// SPDX-License-Identifier: GPL-2.0-only
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/*
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* BER and PER decoding library for H.323 conntrack/NAT module.
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*
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* Copyright (c) 2006 by Jing Min Zhao <zhaojingmin@users.sourceforge.net>
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*
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* See nf_conntrack_helper_h323_asn1.h for details.
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*/
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#ifdef __KERNEL__
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#include <linux/kernel.h>
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#else
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#include <stdio.h>
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#endif
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#include <linux/netfilter/nf_conntrack_h323_asn1.h>
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/* Trace Flag */
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#ifndef H323_TRACE
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#define H323_TRACE 0
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#endif
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#if H323_TRACE
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#define TAB_SIZE 4
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#define IFTHEN(cond, act) if(cond){act;}
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#ifdef __KERNEL__
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#define PRINT printk
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#else
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#define PRINT printf
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#endif
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#define FNAME(name) name,
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#else
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#define IFTHEN(cond, act)
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#define PRINT(fmt, args...)
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#define FNAME(name)
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#endif
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/* ASN.1 Types */
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#define NUL 0
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#define BOOL 1
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#define OID 2
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#define INT 3
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#define ENUM 4
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#define BITSTR 5
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#define NUMSTR 6
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#define NUMDGT 6
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#define TBCDSTR 6
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#define OCTSTR 7
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#define PRTSTR 7
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#define IA5STR 7
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#define GENSTR 7
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#define BMPSTR 8
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#define SEQ 9
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#define SET 9
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#define SEQOF 10
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#define SETOF 10
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#define CHOICE 11
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/* Constraint Types */
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#define FIXD 0
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/* #define BITS 1-8 */
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#define BYTE 9
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#define WORD 10
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#define CONS 11
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#define SEMI 12
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#define UNCO 13
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/* ASN.1 Type Attributes */
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#define SKIP 0
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#define STOP 1
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#define DECODE 2
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#define EXT 4
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#define OPEN 8
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#define OPT 16
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/* ASN.1 Field Structure */
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typedef struct field_t {
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#if H323_TRACE
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char *name;
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#endif
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unsigned char type;
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unsigned char sz;
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unsigned char lb;
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unsigned char ub;
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unsigned short attr;
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unsigned short offset;
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const struct field_t *fields;
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} field_t;
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/* Bit Stream */
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struct bitstr {
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unsigned char *buf;
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unsigned char *beg;
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unsigned char *end;
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unsigned char *cur;
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unsigned int bit;
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};
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/* Tool Functions */
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#define INC_BIT(bs) if((++(bs)->bit)>7){(bs)->cur++;(bs)->bit=0;}
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#define INC_BITS(bs,b) if(((bs)->bit+=(b))>7){(bs)->cur+=(bs)->bit>>3;(bs)->bit&=7;}
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#define BYTE_ALIGN(bs) if((bs)->bit){(bs)->cur++;(bs)->bit=0;}
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static unsigned int get_len(struct bitstr *bs);
