From 84a6d07cdd7fba5e57c535a87076d732cbb693d9 Mon Sep 17 00:00:00 2001 From: Simon Kelley Date: Tue, 6 Sep 2022 15:40:42 +0100 Subject: [PATCH] Fix DHCPv6 relay to use a more sensble source address. Tweak things so that packets relayed towards a server have source address on the server-facing network, not the client-facing network. Thanks to Luis Thomas for spotting this and initial patch. --- CHANGELOG | 5 +++++ src/rfc3315.c | 20 +++++--------------- 2 files changed, 10 insertions(+), 15 deletions(-) diff --git a/CHANGELOG b/CHANGELOG index f3bd7bd..48ce2dd 100644 --- a/CHANGELOG +++ b/CHANGELOG @@ -79,6 +79,11 @@ version 2.87 This would return for queries in some.domain, rather than forwarding the query via the default server. + Tweak DHCPv6 relay code so that packets relayed towards a server + have source address on the server-facing network, not the + client facing network. Thanks to Luis Thomas for spotting this + and initial patch. + version 2.86 Handle DHCPREBIND requests in the DHCPv6 server code. diff --git a/src/rfc3315.c b/src/rfc3315.c index 947bf04..8754481 100644 --- a/src/rfc3315.c +++ b/src/rfc3315.c @@ -2181,10 +2181,7 @@ int relay_upstream6(int iface_index, ssize_t sz, if (relay->iface_index != 0 && relay->iface_index == iface_index) { union mysockaddr to; - union all_addr from; - - /* source address == relay address */ - from.addr6 = relay->local.addr6; + memcpy(&header[2], &relay->local.addr6, IN6ADDRSZ); to.sa.sa_family = AF_INET6; @@ -2206,18 +2203,11 @@ int relay_upstream6(int iface_index, ssize_t sz, } #ifdef HAVE_DUMPFILE - { - union mysockaddr fromsock; - fromsock.in6.sin6_port = htons(DHCPV6_SERVER_PORT); - fromsock.in6.sin6_addr = from.addr6; - fromsock.sa.sa_family = AF_INET6; - fromsock.in6.sin6_flowinfo = 0; - fromsock.in6.sin6_scope_id = 0; - - dump_packet_udp(DUMP_DHCPV6, (void *)daemon->outpacket.iov_base, save_counter(-1), &fromsock, &to, -1); - } + dump_packet_udp(DUMP_DHCPV6, (void *)daemon->outpacket.iov_base, save_counter(-1), NULL, &to, daemon->dhcp6fd); #endif - send_from(daemon->dhcp6fd, 0, daemon->outpacket.iov_base, save_counter(-1), &to, &from, 0); + + while (retry_send(sendto(daemon->dhcp6fd, (void *)daemon->outpacket.iov_base, save_counter(-1), + 0, (struct sockaddr *)&to, sa_len(&to)))); if (option_bool(OPT_LOG_OPTS)) {