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base64dec: skip non-printable characters like \r\n

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Non-printable characters, such as line breaks, in a base64 encoded
string violate the "string length must be a multiple of four" rule.

This patch pads the result buffer by one extra unit of four bytes,
and skips over non-printable characters found in the input string.
This commit is contained in:
Suraj N. Kurapati
2017-08-17 23:00:10 -07:00
committed by Hiltjo Posthuma
parent 274d46ace0
commit ee5cc8e903
1 changed files with 12 additions and 5 deletions
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17
st.c
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@@ -386,6 +386,13 @@ static const char base64_digits[] = {
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
}; };
char
base64dec_getc(const char **src)
{
while (**src && !isprint(**src)) (*src)++;
return *((*src)++);
}
char * char *
base64dec(const char *src) base64dec(const char *src)
{ {
@@ -393,13 +400,13 @@ base64dec(const char *src)
char *result, *dst; char *result, *dst;
if (in_len % 4) if (in_len % 4)
return NULL; in_len += 4 - (in_len % 4);
result = dst = xmalloc(in_len / 4 * 3 + 1); result = dst = xmalloc(in_len / 4 * 3 + 1);
while (*src) { while (*src) {
int a = base64_digits[(unsigned char) *src++]; int a = base64_digits[(unsigned char) base64dec_getc(&src)];
int b = base64_digits[(unsigned char) *src++]; int b = base64_digits[(unsigned char) base64dec_getc(&src)];
int c = base64_digits[(unsigned char) *src++]; int c = base64_digits[(unsigned char) base64dec_getc(&src)];
int d = base64_digits[(unsigned char) *src++]; int d = base64_digits[(unsigned char) base64dec_getc(&src)];
*dst++ = (a << 2) | ((b & 0x30) >> 4); *dst++ = (a << 2) | ((b & 0x30) >> 4);
if (c == -1) if (c == -1)