Merge commit 'origin/trunk@12184' into fedora

[iptables.git] / trunk / extensions / libxt_length.c

diff --git a/trunk/extensions/libxt_length.c b/trunk/extensions/libxt_length.c
new file mode 100644 (file)
index 0000000..ec305ae
--- /dev/null
+++ b/trunk/extensions/libxt_length.c
@@ -0,0 +1,142 @@
+/* Shared library add-on to iptables to add packet length matching support. */
+#include <stdio.h>
+#include <netdb.h>
+#include <string.h>
+#include <stdlib.h>
+#include <getopt.h>
+
+#include <xtables.h>
+#include <linux/netfilter/xt_length.h>
+
+/* Function which prints out usage message. */
+static void length_help(void)
+{
+       printf(
+"length match options:\n"
+"[!] --length length[:length]    Match packet length against value or range\n"
+"                                of values (inclusive)\n");
+}
+  
+static const struct option length_opts[] = {
+       { "length", 1, NULL, '1' },
+       { .name = NULL }
+};
+
+static u_int16_t
+parse_length(const char *s)
+{
+       unsigned int len;
+       
+       if (string_to_number(s, 0, 0xFFFF, &len) == -1)
+               exit_error(PARAMETER_PROBLEM, "length invalid: `%s'\n", s);
+       else
+               return (u_int16_t )len;
+}
+
+/* If a single value is provided, min and max are both set to the value */
+static void
+parse_lengths(const char *s, struct xt_length_info *info)
+{
+       char *buffer;
+       char *cp;
+
+       buffer = strdup(s);
+       if ((cp = strchr(buffer, ':')) == NULL)
+               info->min = info->max = parse_length(buffer);
+       else {
+               *cp = '\0';
+               cp++;
+
+               info->min = buffer[0] ? parse_length(buffer) : 0;
+               info->max = cp[0] ? parse_length(cp) : 0xFFFF;
+       }
+       free(buffer);
+       
+       if (info->min > info->max)
+               exit_error(PARAMETER_PROBLEM,
+                          "length min. range value `%u' greater than max. "
+                          "range value `%u'", info->min, info->max);
+       
+}
+
+/* Function which parses command options; returns true if it
+   ate an option */
+static int
+length_parse(int c, char **argv, int invert, unsigned int *flags,
+             const void *entry, struct xt_entry_match **match)
+{
+       struct xt_length_info *info = (struct xt_length_info *)(*match)->data;
+
+       switch (c) {
+               case '1':
+                       if (*flags)
+                               exit_error(PARAMETER_PROBLEM,
+                                          "length: `--length' may only be "
+                                          "specified once");
+                       check_inverse(optarg, &invert, &optind, 0);
+                       parse_lengths(argv[optind-1], info);
+                       if (invert)
+                               info->invert = 1;
+                       *flags = 1;
+                       break;
+                       
+               default:
+                       return 0;
+       }
+       return 1;
+}
+
+/* Final check; must have specified --length. */
+static void length_check(unsigned int flags)
+{
+       if (!flags)
+               exit_error(PARAMETER_PROBLEM,
+                          "length: You must specify `--length'");
+}
+
+/* Common match printing code. */
+static void
+print_length(struct xt_length_info *info)
+{
+       if (info->invert)
+               printf("! ");
+       
+       if (info->max == info->min)
+               printf("%u ", info->min);
+       else
+               printf("%u:%u ", info->min, info->max);
+}
+
+/* Prints out the matchinfo. */
+static void
+length_print(const void *ip, const struct xt_entry_match *match, int numeric)
+{
+       printf("length ");
+       print_length((struct xt_length_info *)match->data);
+}
+
+/* Saves the union ipt_matchinfo in parsable form to stdout. */
+static void length_save(const void *ip, const struct xt_entry_match *match)
+{
+       printf("--length ");
+       print_length((struct xt_length_info *)match->data);
+}
+
+static struct xtables_match length_match = {
+       .family         = AF_UNSPEC,
+       .name           = "length",
+       .version        = XTABLES_VERSION,
+       .size           = XT_ALIGN(sizeof(struct xt_length_info)),
+       .userspacesize  = XT_ALIGN(sizeof(struct xt_length_info)),
+       .help           = length_help,
+       .parse          = length_parse,
+       .final_check    = length_check,
+       .print          = length_print,
+       .save           = length_save,
+       .extra_opts     = length_opts,
+};
+
+void _init(void)
+{
+       xtables_register_match(&length_match);
+}