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fix: t:utf8toUnicode drops the last hex digit of code points above U+FFFF #3685

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fix: t:utf8toUnicode drops the last hex digit of code points above U+FFFF #3685

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11 changes: 7 additions & 4 deletions apache2/msc_util.c
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Original file line number Diff line number Diff line change
Expand Up @@ -103,7 +103,7 @@
*
* \retval rval On Success
*/
char *utf8_unicode_inplace_ex(apr_pool_t *mp, unsigned char *input, long int input_len, int *changed) {

Check failure on line 106 in apache2/msc_util.c

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SonarQubeCloud / SonarCloud Code Analysis

Refactor this function to reduce its Cognitive Complexity from 51 to the 25 allowed. 


See more on https://sonarcloud.io/project/issues?id=owasp-modsecurity_ModSecurity&issues=AaE3PwM2xyjeyssf-DDp&open=AaE3PwM2xyjeyssf-DDp&pullRequest=3685
int unicode_len = 0;
unsigned int d = 0;
unsigned char c, *utf;
Expand All @@ -120,7 +120,8 @@
data = rval = apr_palloc(mp, len);
if (rval == NULL) return NULL;

for (i = 0; i < bytes_left;) {
for (i = 0; i < input_len;) {
bytes_left = input_len - i;
unicode_len = 0; d = 0;
utf = (unsigned char *)&input[i];
c = *utf;
Expand All @@ -129,7 +130,7 @@
if ((c & 0x80) == 0) {
if (c == 0) {
unicode_len = 2;
d = utf[1];
d = (bytes_left >= 2) ? utf[1] : 0;
}
}
/* If first byte begins with binary 110 it is two byte encoding*/
Expand Down Expand Up @@ -178,6 +179,8 @@
}
/* invalid UTF-8 character number range (RFC 3629) */
if ((d >= 0xD800) && (d <= 0xDFFF)) unicode_len = UNICODE_ERROR_RESTRICTED_CHARACTER;
/* restrict characters to UTF-8 range (U+0000 - U+10FFFF) */
if ((unicode_len == 4) && (d > 0x10FFFF)) unicode_len = UNICODE_ERROR_RESTRICTED_CHARACTER;
/* check for overlong */
if ((unicode_len == 4) && (d < 0x010000)) unicode_len = UNICODE_ERROR_OVERLONG_CHARACTER;
/* three byte could be represented with less bytes */
Expand All @@ -187,8 +190,8 @@

if (unicode_len > 0) {
i += unicode_len;
sprintf(data, "%%u%04x", d);
data += 6;
/* code points above U+FFFF need five hex digits */
data += sprintf(data, "%%u%04x", d);

Check failure on line 194 in apache2/msc_util.c

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SonarQubeCloud / SonarCloud Code Analysis

Make sure use of "sprintf" function is safe here or replace it with a call to "snprintf". 


See more on https://sonarcloud.io/project/issues?id=owasp-modsecurity_ModSecurity&issues=AaE3PwM2xyjeyssf-DDq&open=AaE3PwM2xyjeyssf-DDq&pullRequest=3685
*changed = 1;
}
else {
Expand Down
32 changes: 32 additions & 0 deletions tests/tfn/utf8toUnicode.t
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Original file line number Diff line number Diff line change
Expand Up @@ -54,3 +54,35 @@
output => " %u27f0 %u27f1 %u27f2 %u27f3 %u27f4 %u27f5 %u27f6 %u27f7 %u27f8 %u27f9 %u27fa %u27fb %u27fc %u27fd %u27fe %u27ff",
ret => 1,
},
# Supplementary planes (four-byte sequences, five hex digits)
{
type => "tfn",
name => "utf8toUnicode",
input => "😀 𝒜 𠀀 􏿿",
output => "%u1f600 %u1d49c %u20000 %u10ffff",
ret => 1,
},
# Four-byte sequence followed by ASCII must not lose its last digit
{
type => "tfn",
name => "utf8toUnicode",
input => "😀A",
output => "%u1f600A",
ret => 1,
},
# Code point above U+10FFFF is not valid UTF-8 and is passed through
{
type => "tfn",
name => "utf8toUnicode",
input => "\xf4\x90\x80\x80",
output => "\xf4\x90\x80\x80",
ret => 0,
},
# Truncated sequence at the end of the input is passed through
{
type => "tfn",
name => "utf8toUnicode",
input => "a\xe2\x82",
output => "a\xe2\x82",
ret => 0,
},
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