--- /dev/null
+/* Shared library add-on to iptables to add TCP support. */
+#include <stdio.h>
+#include <netdb.h>
+#include <string.h>
+#include <stdlib.h>
+#include <getopt.h>
+#include <xtables.h>
+#include <linux/netfilter/xt_tcpudp.h>
+
+/* Function which prints out usage message. */
+static void tcp_help(void)
+{
+ printf(
+"tcp match options:\n"
+" --tcp-flags [!] mask comp match when TCP flags & mask == comp\n"
+" (Flags: SYN ACK FIN RST URG PSH ALL NONE)\n"
+"[!] --syn match when only SYN flag set\n"
+" (equivalent to --tcp-flags SYN,RST,ACK,FIN SYN)\n"
+" --source-port [!] port[:port]\n"
+" --sport ...\n"
+" match source port(s)\n"
+" --destination-port [!] port[:port]\n"
+" --dport ...\n"
+" match destination port(s)\n"
+" --tcp-option [!] number match if TCP option set\n");
+}
+
+static const struct option tcp_opts[] = {
+ { "source-port", 1, NULL, '1' },
+ { "sport", 1, NULL, '1' }, /* synonym */
+ { "destination-port", 1, NULL, '2' },
+ { "dport", 1, NULL, '2' }, /* synonym */
+ { "syn", 0, NULL, '3' },
+ { "tcp-flags", 1, NULL, '4' },
+ { "tcp-option", 1, NULL, '5' },
+ { .name = NULL }
+};
+
+static void
+parse_tcp_ports(const char *portstring, u_int16_t *ports)
+{
+ char *buffer;
+ char *cp;
+
+ buffer = strdup(portstring);
+ if ((cp = strchr(buffer, ':')) == NULL)
+ ports[0] = ports[1] = parse_port(buffer, "tcp");
+ else {
+ *cp = '\0';
+ cp++;
+
+ ports[0] = buffer[0] ? parse_port(buffer, "tcp") : 0;
+ ports[1] = cp[0] ? parse_port(cp, "tcp") : 0xFFFF;
+
+ if (ports[0] > ports[1])
+ exit_error(PARAMETER_PROBLEM,
+ "invalid portrange (min > max)");
+ }
+ free(buffer);
+}
+
+struct tcp_flag_names {
+ const char *name;
+ unsigned int flag;
+};
+
+static const struct tcp_flag_names tcp_flag_names[]
+= { { "FIN", 0x01 },
+ { "SYN", 0x02 },
+ { "RST", 0x04 },
+ { "PSH", 0x08 },
+ { "ACK", 0x10 },
+ { "URG", 0x20 },
+ { "ALL", 0x3F },
+ { "NONE", 0 },
+};
+
+static unsigned int
+parse_tcp_flag(const char *flags)
+{
+ unsigned int ret = 0;
+ char *ptr;
+ char *buffer;
+
+ buffer = strdup(flags);
+
+ for (ptr = strtok(buffer, ","); ptr; ptr = strtok(NULL, ",")) {
+ unsigned int i;
+ for (i = 0;
+ i < sizeof(tcp_flag_names)/sizeof(struct tcp_flag_names);
+ i++) {
+ if (strcasecmp(tcp_flag_names[i].name, ptr) == 0) {
+ ret |= tcp_flag_names[i].flag;
+ break;
+ }
+ }
+ if (i == sizeof(tcp_flag_names)/sizeof(struct tcp_flag_names))
+ exit_error(PARAMETER_PROBLEM,
+ "Unknown TCP flag `%s'", ptr);
+ }
+
+ free(buffer);
+ return ret;
+}
+
+static void
+parse_tcp_flags(struct xt_tcp *tcpinfo,
+ const char *mask,
+ const char *cmp,
+ int invert)
+{
+ tcpinfo->flg_mask = parse_tcp_flag(mask);
+ tcpinfo->flg_cmp = parse_tcp_flag(cmp);
+
+ if (invert)
+ tcpinfo->invflags |= XT_TCP_INV_FLAGS;
+}
+
+static void
+parse_tcp_option(const char *option, u_int8_t *result)
+{
+ unsigned int ret;
+
+ if (string_to_number(option, 1, 255, &ret) == -1)
+ exit_error(PARAMETER_PROBLEM, "Bad TCP option `%s'", option);
+
+ *result = (u_int8_t)ret;
+}
+
+/* Initialize the match. */
+static void tcp_init(struct xt_entry_match *m)
+{
+ struct xt_tcp *tcpinfo = (struct xt_tcp *)m->data;
+
+ tcpinfo->spts[1] = tcpinfo->dpts[1] = 0xFFFF;
+}
+
