4 files changed, 28 insertions, 5 deletions

diff --git a/dhcpv6.c b/dhcpv6.c
index cac220e..27d3a9c 100644
--- a/dhcpv6.c
+++ b/dhcpv6.c
@@ -452,6 +452,7 @@ int dhcpv6(struct ctx *c, struct ethhdr *eh, size_t len)
 {
 	struct ipv6hdr *ip6h = (struct ipv6hdr *)(eh + 1);
 	struct opt_hdr *ia, *bad_ia, *client_id, *server_id;
+	struct in6_addr *src;
 	struct msg_hdr *mh;
 	struct udphdr *uh;
 	uint8_t proto;
@@ -476,6 +477,11 @@ int dhcpv6(struct ctx *c, struct ethhdr *eh, size_t len)
 
 	c->addr6_ll_seen = ip6h->saddr;
 
+	if (IN6_IS_ADDR_LINKLOCAL(&c->gw6))
+		src = &c->gw6;
+	else
+		src = &c->addr6_ll;
+
 	mh = (struct msg_hdr *)(uh + 1);
 	mlen -= sizeof(struct msg_hdr);
 
@@ -527,7 +533,7 @@ int dhcpv6(struct ctx *c, struct ethhdr *eh, size_t len)
 
 			resp_not_on_link.hdr.xid = mh->xid;
 
-			tap_ip_send(c, &c->gw6, IPPROTO_UDP,
+			tap_ip_send(c, src, IPPROTO_UDP,
 				    (char *)&resp_not_on_link, n, mh->xid);
 
 			return 1;
@@ -577,7 +583,7 @@ int dhcpv6(struct ctx *c, struct ethhdr *eh, size_t len)
 
 	resp.hdr.xid = mh->xid;
 
-	tap_ip_send(c, &c->gw6, IPPROTO_UDP, (char *)&resp, n, mh->xid);
+	tap_ip_send(c, src, IPPROTO_UDP, (char *)&resp, n, mh->xid);
 	c->addr6_seen = c->addr6;
 
 	return 1;
diff --git a/ndp.c b/ndp.c
index 10c091c..e779ae0 100644
--- a/ndp.c
+++ b/ndp.c
@@ -183,7 +183,11 @@ int ndp(struct ctx *c, struct ethhdr *eh, size_t len)
 		c->addr6_seen = ip6h->saddr;
 
 	ip6hr->daddr = ip6h->saddr;
-	ip6hr->saddr = c->gw6;
+	if (IN6_IS_ADDR_LINKLOCAL(&c->gw6))
+		ip6hr->saddr = c->gw6;
+	else
+		ip6hr->saddr = c->addr6_ll;
+
 	ip6hr->payload_len = htons(sizeof(*ihr) + len);
 	ip6hr->hop_limit = IPPROTO_ICMPV6;
 	ihr->icmp6_cksum = 0;
diff --git a/tcp.c b/tcp.c
index c8815c5..6b5d29b 100644
--- a/tcp.c
+++ b/tcp.c
@@ -2921,8 +2921,16 @@ static void tcp_conn_from_sock(struct ctx *c, union epoll_ref ref,
 
 		if (IN6_IS_ADDR_LOOPBACK(&sa6.sin6_addr) ||
 		    !memcmp(&sa6.sin6_addr, &c->addr6_seen, sizeof(c->gw6)) ||
-		    !memcmp(&sa6.sin6_addr, &c->addr6, sizeof(c->gw6)))
-			memcpy(&sa6.sin6_addr, &c->gw6, sizeof(c->gw6));
+		    !memcmp(&sa6.sin6_addr, &c->addr6, sizeof(c->gw6))) {
+			struct in6_addr *src;
+
+			if (IN6_IS_ADDR_LINKLOCAL(&c->gw6))
+				src = &c->gw6;
+			else
+				src = &c->addr6_ll;
+
+			memcpy(&sa6.sin6_addr, src, sizeof(*src));
+		}
 
 		memcpy(&conn->a.a6, &sa6.sin6_addr, sizeof(conn->a.a6));
 
diff --git a/udp.c b/udp.c
index bd03036..229c038 100644
--- a/udp.c
+++ b/udp.c
@@ -698,6 +698,11 @@ void udp_sock_handler(struct ctx *c, union epoll_ref ref, uint32_t events,
 				in_port_t src = htons(b->s_in6.sin6_port);
 
 				b->ip6h.daddr = c->addr6_ll_seen;
+				if (IN6_IS_ADDR_LINKLOCAL(&c->gw6))
+					b->ip6h.saddr = c->gw6;
+				else
+					b->ip6h.saddr = c->addr6_ll;
+
 				b->ip6h.saddr = c->gw6;
 
 				udp_tap_map[V6][src].ts_local = now->tv_sec;