Hi,
I just recently moved from 0.9.7 to 0.9.7c and discovered what I think
is a bug in the base64 BIO decoding code.
When the source bio is a read-write memory bio, and has more than 1024
bytes of data to decode (in my test case it was less than 2048, but I
suspect more would fail as well), the BIO only writes out 720 bytes of
decoded data and then fails. The cause seems to be in these new lines
(290-294) of bio_b64.c:
/* If buffer isn't full and we can retry then
* restart to read in more data.
*/
else if ((i < B64_BLOCK_SIZE) && (ctx->cont > 0))
continue;
What's happening is that on the second pass through the while loop (the
first pass reads 1024 (B64_BLOCK_SIZE) bytes and writes out 720),
BIO_read is reading < 1024 bytes (as that's all that's left in the
memory BIO). Then, when it hits this else, it goes back to the
beginning and calls BIO_read again. But BIO_read returns -1 (no more
data), and the function returns failure, with only the 720 bytes written
out.
Here is some code that will reproduce the bug:
#include <openssl/evp.h>
void main(void)
{
BIO *inb, *dec;
char in[2048];
char out[2048];
int len;
FILE *fp;
fp = fopen("in", "r");
len = fread(in, 1, 2048, fp);
fclose(fp);
inb = BIO_new(BIO_s_mem());
BIO_write(inb, in, len);
dec = BIO_new(BIO_f_base64());
dec = BIO_push(dec, inb);
len = BIO_read(dec, out, 2048);
BIO_free_all(dec);
fp = fopen("out", "w");
fwrite(out, len, 1, fp);
fclose(fp);
}
The file "in" should be populated with base64 encoded data (I just used
the openssl command line tool) of size > 1024 and < 2048. After you run
this, the file "out" will have size 720.
The easy fix would probably be just to get rid of that else if
statement, but I suspect there was a reason for putting it in, so I'm
hesitant to just pull it out. (I may just go back to the 0.9.7 version
of bio_b64.c for the time being.)
Is this already a known issue?
Thanks,
Matt
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