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-rw-r--r--extensions/libct_proto_tcp.c180
1 files changed, 180 insertions, 0 deletions
diff --git a/extensions/libct_proto_tcp.c b/extensions/libct_proto_tcp.c
new file mode 100644
index 0000000..ee24206
--- /dev/null
+++ b/extensions/libct_proto_tcp.c
@@ -0,0 +1,180 @@
+/*
+ * (C) 2005 by Pablo Neira Ayuso <pablo@eurodev.net>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ */
+#include <stdio.h>
+#include <getopt.h>
+#include <stdlib.h>
+#include <string.h>
+#include <netinet/in.h> /* For htons */
+#include <libnetfilter_conntrack/libnetfilter_conntrack.h>
+#include <libnetfilter_conntrack/libnetfilter_conntrack_tcp.h>
+
+#include "conntrack.h"
+
+static struct option opts[] = {
+ {"orig-port-src", 1, 0, '1'},
+ {"orig-port-dst", 1, 0, '2'},
+ {"reply-port-src", 1, 0, '3'},
+ {"reply-port-dst", 1, 0, '4'},
+ {"mask-port-src", 1, 0, '5'},
+ {"mask-port-dst", 1, 0, '6'},
+ {"state", 1, 0, '7'},
+ {"tuple-port-src", 1, 0, '8'},
+ {"tuple-port-dst", 1, 0, '9'},
+ {0, 0, 0, 0}
+};
+
+static const char *states[] = {
+ "NONE",
+ "SYN_SENT",
+ "SYN_RECV",
+ "ESTABLISHED",
+ "FIN_WAIT",
+ "CLOSE_WAIT",
+ "LAST_ACK",
+ "TIME_WAIT",
+ "CLOSE",
+ "LISTEN"
+};
+
+static void help()
+{
+ fprintf(stdout, "--orig-port-src original source port\n");
+ fprintf(stdout, "--orig-port-dst original destination port\n");
+ fprintf(stdout, "--reply-port-src reply source port\n");
+ fprintf(stdout, "--reply-port-dst reply destination port\n");
+ fprintf(stdout, "--mask-port-src mask source port\n");
+ fprintf(stdout, "--mask-port-dst mask destination port\n");
+ fprintf(stdout, "--tuple-port-src expectation tuple src port\n");
+ fprintf(stdout, "--tuple-port-src expectation tuple dst port\n");
+ fprintf(stdout, "--state TCP state, fe. ESTABLISHED\n");
+}
+
+static int parse_options(char c, char *argv[],
+ struct nfct_tuple *orig,
+ struct nfct_tuple *reply,
+ struct nfct_tuple *exptuple,
+ struct nfct_tuple *mask,
+ union nfct_protoinfo *proto,
+ unsigned int *flags)
+{
+ switch(c) {
+ case '1':
+ if (optarg) {
+ orig->l4src.tcp.port = htons(atoi(optarg));
+ *flags |= TCP_ORIG_SPORT;
+ }
+ break;
+ case '2':
+ if (optarg) {
+ orig->l4dst.tcp.port = htons(atoi(optarg));
+ *flags |= TCP_ORIG_DPORT;
+ }
+ break;
+ case '3':
+ if (optarg) {
+ reply->l4src.tcp.port = htons(atoi(optarg));
+ *flags |= TCP_REPL_SPORT;
+ }
+ break;
+ case '4':
+ if (optarg) {
+ reply->l4dst.tcp.port = htons(atoi(optarg));
+ *flags |= TCP_REPL_DPORT;
+ }
+ break;
+ case '5':
+ if (optarg) {
+ mask->l4src.tcp.port = htons(atoi(optarg));
+ *flags |= TCP_MASK_SPORT;
+ }
+ break;
+ case '6':
+ if (optarg) {
+ mask->l4dst.tcp.port = htons(atoi(optarg));
+ *flags |= TCP_MASK_DPORT;
+ }
+ break;
+ case '7':
+ if (optarg) {
+ int i;
+ for (i=0; i<10; i++) {
+ if (strcmp(optarg, states[i]) == 0) {
+ proto->tcp.state = i;
+ break;
+ }
+ }
+ if (i == 10) {
+ printf("doh?\n");
+ return 0;
+ }
+ *flags |= TCP_STATE;
+ }
+ break;
+ case '8':
+ if (optarg) {
+ exptuple->l4src.tcp.port = htons(atoi(optarg));
+ *flags |= TCP_EXPTUPLE_SPORT;
+ }
+ break;
+ case '9':
+ if (optarg) {
+ exptuple->l4dst.tcp.port = htons(atoi(optarg));
+ *flags |= TCP_EXPTUPLE_DPORT;
+ }
+ break;
+ }
+ return 1;
+}
+
+static int final_check(unsigned int flags,
+ unsigned int command,
+ struct nfct_tuple *orig,
+ struct nfct_tuple *reply)
+{
+ int ret = 0;
+
+ if ((flags & (TCP_ORIG_SPORT|TCP_ORIG_DPORT))
+ && !(flags & (TCP_REPL_SPORT|TCP_REPL_DPORT))) {
+ reply->l4src.tcp.port = orig->l4dst.tcp.port;
+ reply->l4dst.tcp.port = orig->l4src.tcp.port;
+ ret = 1;
+ } else if (!(flags & (TCP_ORIG_SPORT|TCP_ORIG_DPORT))
+ && (flags & (TCP_REPL_SPORT|TCP_REPL_DPORT))) {
+ orig->l4src.tcp.port = reply->l4dst.tcp.port;
+ orig->l4dst.tcp.port = reply->l4src.tcp.port;
+ ret = 1;
+ }
+ if ((flags & (TCP_ORIG_SPORT|TCP_ORIG_DPORT))
+ && ((flags & (TCP_REPL_SPORT|TCP_REPL_DPORT))))
+ ret = 1;
+
+ /* --state is missing and we are trying to create a conntrack */
+ if (ret && (command & CT_CREATE) && (!(flags & TCP_STATE)))
+ ret = 0;
+
+ return ret;
+}
+
+static struct ctproto_handler tcp = {
+ .name = "tcp",
+ .protonum = IPPROTO_TCP,
+ .parse_opts = parse_options,
+ .final_check = final_check,
+ .help = help,
+ .opts = opts,
+ .version = VERSION,
+};
+
+static void __attribute__ ((constructor)) init(void);
+
+static void init(void)
+{
+ register_proto(&tcp);
+}