Use v4-mapped addresses for IPv4 peers on IPv6 sockets

This is needed at least on FreeBSD

3 files changed, 23 insertions, 0 deletions

diff --git a/src/peer.c b/src/peer.c
index dae8141..fc22a50 100644
--- a/src/peer.c
+++ b/src/peer.c
@@ -324,6 +324,19 @@ void fastd_peer_address_simplify(fastd_peer_address_t *addr) {
 	}
 }
 
+void fastd_peer_address_widen(fastd_peer_address_t *addr) {
+	if (addr->sa.sa_family == AF_INET) {
+		struct sockaddr_in addr4 = addr->in;
+
+		memset(addr, 0, sizeof(fastd_peer_address_t));
+		addr->in6.sin6_family = AF_INET6;
+		addr->in6.sin6_port = addr4.sin_port;
+		addr->in6.sin6_addr.s6_addr[10] = 0xff;
+		addr->in6.sin6_addr.s6_addr[11] = 0xff;
+		memcpy(&addr->in6.sin6_addr.s6_addr[12], &addr4.sin_addr.s_addr, 4);
+	}
+}
+
 
 static inline void reset_peer_address(fastd_context_t *ctx, fastd_peer_t *peer) {
 	if (fastd_peer_is_established(peer))
diff --git a/src/peer.h b/src/peer.h
index 7d85c39..1c939b5 100644
--- a/src/peer.h
+++ b/src/peer.h
@@ -100,6 +100,7 @@ struct fastd_remote_config {
 
 bool fastd_peer_address_equal(const fastd_peer_address_t *addr1, const fastd_peer_address_t *addr2);
 void fastd_peer_address_simplify(fastd_peer_address_t *addr);
+void fastd_peer_address_widen(fastd_peer_address_t *addr);
 
 static inline uint16_t fastd_peer_address_get_port(const fastd_peer_address_t *addr) {
 	switch (addr->sa.sa_family) {
diff --git a/src/send.c b/src/send.c
index 8707e31..3a990d2 100644
--- a/src/send.c
+++ b/src/send.c
@@ -70,6 +70,7 @@ static void send_type(fastd_context_t *ctx, const fastd_socket_t *sock, const fa
 
 	struct msghdr msg = {};
 	char cbuf[1024] = {};
+	fastd_peer_address_t remote_addr6;
 
 	switch (remote_addr->sa.sa_family) {
 	case AF_INET:
@@ -86,6 +87,14 @@ static void send_type(fastd_context_t *ctx, const fastd_socket_t *sock, const fa
 		exit_bug(ctx, "unsupported address family");
 	}
 
+	if (sock->bound_addr->sa.sa_family == AF_INET6) {
+		remote_addr6 = *remote_addr;
+		fastd_peer_address_widen(&remote_addr6);
+
+		msg.msg_name = (void*)&remote_addr6.in6;
+		msg.msg_namelen = sizeof(struct sockaddr_in6);
+	}
+
 	struct iovec iov[2] = {
 		{ .iov_base = &packet_type, .iov_len = 1 },
 		{ .iov_base = buffer.data, .iov_len = buffer.len }