alias_skinny.c revision 145961 
1/*-
2 * alias_skinny.c
3 *
4 * Copyright (c) 2002, 2003 MarcusCom, Inc.
5 * All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 *    notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 *    notice, this list of conditions and the following disclaimer in the
14 *    documentation and/or other materials provided with the distribution.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
17 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
18 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
19 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
20 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
21 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
22 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
23 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
24 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
25 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26 * SUCH DAMAGE.
27 *
28 * Author: Joe Marcus Clarke <marcus@FreeBSD.org>
29 *
30 * $FreeBSD: head/sys/netinet/libalias/alias_skinny.c 145961 2005-05-06 11:07:49Z glebius $
31 */
32
33#ifdef _KERNEL
34#include <sys/param.h>
35#else
36#include <sys/types.h>
37#include <sys/socket.h>
38#include <stdio.h>
39#include <string.h>
40#include <unistd.h>
41#include <arpa/inet.h>
42#endif
43
44#include <netinet/in_systm.h>
45#include <netinet/in.h>
46#include <netinet/ip.h>
47#include <netinet/tcp.h>
48#include <netinet/udp.h>
49
50#ifdef _KERNEL
51#include <netinet/libalias/alias.h>
52#include <netinet/libalias/alias_local.h>
53#else
54#include "alias_local.h"
55#endif
56
57/*
58 * alias_skinny.c handles the translation for the Cisco Skinny Station
59 * protocol.  Skinny typically uses TCP port 2000 to set up calls between
60 * a Cisco Call Manager and a Cisco IP phone.  When a phone comes on line,
61 * it first needs to register with the Call Manager.  To do this it sends
62 * a registration message.  This message contains the IP address of the
63 * IP phone.  This message must then be translated to reflect our global
64 * IP address.  Along with the registration message (and usually in the
65 * same packet), the phone sends an IP port message.  This message indicates
66 * the TCP port over which it will communicate.
67 *
68 * When a call is placed from the phone, the Call Manager will send an
69 * Open Receive Channel message to the phone to let the caller know someone
70 * has answered.  The phone then sends back an Open Receive Channel
71 * Acknowledgement.  In this packet, the phone sends its IP address again,
72 * and the UDP port over which the voice traffic should flow.  These values
73 * need translation.  Right after the Open Receive Channel Acknowledgement,
74 * the Call Manager sends a Start Media Transmission message indicating the
75 * call is connected.  This message contains the IP address and UDP port
76 * number of the remote (called) party.  Once this message is translated, the
77 * call can commence.  The called part sends the first UDP packet to the
78 * calling phone at the pre-arranged UDP port in the Open Receive Channel
79 * Acknowledgement.
80 *
81 * Skinny is a Cisco-proprietary protocol and is a trademark of Cisco Systems,
82 * Inc.  All rights reserved.
83*/
84
85/* #define LIBALIAS_DEBUG 1 */
86
87/* Message types that need translating */
88#define REG_MSG         0x00000001
89#define IP_PORT_MSG     0x00000002
90#define OPNRCVCH_ACK    0x00000022
91#define START_MEDIATX   0x0000008a
92
93struct skinny_header {
94	u_int32_t	len;
95	u_int32_t	reserved;
96	u_int32_t	msgId;
97};
98
99struct RegisterMessage {
100	u_int32_t	msgId;
101	char		devName   [16];
