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Fix surrogate decoding and invalid hex handling #466

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Fix surrogate decoding and invalid hex handling #466

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41 changes: 26 additions & 15 deletions src/yajl/yajl_encode.c
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Original file line number Diff line number Diff line change
Expand Up @@ -75,16 +75,18 @@ yajl_string_encode(const yajl_print_t print,
print(ctx, (const char *) (str + beg), end - beg);
}

static void hexToDigit(unsigned int * val, const unsigned char * hex)
static int hexToDigit(unsigned int * val, const unsigned char * hex)
{
unsigned int i;
for (i=0;i<4;i++) {
unsigned char c = hex[i];
if (c >= 'A') c = (c & ~0x20) - 7;
c -= '0';
assert(!(c & 0xF0));
if (c >= 'a' && c <= 'f') c = c - 'a' + 10;
else if (c >= 'A' && c <= 'F') c = c - 'A' + 10;
else if (c >= '0' && c <= '9') c = c - '0';
else return 0;
*val = (*val << 4) | c;
}
return 1;
}

static void Utf32toUtf8(unsigned int codepoint, char * utf8Buf)
Expand Down Expand Up @@ -135,19 +137,27 @@ void yajl_string_decode(yajl_buf buf, const unsigned char * str,
case 't': unescaped = "\t"; break;
case 'u': {
unsigned int codepoint = 0;
hexToDigit(&codepoint, str + ++end);
end+=3;
if (end + 4 >= len || !hexToDigit(&codepoint, str + ++end)) {
unescaped = "?";
/* jump past anything remaining if hex was truncated/invalid */
end += 3;
break;
}
end += 3;
/* check if this is a surrogate */
if ((codepoint & 0xFC00) == 0xD800) {
if (end + 2 < len && str[end + 1] == '\\' && str[end + 2] == 'u') {
end++;
if (end + 6 < len && str[end + 1] == '\\' && str[end + 2] == 'u') {
unsigned int surrogate = 0;
hexToDigit(&surrogate, str + end + 2);
codepoint =
(((codepoint & 0x3F) << 10) |
((((codepoint >> 6) & 0xF) + 1) << 16) |
(surrogate & 0x3FF));
end += 5;
if (hexToDigit(&surrogate, str + end + 3) && (surrogate & 0xFC00) == 0xDC00) {
codepoint =
(((codepoint & 0x3F) << 10) |
((((codepoint >> 6) & 0xF) + 1) << 16) |
(surrogate & 0x3FF));
end += 6;
} else {
unescaped = "?";
break;
}
} else {
unescaped = "?";
break;
Expand All @@ -166,7 +176,8 @@ void yajl_string_decode(yajl_buf buf, const unsigned char * str,
break;
}
default:
assert("this should never happen" == NULL);
unescaped = "?";
break;
}
yajl_buf_append(buf, unescaped, (unsigned int)strlen(unescaped));
beg = ++end;
Expand Down
8 changes: 8 additions & 0 deletions tests/testthat/test-libjson-utf8.R
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Expand Up @@ -42,4 +42,12 @@ test_that("test that non ascii characters are ok", {
expect_equal(length(unique(fromJSON('["Z\\u00FCrich", "Z\u00fcrich"]'))), 1L)
expect_equal(fromJSON('["\\u586B"]'), "\u586b")
expect_equal(fromJSON(prettify('["\\u586B"]')), "\u586B")

# Invalid surrogate and unicode decoding (should not crash)
expect_equal(fromJSON('["\\udbbb\\\\Lbbbb"]'), "?\\Lbbbb")
expect_equal(fromJSON('["\\udbbb\\u005c"]'), "?\\")
expect_error(fromJSON('["\\udbbb\\u005g"]'), "lexical error")
expect_error(fromJSON('["\\udbbb\\u00"]'), "lexical error")
expect_error(fromJSON('["\\u00"]'), "lexical error")
expect_error(fromJSON('["\\u005g"]'), "lexical error")
})
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