cpack.c revision 146773
1146773Ssam/*- 2146773Ssam * Copyright (c) 2003, 2004 David Young. All rights reserved. 3146773Ssam * 4146773Ssam * Redistribution and use in source and binary forms, with or without 5146773Ssam * modification, are permitted provided that the following conditions 6146773Ssam * are met: 7146773Ssam * 1. Redistributions of source code must retain the above copyright 8146773Ssam * notice, this list of conditions and the following disclaimer. 9146773Ssam * 2. Redistributions in binary form must reproduce the above copyright 10146773Ssam * notice, this list of conditions and the following disclaimer in the 11146773Ssam * documentation and/or other materials provided with the distribution. 12146773Ssam * 3. The name of David Young may not be used to endorse or promote 13146773Ssam * products derived from this software without specific prior 14146773Ssam * written permission. 15146773Ssam * 16146773Ssam * THIS SOFTWARE IS PROVIDED BY DAVID YOUNG ``AS IS'' AND ANY 17146773Ssam * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, 18146773Ssam * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A 19146773Ssam * PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL DAVID 20146773Ssam * YOUNG BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, 21146773Ssam * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED 22146773Ssam * TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 23146773Ssam * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND 24146773Ssam * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, 25146773Ssam * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 26146773Ssam * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY 27146773Ssam * OF SUCH DAMAGE. 28146773Ssam */ 29146773Ssam 30146773Ssam#ifdef HAVE_CONFIG_H 31146773Ssam#include "config.h" 32146773Ssam#endif 33146773Ssam 34146773Ssam#include <stdlib.h> 35146773Ssam#include <string.h> 36146773Ssam#include <tcpdump-stdinc.h> 37146773Ssam 38146773Ssam#include "cpack.h" 39146773Ssam#include "extract.h" 40146773Ssam 41146773Ssamstatic u_int8_t * 42146773Ssamcpack_next_boundary(u_int8_t *buf, u_int8_t *p, size_t alignment) 43146773Ssam{ 44146773Ssam size_t misalignment = (size_t)(p - buf) % alignment; 45146773Ssam 46146773Ssam if (misalignment == 0) 47146773Ssam return p; 48146773Ssam 49146773Ssam return p + (alignment - misalignment); 50146773Ssam} 51146773Ssam 52146773Ssam/* Advance to the next wordsize boundary. Return NULL if fewer than 53146773Ssam * wordsize bytes remain in the buffer after the boundary. Otherwise, 54146773Ssam * return a pointer to the boundary. 55146773Ssam */ 56146773Ssamstatic u_int8_t * 57146773Ssamcpack_align_and_reserve(struct cpack_state *cs, size_t wordsize) 58146773Ssam{ 59146773Ssam u_int8_t *next; 60146773Ssam 61146773Ssam /* Ensure alignment. */ 62146773Ssam next = cpack_next_boundary(cs->c_buf, cs->c_next, wordsize); 63146773Ssam 64146773Ssam /* Too little space for wordsize bytes? */ 65146773Ssam if (next - cs->c_buf + wordsize > cs->c_len) 66146773Ssam return NULL; 67146773Ssam 68146773Ssam return next; 69146773Ssam} 70146773Ssam 71146773Ssamint 72146773Ssamcpack_init(struct cpack_state *cs, u_int8_t *buf, size_t buflen) 73146773Ssam{ 74146773Ssam memset(cs, 0, sizeof(*cs)); 75146773Ssam 76146773Ssam cs->c_buf = buf; 77146773Ssam cs->c_len = buflen; 78146773Ssam cs->c_next = cs->c_buf; 79146773Ssam 80146773Ssam return 0; 81146773Ssam} 82146773Ssam 83146773Ssam/* Unpack a 64-bit unsigned integer. */ 84146773Ssamint 85146773Ssamcpack_uint64(struct cpack_state *cs, u_int64_t *u) 86146773Ssam{ 87146773Ssam u_int8_t *next; 88146773Ssam 89146773Ssam if ((next = cpack_align_and_reserve(cs, sizeof(*u))) == NULL) 90146773Ssam return -1; 91146773Ssam 92146773Ssam *u = EXTRACT_LE_64BITS(next); 93146773Ssam 94146773Ssam /* Move pointer past the u_int64_t. */ 95146773Ssam cs->c_next = next + sizeof(*u); 96146773Ssam return 0; 97146773Ssam} 98146773Ssam 99146773Ssam/* Unpack a 32-bit unsigned integer. */ 100146773Ssamint 101146773Ssamcpack_uint32(struct cpack_state *cs, u_int32_t *u) 102146773Ssam{ 103146773Ssam u_int8_t *next; 104146773Ssam 105146773Ssam if ((next = cpack_align_and_reserve(cs, sizeof(*u))) == NULL) 106146773Ssam return -1; 107146773Ssam 108146773Ssam *u = EXTRACT_LE_32BITS(next); 109146773Ssam 110146773Ssam /* Move pointer past the u_int32_t. */ 111146773Ssam cs->c_next = next + sizeof(*u); 112146773Ssam return 0; 113146773Ssam} 114146773Ssam 115146773Ssam/* Unpack a 16-bit unsigned integer. */ 116146773Ssamint 117146773Ssamcpack_uint16(struct cpack_state *cs, u_int16_t *u) 118146773Ssam{ 119146773Ssam u_int8_t *next; 120146773Ssam 121146773Ssam if ((next = cpack_align_and_reserve(cs, sizeof(*u))) == NULL) 122146773Ssam return -1; 123146773Ssam 124146773Ssam *u = EXTRACT_LE_16BITS(next); 125146773Ssam 126146773Ssam /* Move pointer past the u_int16_t. */ 127146773Ssam cs->c_next = next + sizeof(*u); 128146773Ssam return 0; 129146773Ssam} 130146773Ssam 131146773Ssam/* Unpack an 8-bit unsigned integer. */ 132146773Ssamint 133146773Ssamcpack_uint8(struct cpack_state *cs, u_int8_t *u) 134146773Ssam{ 135146773Ssam /* No space left? */ 136146773Ssam if ((size_t)(cs->c_next - cs->c_buf) >= cs->c_len) 137146773Ssam return -1; 138146773Ssam 139146773Ssam *u = *cs->c_next; 140146773Ssam 141146773Ssam /* Move pointer past the u_int8_t. */ 142146773Ssam cs->c_next++; 143146773Ssam return 0; 144146773Ssam} 145