1 /* -*- mode: c; c-basic-offset: 4; indent-tabs-mode: nil -*- */ 2 /* include/k5-input.h - k5input helper functions */ 3 /* 4 * Copyright (C) 2014 by the Massachusetts Institute of Technology. 5 * All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 11 * * Redistributions of source code must retain the above copyright 12 * notice, this list of conditions and the following disclaimer. 13 * 14 * * Redistributions in binary form must reproduce the above copyright 15 * notice, this list of conditions and the following disclaimer in 16 * the documentation and/or other materials provided with the 17 * distribution. 18 * 19 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 20 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 21 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS 22 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE 23 * COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, 24 * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES 25 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR 26 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, 28 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 29 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED 30 * OF THE POSSIBILITY OF SUCH DAMAGE. 31 */ 32 33 #ifndef K5_INPUT_H 34 #define K5_INPUT_H 35 36 #include "k5-platform.h" 37 38 /* 39 * The k5input module defines helpers for safely consuming a fixed-sized block 40 * of memory. If an overrun or allocation failure occurs at any step, 41 * subsequent functions will return default values until the error is detected 42 * by looking at the status field. 43 */ 44 45 struct k5input { 46 const unsigned char *ptr; 47 size_t len; 48 int32_t status; 49 }; 50 51 static inline void 52 k5_input_init(struct k5input *in, const void *ptr, size_t len) 53 { 54 in->ptr = ptr; 55 in->len = len; 56 in->status = 0; 57 } 58 59 /* Only set the status value of in if it hasn't already been set, so status 60 * reflects the first thing to go wrong. */ 61 static inline void 62 k5_input_set_status(struct k5input *in, int32_t status) 63 { 64 if (!in->status) 65 in->status = status; 66 } 67 68 static inline const unsigned char * 69 k5_input_get_bytes(struct k5input *in, size_t len) 70 { 71 if (in->len < len) 72 k5_input_set_status(in, EINVAL); 73 if (in->status) 74 return NULL; 75 in->len -= len; 76 in->ptr += len; 77 return in->ptr - len; 78 } 79 80 static inline unsigned char 81 k5_input_get_byte(struct k5input *in) 82 { 83 const unsigned char *ptr = k5_input_get_bytes(in, 1); 84 return (ptr == NULL) ? '\0' : *ptr; 85 } 86 87 static inline uint16_t 88 k5_input_get_uint16_be(struct k5input *in) 89 { 90 const unsigned char *ptr = k5_input_get_bytes(in, 2); 91 return (ptr == NULL) ? 0 : load_16_be(ptr); 92 } 93 94 static inline uint16_t 95 k5_input_get_uint16_le(struct k5input *in) 96 { 97 const unsigned char *ptr = k5_input_get_bytes(in, 2); 98 return (ptr == NULL) ? 0 : load_16_le(ptr); 99 } 100 101 static inline uint16_t 102 k5_input_get_uint16_n(struct k5input *in) 103 { 104 const unsigned char *ptr = k5_input_get_bytes(in, 2); 105 return (ptr == NULL) ? 0 : load_16_n(ptr); 106 } 107 108 static inline uint32_t 109 k5_input_get_uint32_be(struct k5input *in) 110 { 111 const unsigned char *ptr = k5_input_get_bytes(in, 4); 112 return (ptr == NULL) ? 0 : load_32_be(ptr); 113 } 114 115 static inline uint32_t 116 k5_input_get_uint32_le(struct k5input *in) 117 { 118 const unsigned char *ptr = k5_input_get_bytes(in, 4); 119 return (ptr == NULL) ? 0 : load_32_le(ptr); 120 } 121 122 static inline uint32_t 123 k5_input_get_uint32_n(struct k5input *in) 124 { 125 const unsigned char *ptr = k5_input_get_bytes(in, 4); 126 return (ptr == NULL) ? 0 : load_32_n(ptr); 127 } 128 129 static inline uint64_t 130 k5_input_get_uint64_be(struct k5input *in) 131 { 132 const unsigned char *ptr = k5_input_get_bytes(in, 8); 133 return (ptr == NULL) ? 0 : load_64_be(ptr); 134 } 135 136 static inline uint64_t 137 k5_input_get_uint64_le(struct k5input *in) 138 { 139 const unsigned char *ptr = k5_input_get_bytes(in, 8); 140 return (ptr == NULL) ? 0 : load_64_le(ptr); 141 } 142 143 #endif /* K5_BUF_H */ 144