ip(6)tables-multi: unify subcommand handling

I found the subcommand handling and naming done by iptables-multi and
ip6tables-multi very confusing and complicated; this patch
reorganizes the subcommands in a single table, allowing both variants
of them to be used (iptables/main) and also prints a list of the
allowed commands if an unknown command is entered by the user.

Signed-off-by: Jan Engelhardt <jengelh@medozas.de>

diff --git a/ip6tables-multi.c b/ip6tables-multi.c
index 671558c507bed76042c277725290682e25b46827..7e6603f83ac0449e7f62c5bd88ed0345ec3ba297 100644 (file)
--- a/ip6tables-multi.c
+++ b/ip6tables-multi.c
@@ -1,45 +1,23 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
-#include <libgen.h>
+#include "xshared.h"
 
 int ip6tables_main(int argc, char **argv);
 int ip6tables_save_main(int argc, char **argv);
 int ip6tables_restore_main(int argc, char **argv);
 
+static const struct subcommand multi6_subcommands[] = {
+       {"ip6tables",         ip6tables_main},
+       {"main",              ip6tables_main},
+       {"ip6tables-save",    ip6tables_save_main},
+       {"save",              ip6tables_save_main},
+       {"ip6tables-restore", ip6tables_restore_main},
+       {"restore",           ip6tables_restore_main},
+       {NULL},
+};
+
 int main(int argc, char **argv)
 {
-       char *progname;
-
-       if (argc < 1) {
-               fprintf(stderr, "ERROR: This should not happen.\n");
-               exit(EXIT_FAILURE);
-       }
-
-       progname = basename(argv[0]);
-       if (strcmp(progname, "ip6tables") == 0)
-               return ip6tables_main(argc, argv);
-       if (strcmp(progname, "ip6tables-save") == 0)
-               return ip6tables_save_main(argc, argv);
-       if (strcmp(progname, "ip6tables-restore") == 0)
-               return ip6tables_restore_main(argc, argv);
-
-       ++argv;
-       --argc;
-       if (argc < 1) {
-               fprintf(stderr, "ERROR: No subcommand given.\n");
-               exit(EXIT_FAILURE);
-       }
-
-       progname = basename(argv[0]);
-       if (strcmp(progname, "main") == 0)
-               return ip6tables_main(argc, argv);
-       if (strcmp(progname, "save") == 0)
-               return ip6tables_save_main(argc, argv);
-       if (strcmp(progname, "restore") == 0)
-               return ip6tables_restore_main(argc, argv);
-
-       fprintf(stderr, "ip6tables multi-purpose version: "
-               "unknown subcommand \"%s\"\n", progname);
-       exit(EXIT_FAILURE);
+       return subcmd_main(argc, argv, multi6_subcommands);
 }

diff --git a/iptables-multi.c b/iptables-multi.c
index 4dcc26de3ab33fe72ade5daee31e5e6d27bbc2db..754b5873fa53fd593ceb0b9f425316007a2ffb92 100644 (file)
--- a/iptables-multi.c
+++ b/iptables-multi.c
@@ -1,50 +1,26 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
-#include <libgen.h>
+#include "xshared.h"
 
 int iptables_main(int argc, char **argv);
 int iptables_save_main(int argc, char **argv);
 int iptables_restore_main(int argc, char **argv);
 int iptables_xml_main(int argc, char **argv);
 
