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Diffstat (limited to 'src/common/base64.c')
| -rw-r--r-- | src/common/base64.c | 242 |
1 files changed, 242 insertions, 0 deletions
diff --git a/src/common/base64.c b/src/common/base64.c new file mode 100644 index 0000000..37b0070 --- /dev/null +++ b/src/common/base64.c @@ -0,0 +1,242 @@ +/*------------------------------------------------------------------------- + * + * base64.c + * Encoding and decoding routines for base64 without whitespace. + * + * Copyright (c) 2001-2022, PostgreSQL Global Development Group + * + * + * IDENTIFICATION + * src/common/base64.c + * + *------------------------------------------------------------------------- + */ + +#ifndef FRONTEND +#include "postgres.h" +#else +#include "postgres_fe.h" +#endif + +#include "common/base64.h" + +/* + * BASE64 + */ + +static const char _base64[] = +"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"; + +static const int8 b64lookup[128] = { + -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, + -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, + -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 62, -1, -1, -1, 63, + 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, -1, -1, -1, -1, -1, -1, + -1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, + 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, -1, -1, -1, -1, -1, + -1, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, + 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, -1, -1, -1, -1, -1, +}; + +/* + * pg_b64_encode + * + * Encode into base64 the given string. Returns the length of the encoded + * string, and -1 in the event of an error with the result buffer zeroed + * for safety. + */ +int +pg_b64_encode(const char *src, int len, char *dst, int dstlen) +{ + char *p; + const char *s, + *end = src + len; + int pos = 2; + uint32 buf = 0; + + s = src; + p = dst; + + while (s < end) + { + buf |= (unsigned char) *s << (pos << 3); + pos--; + s++; + + /* write it out */ + if (pos < 0) + { + /* + * Leave if there is an overflow in the area allocated for the + * encoded string. + */ + if ((p - dst + 4) > dstlen) + goto error; + + *p++ = _base64[(buf >> 18) & 0x3f]; + *p++ = _base64[(buf >> 12) & 0x3f]; + *p++ = _base64[(buf >> 6) & 0x3f]; + *p++ = _base64[buf & 0x3f]; + + pos = 2; + buf = 0; + } + } + if (pos != 2) + { + /* + * Leave if there is an overflow in the area allocated for the encoded + * string. + */ + if ((p - dst + 4) > dstlen) + goto error; + + *p++ = _base64[(buf >> 18) & 0x3f]; + *p++ = _base64[(buf >> 12) & 0x3f]; + *p++ = (pos == 0) ? _base64[(buf >> 6) & 0x3f] : '='; + *p++ = '='; + } + + Assert((p - dst) <= dstlen); + return p - dst; + +error: + memset(dst, 0, dstlen); + return -1; +} + +/* + * pg_b64_decode + * + * Decode the given base64 string. Returns the length of the decoded + * string on success, and -1 in the event of an error with the result + * buffer zeroed for safety. + */ +int +pg_b64_decode(const char *src, int len, char *dst, int dstlen) +{ + const char *srcend = src + len, + *s = src; + char *p = dst; + char c; + int b = 0; + uint32 buf = 0; + int pos = 0, + end = 0; + + while (s < srcend) + { + c = *s++; + + /* Leave if a whitespace is found */ + if (c == ' ' || c == '\t' || c == '\n' || c == '\r') + goto error; + + if (c == '=') + { + /* end sequence */ + if (!end) + { + if (pos == 2) + end = 1; + else if (pos == 3) + end = 2; + else + { + /* + * Unexpected "=" character found while decoding base64 + * sequence. + */ + goto error; + } + } + b = 0; + } + else + { + b = -1; + if (c > 0 && c < 127) + b = b64lookup[(unsigned char) c]; + if (b < 0) + { + /* invalid symbol found */ + goto error; + } + } + /* add it to buffer */ + buf = (buf << 6) + b; + pos++; + if (pos == 4) + { + /* + * Leave if there is an overflow in the area allocated for the + * decoded string. + */ + if ((p - dst + 1) > dstlen) + goto error; + *p++ = (buf >> 16) & 255; + + if (end == 0 || end > 1) + { + /* overflow check */ + if ((p - dst + 1) > dstlen) + goto error; + *p++ = (buf >> 8) & 255; + } + if (end == 0 || end > 2) + { + /* overflow check */ + if ((p - dst + 1) > dstlen) + goto error; + *p++ = buf & 255; + } + buf = 0; + pos = 0; + } + } + + if (pos != 0) + { + /* + * base64 end sequence is invalid. Input data is missing padding, is + * truncated or is otherwise corrupted. + */ + goto error; + } + + Assert((p - dst) <= dstlen); + return p - dst; + +error: + memset(dst, 0, dstlen); + return -1; +} + +/* + * pg_b64_enc_len + * + * Returns to caller the length of the string if it were encoded with + * base64 based on the length provided by caller. This is useful to + * estimate how large a buffer allocation needs to be done before doing + * the actual encoding. + */ +int +pg_b64_enc_len(int srclen) +{ + /* 3 bytes will be converted to 4 */ + return (srclen + 2) * 4 / 3; +} + +/* + * pg_b64_dec_len + * + * Returns to caller the length of the string if it were to be decoded + * with base64, based on the length given by caller. This is useful to + * estimate how large a buffer allocation needs to be done before doing + * the actual decoding. + */ +int +pg_b64_dec_len(int srclen) +{ + return (srclen * 3) >> 2; +} |