1 /* SPDX-License-Identifier: GPL-2.0-only */
2 /****************************************************************************
3  * BER and PER decoding library for H.323 conntrack/NAT module.
4  *
5  * Copyright (c) 2006 by Jing Min Zhao <zhaojingmin@users.sourceforge.net>
6  *
7  * This library is based on H.225 version 4, H.235 version 2 and H.245
8  * version 7. It is extremely optimized to decode only the absolutely
9  * necessary objects in a signal for Linux kernel NAT module use, so don't
10  * expect it to be a full ASN.1 library.
11  *
12  * Features:
13  *
14  * 1. Small. The total size of code plus data is less than 20 KB (IA32).
15  * 2. Fast. Decoding Netmeeting's Setup signal 1 million times on a PIII 866
16  *    takes only 3.9 seconds.
17  * 3. No memory allocation. It uses a static object. No need to initialize or
18  *    cleanup.
19  * 4. Thread safe.
20  * 5. Support embedded architectures that has no misaligned memory access
21  *    support.
22  *
23  * Limitations:
24  *
25  * 1. At most 30 faststart entries. Actually this is limited by ethernet's MTU.
26  *    If a Setup signal contains more than 30 faststart, the packet size will
27  *    very likely exceed the MTU size, then the TPKT will be fragmented. I
28  *    don't know how to handle this in a Netfilter module. Anybody can help?
29  *    Although I think 30 is enough for most of the cases.
30  * 2. IPv4 addresses only.
31  *
32  ****************************************************************************/
33 
34 #ifndef _NF_CONNTRACK_HELPER_H323_ASN1_H_
35 #define _NF_CONNTRACK_HELPER_H323_ASN1_H_
36 
37 /*****************************************************************************
38  * H.323 Types
39  ****************************************************************************/
40 
41 #include <linux/types.h>
42 #include <linux/netfilter/nf_conntrack_h323_types.h>
43 
44 typedef struct {
45 	enum {
46 		Q931_NationalEscape = 0x00,
47 		Q931_Alerting = 0x01,
48 		Q931_CallProceeding = 0x02,
49 		Q931_Connect = 0x07,
50 		Q931_ConnectAck = 0x0F,
51 		Q931_Progress = 0x03,
52 		Q931_Setup = 0x05,
53 		Q931_SetupAck = 0x0D,
54 		Q931_Resume = 0x26,
55 		Q931_ResumeAck = 0x2E,
56 		Q931_ResumeReject = 0x22,
57 		Q931_Suspend = 0x25,
58 		Q931_SuspendAck = 0x2D,
59 		Q931_SuspendReject = 0x21,
60 		Q931_UserInformation = 0x20,
61 		Q931_Disconnect = 0x45,
62 		Q931_Release = 0x4D,
63 		Q931_ReleaseComplete = 0x5A,
64 		Q931_Restart = 0x46,
65 		Q931_RestartAck = 0x4E,
66 		Q931_Segment = 0x60,
67 		Q931_CongestionCtrl = 0x79,
68 		Q931_Information = 0x7B,
69 		Q931_Notify = 0x6E,
70 		Q931_Status = 0x7D,
71 		Q931_StatusEnquiry = 0x75,
72 		Q931_Facility = 0x62
73 	} MessageType;
74 	H323_UserInformation UUIE;
75 } Q931;
76 
77 /*****************************************************************************
78  * Decode Functions Return Codes
79  ****************************************************************************/
80 
81 #define H323_ERROR_NONE 0	/* Decoded successfully */
82 #define H323_ERROR_STOP 1	/* Decoding stopped, not really an error */
83 #define H323_ERROR_BOUND -1
84 #define H323_ERROR_RANGE -2
85 
86 
87 /*****************************************************************************
88  * Decode Functions
89  ****************************************************************************/
90 
91 int DecodeRasMessage(unsigned char *buf, size_t sz, RasMessage * ras);
92 int DecodeQ931(unsigned char *buf, size_t sz, Q931 * q931);
93 int DecodeMultimediaSystemControlMessage(unsigned char *buf, size_t sz,
94 					 MultimediaSystemControlMessage *
95 					 mscm);
96 
97 #endif
98