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base64: Post extended extended validation tidy up

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Reduced the separate processing of the last quantum to be performed in
the main decoding loop and renamed some variables for consistency.
This commit is contained in:
Steve Holme 2013-12-01 13:47:11 +00:00
parent c92c30edbd
commit f3ee587775
1 changed files with 19 additions and 28 deletions
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47
lib/base64.c
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@ -68,9 +68,13 @@ static size_t decodeQuantum(unsigned char *dest, const char *src)
} }
} }
dest[2] = curlx_ultouc(x & 0xFFUL); if(padding < 2)
dest[2] = curlx_ultouc(x & 0xFFUL);
x >>= 8; x >>= 8;
dest[1] = curlx_ultouc(x & 0xFFUL); if(padding < 1)
dest[1] = curlx_ultouc(x & 0xFFUL);
x >>= 8; x >>= 8;
dest[0] = curlx_ultouc(x & 0xFFUL); dest[0] = curlx_ultouc(x & 0xFFUL);
@ -94,23 +98,22 @@ static size_t decodeQuantum(unsigned char *dest, const char *src)
CURLcode Curl_base64_decode(const char *src, CURLcode Curl_base64_decode(const char *src,
unsigned char **outptr, size_t *outlen) unsigned char **outptr, size_t *outlen)
{ {
size_t srcLen = 0; size_t srclen = 0;
size_t length = 0; size_t length = 0;
size_t equalsTerm = 0; size_t padding = 0;
size_t i; size_t i;
size_t result; size_t result;
size_t numQuantums; size_t numQuantums;
unsigned char lastQuantum[3];
size_t rawlen = 0; size_t rawlen = 0;
unsigned char *pos; unsigned char *pos;
unsigned char *newstr; unsigned char *newstr;
*outptr = NULL; *outptr = NULL;
*outlen = 0; *outlen = 0;
srcLen = strlen(src); srclen = strlen(src);
/* Check the length of the input string is valid */ /* Check the length of the input string is valid */
if(!srcLen || srcLen % 4) if(!srclen || srclen % 4)
return CURLE_BAD_CONTENT_ENCODING; return CURLE_BAD_CONTENT_ENCODING;
/* Find the position of any = padding characters */ /* Find the position of any = padding characters */
@ -119,20 +122,20 @@ CURLcode Curl_base64_decode(const char *src,
/* A maximum of two = padding characters is allowed */ /* A maximum of two = padding characters is allowed */
if(src[length] == '=') { if(src[length] == '=') {
equalsTerm++; padding++;
if(src[length+equalsTerm] == '=') if(src[length + 1] == '=')
equalsTerm++; padding++;
} }
/* Check the = padding characters weren't part way through the input */ /* Check the = padding characters weren't part way through the input */
if(length + equalsTerm != srcLen) if(length + padding != srclen)
return CURLE_BAD_CONTENT_ENCODING; return CURLE_BAD_CONTENT_ENCODING;
/* Calculate the number of quantums */ /* Calculate the number of quantums */
numQuantums = srcLen / 4; numQuantums = srclen / 4;
/* Calculate the size of the decoded string */ /* Calculate the size of the decoded string */
rawlen = (numQuantums * 3) - equalsTerm; rawlen = (numQuantums * 3) - padding;
/* Allocate our buffer including room for a zero terminator */ /* Allocate our buffer including room for a zero terminator */
newstr = malloc(rawlen + 1); newstr = malloc(rawlen + 1);
@ -141,9 +144,8 @@ CURLcode Curl_base64_decode(const char *src,
pos = newstr; pos = newstr;
/* Decode all but the last quantum (which may not decode to a /* Decode the quantums */
multiple of 3 bytes) */ for(i = 0; i < numQuantums; i++) {
for(i = 0; i < numQuantums - 1; i++) {
result = decodeQuantum(pos, src); result = decodeQuantum(pos, src);
if(!result) { if(!result) {
Curl_safefree(newstr); Curl_safefree(newstr);
@ -155,19 +157,8 @@ CURLcode Curl_base64_decode(const char *src,
src += 4; src += 4;
} }
/* Decode the last quantum */
result = decodeQuantum(lastQuantum, src);
if(!result) {
Curl_safefree(newstr);
return CURLE_BAD_CONTENT_ENCODING;
}
for(i = 0; i < 3 - equalsTerm; i++)
pos[i] = lastQuantum[i];
/* Zero terminate */ /* Zero terminate */
pos[i] = '\0'; *pos = '\0';
/* Return the decoded data */ /* Return the decoded data */
*outptr = newstr; *outptr = newstr;