Add AH/ESP match for ipv6

1 files changed, 238 insertions, 0 deletions

diff --git a/extensions/libip6t_ah.c b/extensions/libip6t_ah.c
new file mode 100644
index 0000000..f169659
--- /dev/null
+++ b/extensions/libip6t_ah.c
@@ -0,0 +1,238 @@
+/* Shared library add-on to ip6tables to add AH support. */
+#include <stdio.h>
+#include <netdb.h>
+#include <string.h>
+#include <stdlib.h>
+#include <getopt.h>
+#include <errno.h>
+#include <ip6tables.h>
+#include <linux/netfilter_ipv6/ip6t_ah.h>
+                                        
+/* Function which prints out usage message. */
+static void
+help(void)
+{
+	printf(
+"AH v%s options:\n"
+" --ahspi [!] spi[:spi]         match spi (range)\n"
+" --ahlen [!] length            total length of this header\n"
+" --ahres                       check the reserved filed, too\n",
+NETFILTER_VERSION);
+}
+
+static struct option opts[] = {
+	{ "ahspi", 1, 0, '1' },
+	{ "ahlen", 1, 0, '2' },
+	{ "ahres", 0, 0, '3' },
+	{0}
+};
+
+static u_int32_t
+parse_ah_spi(const char *spistr, const char *typestr)
+{
+	unsigned long int spi;
+	char* ep;
+
+	spi =  strtoul(spistr,&ep,0) ;
+
+	if ( spistr == ep ) {
+		exit_error(PARAMETER_PROBLEM,
+			   "AH no valid digits in %s `%s'", typestr, spistr);
+	}
+	if ( spi == ULONG_MAX  && errno == ERANGE ) {
+		exit_error(PARAMETER_PROBLEM,
+			   "%s `%s' specified too big: would overflow",
+			   typestr, spistr);
+	}	
+	if ( *spistr != '\0'  && *ep != '\0' ) {
+		exit_error(PARAMETER_PROBLEM,
+			   "AH error parsing %s `%s'", typestr, spistr);
+	}
+	return (u_int32_t) spi;
+}
+
+static void
+parse_ah_spis(const char *spistring, u_int32_t *spis)
+{
+	char *buffer;
+	char *cp;
+
+	buffer = strdup(spistring);
+	if ((cp = strchr(buffer, ':')) == NULL)
+		spis[0] = spis[1] = parse_ah_spi(buffer,"spi");
+	else {
+		*cp = '\0';
+		cp++;
+
+		spis[0] = buffer[0] ? parse_ah_spi(buffer,"spi") : 0;
+		spis[1] = cp[0] ? parse_ah_spi(cp,"spi") : 0xFFFFFFFF;
+	}
+	free(buffer);
+}
+
+/* Initialize the match. */
+static void
+init(struct ip6t_entry_match *m, unsigned int *nfcache)
+{
+	struct ip6t_ah *ahinfo = (struct ip6t_ah *)m->data;
+
+	ahinfo->spis[1] = 0xFFFFFFFF;
+	ahinfo->hdrlen = 0;
+	ahinfo->hdrres = 0;
+}
+
+/* Function which parses command options; returns true if it
+   ate an option */
+static int
+parse(int c, char **argv, int invert, unsigned int *flags,
+      const struct ip6t_entry *entry,
+      unsigned int *nfcache,
+      struct ip6t_entry_match **match)
+{
+	struct ip6t_ah *ahinfo = (struct ip6t_ah *)(*match)->data;
+
+	switch (c) {
+	case '1':
+		if (*flags & IP6T_AH_SPI)
+			exit_error(PARAMETER_PROBLEM,
+				   "Only one `--ahspi' allowed");
+		check_inverse(optarg, &invert, &optind, 0);
+		parse_ah_spis(argv[optind-1], ahinfo->spis);
+		if (invert)
+			ahinfo->invflags |= IP6T_AH_INV_SPI;
+		*flags |= IP6T_AH_SPI;
+		break;
+	case '2':
