X-Git-Url: http://git.sameswireless.fr/l2tpns.git/blobdiff_plain/272e831e8071da5296e8dd2061f8a166fd70fd07..e8c395011302d085135535b2bf7ebd04d11f137f:/l2tpns.c

diff --git a/l2tpns.c b/l2tpns.c
index eb7783b..7d726cb 100644
--- a/l2tpns.c
+++ b/l2tpns.c
@@ -4,7 +4,7 @@
 // Copyright (c) 2002 FireBrick (Andrews & Arnold Ltd / Watchfront Ltd) - GPL licenced
 // vim: sw=8 ts=8
 
-char const *cvs_id_l2tpns = "$Id: l2tpns.c,v 1.25 2004/09/02 04:18:07 fred_nerk Exp $";
+char const *cvs_id_l2tpns = "$Id: l2tpns.c,v 1.28 2004/09/20 23:34:35 fred_nerk Exp $";
 
 #include <arpa/inet.h>
 #include <assert.h>
@@ -57,7 +57,7 @@ int snoopfd = -1;		// UDP file handle for sending out intercept data
 int *radfds = NULL;		// RADIUS requests file handles
 int ifrfd = -1;			// File descriptor for routing, etc
 time_t basetime = 0;		// base clock
-char hostname[1000] = "";	// us.
+char *hostname = NULL;		// us.
 int tunidx;			// ifr_ifindex of tun device
 u32 sessionid = 0;		// session id for radius accounting
 int syslog_log = 0;		// are we logging to syslog
@@ -95,6 +95,7 @@ struct config_descriptt config_values[] = {
 	CONFIG("debug", debug, INT),
 	CONFIG("log_file", log_filename, STRING),
 	CONFIG("pid_file", pid_file, STRING),
+	CONFIG("hostname", hostname, STRING),
 	CONFIG("l2tp_secret", l2tpsecret, STRING),
 	CONFIG("primary_dns", default_dns1, IP),
 	CONFIG("secondary_dns", default_dns2, IP),
@@ -169,6 +170,7 @@ void dump_state();
 void tunnel_clean();
 tunnelidt new_tunnel();
 void update_config();
+int unhide_avp(u8 *avp, tunnelidt t, sessionidt s, u16 length);
 
 static void cache_ipmap(ipt ip, int s);
 static void uncache_ipmap(ipt ip);
@@ -1452,6 +1454,13 @@ void processudp(u8 * buf, int len, struct sockaddr_in *addr)
 						continue;
 					}
 					log(4, ntohl(addr->sin_addr.s_addr), s, t, "Hidden AVP\n");
+					// Unhide the AVP
+					n = unhide_avp(b, t, s, n);
+					if (n == 0)
+					{
+						fatal = flags;
+						continue;
+					}
 				}
 				if (*b & 0x3C)
 				{
@@ -1566,6 +1575,11 @@ void processudp(u8 * buf, int len, struct sockaddr_in *addr)
 						build_chap_response(b, 2, n, &chapresponse);
 					}
 					break;
+				case 13:    // Response
+					// Why did they send a response? We never challenge.
+					log(2, ntohl(addr->sin_addr.s_addr), s, t, "   received unexpected challenge response\n");
+				break;
+
 				case 14:    // assigned session
 					asession = session[s].far = ntohs(*(u16 *) (b));
 					log(4, ntohl(addr->sin_addr.s_addr), s, t, "   assigned session = %d\n", asession);
@@ -2448,6 +2462,7 @@ void mainloop(void)
 void initdata(void)
 {
 	int i;
+	char *p;
 
 	if ((_statistics = shared_malloc(sizeof(struct Tstats))) == MAP_FAILED)
 	{
@@ -2534,13 +2549,11 @@ void initdata(void)
 	for (i = 1; i < MAXTUNNEL- 1; i++)
 		tunnel[i].state = TUNNELUNDEF;	// mark it as not filled in.
 