102	u_int32_t	uid;
103	u_int32_t	instance;
104	u_int32_t	ipAddr;
105	u_char		devType;
106	u_int32_t	maxStreams;
107};
108
109struct IpPortMessage {
110	u_int32_t	msgId;
111	u_int32_t	stationIpPort;	/* Note: Skinny uses 32-bit port
112					 * numbers */
113};
114
115struct OpenReceiveChannelAck {
116	u_int32_t	msgId;
117	u_int32_t	status;
118	u_int32_t	ipAddr;
119	u_int32_t	port;
120	u_int32_t	passThruPartyID;
121};
122
123struct StartMediaTransmission {
124	u_int32_t	msgId;
125	u_int32_t	conferenceID;
126	u_int32_t	passThruPartyID;
127	u_int32_t	remoteIpAddr;
128	u_int32_t	remotePort;
129	u_int32_t	MSPacket;
130	u_int32_t	payloadCap;
131	u_int32_t	precedence;
132	u_int32_t	silenceSuppression;
133	u_short		maxFramesPerPacket;
134	u_int32_t	G723BitRate;
135};
136
137typedef enum {
138	ClientToServer = 0,
139	ServerToClient = 1
140} ConvDirection;
141
142
143static int
144alias_skinny_reg_msg(struct RegisterMessage *reg_msg, struct ip *pip,
145    struct tcphdr *tc, struct alias_link *lnk,
146    ConvDirection direction)
147{
148	(void)direction;
149
150	reg_msg->ipAddr = (u_int32_t) GetAliasAddress(lnk).s_addr;
151
152	tc->th_sum = 0;
153	tc->th_sum = TcpChecksum(pip);
154
155	return (0);
156}
157
158static int
159alias_skinny_startmedia(struct StartMediaTransmission *start_media,
160    struct ip *pip, struct tcphdr *tc,
161    struct alias_link *lnk, u_int32_t localIpAddr,
162    ConvDirection direction)
163{
164	struct in_addr dst, src;
165
166	(void)pip;
167	(void)tc;
168	(void)lnk;
169	(void)direction;
170
171	dst.s_addr = start_media->remoteIpAddr;
172	src.s_addr = localIpAddr;
173
174	/*
175	 * XXX I should probably handle in bound global translations as
176	 * well.
177	 */
178
179	return (0);
180}
181
182static int
183alias_skinny_port_msg(struct IpPortMessage *port_msg, struct ip *pip,
184    struct tcphdr *tc, struct alias_link *lnk,
185    ConvDirection direction)
186{
187	(void)direction;
188
189	port_msg->stationIpPort = (u_int32_t) ntohs(GetAliasPort(lnk));
190
191	tc->th_sum = 0;
192	tc->th_sum = TcpChecksum(pip);
193
194	return (0);
195}
196
197static int
198alias_skinny_opnrcvch_ack(struct libalias *la, struct OpenReceiveChannelAck *opnrcvch_ack,
199    struct ip *pip, struct tcphdr *tc,
200    struct alias_link *lnk, u_int32_t * localIpAddr,
201    ConvDirection direction)
202{
203	struct in_addr null_addr;
204	struct alias_link *opnrcv_lnk;
205	u_int32_t localPort;
206
207	(void)lnk;
208	(void)direction;
209
210	*localIpAddr = (u_int32_t) opnrcvch_ack->ipAddr;
211	localPort = opnrcvch_ack->port;
212
213	null_addr.s_addr = INADDR_ANY;
214	opnrcv_lnk = FindUdpTcpOut(la, pip->ip_src, null_addr,
215	    htons((u_short) opnrcvch_ack->port), 0,
216	    IPPROTO_UDP, 1);
217	opnrcvch_ack->ipAddr = (u_int32_t) GetAliasAddress(opnrcv_lnk).s_addr;
218	opnrcvch_ack->port = (u_int32_t) ntohs(GetAliasPort(opnrcv_lnk));
219
220	tc->th_sum = 0;
221	tc->th_sum = TcpChecksum(pip);
222
223	return (0);
224}
225
226void
227AliasHandleSkinny(struct libalias *la, struct ip *pip, struct alias_link *lnk)
228{
229	size_t hlen, tlen, dlen;
230	struct tcphdr *tc;
231	u_int32_t msgId, t, len, lip;
232	struct skinny_header *sd;
233	size_t orig_len, skinny_hdr_len = sizeof(struct skinny_header);
234	ConvDirection direction;
235
236	tc = (struct tcphdr *)ip_next(pip);
237	hlen = (pip->ip_hl + tc->th_off) << 2;
238	tlen = ntohs(pip->ip_len);
239	dlen = tlen - hlen;
240
241	sd = (struct skinny_header *)tcp_next(tc);
242
243	/*
244	 * XXX This direction is reserved for future use.  I still need to
245	 * handle the scenario where the call manager is on the inside, and
246	 * the calling phone is on the global outside.
