE, chains);
+    virBufferAsprintf(buf, NWFILTER_FUNC_RENAME_CHAINS,
+                      CHAINPREFIX_HOST_IN_TEMP,
+                      ebtables_cmd_path, EBTABLES_DEFAULT_TABLE,
+                      CHAINPREFIX_HOST_IN,
+                      CHAINPREFIX_HOST_OUT_TEMP,
+                      ebtables_cmd_path, EBTABLES_DEFAULT_TABLE,
+                      CHAINPREFIX_HOST_OUT);
+
+    virBufferAsprintf(buf, NWFILTER_FUNC_SET_IFS);
+    virBufferAddLit(buf, "chains=\"$(collect_chains");
+    for (i = 0; chains[i] != 0; i++) {
+        PRINT_ROOT_CHAIN(rootchain, chains[i], ifname);
+        virBufferAsprintf(buf, " %s", rootchain);
     }
+    virBufferAddLit(buf, ")\"\n");
 
-    return 0;
-}
+    virBufferAddLit(buf, "rename_chains $chains\n");
 
+    ebtablesRenameTmpRootChain(buf, 1, ifname);
+    ebtablesRenameTmpRootChain(buf, 0, ifname);
 
-static int
-ebtablesRenameTmpRootChain(virBufferPtr buf,
-                           int incoming,
-                           const char *ifname)
-{
-    return ebtablesRenameTmpSubChain(buf, incoming, ifname, NULL);
+    return 0;
 }
 
-
 static void
 ebiptablesInstCommand(virBufferPtr buf,
                       const char *templ, char cmd, int pos,
@@ -3546,9 +3590,7 @@ ebiptablesTearOldRules(virConnectPtr conn ATTRIBUTE_UNUSED,
         ebtablesRemoveRootChain(&buf, 1, ifname);
         ebtablesRemoveRootChain(&buf, 0, ifname);
 
-        ebtablesRenameTmpSubChains(&buf, ifname);
-        ebtablesRenameTmpRootChain(&buf, 1, ifname);
-        ebtablesRenameTmpRootChain(&buf, 0, ifname);
+        ebtablesRenameTmpSubAndRootChains(&buf, ifname);
 
         ebiptablesExecCLI(&buf, &cli_status);
     }
@@ -3633,12 +3675,11 @@ ebiptablesAllTeardown(const char *ifname)
         ebtablesUnlinkRootChain(&buf, 1, ifname);
         ebtablesUnlinkRootChain(&buf, 0, ifname);
 
+        ebtablesRemoveSubChains(&buf, ifname);
+
         ebtablesRemoveRootChain(&buf, 1, ifname);
         ebtablesRemoveRootChain(&buf, 0, ifname);
-
-        ebtablesRemoveSubChains(&buf, ifname);
     }
-
     ebiptablesExecCLI(&buf, &cli_status);
 
     return 0;