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nghttp2_hd: Check last byte of huffman encoded byte string strictly

This commit is contained in:
Tatsuhiro Tsujikawa 2013-12-18 21:27:16 +09:00
parent cd5043f68c
commit 12144acf4d
1 changed files with 16 additions and 8 deletions
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24
lib/nghttp2_hd_huffman.c
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@ -187,6 +187,14 @@ ssize_t nghttp2_hd_huff_encode(uint8_t *dest, size_t destlen,
return dest - dest_first + (bitoff > 0); return dest - dest_first + (bitoff > 0);
} }
static int check_last_byte(const uint8_t *src, size_t srclen, size_t idx,
size_t bitoff)
{
uint8_t last_mask = (1 << (8 - bitoff)) - 1;
return idx + 1 == srclen && bitoff > 0 &&
(src[idx] & last_mask) == last_mask;
}
ssize_t nghttp2_hd_huff_decode_count(const uint8_t *src, size_t srclen, ssize_t nghttp2_hd_huff_decode_count(const uint8_t *src, size_t srclen,
nghttp2_hd_side side) nghttp2_hd_side side)
{ {
@ -207,15 +215,15 @@ ssize_t nghttp2_hd_huff_decode_count(const uint8_t *src, size_t srclen,
int rv = huff_decode(src + i, srclen - i, bitoff, int rv = huff_decode(src + i, srclen - i, bitoff,
huff_sym_table, huff_decode_table); huff_sym_table, huff_decode_table);
if(rv == -1) { if(rv == -1) {
/* TODO Check prefix of EOS */ if(check_last_byte(src, srclen, i, bitoff)) {
if(i + 1 == srclen && bitoff > 0) {
break; break;
} }
return -1; return -1;
} }
if(rv == 256) { if(rv == 256) {
/* 256 is special terminal symbol */ /* 256 is special terminal symbol and it should not encoded in
break; byte string. */
return -1;
} }
j++; j++;
bitoff += huff_sym_table[rv].nbits; bitoff += huff_sym_table[rv].nbits;
@ -246,15 +254,15 @@ ssize_t nghttp2_hd_huff_decode(uint8_t *dest, size_t destlen,
int rv = huff_decode(src + i, srclen - i, bitoff, int rv = huff_decode(src + i, srclen - i, bitoff,
huff_sym_table, huff_decode_table); huff_sym_table, huff_decode_table);
if(rv == -1) { if(rv == -1) {
/* TODO Check prefix of EOS */ if(check_last_byte(src, srclen, i, bitoff)) {
if(i + 1 == srclen && bitoff > 0) {
break; break;
} }
return -1; return -1;
} }
if(rv == 256) { if(rv == 256) {
/* 256 is special terminal symbol */ /* 256 is special terminal symbol and it should not encoded in
break; byte string. */
return -1;
} }
dest[j++] = rv; dest[j++] = rv;
bitoff += huff_sym_table[rv].nbits; bitoff += huff_sym_table[rv].nbits;