WIP: Initial check-in of a new virtual BTS

1 files changed, 211 insertions, 0 deletions

diff --git a/src/osmo-bts-virtual/virtual_um.c b/src/osmo-bts-virtual/virtual_um.c
new file mode 100644
index 00000000..2126b092
--- /dev/null
+++ b/src/osmo-bts-virtual/virtual_um.c
@@ -0,0 +1,211 @@
+/* Routines for a Virtual Um interface over GSMTAP/UDP */
+
+/* (C) 2015 by Harald Welte <laforge@gnumonks.org>
+ *
+ * All Rights Reserved
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#include <unistd.h>
+#include <string.h>
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <arpa/inet.h>
+#include <netinet/in.h>
+#include <net/if.h>
+
+#include <osmocom/core/select.h>
+#include <osmocom/core/utils.h>
+#include <osmocom/core/socket.h>
+#include <osmocom/core/gsmtap.h>
+
+#include "virtual_um.h"
+
+#define VIRT_UM_MSGB_SIZE	256
+
+static int mcast_join_group(int fd, const char *group, const char *netdev)
+{
+	int ifindex = 0;
+	int rc, af;
+	socklen_t af_len = sizeof(af);
+
+	if (netdev) {
+		ifindex = if_nametoindex(netdev);
+		if (!ifindex)
+			return -1;
+	}
+
+	rc = getsockopt(fd, SOL_SOCKET, SO_DOMAIN, &af, &af_len);
+	if (rc < 0)
+		return rc;
+
+	switch (af) {
+	case AF_INET:
+		{
+			struct ip_mreqn mr;
+			memset(&mr, 0, sizeof(mr));
+			inet_pton(AF_INET, group, &mr.imr_multiaddr);
+			if (ifindex)
+				mr.imr_ifindex = ifindex;
+			rc = setsockopt(fd, SOL_SOCKET, IP_ADD_MEMBERSHIP,
+					&mr, sizeof(mr));
+		}
+		break;
+	case AF_INET6:
+		{
+			struct ipv6_mreq mr;
+			memset(&mr, 0, sizeof(mr));
+			inet_pton(AF_INET6, group, &mr.ipv6mr_multiaddr);
+			if (ifindex)
+				mr.ipv6mr_interface = ifindex;
+			rc = setsockopt(fd, SOL_SOCKET, IPV6_ADD_MEMBERSHIP,
+					&mr, sizeof(mr));
+
+		}
+		break;
+	default:
+		rc = -1;
+		break;
+	}
+
+	return rc;
+}
+
+static int mcast_connect(int fd, const char *group, uint16_t port)
+{
+	int rc, af;
+	socklen_t af_len = sizeof(af);
+	struct sockaddr_in sin;
+	struct sockaddr_in6 sin6;
+
+	rc = getsockopt(fd, SOL_SOCKET, SO_DOMAIN, &af, &af_len);
+	if (rc < 0)
+		return rc;
+
+	switch (af) {
+	case AF_INET:
+		memset(&sin, 0, sizeof(sin));
+		sin.sin_family = AF_INET;
+		sin.sin_port = htons(port);
+		inet_pton(AF_INET, group, &sin.sin_addr);
+		rc = connect(fd, (struct sockaddr *) &sin, sizeof(sin));
+		break;
+	case AF_INET6:
+		memset(&sin6, 0, sizeof(sin6));
+		sin6.sin6_family = AF_INET6;
+		sin6.sin6_port = htons(port);
+		inet_pton(AF_INET6, group, &sin6.sin6_addr);
+		rc = connect(fd, (struct sockaddr *) &sin6, sizeof(sin6));
+		break;
+	default:
+		return -1;
+	}
+
+	return rc;
+}
+
+static int virt_um_fd_cb(struct osmo_fd *ofd, unsigned int what)
+{
+	struct virt_um_inst *vui = ofd->data;
+
+	if (what & BSC_FD_READ) {
+		struct msgb *msg = msgb_alloc(VIRT_UM_MSGB_SIZE, "Virtual UM Rx");
+		int rc;
+
+		rc = read(ofd->fd, msgb_data(msg), msgb_tailroom(msg));
+		if (rc > 0) {
+			msgb_put(msg, rc);
+			vui->recv_cb(vui, msg);
+		} else {
+			vui->recv_cb(vui, NULL);
+			osmo_fd_unregister(ofd);
+			close(ofd->fd);
+			ofd->fd = -1;
+			ofd->when = 0;
+		}
+	}
+
+	return 0;
+}
+
+struct virt_um_inst *virt_um_init(void *ctx, const char *group, uint16_t port,
+				  const char *netdev, void *priv,
+				  void (*recv_cb)(struct virt_um_inst *vui, struct msgb *msg))
+{
+	struct virt_um_inst *vui;
+	int fd, rc;
+
+	if (!port)
+		port = GSMTAP_UDP_PORT;
+	if (!group)
+		group = "239.0.47.29";
+
+	/* crate a socked and bind it to the multicast group. Do NOT
+	 * specify a fixed port locally, to make stack choose a random
+	 * free UDP port. */
+	fd = osmo_sock_init(AF_UNSPEC, SOCK_DGRAM, IPPROTO_UDP, group,
+			    0, OSMO_SOCK_F_BIND);
+	if (fd < 0)
+		return NULL;
+
+	/* join the multicast group */
+	rc = mcast_join_group(fd, group, netdev);
+	if (rc < 0) {
+		close(fd);
+		return NULL;
+	}
+
+	/* and finally also connect */
+	rc = mcast_connect(fd, group, port);
+	if (rc < 0) {
+		close(fd);
+		return NULL;
+	}
+
+	vui = talloc_zero(ctx, struct virt_um_inst);
+	vui->priv = priv;
+	vui->recv_cb = recv_cb;
+	vui->ofd.data = vui;
+	vui->ofd.fd = fd;
+	vui->ofd.when = BSC_FD_READ;
+	vui->ofd.cb = virt_um_fd_cb;
+
+	osmo_fd_register(&vui->ofd);
+
+	return vui;
+}
+
+void virt_um_destroy(struct virt_um_inst *vui)
+{
+	struct osmo_fd *ofd = &vui->ofd;
+
+	osmo_fd_unregister(ofd);
+	close(ofd->fd);
+	ofd->fd = -1;
+	ofd->when = 0;
+
+	talloc_free(vui);
+}
+
+int virt_um_write_msg(struct virt_um_inst *vui, struct msgb *msg)
+{
+	int rc;
+
+	rc = write(vui->ofd.fd, msgb_data(msg), msgb_length(msg));
+	msgb_free(msg);
+
+	return rc;
+}