Merge commit 'origin/trunk@12184' into fedora

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

diff --git a/trunk/extensions/libxt_tcpmss.c b/trunk/extensions/libxt_tcpmss.c
new file mode 100644 (file)
index 0000000..8f56a41
--- /dev/null
+++ b/trunk/extensions/libxt_tcpmss.c
@@ -0,0 +1,159 @@
+/* Shared library add-on to iptables to add tcp MSS matching support. */
+#include <stdio.h>
+#include <netdb.h>
+#include <string.h>
+#include <stdlib.h>
+#include <getopt.h>
+
+#include <xtables.h>
+#include <linux/netfilter/xt_tcpmss.h>
+
+/* Function which prints out usage message. */
+static void tcpmss_help(void)
+{
+       printf(
+"tcpmss match options:\n"
+"[!] --mss value[:value]       Match TCP MSS range.\n"
+"                              (only valid for TCP SYN or SYN/ACK packets)\n");
+}
+
+static const struct option tcpmss_opts[] = {
+       { "mss", 1, NULL, '1' },
+       { .name = NULL }
+};
+
+static u_int16_t
+parse_tcp_mssvalue(const char *mssvalue)
+{
+       unsigned int mssvaluenum;
+
+       if (string_to_number(mssvalue, 0, 65535, &mssvaluenum) != -1)
+               return (u_int16_t)mssvaluenum;
+
+       exit_error(PARAMETER_PROBLEM,
+                  "Invalid mss `%s' specified", mssvalue);
+}
+
+static void
+parse_tcp_mssvalues(const char *mssvaluestring,
+                   u_int16_t *mss_min, u_int16_t *mss_max)
+{
+       char *buffer;
+       char *cp;
+
+       buffer = strdup(mssvaluestring);
+       if ((cp = strchr(buffer, ':')) == NULL)
+               *mss_min = *mss_max = parse_tcp_mssvalue(buffer);
+       else {
+               *cp = '\0';
+               cp++;
+
+               *mss_min = buffer[0] ? parse_tcp_mssvalue(buffer) : 0;
+               *mss_max = cp[0] ? parse_tcp_mssvalue(cp) : 0xFFFF;
+       }
+       free(buffer);
+}
+
+/* Function which parses command options; returns true if it
+   ate an option */
+static int
+tcpmss_parse(int c, char **argv, int invert, unsigned int *flags,
+             const void *entry, struct xt_entry_match **match)
+{
+       struct xt_tcpmss_match_info *mssinfo =
+               (struct xt_tcpmss_match_info *)(*match)->data;
+
+       switch (c) {
+       case '1':
+               if (*flags)
+                       exit_error(PARAMETER_PROBLEM,
+                                  "Only one `--mss' allowed");
+               check_inverse(optarg, &invert, &optind, 0);
+               parse_tcp_mssvalues(argv[optind-1],
+                                   &mssinfo->mss_min, &mssinfo->mss_max);
+               if (invert)
+                       mssinfo->invert = 1;
+               *flags = 1;
+               break;
+       default:
+               return 0;
+       }
+       return 1;
+}
+
+static void
+print_tcpmss(u_int16_t mss_min, u_int16_t mss_max, int invert, int numeric)
+{
+       if (invert)
+               printf("! ");
+
+       if (mss_min == mss_max)
+               printf("%u ", mss_min);
+       else
+               printf("%u:%u ", mss_min, mss_max);
+}
+
+/* Final check; must have specified --mss. */
+static void tcpmss_check(unsigned int flags)
+{
+       if (!flags)
+               exit_error(PARAMETER_PROBLEM,
+                          "tcpmss match: You must specify `--mss'");
+}
+
+/* Prints out the matchinfo. */
+static void
+tcpmss_print(const void *ip, const struct xt_entry_match *match, int numeric)
+{
+       const struct xt_tcpmss_match_info *mssinfo =
+               (const struct xt_tcpmss_match_info *)match->data;
+
+       printf("tcpmss match ");
+       print_tcpmss(mssinfo->mss_min, mssinfo->mss_max,
+                    mssinfo->invert, numeric);
+}
+
+/* Saves the union ipt_matchinfo in parsable form to stdout. */
+static void tcpmss_save(const void *ip, const struct xt_entry_match *match)
+{
+       const struct xt_tcpmss_match_info *mssinfo =
+               (const struct xt_tcpmss_match_info *)match->data;
+
+       printf("--mss ");
+       print_tcpmss(mssinfo->mss_min, mssinfo->mss_max,
+                    mssinfo->invert, 0);
+}
+
+static struct xtables_match tcpmss_match = {
+       .family         = AF_INET,
+       .name           = "tcpmss",
+       .version        = XTABLES_VERSION,
+       .size           = XT_ALIGN(sizeof(struct xt_tcpmss_match_info)),
+       .userspacesize  = XT_ALIGN(sizeof(struct xt_tcpmss_match_info)),
+       .help           = tcpmss_help,
+       .parse          = tcpmss_parse,
+       .final_check    = tcpmss_check,
+       .print          = tcpmss_print,
+       .save           = tcpmss_save,
+       .extra_opts     = tcpmss_opts,
+};
+
+static struct xtables_match tcpmss_match6 = {
+       .family         = AF_INET6,
+       .name           = "tcpmss",
+       .version        = XTABLES_VERSION,
+       .size           = XT_ALIGN(sizeof(struct xt_tcpmss_match_info)),
+       .userspacesize  = XT_ALIGN(sizeof(struct xt_tcpmss_match_info)),
+       .help           = tcpmss_help,
+       .parse          = tcpmss_parse,
+       .final_check    = tcpmss_check,
+       .print          = tcpmss_print,
+       .save           = tcpmss_save,
+       .extra_opts     = tcpmss_opts,
+};
+
+void _init(void)
+{
+       xtables_register_match(&tcpmss_match);
+       xtables_register_match(&tcpmss_match6);
+}