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static unsigned int get_bit(struct bitstr *bs);
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static unsigned int get_bits(struct bitstr *bs, unsigned int b);
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static unsigned int get_bitmap(struct bitstr *bs, unsigned int b);
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static unsigned int get_uint(struct bitstr *bs, int b);
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/* Decoder Functions */
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static int decode_nul(struct bitstr *bs, const struct field_t *f, char *base, int level);
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static int decode_bool(struct bitstr *bs, const struct field_t *f, char *base, int level);
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static int decode_oid(struct bitstr *bs, const struct field_t *f, char *base, int level);
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static int decode_int(struct bitstr *bs, const struct field_t *f, char *base, int level);
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static int decode_enum(struct bitstr *bs, const struct field_t *f, char *base, int level);
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static int decode_bitstr(struct bitstr *bs, const struct field_t *f, char *base, int level);
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static int decode_numstr(struct bitstr *bs, const struct field_t *f, char *base, int level);
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static int decode_octstr(struct bitstr *bs, const struct field_t *f, char *base, int level);
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static int decode_bmpstr(struct bitstr *bs, const struct field_t *f, char *base, int level);
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static int decode_seq(struct bitstr *bs, const struct field_t *f, char *base, int level);
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static int decode_seqof(struct bitstr *bs, const struct field_t *f, char *base, int level);
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static int decode_choice(struct bitstr *bs, const struct field_t *f, char *base, int level);
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/* Decoder Functions Vector */
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typedef int (*decoder_t)(struct bitstr *, const struct field_t *, char *, int);
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static const decoder_t Decoders[] = {
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decode_nul,
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decode_bool,
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decode_oid,
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decode_int,
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decode_enum,
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decode_bitstr,
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decode_numstr,
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decode_octstr,
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decode_bmpstr,
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decode_seq,
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decode_seqof,
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decode_choice,
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};
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/*
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* H.323 Types
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*/
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#include "nf_conntrack_h323_types.c"
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/*
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* Functions
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*/
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/* Assume bs is aligned && v < 16384 */
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static unsigned int get_len(struct bitstr *bs)
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{
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unsigned int v;
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v = *bs->cur++;
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if (v & 0x80) {
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v &= 0x3f;
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v <<= 8;
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v += *bs->cur++;
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}
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return v;
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}
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static int nf_h323_error_boundary(struct bitstr *bs, size_t bytes, size_t bits)
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{
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bits += bs->bit;
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bytes += bits / BITS_PER_BYTE;
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if (bits % BITS_PER_BYTE > 0)
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bytes++;
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if (bs->cur + bytes > bs->end)
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return 1;
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return 0;
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}
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static unsigned int get_bit(struct bitstr *bs)
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{
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unsigned int b = (*bs->cur) & (0x80 >> bs->bit);
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INC_BIT(bs);
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return b;
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}
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/* Assume b <= 8 */
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static unsigned int get_bits(struct bitstr *bs, unsigned int b)
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{
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unsigned int v, l;
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v = (*bs->cur) & (0xffU >> bs->bit);
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l = b + bs->bit;
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if (l < 8) {
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v >>= 8 - l;
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bs->bit = l;
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} else if (l == 8) {
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bs->cur++;
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bs->bit = 0;
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} else { /* l > 8 */
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v <<= 8;
