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Diffstat (limited to 'src/nvim/base64.c')
| -rw-r--r-- | src/nvim/base64.c | 215 |
1 files changed, 215 insertions, 0 deletions
diff --git a/src/nvim/base64.c b/src/nvim/base64.c new file mode 100644 index 0000000000..295dedd8d3 --- /dev/null +++ b/src/nvim/base64.c @@ -0,0 +1,215 @@ +#include <assert.h> +#include <stddef.h> +#include <stdint.h> +#include <string.h> + +#include "auto/config.h" // IWYU pragma: keep +#include "nvim/base64.h" +#include "nvim/memory.h" + +#ifdef HAVE_BE64TOH +# include ENDIAN_INCLUDE_FILE +#endif + +#ifdef INCLUDE_GENERATED_DECLARATIONS +# include "base64.c.generated.h" // IWYU pragma: export +#endif + +static const char alphabet[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"; + +// Indices are 1-based because we use 0 to indicate a letter that is not part of the alphabet +static const uint8_t char_to_index[256] = { + ['A'] = 1, ['B'] = 2, ['C'] = 3, ['D'] = 4, ['E'] = 5, ['F'] = 6, ['G'] = 7, ['H'] = 8, + ['I'] = 9, ['J'] = 10, ['K'] = 11, ['L'] = 12, ['M'] = 13, ['N'] = 14, ['O'] = 15, ['P'] = 16, + ['Q'] = 17, ['R'] = 18, ['S'] = 19, ['T'] = 20, ['U'] = 21, ['V'] = 22, ['W'] = 23, ['X'] = 24, + ['Y'] = 25, ['Z'] = 26, ['a'] = 27, ['b'] = 28, ['c'] = 29, ['d'] = 30, ['e'] = 31, ['f'] = 32, + ['g'] = 33, ['h'] = 34, ['i'] = 35, ['j'] = 36, ['k'] = 37, ['l'] = 38, ['m'] = 39, ['n'] = 40, + ['o'] = 41, ['p'] = 42, ['q'] = 43, ['r'] = 44, ['s'] = 45, ['t'] = 46, ['u'] = 47, ['v'] = 48, + ['w'] = 49, ['x'] = 50, ['y'] = 51, ['z'] = 52, ['0'] = 53, ['1'] = 54, ['2'] = 55, ['3'] = 56, + ['4'] = 57, ['5'] = 58, ['6'] = 59, ['7'] = 60, ['8'] = 61, ['9'] = 62, ['+'] = 63, ['/'] = 64, +}; + +#ifndef HAVE_BE64TOH +static inline uint64_t htobe64(uint64_t host_64bits) +{ +# ifdef ORDER_BIG_ENDIAN + return host_64bits; +# else + uint8_t *buf = (uint8_t *)&host_64bits; + uint64_t ret = 0; + for (size_t i = 8; i; i--) { + ret |= ((uint64_t)buf[i - 1]) << ((8 - i) * 8); + } + return ret; +# endif +} + +static inline uint32_t htobe32(uint32_t host_32bits) +{ +# ifdef ORDER_BIG_ENDIAN + return host_32bits; +# else + uint8_t *buf = (uint8_t *)&host_32bits; + uint32_t ret = 0; + for (size_t i = 4; i; i--) { + ret |= ((uint32_t)buf[i - 1]) << ((4 - i) * 8); + } + return ret; +# endif +} +#endif + +/// Encode a string using Base64. +/// +/// @param src String to encode +/// @param src_len Length of the string +/// @return Base64 encoded string +char *base64_encode(const char *src, size_t src_len) +{ + assert(src != NULL); + + const size_t out_len = ((src_len + 2) / 3) * 4; + char *dest = xmalloc(out_len + 1); + + size_t src_i = 0; + size_t out_i = 0; + + const uint8_t *s = (const uint8_t *)src; + + // Read 8 bytes at a time as much as we can + for (; src_i + 7 < src_len; src_i += 6) { + uint64_t bits_h; + memcpy(&bits_h, &s[src_i], sizeof(uint64_t)); + const uint64_t bits_be = htobe64(bits_h); + dest[out_i + 0] = alphabet[(bits_be >> 58) & 0x3F]; + dest[out_i + 1] = alphabet[(bits_be >> 52) & 0x3F]; + dest[out_i + 