1/*
2 * Copyright (c) 2015, Intel Corporation
3 *
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions are met:
6 *
7 * * Redistributions of source code must retain the above copyright notice,
8 * this list of conditions and the following disclaimer.
9 * * Redistributions in binary form must reproduce the above copyright
10 * notice, this list of conditions and the following disclaimer in the
11 * documentation and/or other materials provided with the distribution.
12 * * Neither the name of Intel Corporation nor the names of its contributors
13 * may be used to endorse or promote products derived from this software
14 * without specific prior written permission.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
17 * AND 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 COPYRIGHT OWNER OR CONTRIBUTORS BE
20 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
21 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
22 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
23 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
24 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
25 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
26 * POSSIBILITY OF SUCH DAMAGE.
27 */
28
29/** \file
30 * \brief Reverse-acceleration optimizations for the NFA API block mode scans.
31 */
32
33#ifndef NFA_REV_API_H
34#define NFA_REV_API_H
35
36#include "accel.h"
37#include "nfa_internal.h"
38#include "vermicelli.h"
39#include "util/unaligned.h"
40
41static really_inline
42size_t nfaRevAccel_i(const struct NFA *nfa, const u8 *buffer, size_t length) {
43 DEBUG_PRINTF("checking rev accel mw %u\n", nfa->minWidth);
44 assert(nfa->rAccelOffset >= 1);
45 assert(nfa->rAccelOffset <= nfa->minWidth);
46
47 const u8 *rv; // result for accel engine
48
49 switch (nfa->rAccelType) {
50 case ACCEL_RVERM:
51 DEBUG_PRINTF("ACCEL_RVERM\n");
52 if (length + 1 - nfa->rAccelOffset < 16) {
53 break;
54 }
55
56 rv = rvermicelliExec(nfa->rAccelData.c, 0, buffer,
57 buffer + length + 1 - nfa->rAccelOffset);
58 length = (size_t)(rv - buffer + nfa->rAccelOffset);
59 break;
60 case ACCEL_RVERM_NOCASE:
61 DEBUG_PRINTF("ACCEL_RVERM_NOCASE\n");
62 if (length + 1 - nfa->rAccelOffset < 16) {
63 break;
64 }
65
66 rv = rvermicelliExec(nfa->rAccelData.c, 1, buffer,
67 buffer + length + 1 - nfa->rAccelOffset);
68 length = (size_t)(rv - buffer + nfa->rAccelOffset);
69 break;
70 case ACCEL_RDVERM:
71 DEBUG_PRINTF("ACCEL_RDVERM\n");
72 if (length + 1 - nfa->rAccelOffset < 17) {
73 break;
74 }
75
76 rv = rvermicelliDoubleExec(nfa->rAccelData.array[0],
77 nfa->rAccelData.array[1], 0, buffer,
78 buffer + length + 1 - nfa->rAccelOffset);
79 length = (size_t)(rv - buffer + nfa->rAccelOffset);
80 break;
81 case ACCEL_RDVERM_NOCASE:
82 DEBUG_PRINTF("ACCEL_RVERM_NOCASE\n");
83 if (length + 1 - nfa->rAccelOffset < 17) {
84 break;
85 }
86
87 rv = rvermicelliDoubleExec(nfa->rAccelData.array[0],
88 nfa->rAccelData.array[1], 1, buffer,
89 buffer + length + 1 - nfa->rAccelOffset);
90 length = (size_t)(rv - buffer + nfa->rAccelOffset);
91 break;
92 case ACCEL_REOD:
93 DEBUG_PRINTF("ACCEL_REOD\n");
94 if (buffer[length - nfa->rAccelOffset] != nfa->rAccelData.c) {
95 return 0;
96 }
97 break;
98 case ACCEL_REOD_NOCASE:
99 DEBUG_PRINTF("ACCEL_REOD_NOCASE\n");
100 if ((buffer[length - nfa->rAccelOffset] & CASE_CLEAR) !=
101 nfa->rAccelData.c) {
102 return 0;
103 }
104 break;
105 case ACCEL_RDEOD:
106 DEBUG_PRINTF("ACCEL_RDEOD\n");
107 if (unaligned_load_u16(buffer + length - nfa->rAccelOffset) !=
108 nfa->rAccelData.dc) {
109 return 0;
110 }
111 break;
112 case ACCEL_RDEOD_NOCASE:
113 DEBUG_PRINTF("ACCEL_RDEOD_NOCASE\n");
114 if ((unaligned_load_u16(buffer + length - nfa->rAccelOffset) &
115 DOUBLE_CASE_CLEAR) != nfa->rAccelData.dc) {
116 return 0;
117 }
118 break;
119 default:
120 assert(!"not here");
121 }
122
123 if (nfa->minWidth > length) {
124 DEBUG_PRINTF("post-accel, scan skipped: %zu < min %u bytes\n", length,
125 nfa->minWidth);
126 return 0;
127 }
128
129 return length;
130}
131
132/** \brief Reverse acceleration check. Returns a new length for the block,
133 * guaranteeing that a match cannot occur beyond that point. */
134static really_inline
135size_t nfaRevAccelCheck(const struct NFA *nfa, const u8 *buffer,
136 size_t length) {
137 assert(nfa);
138
139 // If this block is not long enough to satisfy the minimum width
140 // constraint on this NFA, we can avoid the scan altogether.
141 if (nfa->minWidth > length) {
142 DEBUG_PRINTF("scan skipped: %zu < min %u bytes\n", length,
143 nfa->minWidth);
144 return 0;
145 }
146
147 if (nfa->rAccelType == ACCEL_NONE) {
148 DEBUG_PRINTF("no rev accel available\n");
149 return length;
150 }
151
152 size_t rv_length = nfaRevAccel_i(nfa, buffer, length);
153 assert(rv_length <= length);
154 return rv_length;
155}
156
157#endif
158