| 1 | /* |
| 2 | * This file is part of DisOrder |
| 3 | * Copyright (C) 2004, 2005, 2007-9, 2013 Richard Kettlewell |
| 4 | * |
| 5 | * This program is free software: you can redistribute it and/or modify |
| 6 | * it under the terms of the GNU General Public License as published by |
| 7 | * the Free Software Foundation, either version 3 of the License, or |
| 8 | * (at your option) any later version. |
| 9 | * |
| 10 | * This program is distributed in the hope that it will be useful, |
| 11 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 12 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 13 | * GNU General Public License for more details. |
| 14 | * |
| 15 | * You should have received a copy of the GNU General Public License |
| 16 | * along with this program. If not, see <http://www.gnu.org/licenses/>. |
| 17 | */ |
| 18 | /** @file lib/hex.c @brief Hexadecimal encoding and decoding */ |
| 19 | |
| 20 | #include "common.h" |
| 21 | |
| 22 | #include "hex.h" |
| 23 | #include "mem.h" |
| 24 | #include "log.h" |
| 25 | #include "printf.h" |
| 26 | |
| 27 | /** @brief Convert a byte sequence to hex |
| 28 | * @param ptr Pointer to first byte |
| 29 | * @param n Number of bytes |
| 30 | * @return Allocated string containing hexdump |
| 31 | */ |
| 32 | char *hex(const uint8_t *ptr, size_t n) { |
| 33 | char *buf = xmalloc_noptr(n * 2 + 1), *p = buf; |
| 34 | |
| 35 | while(n-- > 0) |
| 36 | p += byte_snprintf(p, 3, "%02x", (unsigned)*ptr++); |
| 37 | *p = 0; |
| 38 | return buf; |
| 39 | } |
| 40 | |
| 41 | /** @brief Convert a character to its value as a hex digit |
| 42 | * @param c Character code |
| 43 | * @return Value has hex digit or -1 |
| 44 | * |
| 45 | * The 'q' stands for 'quiet' - this function does not report errors. |
| 46 | */ |
| 47 | int unhexdigitq(int c) { |
| 48 | switch(c) { |
| 49 | case '0': return 0; |
| 50 | case '1': return 1; |
| 51 | case '2': return 2; |
| 52 | case '3': return 3; |
| 53 | case '4': return 4; |
| 54 | case '5': return 5; |
| 55 | case '6': return 6; |
| 56 | case '7': return 7; |
| 57 | case '8': return 8; |
| 58 | case '9': return 9; |
| 59 | case 'a': case 'A': return 10; |
| 60 | case 'b': case 'B': return 11; |
| 61 | case 'c': case 'C': return 12; |
| 62 | case 'd': case 'D': return 13; |
| 63 | case 'e': case 'E': return 14; |
| 64 | case 'f': case 'F': return 15; |
| 65 | default: return -1; |
| 66 | } |
| 67 | } |
| 68 | |
| 69 | /** @brief Convert a character to its value as a hex digit |
| 70 | * @param c Character code |
| 71 | * @return Value has hex digit or -1 |
| 72 | * |
| 73 | * If the character is not a valid hex digit then an error is logged. |
| 74 | * See @ref unhexdigitq() if that is a problem. |
| 75 | */ |
| 76 | int unhexdigit(int c) { |
| 77 | int d; |
| 78 | |
| 79 | if((d = unhexdigitq(c)) < 0) |
| 80 | disorder_error(0, "invalid hex digit"); |
| 81 | return d; |
| 82 | } |
| 83 | |
| 84 | /** @brief Convert a hex string to bytes |
| 85 | * @param s Pointer to hex string |
| 86 | * @param np Where to store byte string length or NULL |
| 87 | * @return Allocated buffer, or 0 |
| 88 | * |
| 89 | * @p s should point to a 0-terminated string containing an even number |
| 90 | * of hex digits. They are converted to bytes and returned via the return |
| 91 | * value and optionally the length via @p np. |
| 92 | * |
| 93 | * On any error a message is logged and a null pointer is returned. |
| 94 | */ |
| 95 | uint8_t *unhex(const char *s, size_t *np) { |
| 96 | size_t l; |
| 97 | uint8_t *buf, *p; |
| 98 | int d1, d2; |
| 99 | |
| 100 | if((l = strlen(s)) & 1) { |
| 101 | disorder_error(0, "hex string has odd length"); |
| 102 | return 0; |
| 103 | } |
| 104 | p = buf = xmalloc_noptr(l / 2); |
| 105 | while(*s) { |
| 106 | if((d1 = unhexdigit(*s++)) < 0) return 0; |
| 107 | if((d2 = unhexdigit(*s++)) < 0) return 0; |
| 108 | *p++ = d1 * 16 + d2; |
| 109 | } |
| 110 | if(np) |
| 111 | *np = l / 2; |
| 112 | return buf; |
| 113 | } |
| 114 | |
| 115 | /* |
| 116 | Local Variables: |
| 117 | c-basic-offset:2 |
| 118 | comment-column:40 |
| 119 | End: |
| 120 | */ |