Added t:jsDecodeUni handling unicode similar to t:urlDecodeUni. See #193.

CHANGES

@@ -1,6 +1,8 @@
 12 Dec 2007 - 2.5.0-rc1
 -----------------------
 
+ * Added t:jsDecodeUni to decode JavScript \uXXXX encoding.
+
  * Added IS_NEW and IS_EXPIRED built-in collection variables.
 
  * Added SecMarker <id> directive to allow a fixed target for skipAfter.

apache2/msc_util.c

@@ -16,6 +16,11 @@
 #include <sys/types.h>
 #include <sys/stat.h>
 
+/* NOTE: Be careful as this can only be used on static values for X.
+ * (i.e. VALID_HEX(c++) will NOT work)
+ */
+#define VALID_HEX(X) (((X >= '0')&&(X <= '9')) || ((X >= 'a')&&(X <= 'f')) || ((X >= 'A')&&(X <= 'F')))
+
 /**
  *
  */
@@ -566,7 +571,68 @@ char *_log_escape(apr_pool_t *mp, const unsigned char *input, unsigned long int
     return ret;
 }
 
-#define VALID_HEX(X) (((X >= '0')&&(X <= '9')) || ((X >= 'a')&&(X <= 'f')) || ((X >= 'A')&&(X <= 'F')))
+/**
+ * JavaScript \uXXXX decoding.
+ */
+int jsdecode_uni_nonstrict_inplace_ex(unsigned char *input, long int input_len) {
+    unsigned char *d = (unsigned char *)input;
+    long int i, count;
+
+    if (input == NULL) return -1;
+
+    i = count = 0;
+    while (i < input_len) {
+        if (input[i] == '\\') {
+            /* Character is an escape. */
+
+            if ((i + 5 < input_len) && (input[i + 1] == 'u')) {
+                /* We have at least 4 data bytes. */
+                if (   (VALID_HEX(input[i + 2])) && (VALID_HEX(input[i + 3]))
+                    && (VALID_HEX(input[i + 4])) && (VALID_HEX(input[i + 5])) )
+                {
+                    /* We first make use of the lower byte here, ignoring the higher byte. */
+                    *d = x2c(&input[i + 4]);
+
+                    /* Full width ASCII (ff01 - ff5e) needs 0x20 added */
+                    if (   (*d > 0x00) && (*d < 0x5f)
+                        && ((input[i + 2] == 'f') || (input[i + 2] == 'F'))
+                        && ((input[i + 3] == 'f') || (input[i + 3] == 'F')))
+                    {
+                        (*d) += 0x20;
+                    }
+
+                    d++;
+                    count++;
+                    i += 6;
+                }
+                else {
+                    /* Invalid data. */
+                    int j;
+
+                    for(j = 0; (j < 6)&&(i < input_len); j++) {
+                        *d++ = input[i++];
+                        count++;
+                    }
+                }
+            }
+            else {
+                /* Not enough bytes available (4 data bytes were needed). */
+                while(i < input_len) {
+                    *d++ = input[i++];
+                    count++;
+                }
+            }
+        }
+        else {
+            *d++ = input[i++];
+            count++;
+        }
+    }
+
+    *d = '\0';
+
+    return count;
+}
 
 /**
  *
@@ -632,12 +698,7 @@ int urldecode_uni_nonstrict_inplace_ex(unsigned char *input, long int input_len)
                     char c1 = input[i + 1];
                     char c2 = input[i + 2];
 
-                    /* ENH Use VALID_HEX? */
-                    if ( (((c1 >= '0')&&(c1 <= '9')) || ((c1 >= 'a')&&(c1 <= 'f')) ||
-                          ((c1 >= 'A')&&(c1 <= 'F')))
-                        && (((c2 >= '0')&&(c2 <= '9')) || ((c2 >= 'a')&&(c2 <= 'f')) ||
-                            ((c2 >= 'A')&&(c2 <= 'F'))) )
-                    {
+                    if (VALID_HEX(c1) && VALID_HEX(c2)) {
                         *d++ = x2c(&input[i + 1]);
                         count++;
                         i += 3;
@@ -701,10 +762,7 @@ int urldecode_nonstrict_inplace_ex(unsigned char *input, long int input_len, int
                 char c1 = input[i + 1];
                 char c2 = input[i + 2];
 
