MT#55283 store sfd in fsin in dtls_connection

This makes it possible for the BIO callback to access these values,
instead of obtaining possibly mismatched values from packet_stream.

Restores behaviour prior to 5331506

Closes #1996

Change-Id: I74ccb82f1739ca98eb033e68df4e27619ca7e46a
(cherry picked from commit 271b3b1520)

daemon/dtls.c

@@ -623,7 +623,7 @@ static long dtls_bio_callback(BIO *bio, int oper, const char *argp, size_t len,
 	struct packet_stream *ps = d->ps;
 	if (!ps)
 		return ret;
-	struct stream_fd *sfd = ps->selected_sfd;
+	struct stream_fd *sfd = d->sfd;
 	if (!sfd)
 		return ret;
 
@@ -634,7 +634,9 @@ static long dtls_bio_callback(BIO *bio, int oper, const char *argp, size_t len,
 		argp[8], argp[9], argp[10], argp[11],
 		argp[12], argp[13], argp[14], argp[15]);
 
-	const endpoint_t *fsin = &ps->endpoint;
+	const endpoint_t *fsin = &d->fsin;
+	if (fsin->address.family == NULL)
+		fsin = &ps->endpoint;
 	if (fsin->port == 9 || fsin->address.family == NULL)
 		return ret;
 
@@ -876,6 +878,11 @@ int dtls(stream_fd *sfd, const str *s, const endpoint_t *fsin) {
 	if (!d->init || !d->ssl)
 		return -1;
 
+	// used by the BIO callback
+	d->fsin = fsin ? *fsin : (endpoint_t) {0};
+	obj_release(d->sfd);
+	d->sfd = obj_get(sfd);
+
 	if (s) {
 		ilogs(srtp, LOG_DEBUG, "Processing incoming DTLS packet");
 		BIO_write(d->r_bio, s->s, s->len);
@@ -971,5 +978,6 @@ void dtls_connection_cleanup(struct dtls_connection *c) {
 		if (c->w_bio)
 			BIO_free(c->w_bio);
 	}
+	obj_release(c->sfd);
 	ZERO(*c);
 }

include/dtls.h

@@ -43,6 +43,8 @@ struct dtls_connection {
 	SSL *ssl;
 	BIO *r_bio, *w_bio;
 	struct packet_stream *ps;
+	endpoint_t fsin;
+	stream_fd *sfd;
 	unsigned char tls_id[16];
 	unsigned int init:1,
 	             active:1,