benson031397
asked on
Base64 encoding C library for Unix.
Dear all,
I would like to do the base64 encoding programming in Unix. Can anyone tell me where I can get such library function call to do?
Thanks!
Benson
I would like to do the base64 encoding programming in Unix. Can anyone tell me where I can get such library function call to do?
Thanks!
Benson
ASKER
Axter : Thanks for your help. Can you briefly tell me the meaning of each argument?
Thanks!
Benson
Thanks!
Benson
encode64(const char *_in, unsigned inlen,
char *_out, unsigned outmax, unsigned *outlen)
Example code:
char MyMsg[] = "Hello World";
char DestinationBuf[1024];
int TotalEncodeLen;
encode64(MyMsg, sizeof(MyMsg), DestinationBuf, &TotalEncodeLen);
The above copde will encode MyMsg string.
To decode it use decode64.
int TotalDecodeLen;
decode64(SourceBuf, sizeof(SourceBuf), DestBuf, &TotalDecodeLen);
char *_out, unsigned outmax, unsigned *outlen)
Example code:
char MyMsg[] = "Hello World";
char DestinationBuf[1024];
int TotalEncodeLen;
encode64(MyMsg, sizeof(MyMsg), DestinationBuf, &TotalEncodeLen);
The above copde will encode MyMsg string.
To decode it use decode64.
int TotalDecodeLen;
decode64(SourceBuf, sizeof(SourceBuf), DestBuf, &TotalDecodeLen);
ASKER
Axter : Thanks for your help. Can you briefly tell me the meaning of each argument?
Thanks!
Benson
Thanks!
Benson
ASKER
Axter : There are 5 arguments of encode64. Your example is a bit different.
>>There are 5 arguments of encode64. Your example is a
>>bit different.
I overlooked that.
encode64(
const char *_in, //Pointer to original string
unsigned inlen, //Length of original string
char *_out, //Pointer to destination buffer
unsigned outmax, //Length of destination buffer
unsigned *outlen //Address of a variable that will be modified to take the new length of the buffer after encode is complete
);
char MyMsg[] = "Hello World";
char DestinationBuf[1024];
int TotalEncodeLen;
encode64(MyMsg, sizeof(MyMsg), DestinationBuf, sizeof(DestinationBuf), &TotalEncodeLen);
>>bit different.
I overlooked that.
encode64(
const char *_in, //Pointer to original string
unsigned inlen, //Length of original string
char *_out, //Pointer to destination buffer
unsigned outmax, //Length of destination buffer
unsigned *outlen //Address of a variable that will be modified to take the new length of the buffer after encode is complete
);
char MyMsg[] = "Hello World";
char DestinationBuf[1024];
int TotalEncodeLen;
encode64(MyMsg, sizeof(MyMsg), DestinationBuf, sizeof(DestinationBuf), &TotalEncodeLen);
benson,
Did I answer your question?
Did I answer your question?
ASKER
Axter : Yes! Thank you very much :)
ASKER CERTIFIED SOLUTION
membership
This solution is only available to members.
To access this solution, you must be a member of Experts Exchange.
#define OK (0)
#define FAIL (-1)
#define BUFOVER (-2)
#define CHAR64(c) (((c) < 0 || (c) > 127) ? -1 : index_64[(c)])
static char basis_64[] =
"ABCDEFGHIJKLMNOPQRSTUVWXY
static char index_64[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
};
int encode64(const char *_in, unsigned inlen,
char *_out, unsigned outmax, unsigned *outlen)
{
const unsigned char *in = (const unsigned char *) _in;
unsigned char *out = (unsigned char *) _out;
unsigned char oval;
char *blah;
unsigned olen;
olen = (inlen + 2) / 3 * 4;
if (outlen)
*outlen = olen;
if (outmax < olen)
return BUFOVER;
blah = (char *) out;
while (inlen >= 3)
{
/* user provided max buffer size; make sure we don't go over it */
*out++ = basis_64[in[0] >> 2];
*out++ = basis_64[((in[0] << 4) & 0x30) | (in[1] >> 4)];
*out++ = basis_64[((in[1] << 2) & 0x3c) | (in[2] >> 6)];
*out++ = basis_64[in[2] & 0x3f];
in += 3;
inlen -= 3;
}
if (inlen > 0)
{
/* user provided max buffer size; make sure we don't go over it */
*out++ = basis_64[in[0] >> 2];
oval = (in[0] << 4) & 0x30;
if (inlen > 1)
oval |= in[1] >> 4;
*out++ = basis_64[oval];
*out++ = (inlen < 2) ? '=' : basis_64[(in[1] << 2) & 0x3c];
*out++ = '=';
}
if (olen < outmax)
*out = '\0';
return OK;
}
int decode64(const char *in, unsigned inlen, char *out, unsigned *outlen)
{
unsigned len = 0,
lup;
int c1,
c2,
c3,
c4;
if (in[0] == '+' && in[1] == ' ')
in += 2;
if (*in == '\0')
return FAIL;
for (lup = 0; lup < inlen / 4; lup++)
{
c1 = in[0];
if (CHAR64(c1) == -1)
return FAIL;
c2 = in[1];
if (CHAR64(c2) == -1)
return FAIL;
c3 = in[2];
if (c3 != '=' && CHAR64(c3) == -1)
return FAIL;
c4 = in[3];
if (c4 != '=' && CHAR64(c4) == -1)
return FAIL;
in += 4;
*out++ = (CHAR64(c1) << 2) | (CHAR64(c2) >> 4);
++len;
if (c3 != '=')
{
*out++ = ((CHAR64(c2) << 4) & 0xf0) | (CHAR64(c3) >> 2);
++len;
if (c4 != '=')
{
*out++ = ((CHAR64(c3) << 6) & 0xc0) | CHAR64(c4);
++len;
}
}
}
*out = 0;
*outlen = len;
return OK;
}