-                /* ENH Use VALID_HEX? */
-                if ( (((c1 >= '0')&&(c1 <= '9')) || ((c1 >= 'a')&&(c1 <= 'f')) || ((c1 >= 'A')&&(c1 <= 'F')))
-                    && (((c2 >= '0')&&(c2 <= '9')) || ((c2 >= 'a')&&(c2 <= 'f')) || ((c2 >= 'A')&&(c2 <= 'F'))) )
-                {
+                if (VALID_HEX(c1) && VALID_HEX(c2)) {
                     /* Valid encoding - decode it. */
                     *d++ = x2c(&input[i + 1]);
                     count++;

apache2/msc_util.h

@@ -66,6 +66,8 @@ char DSOLOCAL *log_escape_raw(apr_pool_t *mp, const unsigned char *text, unsigne
 char DSOLOCAL *_log_escape(apr_pool_t *p, const unsigned char *input,
     unsigned long int input_length, int escape_quotes, int escape_colon);
 
+int DSOLOCAL jsdecode_uni_nonstrict_inplace_ex(unsigned char *input, long int input_len);
+
 int DSOLOCAL urldecode_uni_nonstrict_inplace_ex(unsigned char *input, long int input_length);
 
 int DSOLOCAL urldecode_nonstrict_inplace_ex(unsigned char *input, long int input_length, int *invalid_count);

apache2/re_tfns.c

@@ -251,6 +251,20 @@ static int msre_fn_replaceComments_execute(apr_pool_t *mptmp, unsigned char *inp
     return changed;
 }
 
+/* jsDecodeUni */
+
+static int msre_fn_jsDecodeUni_execute(apr_pool_t *mptmp, unsigned char *input,
+    long int input_len, char **rval, long int *rval_len)
+{
+    long int length;
+
+    length = jsdecode_uni_nonstrict_inplace_ex(input, input_len);
+    *rval = (char *)input;
+    *rval_len = length;
+    
+    return (*rval_len == input_len ? 0 : 1);
+}
+
 /* urlDecode */
 
 static int msre_fn_urlDecode_execute(apr_pool_t *mptmp, unsigned char *input,
@@ -504,6 +518,12 @@ void msre_engine_register_default_tfns(msre_engine *engine) {
         msre_fn_htmlEntityDecode_execute
     );
 
+    /* jsDecodeUni */
+    msre_engine_tfn_register(engine,
+        "jsDecodeUni",
+        msre_fn_jsDecodeUni_execute
+    );
+
     /* length */
     msre_engine_tfn_register(engine,
         "length",

doc/modsecurity2-apache-reference.xml

@@ -3368,6 +3368,16 @@ SecRule <emphasis>XML:/xq:employees/employee/name/text()</emphasis> Fred \
       </itemizedlist>
     </section>
 
+    <section>
+      <title><literal>jsDecodeUni</literal></title>
+
+      <para>Decodes <literal moreinfo="none">\uXXXX</literal> JavaScript
+      encoding. If the code is in the range of FF01-FF5E (the full width ASCII
+      codes), then the higher byte is used to detect and adjust the lower
+      byte. Otherwise, only the lower byte will be used and the higher byte
+      zeroed.</para>
+    </section>
+
     <section>
       <title><literal>length</literal></title>
 
@@ -5156,4 +5166,4 @@ SecRule REQUEST_METHOD "!<emphasis>@within %{tx.allowed_methods}</emphasis>" t:l
       </section>
     </section>
   </section>
-</article>
+</article>