-	if (!*hostname)
-	{
-		char *p;
-		// Grab my hostname unless it's been specified
-		gethostname(hostname, sizeof(hostname));
-		if ((p = strchr(hostname, '.'))) *p = 0;
-	}
+	// Grab my hostname unless it's been specified
+	gethostname(config->hostname, sizeof(config->hostname));
+	if ((p = strchr(config->hostname, '.'))) *p = 0;
+	hostname = config->hostname;
+
 	_statistics->start_time = _statistics->last_reset = time(NULL);
 
 #ifdef BGP
@@ -2854,7 +2867,7 @@ void dump_acct_info()
 
 	for (i = 0; i < MAXSESSION; i++)
 	{
-		if (!session[i].opened || !session[i].ip || !session[i].cin || !session[i].cout || !*session[i].user || session[i].walled_garden)
+		if (!session[i].opened || !session[i].ip || (!session[i].cin && !session[i].cout) || !*session[i].user || session[i].walled_garden)
 			continue;
 		if (!f)
 		{
@@ -2944,7 +2957,7 @@ int main(int argc, char *argv[])
 	config->debug = optdebug;
 
 	init_tbf();
-	init_cli(hostname);
+	init_cli();
 	read_config_file();
 
 	log(0, 0, 0, 0, "L2TPNS version " VERSION "\n");
@@ -4013,3 +4026,77 @@ int cmd_show_hist_open(struct cli_def *cli, char *command, char **argv, int argc
 	cli_print(cli, "%d total sessions open.", count);
 	return CLI_OK;
 }
+
+/* Unhide an avp.
+ *
+ * This unencodes the AVP using the L2TP CHAP secret and the
+ * previously stored random vector. It replaces the hidden data with
+ * the cleartext data and returns the length of the cleartext data
+ * (including the AVP "header" of 6 bytes).
+ *
+ * Based on code from rp-l2tpd by Roaring Penguin Software Inc.
+ */
+int unhide_avp(u8 *avp, tunnelidt t, sessionidt s, u16 length)
+{
+	MD5_CTX ctx;
+	u8 *cursor;
+	u8 digest[16];
+	u8 working_vector[16];
+	uint16_t hidden_length;
+	u8 type[2];
+	size_t done, todo;
+	u8 *output;
+
+	// Find the AVP type.
+	type[0] = *(avp + 4);
+	type[1] = *(avp + 5);
+
+	// Line up with the hidden data
+	cursor = output = avp + 6;
+
+	// Compute initial pad
+	MD5Init(&ctx);
+	MD5Update(&ctx, type, 2);
+	MD5Update(&ctx, config->l2tpsecret, strlen(config->l2tpsecret));
+	MD5Update(&ctx, session[s].random_vector, session[s].random_vector_length);
+	MD5Final(digest, &ctx);
+
+	// Get hidden length
+	hidden_length = ((uint16_t) (digest[0] ^ cursor[0])) * 256 + (uint16_t) (digest[1] ^ cursor[1]);
+
+	// Keep these for later use
+	working_vector[0] = *cursor;
+	working_vector[1] = *(cursor + 1);
+	cursor += 2;
+
+	if (hidden_length > length - 8)
+	{
+		log(1, 0, s, t, "Hidden length %d too long in AVP of length %d\n", (int) hidden_length, (int) length);
+		return 0;
+	}
+
+	/* Decrypt remainder */
+	done = 2;
+	todo = hidden_length;
+	while (todo)
+	{
+		working_vector[done] = *cursor;
+		*output = digest[done] ^ *cursor;
+		++output;
+		++cursor;
+		--todo;
+		++done;
+		if (done == 16 && todo)
+		{
+			// Compute new digest
+			done = 0;
+			MD5Init(&ctx);
+			MD5Update(&ctx, config->l2tpsecret, strlen(config->l2tpsecret));
+			MD5Update(&ctx, &working_vector, 16);
+			MD5Final(digest, &ctx);
+		}
+	}
+
+	return hidden_length + 6;
+}
+