+#define TCP_SRC_PORTS 0x01
+#define TCP_DST_PORTS 0x02
+#define TCP_FLAGS 0x04
+#define TCP_OPTION 0x08
+
+/* Function which parses command options; returns true if it
+ ate an option. */
+static int
+tcp_parse(int c, char **argv, int invert, unsigned int *flags,
+ const void *entry, struct xt_entry_match **match)
+{
+ struct xt_tcp *tcpinfo = (struct xt_tcp *)(*match)->data;
+
+ switch (c) {
+ case '1':
+ if (*flags & TCP_SRC_PORTS)
+ exit_error(PARAMETER_PROBLEM,
+ "Only one `--source-port' allowed");
+ check_inverse(optarg, &invert, &optind, 0);
+ parse_tcp_ports(argv[optind-1], tcpinfo->spts);
+ if (invert)
+ tcpinfo->invflags |= XT_TCP_INV_SRCPT;
+ *flags |= TCP_SRC_PORTS;
+ break;
+
+ case '2':
+ if (*flags & TCP_DST_PORTS)
+ exit_error(PARAMETER_PROBLEM,
+ "Only one `--destination-port' allowed");
+ check_inverse(optarg, &invert, &optind, 0);
+ parse_tcp_ports(argv[optind-1], tcpinfo->dpts);
+ if (invert)
+ tcpinfo->invflags |= XT_TCP_INV_DSTPT;
+ *flags |= TCP_DST_PORTS;
+ break;
+
+ case '3':
+ if (*flags & TCP_FLAGS)
+ exit_error(PARAMETER_PROBLEM,
+ "Only one of `--syn' or `--tcp-flags' "
+ " allowed");
+ parse_tcp_flags(tcpinfo, "SYN,RST,ACK,FIN", "SYN", invert);
+ *flags |= TCP_FLAGS;
+ break;
+
+ case '4':
+ if (*flags & TCP_FLAGS)
+ exit_error(PARAMETER_PROBLEM,
+ "Only one of `--syn' or `--tcp-flags' "
+ " allowed");
+ check_inverse(optarg, &invert, &optind, 0);
+
+ if (!argv[optind]
+ || argv[optind][0] == '-' || argv[optind][0] == '!')
+ exit_error(PARAMETER_PROBLEM,
+ "--tcp-flags requires two args.");
+
+ parse_tcp_flags(tcpinfo, argv[optind-1], argv[optind],
+ invert);
+ optind++;
+ *flags |= TCP_FLAGS;
+ break;
+
+ case '5':
+ if (*flags & TCP_OPTION)
+ exit_error(PARAMETER_PROBLEM,
+ "Only one `--tcp-option' allowed");
+ check_inverse(optarg, &invert, &optind, 0);
+ parse_tcp_option(argv[optind-1], &tcpinfo->option);
+ if (invert)
+ tcpinfo->invflags |= XT_TCP_INV_OPTION;
+ *flags |= TCP_OPTION;
+ break;
+
+ default:
+ return 0;
+ }
+
+ return 1;
+}
+
+static char *
+port_to_service(int port)
+{
+ struct servent *service;
+
+ if ((service = getservbyport(htons(port), "tcp")))
+ return service->s_name;
+
+ return NULL;
+}
+
+static void
+print_port(u_int16_t port, int numeric)
+{
+ char *service;
+
+ if (numeric || (service = port_to_service(port)) == NULL)
+ printf("%u", port);
+ else
+ printf("%s", service);
+}
+
+static void
+print_ports(const char *name, u_int16_t min, u_int16_t max,
+ int invert, int numeric)
+{
+ const char *inv = invert ? "!" : "";
+
+ if (min != 0 || max != 0xFFFF || invert) {
+ printf("%s", name);
+ if (min == max) {
+ printf(":%s", inv);
+ print_port(min, numeric);
+ } else {
+ printf("s:%s", inv);
+ print_port(min, numeric);
+ printf(":");
+ print_port(max, numeric);
+ }
+ printf(" ");
+ }
+}
+
+static void
+print_option(u_int8_t option, int invert, int numeric)
+{
+ if (option || invert)
+ printf("option=%s%u ", invert ? "!" : "", option);
+}
+
+static void
+print_tcpf(u_int8_t flags)
+{
+ int have_flag = 0;
+
+ while (flags) {
+ unsigned int i;
+
+ for (i = 0; (flags & tcp_flag_names[i].flag) == 0; i++);
+
+ if (have_flag)
+ printf(",");
+ printf("%s", tcp_flag_names[i].name);
+ have_flag = 1;