2] = alphabet[(bits_be >> 46) & 0x3F]; + dest[out_i + 3] = alphabet[(bits_be >> 40) & 0x3F]; + dest[out_i + 4] = alphabet[(bits_be >> 34) & 0x3F]; + dest[out_i + 5] = alphabet[(bits_be >> 28) & 0x3F]; + dest[out_i + 6] = alphabet[(bits_be >> 22) & 0x3F]; + dest[out_i + 7] = alphabet[(bits_be >> 16) & 0x3F]; + out_i += sizeof(uint64_t); + } + + for (; src_i + 3 < src_len; src_i += 3) { + uint32_t bits_h; + memcpy(&bits_h, &s[src_i], sizeof(uint32_t)); + const uint32_t bits_be = htobe32(bits_h); + dest[out_i + 0] = alphabet[(bits_be >> 26) & 0x3F]; + dest[out_i + 1] = alphabet[(bits_be >> 20) & 0x3F]; + dest[out_i + 2] = alphabet[(bits_be >> 14) & 0x3F]; + dest[out_i + 3] = alphabet[(bits_be >> 8) & 0x3F]; + out_i += sizeof(uint32_t); + } + + if (src_i + 2 < src_len) { + dest[out_i + 0] = alphabet[s[src_i] >> 2]; + dest[out_i + 1] = alphabet[((s[src_i] & 0x3) << 4) | (s[src_i + 1] >> 4)]; + dest[out_i + 2] = alphabet[(s[src_i + 1] & 0xF) << 2 | (s[src_i + 2] >> 6)]; + dest[out_i + 3] = alphabet[(s[src_i + 2] & 0x3F)]; + out_i += 4; + } else if (src_i + 1 < src_len) { + dest[out_i + 0] = alphabet[s[src_i] >> 2]; + dest[out_i + 1] = alphabet[((s[src_i] & 0x3) << 4) | (s[src_i + 1] >> 4)]; + dest[out_i + 2] = alphabet[(s[src_i + 1] & 0xF) << 2]; + out_i += 3; + } else if (src_i < src_len) { + dest[out_i + 0] = alphabet[s[src_i] >> 2]; + dest[out_i + 1] = alphabet[(s[src_i] & 0x3) << 4]; + out_i += 2; + } + + for (; out_i < out_len; out_i++) { + dest[out_i] = '='; + } + + dest[out_len] = '\0'; + + return dest; +} + +/// Decode a Base64 encoded string. +/// +/// @param src Base64 encoded string +/// @param src_len Length of {src} +/// @return Decoded string +char *base64_decode(const char *src, size_t src_len) +{ + assert(src != NULL); + + char *dest = NULL; + + if (src_len % 4 != 0) { + goto invalid; + } + + size_t out_len = (src_len / 4) * 3; + if (src_len >= 1 && src[src_len - 1] == '=') { + out_len--; + } + if (src_len >= 2 && src[src_len - 2] == '=') { + out_len--; + } + + const uint8_t *s = (const uint8_t *)src; + + dest = xmalloc(out_len + 1); + + int acc = 0; + int acc_len = 0; + size_t out_i = 0; + size_t src_i = 0; + int leftover_i = -1; + + for (; src_i < src_len; src_i++) { + const uint8_t c = s[src_i]; + const uint8_t d = char_to_index[c]; + if (d == 0) { + if (c == '=') { + leftover_i = (int)src_i; + break; + } + goto invalid; + } + + acc = ((acc << 6) & 0xFFF) + (d - 1); + acc_len += 6; + if (acc_len >= 8) { + acc_len -= 8; + dest[out_i] = (char)(acc >> acc_len); + out_i += 1; + } + } + + if (acc_len > 4 || ((acc & ((1 << acc_len) - 1)) != 0)) { + goto invalid; + } + + if (leftover_i > -1) { + int padding_len = acc_len / 2; + int padding_chars = 0; + for (; (size_t)leftover_i < src_len; leftover_i++) { + const uint8_t c = s[leftover_i]; + if (c != '=') { + goto invalid; + } + padding_chars += 1; + } + + if (padding_chars != padding_len) { + goto invalid; + } + } + + dest[out_len] = '\0'; + + return dest; + +invalid: + if (dest) { + xfree((void *)dest); + } + + return NULL; +} |