#ifndef lint
static char rcsid[] = "@(#$Id: base64.cpp,v 1.4 2005-11-25 08:49:31 dockes Exp $ (C) 2005 J.F.Dockes";
#endif
#include <sys/types.h>
#include <string>
#ifndef NO_NAMESPACES
using std::string;
#endif /* NO_NAMESPACES */
//#define DEBUG_BASE64
#ifdef DEBUG_BASE64
#define DPRINT(X) fprintf X
#else
#define DPRINT(X)
#endif
// This is adapted from FreeBSD's code.
static const char Base64[] =
"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
static const char Pad64 = '=';
bool base64_decode(const string& in, string& out)
{
int io = 0, state = 0, ch;
char *pos;
unsigned int ii = 0;
out.erase();
out.reserve(in.length());
for (ii = 0; ii < in.length(); ii++) {
ch = in[ii];
if (isspace((unsigned char)ch)) /* Skip whitespace anywhere. */
continue;
if (ch == Pad64)
break;
pos = strchr(Base64, ch);
if (pos == 0) {
/* A non-base64 character. */
DPRINT((stderr, "base64_dec: non-base64 char at pos %d\n", ii));
return false;
}
switch (state) {
case 0:
out += (pos - Base64) << 2;
state = 1;
break;
case 1:
out[io] |= (pos - Base64) >> 4;
out += ((pos - Base64) & 0x0f) << 4 ;
io++;
state = 2;
break;
case 2:
out[io] |= (pos - Base64) >> 2;
out += ((pos - Base64) & 0x03) << 6;
io++;
state = 3;
break;
case 3:
out[io] |= (pos - Base64);
io++;
state = 0;
break;
default:
DPRINT((stderr, "base64_dec: internal!bad state!\n"));
return false;
}
}
/*
* We are done decoding Base-64 chars. Let's see if we ended
* on a byte boundary, and/or with erroneous trailing characters.
*/
if (ch == Pad64) { /* We got a pad char. */
ch = in[ii++]; /* Skip it, get next. */
switch (state) {
case 0: /* Invalid = in first position */
case 1: /* Invalid = in second position */
DPRINT((stderr, "base64_dec: pad char in state 0/1\n"));
return false;
case 2: /* Valid, means one byte of info */
/* Skip any number of spaces. */
for (; ii < in.length(); ch = in[ii++])
if (!isspace((unsigned char)ch))
break;
/* Make sure there is another trailing = sign. */
if (ch != Pad64) {
DPRINT((stderr, "base64_dec: missing pad char!\n"));
// Well, there are bad encoders out there. Let it pass
// return false;
}
ch = in[ii++]; /* Skip the = */
/* Fall through to "single trailing =" case. */
/* FALLTHROUGH */
case 3: /* Valid, means two bytes of info */
/*
* We know this char is an =. Is there anything but
* whitespace after it?
*/
for (; ii < in.length(); ch = in[ii++])
if (!isspace((unsigned char)ch)) {
DPRINT((stderr, "base64_dec: non-white at eod: 0x%x\n",
(unsigned int)ch));
// Well, there are bad encoders out there. Let it pass
//return false;
}
/*
* Now make sure for cases 2 and 3 that the "extra"
* bits that slopped past the last full byte were
* zeros. If we don't check them, they become a
* subliminal channel.
*/
if (out[io] != 0) {
DPRINT((stderr, "base64_dec: bad extra bits!\n"));
// Well, there are bad encoders out there. Let it pass
out[io] = 0;
// return false;
}
// We've appended an extra 0.
out.resize(io);
}
} else {
/*
* We ended by seeing the end of the string. Make sure we
* have no partial bytes lying around.
*/
if (state != 0) {
DPRINT((stderr, "base64_dec: bad final state\n"));
return false;
}
}
DPRINT((stderr, "base64_dec: ret ok, io %d sz %d len %d value [%s]\n",
io, out.size(), out.length(), out.c_str()));
return true;
}
#undef Assert
#define Assert(X)
void base64_encode(const string &in, string &out)
{
size_t datalength = 0;
unsigned char input[3];
unsigned char output[4];
size_t i;
out.erase();
int srclength = in.length();
int sidx = 0;
while (2 < srclength) {
input[0] = in[sidx++];
input[1] = in[sidx++];
input[2] = in[sidx++];
srclength -= 3;
output[0] = input[0] >> 2;
output[1] = ((input[0] & 0x03) << 4) + (input[1] >> 4);
output[2] = ((input[1] & 0x0f) << 2) + (input[2] >> 6);
output[3] = input[2] & 0x3f;
Assert(output[0] < 64);
Assert(output[1] < 64);
Assert(output[2] < 64);
Assert(output[3] < 64);
out += Base64[output[0]];
out += Base64[output[1]];
out += Base64[output[2]];
out += Base64[output[3]];
}
/* Now we worry about padding. */
if (0 != srclength) {
/* Get what's left. */
input[0] = input[1] = input[2] = '\0';
for (int i = 0; i < srclength; i++)
input[i] = in[sidx++];
output[0] = input[0] >> 2;
output[1] = ((input[0] & 0x03) << 4) + (input[1] >> 4);
output[2] = ((input[1] & 0x0f) << 2) + (input[2] >> 6);
Assert(output[0] < 64);
Assert(output[1] < 64);
Assert(output[2] < 64);
out += Base64[output[0]];
out += Base64[output[1]];
if (srclength == 1)
out += Pad64;
else
out += Base64[output[2]];
out += Pad64;
}
return;
}
#ifdef TEST_BASE64
#include <stdio.h>
const char *values[] = {"", "1", "12", "123", "1234", "12345", "123456"};
int nvalues = sizeof(values) / sizeof(char *);
int main(int argc, char **argv)
{
string in, out, back;
int err = 0;
for (int i = 0; i < nvalues; i++) {
in = values[i];
base64_encode(in, out);
base64_decode(out, back);
if (in != back) {
fprintf(stderr, "In [%s] %d != back [%s] %d (out [%s] %d\n",
in.c_str(),in.length(),
back.c_str(), back.length(),
out.c_str(), out.length()
);
err++;
}
}
in.erase();
in += char(0);
in += char(0);
in += char(0);
in += char(0);
base64_encode(in, out);
base64_decode(out, back);
if (in != back) {
fprintf(stderr, "In [%s] %d != back [%s] %d (out [%s] %d\n",
in.c_str(),in.length(),
back.c_str(), back.length(),
out.c_str(), out.length()
);
err++;
}
exit(!(err == 0));
}
#endif