+static const struct subcommand multi4_subcommands[] = {
+       {"iptables",         iptables_main},
+       {"main",             iptables_main},
+       {"iptables-save",    iptables_save_main},
+       {"save",             iptables_save_main},
+       {"iptables-restore", iptables_restore_main},
+       {"restore",          iptables_restore_main},
+       {"iptables-xml",     iptables_xml_main},
+       {"xml",              iptables_xml_main},
+       {NULL},
+};
+
 int main(int argc, char **argv)
 {
-       char *progname;
-
-       if (argc < 1) {
-               fprintf(stderr, "ERROR: This should not happen.\n");
-               exit(EXIT_FAILURE);
-       }
-
-       progname = basename(argv[0]);
-       if (strcmp(progname, "iptables") == 0)
-               return iptables_main(argc, argv);
-       if (strcmp(progname, "iptables-save") == 0)
-               return iptables_save_main(argc, argv);
-       if (strcmp(progname, "iptables-restore") == 0)
-               return iptables_restore_main(argc, argv);
-       if (strcmp(progname, "iptables-xml") == 0)
-               return iptables_xml_main(argc, argv);
-
-       ++argv;
-       --argc;
-       if (argc < 1) {
-               fprintf(stderr, "ERROR: No subcommand given.\n");
-               exit(EXIT_FAILURE);
-       }
-
-       progname = basename(argv[0]);
-       if (strcmp(progname, "main") == 0)
-               return iptables_main(argc, argv);
-       if (strcmp(progname, "save") == 0)
-               return iptables_save_main(argc, argv);
-       if (strcmp(progname, "restore") == 0)
-               return iptables_restore_main(argc, argv);
-       if (strcmp(progname, "xml") == 0)
-               return iptables_xml_main(argc, argv);
-
-       fprintf(stderr, "iptables multi-purpose version: "
-               "unknown subcommand \"%s\"\n", progname);
-       exit(EXIT_FAILURE);
+       return subcmd_main(argc, argv, multi4_subcommands);
 }

diff --git a/xshared.c b/xshared.c
index c5a9015de8527648c43c695a1cd6479d6346209f..404a9f5fdf249b9431bc5ea3a222ae080bedad0b 100644 (file)
--- a/xshared.c
+++ b/xshared.c
@@ -1,7 +1,10 @@
+#include <libgen.h>
 #include <netdb.h>
 #include <stdbool.h>
 #include <stdint.h>
 #include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
 #include <xtables.h>
 #include "xshared.h"
 
@@ -99,3 +102,36 @@ struct xtables_match *load_proto(struct iptables_command_state *cs)
        return find_proto(cs->protocol, XTF_TRY_LOAD,
                          cs->options & OPT_NUMERIC, &cs->matches);
 }
+
+static mainfunc_t subcmd_get(const char *cmd, const struct subcommand *cb)
+{
+       for (; cb->name != NULL; ++cb)
+               if (strcmp(cb->name, cmd) == 0)
+                       return cb->main;
+       return NULL;
+}
+
+int subcmd_main(int argc, char **argv, const struct subcommand *cb)
+{
+       const char *cmd = basename(*argv);
+       mainfunc_t f = subcmd_get(cmd, cb);
+
+       if (f == NULL && argc > 1) {
+               /*
+                * Unable to find a main method for our command name?
+                * Let's try again with the first argument!
+                */
+               ++argv;
+               --argc;
+               f = subcmd_get(*argv, cb);
+       }
+
+       /* now we should have a valid function pointer */
+       if (f != NULL)
+               return f(argc, argv);
+
+       fprintf(stderr, "ERROR: No valid subcommand given.\nValid subcommands:\n");
+       for (; cb->name != NULL; ++cb)
+               fprintf(stderr, " * %s\n", cb->name);
+       exit(EXIT_FAILURE);
+}

diff --git a/xshared.h b/xshared.h
index a08e6d98e4362a11c3c87de2cf254959f4837353..94abb3922e3404c2420624ce29f35026797c52d3 100644 (file)
--- a/xshared.h
+++ b/xshared.h
@@ -1,7 +1,10 @@
 #ifndef IPTABLES_XSHARED_H
 #define IPTABLES_XSHARED_H 1
 
+#include <limits.h>
 #include <stdint.h>
+#include <netinet/in.h>
+#include <net/if.h>
 #include <linux/netfilter_ipv4/ip_tables.h>
 #include <linux/netfilter_ipv6/ip6_tables.h>
 
@@ -39,6 +42,13 @@ struct iptables_command_state {
        char **argv;
 };
 
+typedef int (*mainfunc_t)(int, char **);
+
+struct subcommand {
+       const char *name;
+       mainfunc_t main;
+};
+
 enum {
        XT_OPTION_OFFSET_SCALE = 256,
 };
@@ -47,5 +57,6 @@ extern void print_extension_helps(const struct xtables_target *,
        const struct xtables_rule_match *);
 extern const char *proto_to_name(uint8_t, int);
 extern struct xtables_match *load_proto(struct iptables_command_state *);
+extern int subcmd_main(int, char **, const struct subcommand *);
 
 #endif /* IPTABLES_XSHARED_H */