Reduce v4-mapped IPv6 addresses to IPv4 addresses

We need this for "any" binds to work correctly again.

1 files changed, 9 insertions, 0 deletions

diff --git a/src/fastd.c b/src/fastd.c
index af9ba6e..d751a59 100644
--- a/src/fastd.c
+++ b/src/fastd.c
@@ -748,6 +748,15 @@ static void handle_socket(fastd_context *ctx, fastd_socket *sock) {
 	packet_type = buffer.data;
 	buffer.len = len;
 
+	if (recvaddr.sa.sa_family == AF_INET6 && IN6_IS_ADDR_V4MAPPED(&recvaddr.in6.sin6_addr)) {
+		struct sockaddr_in6 mapped = recvaddr.in6;
+
+		memset(&recvaddr, 0, sizeof(recvaddr));
+		recvaddr.in.sin_family = AF_INET;
+		recvaddr.in.sin_port = mapped.sin6_port;
+		memcpy(&recvaddr.in.sin_addr.s_addr, &mapped.sin6_addr.s6_addr[12], 4);
+	}
+
 	fastd_buffer_push_head(&buffer, 1);
 
 	fastd_peer *peer = NULL;