+		if (*flags & IP6T_AH_LEN)
+			exit_error(PARAMETER_PROBLEM,
+				   "Only one `--ahlen' allowed");
+		check_inverse(optarg, &invert, &optind, 0);
+		ahinfo->hdrlen = parse_ah_spi(argv[optind-1], "length");
+		if (invert)
+			ahinfo->invflags |= IP6T_AH_INV_LEN;
+		*flags |= IP6T_AH_LEN;
+		break;
+	case '3':
+		if (*flags & IP6T_AH_RES)
+			exit_error(PARAMETER_PROBLEM,
+				   "Only one `--ahres' allowed");
+		ahinfo->hdrres = 1;
+		*flags |= IP6T_AH_RES;
+		break;
+	default:
+		return 0;
+	}
+
+	return 1;
+}
+
+/* Final check; we don't care. */
+static void
+final_check(unsigned int flags)
+{
+}
+
+static void
+print_spis(const char *name, u_int32_t min, u_int32_t max,
+	    int invert)
+{
+	const char *inv = invert ? "!" : "";
+
+	if (min != 0 || max != 0xFFFFFFFF || invert) {
+		printf("%s", name);
+		if (min == max) {
+			printf(":%s", inv);
+			printf("%u", min);
+		} else {
+			printf("s:%s", inv);
+			printf("%u",min);
+			printf(":");
+			printf("%u",max);
+		}
+		printf(" ");
+	}
+}
+
+static void
+print_len(const char *name, u_int32_t len, int invert)
+{
+	const char *inv = invert ? "!" : "";
+
+	if (len != 0 || invert) {
+		printf("%s", name);
+		printf(":%s", inv);
+		printf("%u", len);
+		printf(" ");
+	}
+}
+
+/* Prints out the union ip6t_matchinfo. */
+static void
+print(const struct ip6t_ip6 *ip,
+      const struct ip6t_entry_match *match, int numeric)
+{
+	const struct ip6t_ah *ah = (struct ip6t_ah *)match->data;
+
+	printf("ah ");
+	print_spis("spi", ah->spis[0], ah->spis[1],
+		    ah->invflags & IP6T_AH_INV_SPI);
+	print_len("length", ah->hdrlen, 
+		    ah->invflags & IP6T_AH_INV_LEN);
+	if (ah->hdrres) printf("reserved ");
+	if (ah->invflags & ~IP6T_AH_INV_MASK)
+		printf("Unknown invflags: 0x%X ",
+		       ah->invflags & ~IP6T_AH_INV_MASK);
+}
+
+/* Saves the union ip6t_matchinfo in parsable form to stdout. */
+static void save(const struct ip6t_ip6 *ip, const struct ip6t_entry_match *match)
+{
+	const struct ip6t_ah *ahinfo = (struct ip6t_ah *)match->data;
+
+	if (!(ahinfo->spis[0] == 0
+	    && ahinfo->spis[1] == 0xFFFFFFFF)) {
+		printf("--ahspi %s", 
+			(ahinfo->invflags & IP6T_AH_INV_SPI) ? "! " : "");
+		if (ahinfo->spis[0]
+		    != ahinfo->spis[1])
+			printf("%u:%u ",
+			       ahinfo->spis[0],
+			       ahinfo->spis[1]);
+		else
+			printf("%u ",
+			       ahinfo->spis[0]);
+	}
+
+	if (ahinfo->hdrlen != 0 ) {
+		printf("--ahlen %s%u ", 
+			(ahinfo->invflags & IP6T_AH_INV_LEN) ? "! " : "", 
+			ahinfo->hdrlen);
+	}
+
+	if (ahinfo->hdrres != 0 ) {
+		printf("--ahres ");
+	}
+
+}
+
+static
+struct ip6tables_match ah
+= { NULL,
+    "ah",
+    NETFILTER_VERSION,
+    IP6T_ALIGN(sizeof(struct ip6t_ah)),
+    IP6T_ALIGN(sizeof(struct ip6t_ah)),
+    &help,
+    &init,
+    &parse,
+    &final_check,
+    &print,
+    &save,
+    opts
+};
+
+void
+_init(void)
+{
+	register_match6(&ah);
+}