From 169080db01101a4db6b1c265d04d972f3c39488a Mon Sep 17 00:00:00 2001 From: Michael Santos Date: Tue, 24 May 2011 08:02:25 -0400 Subject: inet: error if fd does not match socket domain If an IPv4 fd is opened as an IPv6 socket, unexpected behaviour can occur. For example, if an IPv4 UDP socket is opened and passed into Erlang as an IPv6 socket, the first 3 bytes (corresponding to 1 byte representing the protocol family, 2 bytes set to the port) are stripped from the payload. The cause of the UDP payload truncation happens in inet_drv.c:packet_inet_input when a call to inet_get_address fails silently because the family is set to PF_INET6 but the buffer len is the size of an IPv4 struct sockaddr_in. Prevent this behaviour by checking that the protocol family of the file descriptor matches the family of the requested Erlang socket. {ok, S1} = gen_udp:open(0, [binary, inet]), {ok, FD} = inet:getfd(S1), {ok, Port} = inet:port(S1), {ok, S} = gen_udp:open(Port, [binary, {fd, FD}, inet6]), {ok, C} = gen_udp:open(0, [binary]), Msg = <<1,2,3,4,5>>, gen_udp:send(C, "127.0.0.1", Port, Msg), receive {udp, S, _, _, Msg} -> ok; {udp, S, _, _, NewMsg} -> {error, Msg, NewMsg} end. This test results in: {error,<<1,2,3,4,5>>,<<4,5>>} Thanks to Andrew Tunnell-Jones for finding the bug and the test case! --- lib/kernel/test/gen_udp_SUITE.erl | 1 + 1 file changed, 1 insertion(+) (limited to 'lib') diff --git a/lib/kernel/test/gen_udp_SUITE.erl b/lib/kernel/test/gen_udp_SUITE.erl index d8a5519195..b734d7fd98 100644 --- a/lib/kernel/test/gen_udp_SUITE.erl +++ b/lib/kernel/test/gen_udp_SUITE.erl @@ -400,6 +400,7 @@ open_fd(Config) when is_list(Config) -> {ok,S1} = gen_udp:open(0), {ok,P2} = inet:port(S1), {ok,FD} = prim_inet:getfd(S1), + {error,einval} = gen_udp:open(P2, [inet6, {fd,FD}]), {ok,S2} = gen_udp:open(P2, [{fd,FD}]), {ok,S3} = gen_udp:open(0), {ok,P3} = inet:port(S3), -- cgit v1.2.3