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v += *(++bs->cur);
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v >>= 16 - l;
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bs->bit = l - 8;
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}
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return v;
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}
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/* Assume b <= 32 */
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static unsigned int get_bitmap(struct bitstr *bs, unsigned int b)
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{
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unsigned int v, l, shift, bytes;
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if (!b)
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return 0;
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l = bs->bit + b;
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if (l < 8) {
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v = (unsigned int)(*bs->cur) << (bs->bit + 24);
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bs->bit = l;
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} else if (l == 8) {
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v = (unsigned int)(*bs->cur++) << (bs->bit + 24);
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bs->bit = 0;
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} else {
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for (bytes = l >> 3, shift = 24, v = 0; bytes;
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bytes--, shift -= 8)
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v |= (unsigned int)(*bs->cur++) << shift;
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if (l < 32) {
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v |= (unsigned int)(*bs->cur) << shift;
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v <<= bs->bit;
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} else if (l > 32) {
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v <<= bs->bit;
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v |= (*bs->cur) >> (8 - bs->bit);
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}
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bs->bit = l & 0x7;
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}
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v &= 0xffffffff << (32 - b);
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return v;
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}
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/*
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* Assume bs is aligned and sizeof(unsigned int) == 4
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*/
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static unsigned int get_uint(struct bitstr *bs, int b)
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{
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unsigned int v = 0;
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switch (b) {
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case 4:
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v |= *bs->cur++;
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v <<= 8;
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fallthrough;
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case 3:
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v |= *bs->cur++;
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v <<= 8;
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fallthrough;
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case 2:
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v |= *bs->cur++;
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v <<= 8;
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fallthrough;
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case 1:
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v |= *bs->cur++;
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break;
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}
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return v;
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}
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static int decode_nul(struct bitstr *bs, const struct field_t *f,
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char *base, int level)
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{
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PRINT("%*.s%s\n", level * TAB_SIZE, " ", f->name);
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return H323_ERROR_NONE;
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}
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static int decode_bool(struct bitstr *bs, const struct field_t *f,
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char *base, int level)
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{
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PRINT("%*.s%s\n", level * TAB_SIZE, " ", f->name);
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INC_BIT(bs);
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if (nf_h323_error_boundary(bs, 0, 0))
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return H323_ERROR_BOUND;
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return H323_ERROR_NONE;
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}
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static int decode_oid(struct bitstr *bs, const struct field_t *f,
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char *base, int level)
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{
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int len;
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PRINT("%*.s%s\n", level * TAB_SIZE, " ", f->name);
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BYTE_ALIGN(bs);
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if (nf_h323_error_boundary(bs, 1, 0))
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return H323_ERROR_BOUND;
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len = *bs->cur++;
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bs->cur += len;
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if (nf_h323_error_boundary(bs, 0, 0))
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return H323_ERROR_BOUND;
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return H323_ERROR_NONE;
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}
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static int decode_int(struct bitstr *bs, const struct field_t *f,
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char *base, int level)
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{
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unsigned int len;
