dhcpv6: fix wrong retransmission of DHCPv6 Solicit

When the DHCPv6 client sends a DHCPv6 Solicit with both IA_NA and IA_PD
options, and if the server replies with a status code = NoAddrsAvailable
in the IA_NA option, then currently the DHCPv6 client sends a new
Solicit with only the IA_PD option despite the fact that a prefix was
sent by the server in the previous Advertise.

This behavior is described in
https://datatracker.ietf.org/doc/html/rfc7550#section-4.2

The client must handle the case of a server that does not offer both
valid IA_NA and IA_PD options when both are requested, according to
RFC 7550. It should not send a new Solicit, but a Request. The client
should, however, ignore the Advertise message if none of the IA_NA and
IA_PD options are offered by the server.

Signed-off-by: Nicolas BESNARD <[email protected]>
Signed-off-by: Paul Donald <[email protected]>
Link: https://github.com/openwrt/odhcp6c/pull/106
Signed-off-by: Álvaro Fernández Rojas <[email protected]>

diff --git a/src/dhcpv6.c b/src/dhcpv6.c
index 9b22a7d5883329fe42a823d83aea538c8eb17d74..50b6f7bda189f7b3d96102b6bf938a2f610e644b 100644 (file)
--- a/src/dhcpv6.c
+++ b/src/dhcpv6.c
@@ -1744,7 +1744,7 @@ int dhcpv6_promote_server_cand(void)
        if (!cand_len)
                return -1;
 
-       if (cand->has_noaddravail && na_mode == IA_MODE_TRY) {
+       if (!cand->ia_pd_len && cand->has_noaddravail && na_mode == IA_MODE_TRY) {
                na_mode = IA_MODE_NONE;
 
                dhcpv6_retx[DHCPV6_MSG_SOLICIT].max_timeo = cand->sol_max_rt;