1 /*- 2 * Copyright (c) 2003, 2004 David Young. All rights reserved. 3 * 4 * Redistribution and use in source and binary forms, with or without 5 * modification, are permitted provided that the following conditions 6 * are met: 7 * 1. Redistributions of source code must retain the above copyright 8 * notice, this list of conditions and the following disclaimer. 9 * 2. 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 * 3. The name of David Young may not be used to endorse or promote 13 * products derived from this software without specific prior 14 * written permission. 15 * 16 * THIS SOFTWARE IS PROVIDED BY DAVID YOUNG ``AS IS'' AND ANY 17 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, 18 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A 19 * PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL DAVID 20 * YOUNG BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, 21 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED 22 * TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 23 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND 24 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, 25 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY 27 * OF SUCH DAMAGE. 28 */ 29 30 #include <config.h> 31 32 #include <stdlib.h> 33 #include <string.h> 34 #include "netdissect-stdinc.h" 35 36 #include "netdissect.h" 37 #include "extract.h" 38 39 #include "cpack.h" 40 41 const uint8_t * 42 nd_cpack_next_boundary(const uint8_t *buf, const uint8_t *p, size_t alignment) 43 { 44 size_t misalignment = (size_t)(p - buf) % alignment; 45 46 if (misalignment == 0) 47 return p; 48 49 return p + (alignment - misalignment); 50 } 51 52 /* Advance to the next wordsize boundary. Return NULL if fewer than 53 * wordsize bytes remain in the buffer after the boundary. Otherwise, 54 * return a pointer to the boundary. 55 */ 56 const uint8_t * 57 nd_cpack_align_and_reserve(struct cpack_state *cs, size_t wordsize) 58 { 59 const uint8_t *next; 60 61 /* Ensure alignment. */ 62 next = nd_cpack_next_boundary(cs->c_buf, cs->c_next, wordsize); 63 64 /* Too little space for wordsize bytes? */ 65 if (next - cs->c_buf + wordsize > cs->c_len) 66 return NULL; 67 68 return next; 69 } 70 71 /* Advance by N bytes without returning them. */ 72 int 73 nd_cpack_advance(struct cpack_state *cs, const size_t toskip) 74 { 75 /* No space left? */ 76 if (cs->c_next - cs->c_buf + toskip > cs->c_len) 77 return -1; 78 cs->c_next += toskip; 79 return 0; 80 } 81 82 int 83 nd_cpack_init(struct cpack_state *cs, const uint8_t *buf, size_t buflen) 84 { 85 memset(cs, 0, sizeof(*cs)); 86 87 cs->c_buf = buf; 88 cs->c_len = buflen; 89 cs->c_next = cs->c_buf; 90 91 return 0; 92 } 93 94 /* Unpack a 64-bit unsigned integer. */ 95 int 96 nd_cpack_uint64(netdissect_options *ndo, struct cpack_state *cs, uint64_t *u) 97 { 98 const uint8_t *next; 99 100 if ((next = nd_cpack_align_and_reserve(cs, sizeof(*u))) == NULL) 101 return -1; 102 103 *u = GET_LE_U_8(next); 104 105 /* Move pointer past the uint64_t. */ 106 cs->c_next = next + sizeof(*u); 107 return 0; 108 } 109 110 /* Unpack a 64-bit signed integer. */ 111 int 112 nd_cpack_int64(netdissect_options *ndo, struct cpack_state *cs, int64_t *u) 113 { 114 const uint8_t *next; 115 116 if ((next = nd_cpack_align_and_reserve(cs, sizeof(*u))) == NULL) 117 return -1; 118 119 *u = GET_LE_S_8(next); 120 121 /* Move pointer past the int64_t. */ 122 cs->c_next = next + sizeof(*u); 123 return 0; 124 } 125 126 /* Unpack a 32-bit unsigned integer. */ 127 int 128 nd_cpack_uint32(netdissect_options *ndo, struct cpack_state *cs, uint32_t *u) 129 { 130 const uint8_t *next; 131 132 if ((next = nd_cpack_align_and_reserve(cs, sizeof(*u))) == NULL) 133 return -1; 134 135 *u = GET_LE_U_4(next); 136 137 /* Move pointer past the uint32_t. */ 138 cs->c_next = next + sizeof(*u); 139 return 0; 140 } 141 142 /* Unpack a 32-bit signed integer. */ 143 int 144 nd_cpack_int32(netdissect_options *ndo, struct cpack_state *cs, int32_t *u) 145 { 146 const uint8_t *next; 147 148 if ((next = nd_cpack_align_and_reserve(cs, sizeof(*u))) == NULL) 149 return -1; 150 151 *u = GET_LE_S_4(next); 152 153 /* Move pointer past the int32_t. */ 154 cs->c_next = next + sizeof(*u); 155 return 0; 156 } 157 158 /* Unpack a 16-bit unsigned integer. */ 159 int 160 nd_cpack_uint16(netdissect_options *ndo, struct cpack_state *cs, uint16_t *u) 161 { 162 const uint8_t *next; 163 164 if ((next = nd_cpack_align_and_reserve(cs, sizeof(*u))) == NULL) 165 return -1; 166 167 *u = GET_LE_U_2(next); 168 169 /* Move pointer past the uint16_t. */ 170 cs->c_next = next + sizeof(*u); 171 return 0; 172 } 173 174 /* Unpack a 16-bit signed integer. */ 175 int 176 nd_cpack_int16(netdissect_options *ndo, struct cpack_state *cs, int16_t *u) 177 { 178 const uint8_t *next; 179 180 if ((next = nd_cpack_align_and_reserve(cs, sizeof(*u))) == NULL) 181 return -1; 182 183 *u = GET_LE_S_2(next); 184 185 /* Move pointer past the int16_t. */ 186 cs->c_next = next + sizeof(*u); 187 return 0; 188 } 189 190 /* Unpack an 8-bit unsigned integer. */ 191 int 192 nd_cpack_uint8(netdissect_options *ndo, struct cpack_state *cs, uint8_t *u) 193 { 194 /* No space left? */ 195 if ((size_t)(cs->c_next - cs->c_buf) >= cs->c_len) 196 return -1; 197 198 *u = GET_U_1(cs->c_next); 199 200 /* Move pointer past the uint8_t. */ 201 cs->c_next++; 202 return 0; 203 } 204 205 /* Unpack an 8-bit signed integer. */ 206 int 207 nd_cpack_int8(netdissect_options *ndo, struct cpack_state *cs, int8_t *u) 208 { 209 /* No space left? */ 210 if ((size_t)(cs->c_next - cs->c_buf) >= cs->c_len) 211 return -1; 212 213 *u = GET_S_1(cs->c_next); 214 215 /* Move pointer past the int8_t. */ 216 cs->c_next++; 217 return 0; 218 } 219