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 #define NETDISSECT_REWORKED 31 #ifdef HAVE_CONFIG_H 32 #include "config.h" 33 #endif 34 35 #include <stdlib.h> 36 #include <string.h> 37 #include <tcpdump-stdinc.h> 38 39 #include "cpack.h" 40 #include "extract.h" 41 42 uint8_t * 43 cpack_next_boundary(uint8_t *buf, uint8_t *p, size_t alignment) 44 { 45 size_t misalignment = (size_t)(p - buf) % alignment; 46 47 if (misalignment == 0) 48 return p; 49 50 return p + (alignment - misalignment); 51 } 52 53 /* Advance to the next wordsize boundary. Return NULL if fewer than 54 * wordsize bytes remain in the buffer after the boundary. Otherwise, 55 * return a pointer to the boundary. 56 */ 57 uint8_t * 58 cpack_align_and_reserve(struct cpack_state *cs, size_t wordsize) 59 { 60 uint8_t *next; 61 62 /* Ensure alignment. */ 63 next = cpack_next_boundary(cs->c_buf, cs->c_next, wordsize); 64 65 /* Too little space for wordsize bytes? */ 66 if (next - cs->c_buf + wordsize > cs->c_len) 67 return NULL; 68 69 return next; 70 } 71 72 /* Advance by N bytes without returning them. */ 73 int 74 cpack_advance(struct cpack_state *cs, const size_t toskip) 75 { 76 /* No space left? */ 77 if (cs->c_next - cs->c_buf + toskip > cs->c_len) 78 return -1; 79 cs->c_next += toskip; 80 return 0; 81 } 82 83 int 84 cpack_init(struct cpack_state *cs, uint8_t *buf, size_t buflen) 85 { 86 memset(cs, 0, sizeof(*cs)); 87 88 cs->c_buf = buf; 89 cs->c_len = buflen; 90 cs->c_next = cs->c_buf; 91 92 return 0; 93 } 94 95 /* Unpack a 64-bit unsigned integer. */ 96 int 97 cpack_uint64(struct cpack_state *cs, uint64_t *u) 98 { 99 uint8_t *next; 100 101 if ((next = cpack_align_and_reserve(cs, sizeof(*u))) == NULL) 102 return -1; 103 104 *u = EXTRACT_LE_64BITS(next); 105 106 /* Move pointer past the uint64_t. */ 107 cs->c_next = next + sizeof(*u); 108 return 0; 109 } 110 111 /* Unpack a 32-bit unsigned integer. */ 112 int 113 cpack_uint32(struct cpack_state *cs, uint32_t *u) 114 { 115 uint8_t *next; 116 117 if ((next = cpack_align_and_reserve(cs, sizeof(*u))) == NULL) 118 return -1; 119 120 *u = EXTRACT_LE_32BITS(next); 121 122 /* Move pointer past the uint32_t. */ 123 cs->c_next = next + sizeof(*u); 124 return 0; 125 } 126 127 /* Unpack a 16-bit unsigned integer. */ 128 int 129 cpack_uint16(struct cpack_state *cs, uint16_t *u) 130 { 131 uint8_t *next; 132 133 if ((next = cpack_align_and_reserve(cs, sizeof(*u))) == NULL) 134 return -1; 135 136 *u = EXTRACT_LE_16BITS(next); 137 138 /* Move pointer past the uint16_t. */ 139 cs->c_next = next + sizeof(*u); 140 return 0; 141 } 142 143 /* Unpack an 8-bit unsigned integer. */ 144 int 145 cpack_uint8(struct cpack_state *cs, uint8_t *u) 146 { 147 /* No space left? */ 148 if ((size_t)(cs->c_next - cs->c_buf) >= cs->c_len) 149 return -1; 150 151 *u = *cs->c_next; 152 153 /* Move pointer past the uint8_t. */ 154 cs->c_next++; 155 return 0; 156 } 157
