/*------------------------------------------------------------------------- * * base64.c * Encoding and decoding routines for base64 without whitespace. * * Copyright (c) 2001-2023, 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) / 3 * 4; } /* * 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; }