support mongo auth_scram_sha1

lualib-src/lua-crypt.c

@@ -878,6 +878,25 @@ lb64decode(lua_State *L) {
 	return 1;
 }
 
+static int
+lxor_str(lua_State *L) {
+	size_t len1,len2;
+	const char *s1 = luaL_checklstring(L,1,&len1);
+	const char *s2 = luaL_checklstring(L,2,&len2);
+	if (len2 == 0) {
+		return luaL_error(L, "Can't xor empty string");
+	}
+	luaL_Buffer b;
+	char * buffer = luaL_buffinitsize(L, &b, len1);
+	int i;
+	for (i=0;i<len1;i++) {
+		buffer[i] = s1[i] ^ s2[i % len2];
+	}
+	luaL_addsize(&b, len1);
+	luaL_pushresult(&b);
+	return 1;
+}
+
 // defined in lsha1.c
 int lsha1(lua_State *L);
 int lhmac_sha1(lua_State *L);
@@ -906,6 +925,7 @@ luaopen_crypt(lua_State *L) {
 		{ "sha1", lsha1 },
 		{ "hmac_sha1", lhmac_sha1 },
 		{ "hmac_hash", lhmac_hash },
+		{ "xor_str", lxor_str },
 		{ NULL, NULL },
 	};
 	luaL_newlib(L,l);