1 /****************************************************************************
2  * ip_conntrack_h323_asn1.h - BER and PER decoding library for H.323
3  * 			      conntrack/NAT module.
4  *
5  * Copyright (c) 2006 by Jing Min Zhao <zhaojingmin@users.sourceforge.net>
6  *
7  * This source code is licensed under General Public License version 2.
8  *
9  *
10  * This library is based on H.225 version 4, H.235 version 2 and H.245
11  * version 7. It is extremely optimized to decode only the absolutely
12  * necessary objects in a signal for Linux kernel NAT module use, so don't
13  * expect it to be a full ASN.1 library.
14  *
15  * Features:
16  *
17  * 1. Small. The total size of code plus data is less than 20 KB (IA32).
18  * 2. Fast. Decoding Netmeeting's Setup signal 1 million times on a PIII 866
19  *    takes only 3.9 seconds.
20  * 3. No memory allocation. It uses a static object. No need to initialize or
21  *    cleanup.
22  * 4. Thread safe.
23  * 5. Support embedded architectures that has no misaligned memory access
24  *    support.
25  *
26  * Limitations:
27  *
28  * 1. At most 30 faststart entries. Actually this is limited by ethernet's MTU.
29  *    If a Setup signal contains more than 30 faststart, the packet size will
30  *    very likely exceed the MTU size, then the TPKT will be fragmented. I
31  *    don't know how to handle this in a Netfilter module. Anybody can help?
32  *    Although I think 30 is enough for most of the cases.
33  * 2. IPv4 addresses only.
34  *
35  ****************************************************************************/
36 
37 #ifndef _NF_CONNTRACK_HELPER_H323_ASN1_H_
38 #define _NF_CONNTRACK_HELPER_H323_ASN1_H_
39 
40 /*****************************************************************************
41  * H.323 Types
42  ****************************************************************************/
43 #include "nf_conntrack_h323_types.h"
44 
45 typedef struct {
46 	enum {
47 		Q931_NationalEscape = 0x00,
48 		Q931_Alerting = 0x01,
49 		Q931_CallProceeding = 0x02,
50 		Q931_Connect = 0x07,
51 		Q931_ConnectAck = 0x0F,
52 		Q931_Progress = 0x03,
53 		Q931_Setup = 0x05,
54 		Q931_SetupAck = 0x0D,
55 		Q931_Resume = 0x26,
56 		Q931_ResumeAck = 0x2E,
57 		Q931_ResumeReject = 0x22,
58 		Q931_Suspend = 0x25,
59 		Q931_SuspendAck = 0x2D,
60 		Q931_SuspendReject = 0x21,
61 		Q931_UserInformation = 0x20,
62 		Q931_Disconnect = 0x45,
63 		Q931_Release = 0x4D,
64 		Q931_ReleaseComplete = 0x5A,
65 		Q931_Restart = 0x46,
66 		Q931_RestartAck = 0x4E,
67 		Q931_Segment = 0x60,
68 		Q931_CongestionCtrl = 0x79,
69 		Q931_Information = 0x7B,
70 		Q931_Notify = 0x6E,
71 		Q931_Status = 0x7D,
72 		Q931_StatusEnquiry = 0x75,
73 		Q931_Facility = 0x62
74 	} MessageType;
75 	H323_UserInformation UUIE;
76 } Q931;
77 
78 /*****************************************************************************
79  * Decode Functions Return Codes
80  ****************************************************************************/
81 
82 #define H323_ERROR_NONE 0	/* Decoded successfully */
83 #define H323_ERROR_STOP 1	/* Decoding stopped, not really an error */
84 #define H323_ERROR_BOUND -1
85 #define H323_ERROR_RANGE -2
86 
87 
88 /*****************************************************************************
89  * Decode Functions
90  ****************************************************************************/
91 
92 int DecodeRasMessage(unsigned char *buf, size_t sz, RasMessage * ras);
93 int DecodeQ931(unsigned char *buf, size_t sz, Q931 * q931);
94 int DecodeMultimediaSystemControlMessage(unsigned char *buf, size_t sz,
95 					 MultimediaSystemControlMessage *
96 					 mscm);
97 
98 #endif
99