diff options
Diffstat (limited to 'ares_process.c')
| -rw-r--r-- | ares_process.c | 16 |
1 files changed, 15 insertions, 1 deletions
diff --git a/ares_process.c b/ares_process.c index becbfce..0a99a1b 100644 --- a/ares_process.c +++ b/ares_process.c @@ -429,6 +429,8 @@ static void read_udp_packets(ares_channel channel, fd_set *read_fds, int i; ssize_t count; unsigned char buf[PACKETSZ + 1]; + struct sockaddr_in from; + socklen_t fromlen; if(!read_fds && (read_fd == ARES_SOCKET_BAD)) /* no possible action */ @@ -462,11 +464,23 @@ static void read_udp_packets(ares_channel channel, fd_set *read_fds, /* To reduce event loop overhead, read and process as many * packets as we can. */ do { - count = sread(server->udp_socket, buf, sizeof(buf)); + /* Must memset 'from' to 0 as recvfrom() on some systems may + * not use 'from' at all if it doesn't support receiving the + * source address of the response */ + memset(&from, 0, sizeof(from)); + fromlen = sizeof(from); + count = (ssize_t)recvfrom(server->udp_socket, (void *)buf, sizeof(buf), + 0, (struct sockaddr *)&from, &fromlen); if (count == -1 && try_again(SOCKERRNO)) continue; else if (count <= 0) handle_error(channel, i, now); + else if (fromlen && from.sin_addr.s_addr != 0 && + from.sin_addr.s_addr != server->addr.s_addr) + /* Address response came from did not match the address + * we sent the request to. Someone may be attempting + * to perform a cache poisoning attack */ + break; else process_answer(channel, buf, (int)count, i, 0, now); } while (count > 0); |