Generate error when attempting to decode UTF-16/32

2 files changed, 12 insertions, 0 deletions

diff --git a/lua_cjson.c b/lua_cjson.c
index 52b259d..179c830 100644
--- a/lua_cjson.c
+++ b/lua_cjson.c
@@ -1167,6 +1167,14 @@ static int json_decode(lua_State *l)
 
     json = luaL_checklstring(l, 1, &len);
 
+    /* Detect Unicode other than UTF-8 (see RFC 4627, Sec 3)
+     *
+     * CJSON can support any simple data type, hence only the first
+     * character is guaranteed to be ASCII (at worst: "). This is
+     * still enough to detect whether the wrong encoding is in use. */
+    if (len >= 2 && (!json[0] || !json[1]))
+        luaL_error(l, "JSON parser does not support UTF-16 or UTF-32");
+
     lua_json_decode(l, json, len);
 
     return 1;
diff --git a/tests/test.lua b/tests/test.lua
index 0e0aad8..ab2fe7c 100755
--- a/tests/test.lua
+++ b/tests/test.lua
@@ -64,6 +64,10 @@ local encode_table_tests = {
 }
 
 local decode_error_tests = {
+    { json.decode, { '\0"\0"' },
+      false, { "JSON parser does not support UTF-16 or UTF-32" } },
+    { json.decode, { '"\0"\0' },
+      false, { "JSON parser does not support UTF-16 or UTF-32" } },
     { json.decode, { '{ "unexpected eof": ' },
       false, { "Expected value but found T_END at character 21" } },
     { json.decode, { '{ "extra data": true }, false' },