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PRINT("%*.s%s", level * TAB_SIZE, " ", f->name);
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switch (f->sz) {
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case BYTE: /* Range == 256 */
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BYTE_ALIGN(bs);
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bs->cur++;
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break;
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case WORD: /* 257 <= Range <= 64K */
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BYTE_ALIGN(bs);
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bs->cur += 2;
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break;
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case CONS: /* 64K < Range < 4G */
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if (nf_h323_error_boundary(bs, 0, 2))
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return H323_ERROR_BOUND;
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len = get_bits(bs, 2) + 1;
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BYTE_ALIGN(bs);
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if (base && (f->attr & DECODE)) { /* timeToLive */
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unsigned int v = get_uint(bs, len) + f->lb;
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PRINT(" = %u", v);
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*((unsigned int *)(base + f->offset)) = v;
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}
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bs->cur += len;
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break;
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case UNCO:
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BYTE_ALIGN(bs);
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if (nf_h323_error_boundary(bs, 2, 0))
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return H323_ERROR_BOUND;
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len = get_len(bs);
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bs->cur += len;
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break;
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default: /* 2 <= Range <= 255 */
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INC_BITS(bs, f->sz);
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break;
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}
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PRINT("\n");
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if (nf_h323_error_boundary(bs, 0, 0))
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return H323_ERROR_BOUND;
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return H323_ERROR_NONE;
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}
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static int decode_enum(struct bitstr *bs, const struct field_t *f,
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char *base, int level)
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{
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PRINT("%*.s%s\n", level * TAB_SIZE, " ", f->name);
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if ((f->attr & EXT) && get_bit(bs)) {
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INC_BITS(bs, 7);
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} else {
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INC_BITS(bs, f->sz);
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}
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if (nf_h323_error_boundary(bs, 0, 0))
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return H323_ERROR_BOUND;
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return H323_ERROR_NONE;
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}
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static int decode_bitstr(struct bitstr *bs, const struct field_t *f,
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char *base, int level)
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{
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unsigned int len;
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PRINT("%*.s%s\n", level * TAB_SIZE, " ", f->name);
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BYTE_ALIGN(bs);
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switch (f->sz) {
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case FIXD: /* fixed length > 16 */
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len = f->lb;
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break;
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case WORD: /* 2-byte length */
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if (nf_h323_error_boundary(bs, 2, 0))
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return H323_ERROR_BOUND;
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len = (*bs->cur++) << 8;
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len += (*bs->cur++) + f->lb;
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break;
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case SEMI:
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if (nf_h323_error_boundary(bs, 2, 0))
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return H323_ERROR_BOUND;
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len = get_len(bs);
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break;
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default:
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len = 0;
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break;
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}
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bs->cur += len >> 3;
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bs->bit = len & 7;
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if (nf_h323_error_boundary(bs, 0, 0))
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return H323_ERROR_BOUND;
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return H323_ERROR_NONE;
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}
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static int decode_numstr(struct bitstr *bs, const struct field_t *f,
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char *base, int level)
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{
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unsigned int len;
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PRINT("%*.s%s\n", level * TAB_SIZE, " ", f->name);
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/* 2 <= Range <= 255 */
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if (nf_h323_error_boundary(bs, 0, f->sz))
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return H323_ERROR_BOUND;
