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[MINOR] add encode/decode function for 30-bit integers from/to base64

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These functions only require 5 chars to encode 30 bits, and don't expect
any padding. They will be used to encode dates in cookies.
(cherry picked from commit a7e2b5fc4612994c7b13bcb103a4a2c3ecd6438a)
This commit is contained in:
Willy Tarreau 2010-10-07 19:27:29 +02:00
parent f1348310e8
commit c01062bead
2 changed files with 51 additions and 2 deletions
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4
include/common/base64.h
View File

@ -2,7 +2,7 @@
* include/common/base64.h
* Ascii to Base64 conversion as described in RFC1421.
*
* Copyright 2006 Willy Tarreau <w@1wt.eu>
* Copyright 2006-2010 Willy Tarreau <w@1wt.eu>
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
@ -18,6 +18,8 @@
int a2base64(char *in, int ilen, char *out, int olen);
int base64dec(const char *in, size_t ilen, char *out, size_t olen);
const char *s30tob64(int in, char *out);
int b64tos30(const char *in);
extern const char base64tab[];

49
src/base64.c
View File

@ -1,7 +1,7 @@
/*
* ASCII <-> Base64 conversion as described in RFC1421.
*
* Copyright 2006-2008 Willy Tarreau <w@1wt.eu>
* Copyright 2006-2010 Willy Tarreau <w@1wt.eu>
* Copyright 2009-2010 Krzysztof Piotr Oledzki <ole@ans.pl>
*
* This program is free software; you can redistribute it and/or
@ -135,3 +135,50 @@ int base64dec(const char *in, size_t ilen, char *out, size_t olen) {
return convlen;
}
/* Converts the lower 30 bits of an integer to a 5-char base64 string. The
* caller is responsible for ensuring that the output buffer can accept 6 bytes
* (5 + the trailing zero). The pointer to the string is returned. The
* conversion is performed with MSB first and in a format that can be
* decoded with b64tos30(). This format is not padded and thus is not
* compatible with usual base64 routines.
*/
const char *s30tob64(int in, char *out)
{
int i;
for (i = 0; i < 5; i++) {
out[i] = base64tab[(in >> 24) & 0x3F];
in <<= 6;
}
out[5] = '\0';
return out;
}
/* Converts a 5-char base64 string encoded by s30tob64() into a 30-bit integer.
* The caller is responsible for ensuring that the input contains at least 5
* chars. If any unexpected character is encountered, a negative value is
* returned. Otherwise the decoded value is returned.
*/
int b64tos30(const char *in)
{
int i, out;
signed char b;
out = 0;
for (i = 0; i < 5; i++) {
b = (signed char)in[i] - B64CMIN;
if ((unsigned char)b > (B64CMAX - B64CMIN))
return -1; /* input character out of range */
b = base64rev[b] - B64BASE - 1;
if (b < 0) /* invalid character */
return -1;
if (b == B64PADV) /* padding not allowed */
return -1;
out = (out << 6) + b;
}
return out;
}