247	 */
248	if (ntohs(tc->th_dport) == la->skinnyPort) {
249		direction = ClientToServer;
250	} else if (ntohs(tc->th_sport) == la->skinnyPort) {
251		direction = ServerToClient;
252	} else {
253#ifdef LIBALIAS_DEBUG
254		fprintf(stderr,
255		    "PacketAlias/Skinny: Invalid port number, not a Skinny packet\n");
256#endif
257		return;
258	}
259
260	orig_len = dlen;
261	/*
262	 * Skinny packets can contain many messages.  We need to loop
263	 * through the packet using len to determine message boundaries.
264	 * This comes into play big time with port messages being in the
265	 * same packet as register messages.  Also, open receive channel
266	 * acks are usually buried in a pakcet some 400 bytes long.
267	 */
268	while (dlen >= skinny_hdr_len) {
269		len = (sd->len);
270		msgId = (sd->msgId);
271		t = len;
272
273		if (t > orig_len || t > dlen) {
274#ifdef LIBALIAS_DEBUG
275			fprintf(stderr,
276			    "PacketAlias/Skinny: Not a skinny packet, invalid length \n");
277#endif
278			return;
279		}
280		switch (msgId) {
281		case REG_MSG: {
282			struct RegisterMessage *reg_mesg;
283
284			if (len < (int)sizeof(struct RegisterMessage)) {
285#ifdef LIBALIAS_DEBUG
286				fprintf(stderr,
287				    "PacketAlias/Skinny: Not a skinny packet, bad registration message\n");
288#endif
289				return;
290			}
291			reg_mesg = (struct RegisterMessage *)&sd->msgId;
292#ifdef LIBALIAS_DEBUG
293			fprintf(stderr,
294			    "PacketAlias/Skinny: Received a register message");
295#endif
296			alias_skinny_reg_msg(reg_mesg, pip, tc, lnk, direction);
297			break;
298		}
299		case IP_PORT_MSG: {
300			struct IpPortMessage *port_mesg;
301
302			if (len < (int)sizeof(struct IpPortMessage)) {
303#ifdef LIBALIAS_DEBUG
304				fprintf(stderr,
305				    "PacketAlias/Skinny: Not a skinny packet, port message\n");
306#endif
307				return;
308			}
309#ifdef LIBALIAS_DEBUG
310			fprintf(stderr,
311			    "PacketAlias/Skinny: Received ipport message\n");
312#endif
313			port_mesg = (struct IpPortMessage *)&sd->msgId;
314			alias_skinny_port_msg(port_mesg, pip, tc, lnk, direction);
315			break;
316		}
317		case OPNRCVCH_ACK: {
318			struct OpenReceiveChannelAck *opnrcvchn_ack;
319
320			if (len < (int)sizeof(struct OpenReceiveChannelAck)) {
321#ifdef LIBALIAS_DEBUG
322				fprintf(stderr,
323				    "PacketAlias/Skinny: Not a skinny packet, packet,OpnRcvChnAckMsg\n");
324#endif
325				return;
326			}
327#ifdef LIBALIAS_DEBUG
328			fprintf(stderr,
329			    "PacketAlias/Skinny: Received open rcv channel msg\n");
330#endif
331			opnrcvchn_ack = (struct OpenReceiveChannelAck *)&sd->msgId;
332			alias_skinny_opnrcvch_ack(la, opnrcvchn_ack, pip, tc, lnk, &lip, direction);
333			break;
334		}
335		case START_MEDIATX: {
336			struct StartMediaTransmission *startmedia_tx;
337
338			if (len < (int)sizeof(struct StartMediaTransmission)) {
339#ifdef LIBALIAS_DEBUG
340				fprintf(stderr,
341				    "PacketAlias/Skinny: Not a skinny packet,StartMediaTx Message\n");
342#endif
343				return;
344			}
345#ifdef LIBALIAS_DEBUG
346			fprintf(stderr,
347			    "PacketAlias/Skinny: Received start media trans msg\n");
348#endif
349			startmedia_tx = (struct StartMediaTransmission *)&sd->msgId;
350			alias_skinny_startmedia(startmedia_tx, pip, tc, lnk, lip, direction);
351			break;
352		}
353		default:
354			break;
355		}
356		/* Place the pointer at the next message in the packet. */
357		dlen -= len + (skinny_hdr_len - sizeof(msgId));
358		sd = (struct skinny_header *)(((char *)&sd->msgId) + len);
359	}
360}
361