diff options
| -rw-r--r-- | lib/base64.c | 109 |
1 files changed, 68 insertions, 41 deletions
diff --git a/lib/base64.c b/lib/base64.c index 2d0b775def64..41961a444028 100644 --- a/lib/base64.c +++ b/lib/base64.c @@ -80,28 +80,38 @@ static const s8 base64_rev_maps[][256] = { int base64_encode(const u8 *src, int srclen, char *dst, bool padding, enum base64_variant variant) { u32 ac = 0; - int bits = 0; - int i; char *cp = dst; const char *base64_table = base64_tables[variant]; - for (i = 0; i < srclen; i++) { - ac = (ac << 8) | src[i]; - bits += 8; - do { - bits -= 6; - *cp++ = base64_table[(ac >> bits) & 0x3f]; - } while (bits >= 6); - } - if (bits) { - *cp++ = base64_table[(ac << (6 - bits)) & 0x3f]; - bits -= 6; + while (srclen >= 3) { + ac = src[0] << 16 | src[1] << 8 | src[2]; + *cp++ = base64_table[ac >> 18]; + *cp++ = base64_table[(ac >> 12) & 0x3f]; + *cp++ = base64_table[(ac >> 6) & 0x3f]; + *cp++ = base64_table[ac & 0x3f]; + + src += 3; + srclen -= 3; } - if (padding) { - while (bits < 0) { + + switch (srclen) { + case 2: + ac = src[0] << 16 | src[1] << 8; + *cp++ = base64_table[ac >> 18]; + *cp++ = base64_table[(ac >> 12) & 0x3f]; + *cp++ = base64_table[(ac >> 6) & 0x3f]; + if (padding) + *cp++ = '='; + break; + case 1: + ac = src[0] << 16; + *cp++ = base64_table[ac >> 18]; + *cp++ = base64_table[(ac >> 12) & 0x3f]; + if (padding) { + *cp++ = '='; *cp++ = '='; - bits += 2; } + break; } return cp - dst; } @@ -117,41 +127,58 @@ EXPORT_SYMBOL_GPL(base64_encode); * * Decodes a string using the selected Base64 variant. * - * This implementation hasn't been optimized for performance. - * * Return: the length of the resulting decoded binary data in bytes, * or -1 if the string isn't a valid Base64 string. */ int base64_decode(const char *src, int srclen, u8 *dst, bool padding, enum base64_variant variant) { - u32 ac = 0; - int bits = 0; - int i; u8 *bp = dst; - s8 ch; + s8 input[4]; + s32 val; + const u8 *s = (const u8 *)src; + const s8 *base64_rev_tables = base64_rev_maps[variant]; - for (i = 0; i < srclen; i++) { - if (padding) { - if (src[i] == '=') { - ac = (ac << 6); - bits += 6; - if (bits >= 8) - bits -= 8; - continue; - } - } - ch = base64_rev_maps[variant][(u8)src[i]]; - if (ch == -1) - return -1; - ac = (ac << 6) | ch; - bits += 6; - if (bits >= 8) { - bits -= 8; - *bp++ = (u8)(ac >> bits); + while (srclen >= 4) { + input[0] = base64_rev_tables[s[0]]; + input[1] = base64_rev_tables[s[1]]; + input[2] = base64_rev_tables[s[2]]; + input[3] = base64_rev_tables[s[3]]; + + val = input[0] << 18 | input[1] << 12 | input[2] << 6 | input[3]; + + if (unlikely(val < 0)) { + if (!padding || srclen != 4 || s[3] != '=') + return -1; + padding = 0; + srclen = s[2] == '=' ? 2 : 3; + break; } + + *bp++ = val >> 16; + *bp++ = val >> 8; + *bp++ = val; + + s += 4; + srclen -= 4; } - if (ac & ((1 << bits) - 1)) + + if (likely(!srclen)) + return bp - dst; + if (padding || srclen == 1) return -1; + + val = (base64_rev_tables[s[0]] << 12) | (base64_rev_tables[s[1]] << 6); + *bp++ = val >> 10; + + if (srclen == 2) { + if (val & 0x800003ff) + return -1; + } else { + val |= base64_rev_tables[s[2]]; + if (val & 0x80000003) + return -1; + *bp++ = val >> 2; + } return bp - dst; } EXPORT_SYMBOL_GPL(base64_decode); |