Fix out-of-bounds acces in url_decode()

mongoose.c

@@ -1646,7 +1646,7 @@ static int url_decode(const char *src, int src_len, char *dst,
 #define HEXTOI(x) (isdigit(x) ? x - '0' : x - 'W')
 
   for (i = j = 0; i < src_len && j < dst_len - 1; i++, j++) {
-    if (src[i] == '%' &&
+    if (src[i] == '%' && i < src_len - 2 &&
         isxdigit(* (const unsigned char *) (src + i + 1)) &&
         isxdigit(* (const unsigned char *) (src + i + 2))) {
       a = tolower(* (const unsigned char *) (src + i + 1));