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len = get_bits(bs, f->sz) + f->lb;
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BYTE_ALIGN(bs);
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INC_BITS(bs, (len << 2));
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if (nf_h323_error_boundary(bs, 0, 0))
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return H323_ERROR_BOUND;
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return H323_ERROR_NONE;
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}
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static int decode_octstr(struct bitstr *bs, const struct field_t *f,
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char *base, int level)
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{
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unsigned int len;
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PRINT("%*.s%s", level * TAB_SIZE, " ", f->name);
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switch (f->sz) {
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case FIXD: /* Range == 1 */
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if (f->lb > 2) {
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BYTE_ALIGN(bs);
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if (base && (f->attr & DECODE)) {
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/* The IP Address */
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IFTHEN(f->lb == 4,
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PRINT(" = %d.%d.%d.%d:%d",
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bs->cur[0], bs->cur[1],
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bs->cur[2], bs->cur[3],
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bs->cur[4] * 256 + bs->cur[5]));
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*((unsigned int *)(base + f->offset)) =
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bs->cur - bs->buf;
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}
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}
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len = f->lb;
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break;
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case BYTE: /* Range == 256 */
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BYTE_ALIGN(bs);
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if (nf_h323_error_boundary(bs, 1, 0))
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return H323_ERROR_BOUND;
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len = (*bs->cur++) + f->lb;
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break;
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case SEMI:
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BYTE_ALIGN(bs);
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if (nf_h323_error_boundary(bs, 2, 0))
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return H323_ERROR_BOUND;
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len = get_len(bs) + f->lb;
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break;
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default: /* 2 <= Range <= 255 */
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if (nf_h323_error_boundary(bs, 0, f->sz))
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return H323_ERROR_BOUND;
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len = get_bits(bs, f->sz) + f->lb;
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BYTE_ALIGN(bs);
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break;
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}
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bs->cur += len;
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PRINT("\n");
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if (nf_h323_error_boundary(bs, 0, 0))
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return H323_ERROR_BOUND;
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return H323_ERROR_NONE;
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}
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static int decode_bmpstr(struct bitstr *bs, const struct field_t *f,
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char *base, int level)
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{
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unsigned int len;
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PRINT("%*.s%s\n", level * TAB_SIZE, " ", f->name);
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switch (f->sz) {
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case BYTE: /* Range == 256 */
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BYTE_ALIGN(bs);
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if (nf_h323_error_boundary(bs, 1, 0))
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return H323_ERROR_BOUND;
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len = (*bs->cur++) + f->lb;
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break;
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default: /* 2 <= Range <= 255 */
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if (nf_h323_error_boundary(bs, 0, f->sz))
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return H323_ERROR_BOUND;
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len = get_bits(bs, f->sz) + f->lb;
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BYTE_ALIGN(bs);
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break;
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}
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bs->cur += len << 1;
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if (nf_h323_error_boundary(bs, 0, 0))
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return H323_ERROR_BOUND;
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return H323_ERROR_NONE;
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}
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static int decode_seq(struct bitstr *bs, const struct field_t *f,
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char *base, int level)
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{
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unsigned int ext, bmp, i, opt, len = 0, bmp2, bmp2_len;
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int err;
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const struct field_t *son;
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unsigned char *beg = NULL;
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PRINT("%*.s%s\n", level * TAB_SIZE, " ", f->name);
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/* Decode? */
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base = (base && (f->attr & DECODE)) ? base + f->offset : NULL;
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/* Extensible? */
