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 static 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 static 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 int 72 cpack_init(struct cpack_state *cs, u_int8_t *buf, size_t buflen) 73 { 74 memset(cs, 0, sizeof(*cs)); 75 76 cs->c_buf = buf; 77 cs->c_len = buflen; 78 cs->c_next = cs->c_buf; 79 80 return 0; 81 } 82 83 /* Unpack a 64-bit unsigned integer. */ 84 int 85 cpack_uint64(struct cpack_state *cs, u_int64_t *u) 86 { 87 u_int8_t *next; 88 89 if ((next = cpack_align_and_reserve(cs, sizeof(*u))) == NULL) 90 return -1; 91 92 *u = EXTRACT_LE_64BITS(next); 93 94 /* Move pointer past the u_int64_t. */ 95 cs->c_next = next + sizeof(*u); 96 return 0; 97 } 98 99 /* Unpack a 32-bit unsigned integer. */ 100 int 101 cpack_uint32(struct cpack_state *cs, u_int32_t *u) 102 { 103 u_int8_t *next; 104 105 if ((next = cpack_align_and_reserve(cs, sizeof(*u))) == NULL) 106 return -1; 107 108 *u = EXTRACT_LE_32BITS(next); 109 110 /* Move pointer past the u_int32_t. */ 111 cs->c_next = next + sizeof(*u); 112 return 0; 113 } 114 115 /* Unpack a 16-bit unsigned integer. */ 116 int 117 cpack_uint16(struct cpack_state *cs, u_int16_t *u) 118 { 119 u_int8_t *next; 120 121 if ((next = cpack_align_and_reserve(cs, sizeof(*u))) == NULL) 122 return -1; 123 124 *u = EXTRACT_LE_16BITS(next); 125 126 /* Move pointer past the u_int16_t. */ 127 cs->c_next = next + sizeof(*u); 128 return 0; 129 } 130 131 /* Unpack an 8-bit unsigned integer. */ 132 int 133 cpack_uint8(struct cpack_state *cs, u_int8_t *u) 134 { 135 /* No space left? */ 136 if ((size_t)(cs->c_next - cs->c_buf) >= cs->c_len) 137 return -1; 138 139 *u = *cs->c_next; 140 141 /* Move pointer past the u_int8_t. */ 142 cs->c_next++; 143 return 0; 144 } 145