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 #ifdef HAVE_CONFIG_H 31 #include "config.h" 32 #endif 33 34 #include <stdlib.h> 35 #include <string.h> 36 #include <tcpdump-stdinc.h> 37 38 #include "cpack.h" 39 #include "extract.h" 40 41 u_int8_t * 42 cpack_next_boundary(u_int8_t *buf, u_int8_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 u_int8_t * 57 cpack_align_and_reserve(struct cpack_state *cs, size_t wordsize) 58 { 59 u_int8_t *next; 60 61 /* Ensure alignment. */ 62 next = 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 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 cpack_init(struct cpack_state *cs, u_int8_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 cpack_uint64(struct cpack_state *cs, u_int64_t *u) 97 { 98 u_int8_t *next; 99 100 if ((next = cpack_align_and_reserve(cs, sizeof(*u))) == NULL) 101 return -1; 102 103 *u = EXTRACT_LE_64BITS(next); 104 105 /* Move pointer past the u_int64_t. */ 106 cs->c_next = next + sizeof(*u); 107 return 0; 108 } 109 110 /* Unpack a 32-bit unsigned integer. */ 111 int 112 cpack_uint32(struct cpack_state *cs, u_int32_t *u) 113 { 114 u_int8_t *next; 115 116 if ((next = cpack_align_and_reserve(cs, sizeof(*u))) == NULL) 117 return -1; 118 119 *u = EXTRACT_LE_32BITS(next); 120 121 /* Move pointer past the u_int32_t. */ 122 cs->c_next = next + sizeof(*u); 123 return 0; 124 } 125 126 /* Unpack a 16-bit unsigned integer. */ 127 int 128 cpack_uint16(struct cpack_state *cs, u_int16_t *u) 129 { 130 u_int8_t *next; 131 132 if ((next = cpack_align_and_reserve(cs, sizeof(*u))) == NULL) 133 return -1; 134 135 *u = EXTRACT_LE_16BITS(next); 136 137 /* Move pointer past the u_int16_t. */ 138 cs->c_next = next + sizeof(*u); 139 return 0; 140 } 141 142 /* Unpack an 8-bit unsigned integer. */ 143 int 144 cpack_uint8(struct cpack_state *cs, u_int8_t *u) 145 { 146 /* No space left? */ 147 if ((size_t)(cs->c_next - cs->c_buf) >= cs->c_len) 148 return -1; 149 150 *u = *cs->c_next; 151 152 /* Move pointer past the u_int8_t. */ 153 cs->c_next++; 154 return 0; 155 } 156
