bigsize.c (3205B)
1 /* Copyright Rusty Russell (Blockstream) 2015. 2 William Casarin 2022 3 4 Permission is hereby granted, free of charge, to any person obtaining a copy 5 of this software and associated documentation files (the "Software"), to deal 6 in the Software without restriction, including without limitation the rights 7 to use, copy, modify, merge, publish, distribute, sublicense, and/or sell 8 copies of the Software, and to permit persons to whom the Software is 9 furnished to do so, subject to the following conditions: 10 11 The above copyright notice and this permission notice shall be included in 12 all copies or substantial portions of the Software. 13 14 THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR 15 IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 16 FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE 17 AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER 18 LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, 19 OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN 20 THE SOFTWARE. 21 */ 22 23 24 #include <assert.h> 25 #include "config.h" 26 #include "bigsize.h" 27 28 #ifndef SUPERVERBOSE 29 #define SUPERVERBOSE(...) 30 #endif 31 32 size_t bigsize_len(bigsize_t v) 33 { 34 if (v < 0xfd) { 35 return 1; 36 } else if (v <= 0xffff) { 37 return 3; 38 } else if (v <= 0xffffffff) { 39 return 5; 40 } else { 41 return 9; 42 } 43 } 44 45 size_t bigsize_put(u8 buf[BIGSIZE_MAX_LEN], bigsize_t v) 46 { 47 u8 *p = buf; 48 49 if (v < 0xfd) { 50 *(p++) = v; 51 } else if (v <= 0xffff) { 52 (*p++) = 0xfd; 53 (*p++) = v >> 8; 54 (*p++) = v; 55 } else if (v <= 0xffffffff) { 56 (*p++) = 0xfe; 57 (*p++) = v >> 24; 58 (*p++) = v >> 16; 59 (*p++) = v >> 8; 60 (*p++) = v; 61 } else { 62 (*p++) = 0xff; 63 (*p++) = v >> 56; 64 (*p++) = v >> 48; 65 (*p++) = v >> 40; 66 (*p++) = v >> 32; 67 (*p++) = v >> 24; 68 (*p++) = v >> 16; 69 (*p++) = v >> 8; 70 (*p++) = v; 71 } 72 return p - buf; 73 } 74 75 size_t bigsize_get(const u8 *p, size_t max, bigsize_t *val) 76 { 77 if (max < 1) { 78 SUPERVERBOSE("EOF"); 79 return 0; 80 } 81 82 switch (*p) { 83 case 0xfd: 84 if (max < 3) { 85 SUPERVERBOSE("unexpected EOF"); 86 return 0; 87 } 88 *val = ((u64)p[1] << 8) + p[2]; 89 if (*val < 0xfd) { 90 SUPERVERBOSE("decoded bigsize is not canonical"); 91 return 0; 92 } 93 return 3; 94 case 0xfe: 95 if (max < 5) { 96 SUPERVERBOSE("unexpected EOF"); 97 return 0; 98 } 99 *val = ((u64)p[1] << 24) + ((u64)p[2] << 16) 100 + ((u64)p[3] << 8) + p[4]; 101 if ((*val >> 16) == 0) { 102 SUPERVERBOSE("decoded bigsize is not canonical"); 103 return 0; 104 } 105 return 5; 106 case 0xff: 107 if (max < 9) { 108 SUPERVERBOSE("unexpected EOF"); 109 return 0; 110 } 111 *val = ((u64)p[1] << 56) + ((u64)p[2] << 48) 112 + ((u64)p[3] << 40) + ((u64)p[4] << 32) 113 + ((u64)p[5] << 24) + ((u64)p[6] << 16) 114 + ((u64)p[7] << 8) + p[8]; 115 if ((*val >> 32) == 0) { 116 SUPERVERBOSE("decoded bigsize is not canonical"); 117 return 0; 118 } 119 return 9; 120 default: 121 *val = *p; 122 return 1; 123 } 124 } 125 126 int cursor_pull_bigsize(struct cursor *cur, bigsize_t *out) 127 { 128 return bigsize_get(cur->p, cur->end - cur->p, out); 129 } 130 131 int cursor_push_bigsize(struct cursor *cur, const bigsize_t val) 132 { 133 u8 buf[BIGSIZE_MAX_LEN]; 134 size_t len; 135 136 len = bigsize_put(buf, val); 137 138 return cursor_push(cur, buf, len); 139 } 140