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