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if (nf_h323_error_boundary(bs, 0, 1))
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return H323_ERROR_BOUND;
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ext = (f->attr & EXT) ? get_bit(bs) : 0;
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/* Get fields bitmap */
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if (nf_h323_error_boundary(bs, 0, f->sz))
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return H323_ERROR_BOUND;
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bmp = get_bitmap(bs, f->sz);
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if (base)
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*(unsigned int *)base = bmp;
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/* Decode the root components */
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for (i = opt = 0, son = f->fields; i < f->lb; i++, son++) {
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if (son->attr & STOP) {
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PRINT("%*.s%s\n", (level + 1) * TAB_SIZE, " ",
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son->name);
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return H323_ERROR_STOP;
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}
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if (son->attr & OPT) { /* Optional component */
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if (!((0x80000000U >> (opt++)) & bmp)) /* Not exist */
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continue;
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}
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/* Decode */
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if (son->attr & OPEN) { /* Open field */
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if (nf_h323_error_boundary(bs, 2, 0))
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return H323_ERROR_BOUND;
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len = get_len(bs);
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if (nf_h323_error_boundary(bs, len, 0))
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return H323_ERROR_BOUND;
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if (!base || !(son->attr & DECODE)) {
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PRINT("%*.s%s\n", (level + 1) * TAB_SIZE,
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" ", son->name);
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bs->cur += len;
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continue;
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}
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beg = bs->cur;
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/* Decode */
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if ((err = (Decoders[son->type]) (bs, son, base,
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level + 1)) <
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H323_ERROR_NONE)
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return err;
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bs->cur = beg + len;
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bs->bit = 0;
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} else if ((err = (Decoders[son->type]) (bs, son, base,
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level + 1)) <
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H323_ERROR_NONE)
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return err;
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}
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/* No extension? */
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if (!ext)
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return H323_ERROR_NONE;
|
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/* Get the extension bitmap */
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if (nf_h323_error_boundary(bs, 0, 7))
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return H323_ERROR_BOUND;
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bmp2_len = get_bits(bs, 7) + 1;
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if (nf_h323_error_boundary(bs, 0, bmp2_len))
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return H323_ERROR_BOUND;
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bmp2 = get_bitmap(bs, bmp2_len);
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bmp |= bmp2 >> f->sz;
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if (base)
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*(unsigned int *)base = bmp;
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BYTE_ALIGN(bs);
|
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/* Decode the extension components */
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for (opt = 0; opt < bmp2_len; opt++, i++, son++) {
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/* Check Range */
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if (i >= f->ub) { /* Newer Version? */
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if (nf_h323_error_boundary(bs, 2, 0))
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return H323_ERROR_BOUND;
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len = get_len(bs);
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if (nf_h323_error_boundary(bs, len, 0))
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return H323_ERROR_BOUND;
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bs->cur += len;
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continue;
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}
|
|
if (son->attr & STOP) {
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PRINT("%*.s%s\n", (level + 1) * TAB_SIZE, " ",
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son->name);
|
return H323_ERROR_STOP;
|
}
|
|
if (!((0x80000000 >> opt) & bmp2)) /* Not present */
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continue;
|
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if (nf_h323_error_boundary(bs, 2, 0))
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return H323_ERROR_BOUND;
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len = get_len(bs);
|
if (nf_h323_error_boundary(bs, len, 0))
|
return H323_ERROR_BOUND;
|
if (!base || !(son->attr & DECODE)) {
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PRINT("%*.s%s\n", (level + 1) * TAB_SIZE, " ",
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son->name);
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bs->cur += len;
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continue;
|
}
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beg = bs->cur;
|
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if ((err = (Decoders[son->type]) (bs, son, base,