+
+ flags &= ~tcp_flag_names[i].flag;
+ }
+
+ if (!have_flag)
+ printf("NONE");
+}
+
+static void
+print_flags(u_int8_t mask, u_int8_t cmp, int invert, int numeric)
+{
+ if (mask || invert) {
+ printf("flags:%s", invert ? "!" : "");
+ if (numeric)
+ printf("0x%02X/0x%02X ", mask, cmp);
+ else {
+ print_tcpf(mask);
+ printf("/");
+ print_tcpf(cmp);
+ printf(" ");
+ }
+ }
+}
+
+/* Prints out the union ipt_matchinfo. */
+static void
+tcp_print(const void *ip, const struct xt_entry_match *match, int numeric)
+{
+ const struct xt_tcp *tcp = (struct xt_tcp *)match->data;
+
+ printf("tcp ");
+ print_ports("spt", tcp->spts[0], tcp->spts[1],
+ tcp->invflags & XT_TCP_INV_SRCPT,
+ numeric);
+ print_ports("dpt", tcp->dpts[0], tcp->dpts[1],
+ tcp->invflags & XT_TCP_INV_DSTPT,
+ numeric);
+ print_option(tcp->option,
+ tcp->invflags & XT_TCP_INV_OPTION,
+ numeric);
+ print_flags(tcp->flg_mask, tcp->flg_cmp,
+ tcp->invflags & XT_TCP_INV_FLAGS,
+ numeric);
+ if (tcp->invflags & ~XT_TCP_INV_MASK)
+ printf("Unknown invflags: 0x%X ",
+ tcp->invflags & ~XT_TCP_INV_MASK);
+}
+
+/* Saves the union ipt_matchinfo in parsable form to stdout. */
+static void tcp_save(const void *ip, const struct xt_entry_match *match)
+{
+ const struct xt_tcp *tcpinfo = (struct xt_tcp *)match->data;
+
+ if (tcpinfo->spts[0] != 0
+ || tcpinfo->spts[1] != 0xFFFF) {
+ if (tcpinfo->invflags & XT_TCP_INV_SRCPT)
+ printf("! ");
+ if (tcpinfo->spts[0]
+ != tcpinfo->spts[1])
+ printf("--sport %u:%u ",
+ tcpinfo->spts[0],
+ tcpinfo->spts[1]);
+ else
+ printf("--sport %u ",
+ tcpinfo->spts[0]);
+ }
+
+ if (tcpinfo->dpts[0] != 0
+ || tcpinfo->dpts[1] != 0xFFFF) {
+ if (tcpinfo->invflags & XT_TCP_INV_DSTPT)
+ printf("! ");
+ if (tcpinfo->dpts[0]
+ != tcpinfo->dpts[1])
+ printf("--dport %u:%u ",
+ tcpinfo->dpts[0],
+ tcpinfo->dpts[1]);
+ else
+ printf("--dport %u ",
+ tcpinfo->dpts[0]);
+ }
+
+ if (tcpinfo->option
+ || (tcpinfo->invflags & XT_TCP_INV_OPTION)) {
+ if (tcpinfo->invflags & XT_TCP_INV_OPTION)
+ printf("! ");
+ printf("--tcp-option %u ", tcpinfo->option);
+ }
+
+ if (tcpinfo->flg_mask
+ || (tcpinfo->invflags & XT_TCP_INV_FLAGS)) {
+ if (tcpinfo->invflags & XT_TCP_INV_FLAGS)
+ printf("! ");
+ printf("--tcp-flags ");
+ if (tcpinfo->flg_mask != 0xFF) {
+ print_tcpf(tcpinfo->flg_mask);
+ }
+ printf(" ");
+ print_tcpf(tcpinfo->flg_cmp);
+ printf(" ");
+ }
+}
+
+static struct xtables_match tcp_match = {
+ .family = AF_INET,
+ .name = "tcp",
+ .version = XTABLES_VERSION,
+ .size = XT_ALIGN(sizeof(struct xt_tcp)),
+ .userspacesize = XT_ALIGN(sizeof(struct xt_tcp)),
+ .help = tcp_help,
+ .init = tcp_init,
+ .parse = tcp_parse,
+ .print = tcp_print,
+ .save = tcp_save,
+ .extra_opts = tcp_opts,
+};
+
+static struct xtables_match tcp_match6 = {
+ .family = AF_INET6,
+ .name = "tcp",
+ .version = XTABLES_VERSION,
+ .size = XT_ALIGN(sizeof(struct xt_tcp)),
+ .userspacesize = XT_ALIGN(sizeof(struct xt_tcp)),
+ .help = tcp_help,
+ .init = tcp_init,
+ .parse = tcp_parse,
+ .print = tcp_print,
+ .save = tcp_save,
+ .extra_opts = tcp_opts,
+};
+
+void
+_init(void)
+{
+ xtables_register_match(&tcp_match);
+ xtables_register_match(&tcp_match6);
+}
git://git.onelab.eu / iptables.git / blobdiff