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level + 1)) <
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H323_ERROR_NONE)
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return err;
|
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bs->cur = beg + len;
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bs->bit = 0;
|
}
|
return H323_ERROR_NONE;
|
}
|
|
static int decode_seqof(struct bitstr *bs, const struct field_t *f,
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char *base, int level)
|
{
|
unsigned int count, effective_count = 0, i, len = 0;
|
int err;
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const struct field_t *son;
|
unsigned char *beg = NULL;
|
|
PRINT("%*.s%s\n", level * TAB_SIZE, " ", f->name);
|
|
/* Decode? */
|
base = (base && (f->attr & DECODE)) ? base + f->offset : NULL;
|
|
/* Decode item count */
|
switch (f->sz) {
|
case BYTE:
|
BYTE_ALIGN(bs);
|
if (nf_h323_error_boundary(bs, 1, 0))
|
return H323_ERROR_BOUND;
|
count = *bs->cur++;
|
break;
|
case WORD:
|
BYTE_ALIGN(bs);
|
if (nf_h323_error_boundary(bs, 2, 0))
|
return H323_ERROR_BOUND;
|
count = *bs->cur++;
|
count <<= 8;
|
count += *bs->cur++;
|
break;
|
case SEMI:
|
BYTE_ALIGN(bs);
|
if (nf_h323_error_boundary(bs, 2, 0))
|
return H323_ERROR_BOUND;
|
count = get_len(bs);
|
break;
|
default:
|
if (nf_h323_error_boundary(bs, 0, f->sz))
|
return H323_ERROR_BOUND;
|
count = get_bits(bs, f->sz);
|
break;
|
}
|
count += f->lb;
|
|
/* Write Count */
|
if (base) {
|
effective_count = count > f->ub ? f->ub : count;
|
*(unsigned int *)base = effective_count;
|
base += sizeof(unsigned int);
|
}
|
|
/* Decode nested field */
|
son = f->fields;
|
if (base)
|
base -= son->offset;
|
for (i = 0; i < count; i++) {
|
if (son->attr & OPEN) {
|
BYTE_ALIGN(bs);
|
if (nf_h323_error_boundary(bs, 2, 0))
|
return H323_ERROR_BOUND;
|
len = get_len(bs);
|
if (nf_h323_error_boundary(bs, len, 0))
|
return H323_ERROR_BOUND;
|
if (!base || !(son->attr & DECODE)) {
|
PRINT("%*.s%s\n", (level + 1) * TAB_SIZE,
|
" ", son->name);
|
bs->cur += len;
|
continue;
|
}
|
beg = bs->cur;
|
|
if ((err = (Decoders[son->type]) (bs, son,
|
i <
|
effective_count ?
|
base : NULL,
|
level + 1)) <
|
H323_ERROR_NONE)
|
return err;
|
|
bs->cur = beg + len;
|
bs->bit = 0;
|
} else
|
if ((err = (Decoders[son->type]) (bs, son,
|
i <
|
effective_count ?
|
base : NULL,
|
level + 1)) <
|
H323_ERROR_NONE)
|
return err;
|
|
if (base)
|
base += son->offset;
|
}
|
|
return H323_ERROR_NONE;
|
}
|
|
static int decode_choice(struct bitstr *bs, const struct field_t *f,
|
char *base, int level)
|
{
|
unsigned int type, ext, len = 0;
|
int err;
|
const struct field_t *son;
|
unsigned char *beg = NULL;
|
|
PRINT("%*.s%s\n", level * TAB_SIZE, " ", f->name);
|
|
/* Decode? */
|
base = (base && (f->attr & DECODE)) ? base + f->offset : NULL;
|
|
/* Decode the choice index number */
|
if (nf_h323_error_boundary(bs, 0, 1))
|
return H323_ERROR_BOUND;
|
if ((f->attr & EXT) && get_bit(bs)) {
|
ext = 1;
|
if (nf_h323_error_boundary(bs, 0, 7))
|
return H323_ERROR_BOUND;
|
type = get_bits(bs, 7) + f->lb;
|
} else {
|
ext = 0;
|
if (nf_h323_error_boundary(bs, 0, f->sz))
|
return H323_ERROR_BOUND;
|
type = get_bits(bs, f->sz);
|
if (type >= f->lb)
|
return H323_ERROR_RANGE;
|
}
|
|
/* Write Type */
|
if (base)
|
*(unsigned int *)base = type;
|
|
/* Check Range */
|
if (type >= f->ub) { /* Newer version? */
|
BYTE_ALIGN(bs);
|
if (nf_h323_error_boundary(bs, 2, 0))
|
return H323_ERROR_BOUND;
|
len = get_len(bs);
|
if (nf_h323_error_boundary(bs, len, 0))
|
return H323_ERROR_BOUND;
|
bs->cur += len;
|
return H323_ERROR_NONE;
|
}
|
|
/* Transfer to son level */
|
son = &f->fields[type];
|
if (son->attr & STOP) {
|
PRINT("%*.s%s\n", (level + 1) * TAB_SIZE, " ", son->name);
|
return H323_ERROR_STOP;
|
}
|
|
if (ext || (son->attr & OPEN)) {
|
BYTE_ALIGN(bs);
|
if (nf_h323_error_boundary(bs, len, 0))
|
return H323_ERROR_BOUND;
|
len = get_len(bs);
|
if (nf_h323_error_boundary(bs, len, 0))
|
return H323_ERROR_BOUND;
|
if (!base || !(son->attr & DECODE)) {
|
PRINT("%*.s%s\n", (level + 1) * TAB_SIZE, " ",
|
son->name);
|
bs->cur += len;
|
return H323_ERROR_NONE;
|
}
|
beg = bs->cur;
|
|
if ((err = (Decoders[son->type]) (bs, son, base, level + 1)) <
|
H323_ERROR_NONE)
|
return err;
|
|
bs->cur = beg + len;
|
bs->bit = 0;
|
} else if ((err = (Decoders[son->type]) (bs, son, base, level + 1)) <
|
H323_ERROR_NONE)
|
return err;
|
|
return H323_ERROR_NONE;
|
}
|
|
int DecodeRasMessage(unsigned char *buf, size_t sz, RasMessage *ras)
|
{
|
static const struct field_t ras_message = {
|
FNAME("RasMessage") CHOICE, 5, 24, 32, DECODE | EXT,
|
0, _RasMessage
|
};
|
struct bitstr bs;
|
|
bs.buf = bs.beg = bs.cur = buf;
|
bs.end = buf + sz;
|
bs.bit = 0;
|
|
return decode_choice(&bs, &ras_message, (char *) ras, 0);
|
}
|
|
static int DecodeH323_UserInformation(unsigned char *buf, unsigned char *beg,
|
size_t sz, H323_UserInformation *uuie)
|
{
|
static const struct field_t h323_userinformation = {
|
FNAME("H323-UserInformation") SEQ, 1, 2, 2, DECODE | EXT,
|
0, _H323_UserInformation
|
};
|
struct bitstr bs;
|
|
bs.buf = buf;
|
bs.beg = bs.cur = beg;
|
bs.end = beg + sz;
|
bs.bit = 0;
|
|
return decode_seq(&bs, &h323_userinformation, (char *) uuie, 0);
|
}
|
|
int DecodeMultimediaSystemControlMessage(unsigned char *buf, size_t sz,
|
MultimediaSystemControlMessage *
|
mscm)
|
{
|
static const struct field_t multimediasystemcontrolmessage = {
|
FNAME("MultimediaSystemControlMessage") CHOICE, 2, 4, 4,
|
DECODE | EXT, 0, _MultimediaSystemControlMessage
|
};
|
struct bitstr bs;
|
|
bs.buf = bs.beg = bs.cur = buf;
|
bs.end = buf + sz;
|
bs.bit = 0;
|
|
return decode_choice(&bs, &multimediasystemcontrolmessage,
|
(char *) mscm, 0);
|
}
|
|
int DecodeQ931(unsigned char *buf, size_t sz, Q931 *q931)
|
{
|
unsigned char *p = buf;
|
int len;
|
|
if (!p || sz < 1)
|
return H323_ERROR_BOUND;
|
|
/* Protocol Discriminator */
|
if (*p != 0x08) {
|
PRINT("Unknown Protocol Discriminator\n");
|
return H323_ERROR_RANGE;
|
}
|
p++;
|
sz--;
|
|
/* CallReferenceValue */
|
if (sz < 1)
|
return H323_ERROR_BOUND;
|
len = *p++;
|
sz--;
|
if (sz < len)
|
return H323_ERROR_BOUND;
|
p += len;
|
sz -= len;
|
|
/* Message Type */
|
if (sz < 2)
|
return H323_ERROR_BOUND;
|
q931->MessageType = *p++;
|
sz--;
|
PRINT("MessageType = %02X\n", q931->MessageType);
|
if (*p & 0x80) {
|
p++;
|
sz--;
|
}
|
|
/* Decode Information Elements */
|
while (sz > 0) {
|
if (*p == 0x7e) { /* UserUserIE */
|
if (sz < 3)
|
break;
|
p++;
|
len = *p++ << 8;
|
len |= *p++;
|
sz -= 3;
|
if (sz < len)
|
break;
|
p++;
|
len--;
|
return DecodeH323_UserInformation(buf, p, len,
|
&q931->UUIE);
|
}
|
p++;
|
sz--;
|
if (sz < 1)
|
break;
|
len = *p++;
|
sz--;
|
if (sz < len)
|
break;
|
p += len;
|
sz -= len;
|
}
|
|
PRINT("Q.931 UUIE not found\n");
|
|
return H323_ERROR_BOUND;
|
}
|
